ICOS in scientific publications

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ICOS related publications are publications that used ICOS data or knowledge based on ICOS data, or is based on science that is relevant for ICOS and to which persons from the large ICOS community have contributed.

This list is updated only a few times per year. Last update: 7 September 2020.

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Boas T, Bogena H, Grünwald T, Heinesch B, Ryu D, Schmidt M, Vereecken H, Western A and Franssen HJH (2021), "Improving the representation of cropland sites in the Community Land Model (CLM) version 5.0", Geoscientific Model Development. Vol. 14(1), pp. 573-601.
Abstract: The incorporation of a comprehensive crop module in land surface models offers the possibility to study the effect of agricultural land use and land management changes on the terrestrial water, energy, and biogeochemical cycles. It may help to improve the simulation of biogeophysical and biogeochemical processes on regional and global scales in the framework of climate and land use change. In this study, the performance of the crop module of the Community Land Model version 5 (CLM5) was evaluated at point scale with site-specific field data focusing on the simulation of seasonal and inter-annual variations in crop growth, planting and harvesting cycles, and crop yields, as well as water, energy, and carbon fluxes. In order to better represent agricultural sites, the model was modified by (1) implementing the winter wheat subroutines following Lu et al. (2017) in CLM5; (2) implementing plant-specific parameters for sugar beet, potatoes, and winter wheat, thereby adding the two crop functional types (CFTs) for sugar beet and potatoes to the list of actively managed crops in CLM5; and (3) introducing a cover-cropping subroutine that allows multiple crop types on the same column within 1 year. The latter modification allows the simulation of cropping during winter months before usual cash crop planting begins in spring, which is an agricultural management technique with a long history that is regaining popularity as it reduces erosion and improves soil health and carbon storage and is commonly used in the regions evaluated in this study. We compared simulation results with field data and found that both the new crop-specific parameterization and the winter wheat subroutines led to a significant simulation improvement in terms of energy fluxes (root-mean-square error, RMSE, reduction for latent and sensible heat by up to 57 % and 59 %, respectively), leaf area index (LAI), net ecosystem exchange, and crop yield (up to 87 % improvement in winter wheat yield prediction) compared with default model results. The cover-cropping subroutine yielded a substantial improvement in representation of field conditions after harvest of the main cash crop (winter season) in terms of LAI magnitudes, seasonal cycle of LAI, and latent heat flux (reduction of wintertime RMSE for latent heat flux by 42 %). Our modifications significantly improved model simulations and should therefore be applied in future studies with CLM5 to improve regional yield predictions and to better understand large-scale impacts of agricultural management on carbon, water, and energy fluxes.
BibTeX:
@article{Boas2021,
  author = {Boas, Theresa and Bogena, Heye and Grünwald, Thomas and Heinesch, Bernard and Ryu, Dongryeol and Schmidt, Marius and Vereecken, Harry and Western, Andrew and Franssen, Harrie Jan Hendricks},
  title = {Improving the representation of cropland sites in the Community Land Model (CLM) version 5.0},
  journal = {Geoscientific Model Development},
  year = {2021},
  volume = {14},
  number = {1},
  pages = {573--601},
  doi = {10.5194/gmd-14-573-2021}
}
Hartman SE, Bett BJ, Durden JM, Henson SA, Iversen M, Jeffreys RM, Horton T, Lampitt R and Gates AR (2021), "Enduring science: Three decades of observing the Northeast Atlantic from the Porcupine Abyssal Plain Sustained Observatory (PAP-SO)", Progress in Oceanography. Vol. 191 Elsevier Ltd.
Abstract: Until the 1980s, the deep sea was generally considered to be a particularly stable environment, free from major temporal variations (Sanders, 1968). Studies in the abyssal northeast Atlantic by Billett et al. (1983), and subsequently Lampitt (1985) discovered seasonal pulses of surface primary production-derived particulate organic matter (phytodetritus), and hence carbon, at abyssal depths. These early observations were subsequently extended to the central oceanic region of the NE Atlantic (Pfannkuche, 1993; Thiel et al., 1989), and prompted the establishment of more concerted time series studies in the Porcupine Abyssal Plain area. Today, the Porcupine Abyssal Plain Sustained Observatory (PAP–SO) is a multidisciplinary open-ocean time series site in the NE Atlantic (48°50′N 16°30′W, 4850 m water depth; Fig. 1), focused on the study of connections between the surface and deep ocean. In situ measurements of climatically and environmentally relevant variables have been made for more than 30 years. This represents an exceptionally long time series - a recent compilation of biological time series data, across terrestrial, freshwater, and marine realms, indicates an average duration of only 13-years (Dornelas et al., 2018). Long-term time series in the deep sea are rare, particularly those collecting data from surface to seabed. The PAP-SO is one of two abyssal long-term time series sites globally (Smith et al. 2015), the other being a thirty-year time series at Station M in the northeastern Pacific Ocean (34°50′N, 123°00′W, ˜4000 m water depth), maintained by the Monterey Bay Aquarium Research Institute (Smith et al., 2020). This ‘sibling' abyssal time series site also aims to understand the connections between the surface ocean and the seabed, using many similar techniques (Smith et al., 2017), facilitating comparisons between the two sites (e.g. Durden et al., 2019; Durden et al., 2020a; Laguionie-Marchais et al., 2013; Smith et al., 2009). Another source of extended comparison is the 21 year time series Long-Term Ecological Research Observatory HAUSGARTEN, Frontiers in Arctic Marine Monitoring (FRAM) in the Fram Strait between the North Atlantic and the central Arctic Ocean (78.5°N–80°N, 05°W–11°E, 250–5500 m water depth), maintained by the Alfred Wegener Institute for Polar and Marine Research (Soltwedel et al., 2016; Soltwedel et al., 2005). Much of our understanding of temporal variation in the deep sea, and connections between the surface ocean and the seabed have been derived from research conducted at these observatories.
BibTeX:
@article{Hartman2021,
  author = {Hartman, Susan E and Bett, Brian J and Durden, Jennifer M and Henson, Stephanie A and Iversen, Morten and Jeffreys, Rachel M and Horton, Tammy and Lampitt, Richard and Gates, Andrew R},
  title = {Enduring science: Three decades of observing the Northeast Atlantic from the Porcupine Abyssal Plain Sustained Observatory (PAP-SO)},
  journal = {Progress in Oceanography},
  publisher = {Elsevier Ltd},
  year = {2021},
  volume = {191},
  doi = {10.1016/j.pocean.2020.102508}
}
Huber R, D'Onofrio C, Devaraju A, Klump J, Loescher HW, Kindermann S, Guru S, Grant M, Morris B, Wyborn L, Evans B, Goldfarb D, Genazzio MA, Ren X, Magagna B, Thiemann H and Stocker M (2021), "Integrating data and analysis technologies within leading environmental research infrastructures: Challenges and approaches", Ecological Informatics., mar, 2021. Vol. 61, pp. 101245.
BibTeX:
@article{Huber2021,
  author = {Huber, Robert and D'Onofrio, Claudio and Devaraju, Anusuriya and Klump, Jens and Loescher, Henry W. and Kindermann, Stephan and Guru, Siddeswara and Grant, Mark and Morris, Beryl and Wyborn, Lesley and Evans, Ben and Goldfarb, Doron and Genazzio, Melissa A. and Ren, Xiaoli and Magagna, Barbara and Thiemann, Hannes and Stocker, Markus},
  title = {Integrating data and analysis technologies within leading environmental research infrastructures: Challenges and approaches},
  journal = {Ecological Informatics},
  year = {2021},
  volume = {61},
  pages = {101245},
  url = {https://linkinghub.elsevier.com/retrieve/pii/S1574954121000364},
  doi = {10.1016/j.ecoinf.2021.101245}
}
Lindroth A, Holst J, Linderson ML, Aurela M, Biermann T, Heliasz M, Chi J, Ibrom A, Kolari P, Klemedtsson L, Krasnova A, Laurila T, Lehner I, Lohila A, Mammarella I, Mölder M, Löfvenius MO, Peichl M, Pilegaard K, Soosaar K, Vesala T, Vestin P, Weslien P and Nilsson M (2021), "Erratum: Effects of drought and meteorological forcing on carbon and water fluxes in Nordic forests during the dry summer of 2018 (Philosophical Transactions of the Royal Society B: Biological Sciences (2020) 375 (20190516) DOI: 10.1098/rstb.2019.0516)", Philosophical Transactions of the Royal Society B: Biological Sciences. Vol. 376(1817)
Abstract: The originally published version of this paper incorrectly spelt the author Kaido Soosaar's name as Kaido Soosar. This has been corrected on the publisher's website.
BibTeX:
@article{Lindroth2021,
  author = {Lindroth, Anders and Holst, Jutta and Linderson, Maj Lena and Aurela, Mika and Biermann, Tobias and Heliasz, Michal and Chi, Jinshu and Ibrom, Andreas and Kolari, Pasi and Klemedtsson, Leif and Krasnova, Alisa and Laurila, Tuomas and Lehner, Irene and Lohila, Annalea and Mammarella, Ivan and Mölder, Meelis and Löfvenius, Mikaell Ottosson and Peichl, Matthias and Pilegaard, Kim and Soosaar, Kaido and Vesala, Timo and Vestin, Patrik and Weslien, Per and Nilsson, Mats},
  title = {Erratum: Effects of drought and meteorological forcing on carbon and water fluxes in Nordic forests during the dry summer of 2018 (Philosophical Transactions of the Royal Society B: Biological Sciences (2020) 375 (20190516) DOI: 10.1098/rstb.2019.0516)},
  journal = {Philosophical Transactions of the Royal Society B: Biological Sciences},
  year = {2021},
  volume = {376},
  number = {1817},
  doi = {10.1098/rstb.2020.0453}
}
Reitz O, Graf A, Schmidt M, Ketzler G and Leuchner M (2021), "Upscaling Net Ecosystem Exchange Over Heterogeneous Landscapes With Machine Learning", Journal of Geophysical Research: Biogeosciences. Vol. 126(2), pp. 1-16.
Abstract: This paper discusses different feature selection methods and CO2 flux datasets with a varying quality‐quantity balance for the application of a Random Forest model to predict daily CO2 fluxes at 250 m spatial resolution for the Rur catchment area in western Germany between 2010 and 2018. Measurements from eddy covariance stations of different ecosystem types, remotely sensed vegetation data from MODIS, and COSMO‐REA6 reanalysis data were used to train the model and predictions were validated by a spatial and temporal validation scheme. Results show the capabilities of a backwards feature elimination to remove irrelevant variables and an importance of high‐quality‐low‐quantity flux dataset to improve predictions. However, results also show that spatial prediction is more difficult than temporal prediction by reflecting the mean value accurately though underestimating the variance of CO2 fluxes. Vegetated parts of the catchment acted as a CO2 sink during the investigation period, net capturing about 237 g C m‐2y‐1. Croplands, coniferous forests, deciduous forests and grasslands were all sinks on average. The highest uptake was predicted to occur in late spring and early summer, while the catchment was a CO2 source in fall and winter. In conclusion, the Random Forest model predicted a narrower distribution of CO2 fluxes, though our methodological improvements look promising in order to achieve high resolution net ecosystem exchange datasets at the regional scale.
BibTeX:
@article{Reitz2021,
  author = {Reitz, O and Graf, A and Schmidt, M and Ketzler, G and Leuchner, M},
  title = {Upscaling Net Ecosystem Exchange Over Heterogeneous Landscapes With Machine Learning},
  journal = {Journal of Geophysical Research: Biogeosciences},
  year = {2021},
  volume = {126},
  number = {2},
  pages = {1--16},
  doi = {10.1029/2020jg005814}
}
Schneider J, Groh J, Pütz T, Helmig R, Rothfuss Y, Vereecken H and Vanderborght J (2021), "Prediction of soil evaporation measured with weighable lysimeters using the FAO Penman–Monteith method in combination with Richards' equation", Vadose Zone Journal. (April 2020), pp. 1-20.
Abstract: Multiannual data (2016–2018) from 12 weighed lysimeters (four soil types with textures ranging from sandy loam to silt loam, three replicates) of the TERENO SOILCan network were used to evaluate if evaporation (E) rates could be predicted from weather data using the FAO Penman–Monteith (PM) method combined with soil water flow simulations using the Richards equation. Soil hydraulic properties (SHPs) were estimated either from soil texture using the ROSETTA pedotransfer functions, from in situ measured water retention curves, or from soil surface water contents using inverse modeling. In all years, E was water limited and the measured evaporation rates (Em) surprisingly did not vary significantly among the four different soil types. When SHPs derived from pedotransfer functions were used, simulated evaporation rates of the finer textured soils overestimated the measured ones considerably. Better agreement was obtained when simulations were based on in situ measured or inversely estimated SHPs. The SHPs estimated from pedotransfer functions represented unrealistically large characteristic lengths of evaporation (Lc), and Lc was found to be a useful characteristic to constrain estimates of SHPs. Also, when soil evaporation was water limited and Em rates were below Epot (PM evaporation scaled by an empirical coefficient), the diurnal dynamics of Em followed those of Epot. The Richards equation that considers only isothermal liquid water flow did not reproduce these dynamics caused by temperature dependent vapor transport in the soil.
BibTeX:
@article{Schneider2021,
  author = {Schneider, Jana and Groh, Jannis and Pütz, Thomas and Helmig, Rainer and Rothfuss, Youri and Vereecken, Harry and Vanderborght, Jan},
  title = {Prediction of soil evaporation measured with weighable lysimeters using the FAO Penman–Monteith method in combination with Richards' equation},
  journal = {Vadose Zone Journal},
  year = {2021},
  number = {April 2020},
  pages = {1--20},
  doi = {10.1002/vzj2.20102}
}
Strand SM, Christiansen HH, Johansson M, Åkerman J and Humlum O (2021), "Active layer thickening and controls on interannual variability in the Nordic Arctic compared to the circum-Arctic", Permafrost and Periglacial Processes. Vol. 32(1), pp. 47-58.
Abstract: Active layer probing in northern Sweden, northeast Greenland, and central Svalbard indicates active layer thickening has occurred at Circumpolar Active Layer Monitoring (CALM) sites with long-term, continuous observations, since the sites were established at these locations in 1978, 1996, and 2000, respectively. The study areas exhibit a reverse latitudinal gradient in average active layer thickness (ALT), which is explained by site geomorphology and climate. Specifically, Svalbard has a more maritime climate and thus the thickest active layer of the study areas (average ALT = 99 cm, 2000–2018). The active layer is thinnest at the northern Sweden sites because it is primarily confined to superficial peat. Interannual variability in ALT is not synchronous across this Nordic Arctic region, but study sites in the same area respond similarly to local meteorology. ALT correlates positively with thawing degree days in Sweden and Greenland, as has been observed in other Arctic regions. However, ALT in Svalbard correlates with freezing degree days, where the maritime Arctic climate results in relatively high and variable winter air temperatures. The difference in annual ALT at adjacent sites is attributed to differences in snow cover and geomorphology. From 2000 to 2018, the average rate of active layer thickening at the Nordic Arctic CALM probing sites was 0.5 cm/yr. The average rate was 1 cm/yr for Nordic Arctic CALM database sites with significant trends, which includes a borehole in addition to probing sites. This range is in line with the circum-Arctic average of 0.8 cm/yr from 2000 to 2018.
BibTeX:
@article{Strand2021,
  author = {Strand, Sarah M and Christiansen, Hanne H and Johansson, Margareta and Åkerman, Jonas and Humlum, Ole},
  title = {Active layer thickening and controls on interannual variability in the Nordic Arctic compared to the circum-Arctic},
  journal = {Permafrost and Periglacial Processes},
  year = {2021},
  volume = {32},
  number = {1},
  pages = {47--58},
  doi = {10.1002/ppp.2088}
}
Trisolino P, di Sarra A, Sferlazzo D, Piacentino S, Monteleone F, Di Iorio T, Apadula F, Heltai D, Lanza A, Vocino A, di Torchiarolo L, Bonasoni P, Calzolari F, Busetto M and Cristofanelli P (2021), "Application of a Common Methodology to Select in Situ CO2 Observations Representative of the Atmospheric Background to an Italian Collaborative Network", Atmosphere. Vol. 12(2)
Abstract: We describe and implement a data selection algorithm aimed at identifying background atmospheric CO2 observations from in situ continuous measurements. Several selection criteria for detecting the background data have been developed and are currently used: the main objective of this work was to define a common methodology to extract the atmospheric background signal minimizing heterogeneities due to the use of different selection algorithms. The algorithm used in this study, (BaDS, Background Data Selection) was tested and optimized using data (from 2014 to 2018) from four Italian stations characterized by markedly different environmental conditions (i.e., mountain, coastal and marine): Plateau Rosa (PRS), Mt. Cimone (CMN), Capo Granitola (CGR) and Lampedusa (LMP). Their locations extend from the Alps to the central Mediterranean. The adopted algorithm proved to be effective in separating the local/regional from the background signal in the CO2 time series. About 6% of the data at LMP, 11% at PRS, 20–38% at CMN and 65% at CGR were identified as non-background. LMP and PRS can be used as reference sites for the central Mediterranean, while CMN and CGR were more impacted by regional sources and sinks. Finally, we discuss a possible application of BaDS screened data.
BibTeX:
@article{Trisolino2021,
  author = {Trisolino, Pamela and di Sarra, Alcide and Sferlazzo, Damiano and Piacentino, Salvatore and Monteleone, Francesco and Di Iorio, Tatiana and Apadula, Francesco and Heltai, Daniela and Lanza, Andrea and Vocino, Antonio and di Torchiarolo, Luigi and Bonasoni, Paolo and Calzolari, Francescopiero and Busetto, Maurizio and Cristofanelli, Paolo},
  title = {Application of a Common Methodology to Select in Situ CO2 Observations Representative of the Atmospheric Background to an Italian Collaborative Network},
  journal = {Atmosphere},
  year = {2021},
  volume = {12},
  number = {2},
  url = {https://www.mdpi.com/2073-4433/12/2/246},
  doi = {10.3390/atmos12020246}
}
Alton PB (2020), "Representativeness of global climate and vegetation by carbon-monitoring networks; implications for estimates of gross and net primary productivity at biome and global levels", Agricultural and Forest Meteorology., aug, 2020. Elsevier B.V..
Abstract: One of the major uncertainties in estimating global Net Primary Productivity (NPP) and Gross Primary Productivity (GPP) is the ability of carbon-monitoring sites to represent the climate and canopy-density of global vegetation (“representativeness”). These sites are used for empirical upscaling and calibration of global land-surface models. The current study determines the representativeness of two important carbon-monitoring networks – FLUXNET2015 and the Ecosystem Model-Data Intercomparison (EMDI) – by calculating the euclidian distance in climate-canopy space between each global 0.5∘ cell and all carbon-monitoring sites of the same biome or Plant Functional Type (PFT). Reliance on the single (most similar) site has been adopted in the past. A straightforward weighted upscaling, using inverse euclidian distance, identifies which PFTs contribute most to global primary productivity in the context of how well they are represented in carbon-monitoring networks. Some vegetation types, which are numerically well-represented within the network, are sampled at the ‘wrong' latitude and in more temperate climes than their global distribution. This includes non-mediterranean needleleaf forest which is one of the main vegetation types contributing to global GPP and NPP. (Semi-)arid regions (mean annual precipitation textless 400 mm yr−1) are undersampled as well as the sparse vegetation that tends to characterise them. These regions include the tundra and the northern half of the boreal forest where growth is disproportionately affected by climate change. We find a large spread in NPP and GPP recorded at sites of the same PFT (standard deviation is 56% mean). Consequently, our bootstrap error analysis indicates that a minimum of 50 climate-representative sites per PFT is required to quantify adequately (2% precision) the primary productivity of each global vegetation type. Selecting unchartered climate-canopy space for new sites appears to be more important than a simple increase in site numbers.
BibTeX:
@article{Alton2020,
  author = {Alton, Paul B.},
  title = {Representativeness of global climate and vegetation by carbon-monitoring networks; implications for estimates of gross and net primary productivity at biome and global levels},
  journal = {Agricultural and Forest Meteorology},
  publisher = {Elsevier B.V.},
  year = {2020},
  doi = {10.1016/j.agrformet.2020.108017}
}
de Arellano J, Ney P, Hartogensis O, de Boer H, van Diepen K, Emin D, de Groot G, Klosterhalfen A, Langensiepen M, Matveeva M, Miranda-Garc$$'$$ia G, Moene AF, Rascher U, Röckmann T, Adnew G, Brüggemann N, Rothfuss Y and Graf A (2020), "CloudRoots: integration of advanced instrumental techniques and process modelling of sub-hourly and sub-kilometre land--atmosphere interactions", Biogeosciences. Vol. 17(17), pp. 4375-4404.
BibTeX:
@article{Arellano2020,
  author = {de Arellano, J and Ney, P and Hartogensis, O and de Boer, H and van Diepen, K and Emin, D and de Groot, G and Klosterhalfen, A and Langensiepen, M and Matveeva, M and Miranda-Garc$$'$$ia, G and Moene, A F and Rascher, U and Röckmann, T and Adnew, G and Brüggemann, N and Rothfuss, Y and Graf, A},
  title = {CloudRoots: integration of advanced instrumental techniques and process modelling of sub-hourly and sub-kilometre land--atmosphere interactions},
  journal = {Biogeosciences},
  year = {2020},
  volume = {17},
  number = {17},
  pages = {4375--4404},
  url = {https://bg.copernicus.org/articles/17/4375/2020/},
  doi = {10.5194/bg-17-4375-2020}
}
Arruda R, Atamanchuk D, Cronin M, Steinhoff T and Wallace DWR (2020), "At‐sea intercomparison of three underway textlessitextgreaterptextless/itextgreater CO textlesssubtextgreater2textless/subtextgreater systems", Limnology and Oceanography: Methods., feb, 2020. Vol. 18(2), pp. 63-76. Wiley Blackwell.
Abstract: Ocean surface partial pressure of carbon dioxide (pCO2) is a key factor controlling air–sea CO2 fluxes. Most surface pCO2 data are collected with relatively large and complex air–water equilibrators coupled to stand-alone infrared analyzers installed on Ships of OPportunity (SOOP-CO2). This approach has proven itself through years of successful deployments, but expansion and sustainability of the future measurement network faces challenges in terms of certification, autonomy, and maintenance, which motivates development of new systems. Here, we compare performance of three underway pCO2 measurement systems (General Oceanics, SubCtech, and Pro-Oceanus), including a recently developed compact flow-through, sensor-based system. The systems were intercompared over a period of 34 days during two crossings of the subpolar North Atlantic Ocean. With a mean difference from the General Oceanics system of −5.7 ± 4.0 μatm (Pro-Oceanus) and −4.7 ± 2.9 μatm (SubCtech) during the 1st crossing, our results indicate potential for good agreement between the systems. The study highlighted the challenge of assuring accuracy over long periods of time, particularly seen in a worse agreement during the 2nd crossing, and revealed a number of sources of systematic errors. These can influence accuracy of the measurements, agreement between systems and include slow response of membrane-based systems to pCO2 changes, “within-ship” respiration due to biofouling, and bias in measurement of the temperature of equilibration. These error sources can be controlled or corrected for, however, if unidentified, their magnitude can be significant relative to accuracy criteria assigned to the highest-quality data in global databases. The advantages of the compact flow-through system are presented along with a discussion of future solutions for improving data quality.
BibTeX:
@article{Arruda2020,
  author = {Arruda, Ricardo and Atamanchuk, Dariia and Cronin, Margot and Steinhoff, Tobias and Wallace, Douglas W. R.},
  title = {At‐sea intercomparison of three underway textlessitextgreaterptextless/itextgreater CO textlesssubtextgreater2textless/subtextgreater systems},
  journal = {Limnology and Oceanography: Methods},
  publisher = {Wiley Blackwell},
  year = {2020},
  volume = {18},
  number = {2},
  pages = {63--76},
  url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/lom3.10346},
  doi = {10.1002/lom3.10346}
}
Bachy A, Aubinet M, Amelynck C, Schoon N, Bodson B, Delaplace P, De Ligne A, Digrado A, du Jardin P, Fauconnier ML, Mozaffar A, Müller JF and Heinesch B (2020), "Dynamics and mechanisms of volatile organic compound exchanges in a winter wheat field", Atmospheric Environment. Vol. 221(November 2019), pp. 117105. Elsevier Ltd.
Abstract: The understanding of biogenic volatile organic compound (BVOC) exchanges has become a key scientific issue because of their high reactivity and their impact in the atmosphere. However, so far, few studies have focused on BVOCs exchanged by agricultural species, and in particular by winter wheat, despite this species being the leading worldwide crop in terms of harvested area. This study for the first time investigated BVOC exchanges from winter wheat during most developmental stages of the plant. Fluxes were measured in Belgium at the ecosystem-scale using the disjunct eddy covariance by mass scanning technique, and a proton-transfer-reaction mass spectrometer for BVOC ambient mixing ratio measurements. As is usually observed for crops and grasses, the winter wheat field emitted mainly methanol, although bi-directional exchanges were observed. The second most exchanged compound was acetic acid which was captured during the entire growing season. Bi-directional exchanges of acetaldehyde and acetone were also reported. Terpene exchanges were 22 times smaller than oxygenated VOC (OVOC) exchanges. For all compounds, the exchanges were the most pronounced at the end of the growing season, i.e., under warm, dry and sunny conditions. Senescence-induced emissions were furthermore observed for methanol and acetaldehyde. For all investigated OVOCs, the exchanges very likely originated from both the soil and the plants. Despite their mixed origin, the MEGAN (Model of Emissions of Gases and Aerosols from Nature) v2.1 up-scaling model could adequately reproduce the methanol, acetaldehyde and acetone exchanges measured at this site during the mature and senescence phases of the plant, when the standard emission factor and the leaf age factor were adapted based on the measurements. In contrast, the model failed to reproduce the measured acetic acid exchanges. When the standard emission factor values currently assigned in MEGAN were applied, however, the exchanges were largely over-estimated for all compounds.
BibTeX:
@article{Bachy2020,
  author = {Bachy, A and Aubinet, M and Amelynck, C and Schoon, N and Bodson, B and Delaplace, P and De Ligne, A and Digrado, A and du Jardin, P and Fauconnier, M L and Mozaffar, A and Müller, J F and Heinesch, B},
  title = {Dynamics and mechanisms of volatile organic compound exchanges in a winter wheat field},
  journal = {Atmospheric Environment},
  publisher = {Elsevier Ltd},
  year = {2020},
  volume = {221},
  number = {November 2019},
  pages = {117105},
  url = {https://doi.org/10.1016/j.atmosenv.2019.117105},
  doi = {10.1016/j.atmosenv.2019.117105}
}
Bastos A, Ciais P, Friedlingstein P, Sitch S, Pongratz J, Fan L, Wigneron JP, Weber U, Reichstein M, Fu Z, Anthoni P, Arneth A, Haverd V, Jain AK, Joetzjer E, Knauer J, Lienert S, Loughran T, McGuire PC, Tian H, Viovy N and Zaehle S (2020), "Direct and seasonal legacy effects of the 2018 heat wave and drought on European ecosystem productivity", Science Advances., jun, 2020. Vol. 6(24), pp. eaba2724.
Abstract: In summer 2018, central and northern Europe were stricken by extreme drought and heat (DH2018). The DH2018 differed from previous events in being preceded by extreme spring warming and brightening, but moderate rainfall deficits, yet registering the fastest transition between wet winter conditions and extreme summer drought. Using 11 vegetation models, we show that spring conditions promoted increased vegetation growth, which, in turn, contributed to fast soil moisture depletion, amplifying the summer drought. We find regional asymmetries in summer ecosystem carbon fluxes: increased (reduced) sink in the northern (southern) areas affected by drought. These asymmetries can be explained by distinct legacy effects of spring growth and of water-use efficiency dynamics mediated by vegetation composition, rather than by distinct ecosystem responses to summer heat/drought. The asymmetries in carbon and water exchanges during spring and summer 2018 suggest that future land-management strategies could influence patterns of summer heat waves and droughts under long-term warming.
BibTeX:
@article{Bastos2020,
  author = {Bastos, A and Ciais, P and Friedlingstein, P and Sitch, S and Pongratz, J and Fan, L and Wigneron, J P and Weber, U and Reichstein, M and Fu, Z and Anthoni, P and Arneth, A and Haverd, V and Jain, A K and Joetzjer, E and Knauer, J and Lienert, S and Loughran, T and McGuire, P C and Tian, H and Viovy, N and Zaehle, S},
  title = {Direct and seasonal legacy effects of the 2018 heat wave and drought on European ecosystem productivity},
  journal = {Science Advances},
  year = {2020},
  volume = {6},
  number = {24},
  pages = {eaba2724},
  url = {https://advances.sciencemag.org/lookup/doi/10.1126/sciadv.aba2724},
  doi = {10.1126/sciadv.aba2724}
}
Bastos A, Fu Z, Ciais P, Friedlingstein P, Sitch S, Pongratz J, Weber U, Reichstein M, Anthoni P, Arneth A, Haverd V, Jain A, Joetzjer E, Knauer J, Lienert S, Loughran T, McGuire PC, Obermeier W, Padrón RS, Shi H, Tian H, Viovy N and Zaehle S (2020), "Impacts of extreme summers on European ecosystems: a comparative analysis of 2003, 2010 and 2018", Philosophical Transactions of the Royal Society B: Biological Sciences., oct, 2020. Vol. 375(1810), pp. 20190507.
Abstract: In Europe, three widespread extreme summer drought and heat (DH) events have occurred in 2003, 2010 and 2018. These events were comparable in magnitude but varied in their geographical distribution and biomes affected. In this study, we perform a comparative analysis of the impact of the DH events on ecosystem CO 2 fluxes over Europe based on an ensemble of 11 dynamic global vegetation models (DGVMs), and the observation-based FLUXCOM product. We find that all DH events were associated with decreases in net ecosystem productivity (NEP), but the gross summer flux anomalies differ between DGVMs and FLUXCOM. At the annual scale, FLUXCOM and DGVMs indicate close to neutral or above-average land CO 2 uptake in DH2003 and DH2018, due to increased productivity in spring and reduced respiration in autumn and winter compensating for less photosynthetic uptake in summer. Most DGVMs estimate lower gross primary production (GPP) sensitivity to soil moisture during extreme summers than FLUXCOM. Finally, we show that the different impacts of the DH events at continental-scale GPP are in part related to differences in vegetation composition of the regions affected and to regional compensating or offsetting effects from climate anomalies beyond the DH centres.
BibTeX:
@article{Bastos2020a,
  author = {Bastos, A. and Fu, Z. and Ciais, P. and Friedlingstein, P. and Sitch, S. and Pongratz, J. and Weber, U. and Reichstein, M. and Anthoni, P. and Arneth, A. and Haverd, V. and Jain, A. and Joetzjer, E. and Knauer, J. and Lienert, S. and Loughran, T. and McGuire, P. C. and Obermeier, W. and Padrón, R. S. and Shi, H. and Tian, H. and Viovy, N. and Zaehle, S.},
  title = {Impacts of extreme summers on European ecosystems: a comparative analysis of 2003, 2010 and 2018},
  journal = {Philosophical Transactions of the Royal Society B: Biological Sciences},
  year = {2020},
  volume = {375},
  number = {1810},
  pages = {20190507},
  url = {https://royalsocietypublishing.org/doi/10.1098/rstb.2019.0507},
  doi = {10.1098/rstb.2019.0507}
}
Becker M, Olsen A, Landschützer P, Omar A, Rehder G, Rödenbeck C and Skjelvan I (2020), "The northern European shelf as increasing net sink for CO2", Biogeosciences Discussions., jan, 2020. , pp. 1-28. Copernicus GmbH.
BibTeX:
@article{Becker2020,
  author = {Becker, Meike and Olsen, Are and Landschützer, Peter and Omar, Abdirhaman and Rehder, Gregor and Rödenbeck, Christian and Skjelvan, Ingunn},
  title = {The northern European shelf as increasing net sink for CO2},
  journal = {Biogeosciences Discussions},
  publisher = {Copernicus GmbH},
  year = {2020},
  pages = {1--28},
  doi = {10.5194/bg-2019-480}
}
Beillouin D, Schauberger B, Bastos A, Ciais P and Makowski D (2020), "Impact of extreme weather conditions on European crop production in 2018", Philosophical Transactions of the Royal Society B: Biological Sciences., oct, 2020. Vol. 375(1810), pp. 20190510.
Abstract: Extreme weather increases the risk of large-scale crop failure. The mechanisms involved are complex and intertwined, hence undermining the identification of simple adaptation levers to help improve the resilience of agricultural production. Based on more than 82 000 yield data reported at the regional level in 17 European countries, we assess how climate affected the yields of nine crop species. Using machine learning models, we analyzed historical yield data since 1901 and then focus on 2018, which has experienced a multiplicity and a diversity of atypical extreme climatic conditions. Machine learning models explain up to 65% of historical yield anomalies. We find that both extremes in temperature and precipitation are associated with negative yield anomalies, but with varying impacts in different parts of Europe. In 2018, Northern and Eastern Europe experienced multiple and simultaneous crop failures—among the highest observed in recent decades. These yield losses were associated with extremely low rainfalls in combination with high temperatures between March and August 2018. However, the higher than usual yields recorded in Southern Europe—caused by favourable spring rainfall conditions—nearly offset the large decrease in Northern European crop production. Our results outline the importance of considering single and compound climate extremes to analyse the causes of yield losses in Europe. We found no clear upward or downward trend in the frequency of extreme yield losses for any of the considered crops between 1990 and 2018.
BibTeX:
@article{Beillouin2020,
  author = {Beillouin, Damien and Schauberger, Bernhard and Bastos, Ana and Ciais, Phillipe and Makowski, David},
  title = {Impact of extreme weather conditions on European crop production in 2018},
  journal = {Philosophical Transactions of the Royal Society B: Biological Sciences},
  year = {2020},
  volume = {375},
  number = {1810},
  pages = {20190510},
  url = {https://royalsocietypublishing.org/doi/10.1098/rstb.2019.0510},
  doi = {10.1098/rstb.2019.0510}
}
Bergström AK, Jonsson A, Isles PDF, Creed IF and Lau DCP (2020), "Changes in nutritional quality and nutrient limitation regimes of phytoplankton in response to declining N deposition in mountain lakes", Aquatic Sciences. Vol. 82(2), pp. 1-16. Springer International Publishing.
Abstract: Phytoplankton play a key role in supporting aquatic food webs. However, the effects of ongoing large-scale changes in the concentrations and stoichiometry of important biological compounds [dissolved inorganic N (DIN), total phosphorus (TP), dissolved organic carbon (DOC) and DIN:TP] on the development and nutritional quality of phytoplankton for higher trophic levels are unclear. We conducted lake studies and in situ bioassay experiments in two Swedish mountain regions [Abisko (north) and Jämtland (south)] with different N deposition and where lakes in each region were distributed along a similar gradient in lake DOC (2–7 mg L−1) to assess whether differences in nutrients, DOC and DIN:TP induced differences in phytoplankton quantity [chlorophyll a (Chl-a) and seston carbon (C)] and quality [seston C:N:P stoichiometry and fatty acid (FA) composition]. Using long-term monitoring data from lakes in these two mountain regions, we found declining long-term trends in N deposition and lake DIN and total TP concentrations, but not in lake DIN:TP. Lakes in Abisko received lower N deposition and had lower DIN:TP than those in Jämtland. Phytoplankton was N- to NP-limited in Abisko lakes but NP dual-limited in Jämtland lakes. The N fertilization effects induced by higher DIN:TP were weak on phytoplankton quantity but strong on phytoplankton quality. The phytoplankton had lower eicosapentaenoic acid (EPA) content and higher P content (lower seston C:P) in Abisko compared to in Jämtland. In addition, the quality of the DOC (as indicated by its aromaticity and SUVA) influenced not only the light conditions and the seston C:P ratios, but also the FA composition. We found higher bacteria FA concentrations in seston in Abisko than in Jämtland, despite lower amounts of FA of terrestrial origin in Abisko. Our findings suggest that declining N deposition and enhanced colored terrestrial C loadings leads to lower nutritional quality of basal resources for higher consumers in mountain lakes.
BibTeX:
@article{Bergstroem2020,
  author = {Bergström, Ann Kristin and Jonsson, Anders and Isles, Peter D F and Creed, Irena F and Lau, Danny C P},
  title = {Changes in nutritional quality and nutrient limitation regimes of phytoplankton in response to declining N deposition in mountain lakes},
  journal = {Aquatic Sciences},
  publisher = {Springer International Publishing},
  year = {2020},
  volume = {82},
  number = {2},
  pages = {1--16},
  url = {https://doi.org/10.1007/s00027-020-0697-1},
  doi = {10.1007/s00027-020-0697-1}
}
Bolduc B, Hodgkins SB, Varner RK, Crill PM, McCalley CK, Chanton JP, Tyson GW, Riley WJ, Palace M, Duhaime MB, Hough MA, Saleska SR, Sullivan MB and Rich VI (2020), "The IsoGenie database: An interdisciplinary data management solution for ecosystems biology and environmental research", PeerJ. Vol. 8(ii), pp. 1-30.
Abstract: Modern microbial and ecosystem sciences require diverse interdisciplinary teams that are often challenged in “speaking” to one another due to different languages and data product types. Here we introduce the IsoGenie Database (IsoGenieDB; https://isogenie-db.asc.Ohio-state.edu/), a de novo developed data management and exploration platform, as a solution to this challenge of accurately representing and integrating heterogenous environmental and microbial data across ecosystem scales. The IsoGenieDB is a public and private data infrastructure designed to store and query data generated by the IsoGenie Project, a ˜10 year DOE-funded project focused on discovering ecosystem climate feedbacks in a thawing permafrost landscape. The IsoGenieDB provides (i) a platform for IsoGenie Project members to explore the project's interdisciplinary datasets across scales through the inherent relationships among data entities, (ii) a framework to consolidate and harmonize the datasets needed by the team's modelers, and (iii) a public venue that leverages the same spatially explicit, disciplinarily integrated data structure to share published datasets. The IsoGenieDB is also being expanded to cover the NASA-funded Archaea to Atmosphere (A2A) project, which scales the findings of IsoGenie to a broader suite of Arctic peatlands, via the umbrella A2A Database (A2A-DB). The IsoGenieDB's expandability and flexible architecture allow it to serve as an example ecosystems database.
BibTeX:
@article{Bolduc2020,
  author = {Bolduc, Benjamin and Hodgkins, Suzanne B and Varner, Ruth K and Crill, Patrick M and McCalley, Carmody K and Chanton, Jeffrey P and Tyson, Gene W and Riley, William J and Palace, Michael and Duhaime, Melissa B and Hough, Moira A and Saleska, Scott R and Sullivan, Matthew B and Rich, Virginia I},
  title = {The IsoGenie database: An interdisciplinary data management solution for ecosystems biology and environmental research},
  journal = {PeerJ},
  year = {2020},
  volume = {8},
  number = {ii},
  pages = {1--30},
  doi = {10.7717/peerj.9467}
}
Botter M, Zeeman M, Burlando P and Fatichi S (2020), "Impacts of fertilization on grassland productivity and water quality across the European Alps: insights from a mechanistic model", Biogeosciences Discussions. Vol. 2020, pp. 1-35.
BibTeX:
@article{Botter2020,
  author = {Botter, M and Zeeman, M and Burlando, P and Fatichi, S},
  title = {Impacts of fertilization on grassland productivity and water quality across the European Alps: insights from a mechanistic model},
  journal = {Biogeosciences Discussions},
  year = {2020},
  volume = {2020},
  pages = {1--35},
  url = {https://bg.copernicus.org/preprints/bg-2020-294/},
  doi = {10.5194/bg-2020-294}
}
Bowring SPK, Lauerwald R, Guenet B, Zhu D, Guimberteau M, Regnier P, Tootchi A, Ducharne A and Ciais P (2020), "ORCHIDEE MICT-LEAK (r5459), a global model for the production, transport, and transformation of dissolved organic carbon from Arctic permafrost regions - Part 2: Model evaluation over the Lena River basin", Geoscientific Model Development., feb, 2020. Vol. 13(2), pp. 507-520. Copernicus GmbH.
Abstract: In this second part of a two-part study, we performed a simulation of the carbon and water budget of the Lena catchment with the land surface model ORCHIDEE MICT-LEAK, enabled to simulate dissolved organic carbon (DOC) production in soils and its transport and fate in high-latitude inland waters. The model results are evaluated for their ability to reproduce the fluxes of DOC and carbon dioxide (CO2) along the soil-inland-water continuum and the exchange of CO2 with the atmosphere, including the evasion outgassing of CO2 from inland waters. We present simulation results over the years 1901-2007 and show that the model is able to broadly reproduce observed state variables and their emergent properties across a range of interacting physical and biogeochemical processes. These include (1) net primary production (NPP), respiration and riverine hydrologic amplitude, seasonality, and inter-annual variation; (2) DOC concentrations, bulk annual flow, and their volumetric attribution at the sub-catchment level; (3) high headwater versus downstream CO2 evasion, an emergent phenomenon consistent with observations over a spectrum of high-latitude observational studies. These quantities obey emergent relationships with environmental variables like air temperature and topographic slope that have been described in the literature. This gives us confidence in reporting the following additional findings: of the ĝ'1/434TgCyr-1 left over as input to soil matter after NPP is diminished by heterotrophic respiration, 7TgCyr-1 is leached and transported into the aquatic system. Of this, over half (3.6TgCyr-1) is evaded from the inland water surface back into the atmosphere and the remainder (3.4TgCyr-1) flushed out into the Arctic Ocean, mirroring empirically derived studies. These riverine DOC exports represent ĝ'1/41.5% of NPP. DOC exported from the floodplains is dominantly sourced from recent more "labile" terrestrial production in contrast to DOC leached from the rest of the watershed with runoff and drainage, which is mostly sourced from recalcitrant soil and litter. All else equal, both historical climate change (a spring-summer warming of 1.8ĝ' C over the catchment) and rising atmospheric CO2 (+85.6ppm) are diagnosed from factorial simulations to contribute similar significant increases in DOC transport via primary production, although this similarity may not hold in the future.
BibTeX:
@article{Bowring2020,
  author = {Bowring, Simon P K and Lauerwald, Ronny and Guenet, Bertrand and Zhu, Dan and Guimberteau, Matthieu and Regnier, Pierre and Tootchi, Ardalan and Ducharne, Agnes and Ciais, Philippe},
  title = {ORCHIDEE MICT-LEAK (r5459), a global model for the production, transport, and transformation of dissolved organic carbon from Arctic permafrost regions - Part 2: Model evaluation over the Lena River basin},
  journal = {Geoscientific Model Development},
  publisher = {Copernicus GmbH},
  year = {2020},
  volume = {13},
  number = {2},
  pages = {507--520},
  doi = {10.5194/gmd-13-507-2020}
}
Bridgman MJ, Lomax BH and Sjögersten S (2020), "Impacts of Elevated Atmospheric CO2 and Plant Species Composition on Methane Emissions from Subarctic Wetlands", Wetlands. Vol. 40(3), pp. 609-618. Wetlands.
Abstract: Elevated atmospheric CO2 may create greater methane (CH4) emissions from subarctic wetlands. To date such ecosystem feedbacks remain poorly understood, particularly in relation to how different wetland plant species will control such feedbacks. In this study we exposed plant-peat mesocosms planted with four Cyperaceae species to 400 and 800 ppm atmospheric CO2 concentrations and measured plant and peat properties as well as CH4 fluxes. Above ground biomass for plants grown at 800 ppm CO2 increased for E. angustifolium, Eriophorum vaginatum and Carex brunnescens, but the total biomass of C. acuta decreased relative to the ambient CO2 treatment. The plant species and elevated CO2 treatment affected both peat redox potential and pore water chemistry. There was no overall effect of the elevated CO2 on CH4 emissions, however, CH4 emissions were related to above ground biomass and redox potential, both of which were significantly altered by elevated CO2. Our study shows that species composition poses an important control on how wetland communities will respond to elevated CO2 and that plant mediated changes of peat biogeochemical processes, in response to elevated CO2 levels, may affect CH4 emissions from sub-arctic wetlands, but any such responses will differ among species.
BibTeX:
@article{Bridgman2020,
  author = {Bridgman, Matthew J and Lomax, Barry H and Sjögersten, Sofie},
  title = {Impacts of Elevated Atmospheric CO2 and Plant Species Composition on Methane Emissions from Subarctic Wetlands},
  journal = {Wetlands},
  publisher = {Wetlands},
  year = {2020},
  volume = {40},
  number = {3},
  pages = {609--618},
  doi = {10.1007/s13157-019-01203-5}
}
Brogi C, Huisman JA, Herbst M, Weihermüller L, Klosterhalfen A, Montzka C, Reichenau TG and Vereecken H (2020), "Simulation of spatial variability in crop leaf area index and yield using agroecosystem modeling and geophysics-based quantitative soil information", Vadose Zone Journal. Vol. 19(1), pp. 1-24.
Abstract: Agroecosystem models that simulate crop growth as a function of weather conditions and soil characteristics are among the most promising tools for improving crop yield and achieving more sustainable agricultural production systems. This study aims at using spatially distributed crop growth simulations to investigate how field-scale patterns in soil properties obtained using geophysical mapping affect the spatial variability of soil water content dynamics and growth of crops at the square kilometer scale. For this, a geophysics-based soil map was intersected with land use information. Soil hydraulic parameters were calculated using pedotransfer functions. Simulations of soil water content dynamics performed with the agroecosystem model AgroC were compared with soil water content measured at two locations, resulting in RMSE of 0.032 and of 0.056 cm3 cm−3, respectively. The AgroC model was then used to simulate the growth of sugar beet (Beta vulgaris L.), silage maize (Zea mays L.), potato (Solanum tuberosum L.), winter wheat (Triticum aestivum L.), winter barley (Hordeum vulgare L.), and winter rapeseed (Brassica napus L.) in the 1- by 1-km study area. It was found that the simulated leaf area index (LAI) was affected by the magnitude of simulated water stress, which was a function of both the crop type and soil characteristics. Simulated LAI was generally consistent with the observed LAI calculated from normalized difference vegetation index (LAINDVI) obtained from RapidEye satellite data. Finally, maps of simulated agricultural yield were produced for four crops, and it was found that simulated yield matched well with actual harvest data and literature values. Therefore, it was concluded that the information obtained from geophysics-based soil mapping was valuable for practical agricultural applications.
BibTeX:
@article{Brogi2020,
  author = {Brogi, C and Huisman, J A and Herbst, M and Weihermüller, L and Klosterhalfen, A and Montzka, C and Reichenau, T G and Vereecken, H},
  title = {Simulation of spatial variability in crop leaf area index and yield using agroecosystem modeling and geophysics-based quantitative soil information},
  journal = {Vadose Zone Journal},
  year = {2020},
  volume = {19},
  number = {1},
  pages = {1--24},
  doi = {10.1002/vzj2.20009}
}
Broullón D, Pérez FF, Velo A, Hoppema M, Olsen A, Takahashi T, Key RM, Tanhua T, Santana-Casiano JM and Kozyr A (2020), "A global monthly climatology of oceanic total dissolved inorganic carbon: a neural network approach", Earth System Science Data., aug, 2020. Vol. 12(3), pp. 1725-1743. Copernicus GmbH.
Abstract: textlessptextgreatertextless![CDATA[Abstract. Anthropogenic emissions of CO2 to the atmosphere have modified the carbon cycle for more than 2 centuries. As the ocean stores most of the carbon on our planet, there is an important task in unraveling the natural and anthropogenic processes that drive the carbon cycle at different spatial and temporal scales. We contribute to this by designing a global monthly climatology of total dissolved inorganic carbon (TCO2), which offers a robust basis in carbon cycle modeling but also for other studies related to this cycle. A feedforward neural network (dubbed NNGv2LDEO) was configured to extract from the Global Ocean Data Analysis Project version 2.2019 (GLODAPv2.2019) and the Lamont–Doherty Earth Observatory (LDEO) datasets the relations between TCO2 and a set of variables related to the former's variability. The global root mean square error (RMSE) of mapping TCO2 is relatively low for the two datasets (GLODAPv2.2019: 7.2 µmol kg−1; LDEO: 11.4 µmol kg−1) and also for independent data, suggesting that the network does not overfit possible errors in data. The ability of NNGv2LDEO to capture the monthly variability of TCO2 was testified through the good reproduction of the seasonal cycle in 10 time series stations spread over different regions of the ocean (RMSE: 3.6 to 13.2 µmol kg−1). The climatology was obtained by passing through NNGv2LDEO the monthly climatological fields of temperature, salinity, and oxygen from the World Ocean Atlas 2013 and phosphate, nitrate, and silicate computed from a neural network fed with the previous fields. The resolution is 1∘×1∘ in the horizontal, 102 depth levels (0–5500 m), and monthly (0–1500 m) to annual (1550–5500 m) temporal resolution, and it is centered around the year 1995. The uncertainty of the climatology is low when compared with climatological values derived from measured TCO2 in the largest time series stations. Furthermore, a computed climatology of partial pressure of CO2 (pCO2) from a previous climatology of total alkalinity and the present one of TCO2 supports the robustness of this product through the good correlation with a widely used pCO2 climatology (Landschützer et al., 2017). Our TCO2 climatology is distributed through the data repository of the Spanish National Research Council (CSIC; https://doi.org/10.20350/digitalCSIC/10551, Broullón et al., 2020).]]textgreatertextless/ptextgreater
BibTeX:
@article{Broullon2020,
  author = {Broullón, Daniel and Pérez, Fiz F. and Velo, Antón and Hoppema, Mario and Olsen, Are and Takahashi, Taro and Key, Robert M. and Tanhua, Toste and Santana-Casiano, J. Magdalena and Kozyr, Alex},
  title = {A global monthly climatology of oceanic total dissolved inorganic carbon: a neural network approach},
  journal = {Earth System Science Data},
  publisher = {Copernicus GmbH},
  year = {2020},
  volume = {12},
  number = {3},
  pages = {1725--1743},
  url = {https://essd.copernicus.org/articles/12/1725/2020/},
  doi = {10.5194/essd-12-1725-2020}
}
Byrne B, Liu J, Lee M, Baker I, Bowman KW, Deutscher NM, Feist DG, Griffith DWT, Iraci LT, Kiel M, Kimball JS, Miller CE, Morino I, Parazoo NC, Petri C, Roehl CM, Sha MK, Strong K, Velazco VA, Wennberg PO and Wunch D (2020), " Improved Constraints on Northern Extratropical CO 2 Fluxes Obtained by Combining Surface‐Based and Space‐Based Atmospheric CO 2 Measurements ", Journal of Geophysical Research: Atmospheres., aug, 2020. Vol. 125(15) American Geophysical Union (AGU).
BibTeX:
@article{Byrne2020,
  author = {Byrne, B. and Liu, J. and Lee, M. and Baker, I. and Bowman, K. W. and Deutscher, N. M. and Feist, D. G. and Griffith, D. W. T. and Iraci, L. T. and Kiel, M. and Kimball, J. S. and Miller, C. E. and Morino, I. and Parazoo, N. C. and Petri, C. and Roehl, C. M. and Sha, M. K. and Strong, K. and Velazco, V. A. and Wennberg, P. O. and Wunch, D.},
  title = { Improved Constraints on Northern Extratropical CO 2 Fluxes Obtained by Combining Surface‐Based and Space‐Based Atmospheric CO 2 Measurements },
  journal = {Journal of Geophysical Research: Atmospheres},
  publisher = {American Geophysical Union (AGU)},
  year = {2020},
  volume = {125},
  number = {15},
  doi = {10.1029/2019jd032029}
}
Cai J, Xu K, Zhu Y, Hu F and Li L (2020), "Prediction and analysis of net ecosystem carbon exchange based on gradient boosting regression and random forest", Applied Energy., mar, 2020. Vol. 262 Elsevier Ltd.
Abstract: Carbon balance is essential to keep ecosystems sustainable and healthy. Net ecosystem carbon exchange (NEE), which is affected by a bunch of meteorological variables to different extent, helps to gauge the balance of the carbon cycle between biological organisms and atmosphere. In this study, the NEE data is collected from two flux measuring sites. Gradient boosting regression algorithm is employed to predict NEE based on the meteorology and flux data from site UK-Gri. During the training process, KFold cross-validation algorithm is implemented to avoid overfitting, and random forest algorithm is implemented to identify the important variables influencing NEE mostly. The four most important variables are found to be global radiation, photosynthetic active radiation, minimum soil temperature, and latent heat. The regression model was compared with three state-of-the-art prediction models: support vector machine, stochastic gradient descent, and bayesian ridge to verify its performance. The experimental results show that this regression model outperforms the other three models, and gives higher value of R-squared, lower values of mean absolute error and root mean squared error. To verify the regression model's generalization ability, the data from the second flux site, NL-Loo, was employed, and the hybrid data of the two sites was used. The results show that this model performs well on the hybrid data, too. In practical terms, the gradient boosting regression model provides many tunable hypterparameters and loss functions, which make it more flexible and accurate compared to the other three models. This study has conclusively demonstrated for the first time that the combination of gradient boosting regression and random forest models should be considered as valuable tools to make effective prediction for NEE and acquire reliable important variables influencing NEE mostly. The methodologies could be useful in the research fields of ecosystem stability evaluation, environmental restoration, trend analysis of climate change, and global warming monitoring.
BibTeX:
@article{Cai2020,
  author = {Cai, Jianchao and Xu, Kai and Zhu, Yanhui and Hu, Fang and Li, Liuhuan},
  title = {Prediction and analysis of net ecosystem carbon exchange based on gradient boosting regression and random forest},
  journal = {Applied Energy},
  publisher = {Elsevier Ltd},
  year = {2020},
  volume = {262},
  doi = {10.1016/j.apenergy.2020.114566}
}
Calders K, Adams J, Armston J, Bartholomeus H, Bauwens S, Bentley LP, Chave J, Danson FM, Demol M, Disney M, Gaulton R, Krishna Moorthy SM, Levick SR, Saarinen N, Schaaf C, Stovall A, Terryn L, Wilkes P and Verbeeck H (2020), "Terrestrial laser scanning in forest ecology: Expanding the horizon", Remote Sensing of Environment., dec, 2020. Vol. 251, pp. 112102.
BibTeX:
@article{Calders2020,
  author = {Calders, Kim and Adams, Jennifer and Armston, John and Bartholomeus, Harm and Bauwens, Sebastien and Bentley, Lisa Patrick and Chave, Jerome and Danson, F. Mark and Demol, Miro and Disney, Mathias and Gaulton, Rachel and Krishna Moorthy, Sruthi M. and Levick, Shaun R. and Saarinen, Ninni and Schaaf, Crystal and Stovall, Atticus and Terryn, Louise and Wilkes, Phil and Verbeeck, Hans},
  title = {Terrestrial laser scanning in forest ecology: Expanding the horizon},
  journal = {Remote Sensing of Environment},
  year = {2020},
  volume = {251},
  pages = {112102},
  url = {https://linkinghub.elsevier.com/retrieve/pii/S0034425720304752},
  doi = {10.1016/j.rse.2020.112102}
}
Cao Z, Yang W, Zhao Y, Guo X, Yin Z, Du C, Zhao H and Dai M (2020), "Diagnosis of CO2 dynamics and fluxes in global coastal oceans", National Science Review., apr, 2020. Vol. 7(4), pp. 786-797. Oxford University Press (OUP).
Abstract: Global coastal oceans as a whole represent an important carbon sink but, due to high spatial–temporal variability, a mechanistic conceptualization of the coastal carbon cycle is still under development, hindering the modelling and inclusion of coastal carbon in Earth System Models. Although temperature is considered an important control of sea surface pCO2, we show that the latitudinal distribution of global coastal surface pCO2 does not match that of temperature, and its inter-seasonal changes are substantially regulated by non-thermal factors such as water mass mixing and net primary production. These processes operate in both ocean-dominated and river-dominated margins, with carbon and nutrients sourced from the open ocean and land, respectively. These can be conceptualized by a semi-analytical framework that assesses the consumption of dissolved inorganic carbon relative to nutrients, to determine how a coastal system is a CO2 source or sink. The framework also finds utility in accounting for additional nutrients in organic forms and testing hypotheses such as using Redfield stoichiometry, and is therefore an essential step toward comprehensively understanding and modelling the role of the coastal ocean in the global carbon cycle.
BibTeX:
@article{Cao2020,
  author = {Cao, Zhimian and Yang, Wei and Zhao, Yangyang and Guo, Xianghui and Yin, Zhiqiang and Du, Chuanjun and Zhao, Huade and Dai, Minhan},
  title = {Diagnosis of CO2 dynamics and fluxes in global coastal oceans},
  journal = {National Science Review},
  publisher = {Oxford University Press (OUP)},
  year = {2020},
  volume = {7},
  number = {4},
  pages = {786--797},
  url = {https://academic.oup.com/nsr/article/7/4/786/5542784},
  doi = {10.1093/nsr/nwz105}
}
Carrière SD, Martin-StPaul NK, Cakpo CB, Patris N, Gillon M, Chalikakis K, Doussan C, Olioso A, Babic M, Jouineau A, Simioni G and Davi H (2020), "The role of deep vadose zone water in tree transpiration during drought periods in karst settings – Insights from isotopic tracing and leaf water potential", Science of the Total Environment., jan, 2020. Vol. 699, pp. 134332. Elsevier BV.
Abstract: Karst environments are unusual because their dry, stony and shallow soils seem to be unfavorable to vegetation, and yet they are often covered with forests. How can trees survive in these environments? Where do they find the water that allows them to survive? This study uses midday and predawn water potentials and xylem water isotopes of branches to assess tree water status and the origin of transpired water. Monitoring was conducted during the summers of 2014 and 2015 in two dissimilar plots of Mediterranean forest located in karst environments. The results show that the three monitored tree species (Abies alba Mill, Fagus sylvatica L, and Quercus ilex L.) use deep water resources present in the karst vadose zone (unsaturated zone) more intensively during drier years. Quercus ilex, a species well- adapted to water stress, which grows at the drier site, uses the deep water resource very early in the summer season. Conversely, the two other species exploit the deep water resource only during severe drought. These results open up new perspectives to a better understanding of ecohydrological equilibrium and to improved water balance modeling in karst forest settings.
BibTeX:
@article{Carriere2020,
  author = {Carrière, Simon Damien and Martin-StPaul, Nicolas K and Cakpo, Coffi Belmys and Patris, Nicolas and Gillon, Marina and Chalikakis, Konstantinos and Doussan, Claude and Olioso, Albert and Babic, Milanka and Jouineau, Arnaud and Simioni, Guillaume and Davi, Hendrik},
  title = {The role of deep vadose zone water in tree transpiration during drought periods in karst settings – Insights from isotopic tracing and leaf water potential},
  journal = {Science of the Total Environment},
  publisher = {Elsevier BV},
  year = {2020},
  volume = {699},
  pages = {134332},
  doi = {10.1016/j.scitotenv.2019.134332}
}
Carrière SD, Ruffault J, Pimont F, Doussan C, Simioni G, Chalikakis K, Limousin JM, Scotti I, Courdier F, Cakpo CB, Davi H and Martin-StPaul NK (2020), "Impact of local soil and subsoil conditions on inter-individual variations in tree responses to drought: insights from Electrical Resistivity Tomography", Science of the Total Environment., jan, 2020. Vol. 698, pp. 134247. Elsevier BV.
Abstract: • Inter-individual variability of tree drought responses within a stand has received little attention. Here we explore whether the spatial variations in soil/subsoil properties assessed through Electrical Resistivity Tomography (ERT) could explain variations in drought response traits among trees. • We used ERT to compute the percent variation in resistivity (PVR) between dry and wet conditions as an indicator of spatial variability in total available water content. PVR was computed in two different depth ranges (0–2 and 2–5 m) for eleven Quercus ilex stools in a Mediterranean forest stand. PVR values were compared to biological traits, including tree water status (predawn water potential (Ψ)), leaf traits (δ13C, leaf mass area (LMA)), and canopy defoliation measured after intense drought. • We found significant correlations between PVR and biological variables. For Ψ, the nature and strength of the correlations vary according to the level of drought intensity. The correlation between Ψ and PVR was positive during well-watered conditions in the upper layer (0–2 m) and during water-limited conditions in the deeper layer (2–5 m). During most severe droughts, however, the Ψ was negatively correlated with PVR in the upper layer. Trees with lower PVR in the upper layer were also associated with water use efficiency (higher δ13C), higher LMA, and a lower level of defoliation after extreme drought. • Overall, our results indicate that local differences in soil/subsoil properties affect tree response to drought and suggest that less favorable soil/subsoil conditions (lower PVR) can lead to lower water stress during the driest period and to lower defoliation after extreme drought. Plausible explanations for this better acclimation include higher stomatal regulation and improved deep soil and subsoil water exploration by trees located in more adverse conditions. We encourage the development of ERT in ecological studies to further explore the interrelated relationships between soil/subsoil, climate, and tree functioning.
BibTeX:
@article{Carriere2020a,
  author = {Carrière, S D and Ruffault, J and Pimont, F and Doussan, C and Simioni, G and Chalikakis, K and Limousin, J M and Scotti, I and Courdier, F and Cakpo, C B and Davi, H and Martin-StPaul, N K},
  title = {Impact of local soil and subsoil conditions on inter-individual variations in tree responses to drought: insights from Electrical Resistivity Tomography},
  journal = {Science of the Total Environment},
  publisher = {Elsevier BV},
  year = {2020},
  volume = {698},
  pages = {134247},
  doi = {10.1016/j.scitotenv.2019.134247}
}
Carroll D, Menemenlis D, Adkins JF, Bowman KW, Brix H, Dutkiewicz S, Fenty I, Gierach MM, Hill C, Jahn O, Landschützer P, Lauderdale JM, Liu J, Manizza M, Naviaux JD, Rödenbeck C, Schimel DS, Van der Stocken T and Zhang H (2020), " The ECCO‐Darwin Data‐assimilative Global Ocean Biogeochemistry Model: Estimates of Seasonal to Multi‐decadal Surface Ocean pCO 2 and Air‐sea CO 2 Flux ", Journal of Advances in Modeling Earth Systems., jul, 2020. American Geophysical Union (AGU).
BibTeX:
@article{Carroll2020,
  author = {Carroll, D. and Menemenlis, D. and Adkins, J. F. and Bowman, K. W. and Brix, H. and Dutkiewicz, S. and Fenty, I. and Gierach, M. M. and Hill, C. and Jahn, O. and Landschützer, P. and Lauderdale, J. M. and Liu, J. and Manizza, M. and Naviaux, J. D. and Rödenbeck, C. and Schimel, D. S. and Van der Stocken, T. and Zhang, H.},
  title = { The ECCO‐Darwin Data‐assimilative Global Ocean Biogeochemistry Model: Estimates of Seasonal to Multi‐decadal Surface Ocean pCO 2 and Air‐sea CO 2 Flux },
  journal = {Journal of Advances in Modeling Earth Systems},
  publisher = {American Geophysical Union (AGU)},
  year = {2020},
  url = {https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019MS001888 https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019MS001888 https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019MS001888},
  doi = {10.1029/2019ms001888}
}
Chai F, Johnson KS, Claustre H, Xing X, Wang Y, Boss E, Riser S, Fennel K, Schofield O and Sutton A (2020), "Monitoring ocean biogeochemistry with autonomous platforms", Nature Reviews Earth & Environment., jun, 2020. Vol. 1(6), pp. 315-326. Springer Science and Business Media LLC.
Abstract: Human activities have altered the state of the ocean, leading to warming, acidification and deoxygenation. These changes impact ocean biogeochemistry and influence ecosystem functions and ocean health. The long-term global effects of these changes are difficult to predict using current satellite sensing and traditional in situ observation techniques. Autonomous platforms equipped with biogeochemical sensors allow for the observation of marine biogeochemical processes and ecosystem dynamics, covering a wide range of spatial and temporal scales. The international Biogeochemical-Argo (BGC-Argo) project is currently building a global, multidisciplinary ocean-observing network of autonomous Argo floats equipped with an extensive range of biogeochemical sensors. Other autonomous platforms, such as gliders and surface vehicles, have also incorporated such sensors, mainly operating on regional scales and near the ocean surface. Autonomous mobile assets, along with remotely sensed data, will provide the 4D information required to improve model simulations and forecasts of ocean conditions and ecosystem health. Traditional methods for ocean observation are often inadequate for detecting large-scale biogeochemical processes. This Perspective discusses the advantages of implementing autonomous observation platforms in complementing traditional observation methods and generating global biogeochemical data sets.
BibTeX:
@article{Chai2020,
  author = {Chai, Fei and Johnson, Kenneth S. and Claustre, Hervé and Xing, Xiaogang and Wang, Yuntao and Boss, Emmanuel and Riser, Stephen and Fennel, Katja and Schofield, Oscar and Sutton, Adrienne},
  title = {Monitoring ocean biogeochemistry with autonomous platforms},
  journal = {Nature Reviews Earth & Environment},
  publisher = {Springer Science and Business Media LLC},
  year = {2020},
  volume = {1},
  number = {6},
  pages = {315--326},
  url = {https://www.nature.com/articles/s43017-020-0053-y},
  doi = {10.1038/s43017-020-0053-y}
}
Chave J, Piponiot C, Maréchaux I, de Foresta H, Larpin D, Fischer FJ, Derroire G, Vincent G and Hérault B (2020), "Slow rate of secondary forest carbon accumulation in the Guianas compared with the rest of the Neotropics", Ecological Applications., oct, 2020. Vol. 30(1) Wiley.
Abstract: Secondary forests are a prominent component of tropical landscapes, and they constitute a major atmospheric carbon sink. Rates of carbon accumulation are usually inferred from chronosequence studies, but direct estimates of carbon accumulation based on long-term monitoring of stands are rarely reported. Recent compilations on secondary forest carbon accumulation in the Neotropics are heavily biased geographically as they do not include estimates from the Guiana Shield. We analysed the temporal trajectory of aboveground carbon accumulation and floristic composition at one 25-ha secondary forest site in French Guiana. The site was clear-cut in 1976, abandoned thereafter, and one large plot (6.25 ha) has been monitored continuously since. We used Bayesian modeling to assimilate inventory data and simulate the long-term carbon accumulation trajectory. Canopy change was monitored using two aerial lidar surveys conducted in 2009 and 2017. We compared the dynamics of this site with that of a surrounding old-growth forest. Finally, we compared our results with that from secondary forests in Costa Rica, which is one of the rare long-term monitoring programs reaching a duration comparable to our study. Twenty years after abandonment, aboveground carbon stock was 64.2 (95% credibility interval 46.4, 89.0) Mg C/ha, and this stock increased to 101.3 (78.7, 128.5) Mg C/ha 20 yr later. The time to accumulate one-half of the mean aboveground carbon stored in the nearby old-growth forest (185.6 [155.9, 200.2] Mg C/ha) was estimated at 35.0 [20.9, 55.9] yr. During the first 40 yr, the contribution of the long-lived pioneer species Xylopia nitida, Goupia glabra, and Laetia procera to the aboveground carbon stock increased continuously. Secondary forest mean-canopy height measured by lidar increased by 1.14 m in 8 yr, a canopy-height increase consistent with an aboveground carbon accumulation of 7.1 Mg C/ha (or 0.89 Mg Ctextperiodcenteredhaâˆ'1textperiodcenteredyrâˆ'1) during this period. Long-term AGC accumulation rate in Costa Rica was almost twice as fast as at our site in French Guiana. This may reflect higher fertility of Central American forest communities or a better adaptation of the forest tree community to intense and frequent disturbances. This finding may have important consequences for scaling-up carbon uptake estimates to continental scales.
BibTeX:
@article{Chave2020,
  author = {Chave, Jérôme and Piponiot, Camille and Maréchaux, Isabelle and de Foresta, Hubert and Larpin, Denis and Fischer, Fabian Jörg and Derroire, Géraldine and Vincent, Grégoire and Hérault, Bruno},
  title = {Slow rate of secondary forest carbon accumulation in the Guianas compared with the rest of the Neotropics},
  journal = {Ecological Applications},
  publisher = {Wiley},
  year = {2020},
  volume = {30},
  number = {1},
  doi = {10.1002/eap.2004}
}
Chen X, Maignan F, Viovy N, Bastos A, Goll D, Wu J, Liu L, Yue C, Peng S, Yuan W, da Conceição AC, O'Sullivan M and Ciais P (2020), "Novel Representation of Leaf Phenology Improves Simulation of Amazonian Evergreen Forest Photosynthesis in a Land Surface Model", Journal of Advances in Modeling Earth Systems., jan, 2020. Vol. 12(1) Blackwell Publishing Ltd.
Abstract: Leaf phenology in the humid tropics largely regulates the seasonality of forest carbon and water exchange. However, it is inadequately represented in most global land surface models due to limited understanding of its controls. Based on intensive field studies at four Amazonian evergreen forests, we propose a novel, quantitative representation of tropical forest leaf phenology, which links multiple environmental variables with the seasonality of new leaf production and old leaf litterfall. The new phenology simulates higher rates of leaf turnover (new leaves replacing old leaves) in dry seasons with more sunlight, which is then implemented in ORCHIDEE, together with recent findings of ontogeny-associated photosynthetic capacity, and is evaluated against ground-based measurements of leaf phenology (canopy leaf area index and litterfall), eddy covariance fluxes (photosynthesis and latent heat), and carbon allocations from field observations. Results show the periodical cycles of solar radiation and vapor pressure deficit are the two most important environmental variables that are empirically related to new leaf production and old leaf abscission in tropical evergreen forests. The model with new representation of leaf phenology captures the seasonality of canopy photosynthesis at three out of four sites, as well as the seasonality of litterfall, latent heat, and light use efficiency of photosynthesis at all tested sites, and improves the seasonality of carbon allocations to leaves, roots, and sapwoods. This study advances understanding of the environmental controls on tropical leaf phenology and offers an improved modeling tool for gridded simulations of interannual CO2 and water fluxes in the tropics.
BibTeX:
@article{Chen2020,
  author = {Chen, Xiuzhi and Maignan, Fabienne and Viovy, Nicolas and Bastos, Ana and Goll, Daniel and Wu, Jin and Liu, Liyang and Yue, Chao and Peng, Shushi and Yuan, Wenping and da Conceição, Adriana Castro and O'Sullivan, Michael and Ciais, Philippe},
  title = {Novel Representation of Leaf Phenology Improves Simulation of Amazonian Evergreen Forest Photosynthesis in a Land Surface Model},
  journal = {Journal of Advances in Modeling Earth Systems},
  publisher = {Blackwell Publishing Ltd},
  year = {2020},
  volume = {12},
  number = {1},
  doi = {10.1029/2018MS001565}
}
Ciais P, Wang Y, Andrew R, Bréon FM, Chevallier F, Broquet G, Nabuurs GJ, Peters G, McGrath M, Meng W, Zheng B and Tao S (2020), "Biofuel burning and human respiration bias on satellite estimates of fossil fuel CO 2 emissions", Environmental Research Letters., jul, 2020. Vol. 15(7), pp. 74036.
BibTeX:
@article{Ciais2020,
  author = {Ciais, P and Wang, Y and Andrew, R and Bréon, F M and Chevallier, F and Broquet, G and Nabuurs, G J and Peters, G and McGrath, M and Meng, W and Zheng, B and Tao, S},
  title = {Biofuel burning and human respiration bias on satellite estimates of fossil fuel CO 2 emissions},
  journal = {Environmental Research Letters},
  year = {2020},
  volume = {15},
  number = {7},
  pages = {74036},
  url = {https://iopscience.iop.org/article/10.1088/1748-9326/ab7835},
  doi = {10.1088/1748-9326/ab7835}
}
Collalti A, Ibrom A, Stockmarr A, Cescatti A, Alkama R, Fernández-Martínez M, Matteucci G, Sitch S, Friedlingstein P, Ciais P, Goll DS, Nabel JEMS, Pongratz J, Arneth A, Haverd V and Prentice IC (2020), "Forest production efficiency increases with growth temperature", Nature Communications. Vol. 11(1) Springer US.
Abstract: Forest production efficiency (FPE) metric describes how efficiently the assimilated carbon is partitioned into plants organs (biomass production, BP) or—more generally—for the production of organic matter (net primary production, NPP). We present a global analysis of the relationship of FPE to stand-age and climate, based on a large compilation of data on gross primary production and either BP or NPP. FPE is important for both forest production and atmospheric carbon dioxide uptake. We find that FPE increases with absolute latitude, precipitation and (all else equal) with temperature. Earlier findings—FPE declining with age—are also supported by this analysis. However, the temperature effect is opposite to what would be expected based on the short-term physiological response of respiration rates to temperature, implying a top-down regulation of carbon loss, perhaps reflecting the higher carbon costs of nutrient acquisition in colder climates. Current ecosystem models do not reproduce this phenomenon. They consistently predict lower FPE in warmer climates, and are therefore likely to overestimate carbon losses in a warming climate.
BibTeX:
@article{Collalti2020,
  author = {Collalti, A and Ibrom, A and Stockmarr, A and Cescatti, A and Alkama, R and Fernández-Martínez, M and Matteucci, G and Sitch, S and Friedlingstein, P and Ciais, P and Goll, D S and Nabel, J E M S and Pongratz, J and Arneth, A and Haverd, V and Prentice, I C},
  title = {Forest production efficiency increases with growth temperature},
  journal = {Nature Communications},
  publisher = {Springer US},
  year = {2020},
  volume = {11},
  number = {1},
  url = {http://dx.doi.org/10.1038/s41467-020-19187-w},
  doi = {10.1038/s41467-020-19187-w}
}
Cristofanelli P, Arduini J, Calzolari F, Giostra U, Bonasoni P and Maione M (2020), "First Evidences of Methyl Chloride (CH3Cl) Transport from the Northern Italy Boundary Layer during Summer 2017", Atmosphere., feb, 2020. Vol. 11(3), pp. 238.
Abstract: Methyl Chloride (CH3Cl) is a chlorine-containing trace gas in the atmosphere contributing significantly to stratospheric ozone depletion. While the atmospheric CH3Cl emissions are predominantly caused by natural sources on the global budget, significant uncertainties still remain for the anthropogenic CH3Cl emission strengths. In summer 2007 an intensive field campaign within the ACTRIS-2 Project was hosted at the Mt. Cimone World Meteorological Organization/Global Atmosphere Watch global station (CMN, 44.17° N, 10.68° E, 2165 m a.s.l.). High-frequency and high precision in situ measurements of atmospheric CH3Cl revealed significant high-frequency variability superimposed on the seasonally varying regional background levels. The high-frequency CH3Cl variability was characterized by an evident cycle over 24 h with maxima during the afternoon which points towards a systematic role of thermal vertical transport of air-masses from the regional boundary layer. The temporal correlation analysis with specific tracers of anthropogenic activity (traffic, industry, petrochemical industry) together with bivariate analysis as a function of local wind regime suggested that, even if the role of natural marine emissions appears as predominant, the northern Italy boundary layer could potentially represent a non-negligible source of CH3Cl during summer. Since industrial production and use of CH3Cl have not been regulated under the Montreal Protocol (MP) or its successor amendments, continuous monitoring of CH3Cl outflow from the Po Basin is important to properly assess its anthropogenic emissions.
BibTeX:
@article{Cristofanelli2020,
  author = {Cristofanelli, Paolo and Arduini, Jgor and Calzolari, Francescopiero and Giostra, Umberto and Bonasoni, Paolo and Maione, Michela},
  title = {First Evidences of Methyl Chloride (CH3Cl) Transport from the Northern Italy Boundary Layer during Summer 2017},
  journal = {Atmosphere},
  year = {2020},
  volume = {11},
  number = {3},
  pages = {238},
  url = {https://www.mdpi.com/2073-4433/11/3/238},
  doi = {10.3390/atmos11030238}
}
Dañobeitia JJ, Pouliquen S, Johannessen T, Basset A, Cannat M, Pfeil BG, Fredella MI, Materia P, Gourcuff C, Magnifico G, Delory E, del Rio Fernandez J, Rodero I, Beranzoli L, Nardello I, Iudicone D, Carval T, Gonzalez Aranda JM, Petihakis G, Blandin J, Kutsch WL, Rintala J-M, Gates AR and Favali P (2020), "Toward a Comprehensive and Integrated Strategy of the European Marine Research Infrastructures for Ocean Observations", Frontiers in Marine Science., mar, 2020. Vol. 7, pp. 180. Frontiers Media S.A..
Abstract: Research Infrastructures (RIs) are large-scale facilities encompassing instruments, resources, data and services used by the scientific community to conduct high-level research in their respective fields. The development and integration of marine environmental RIs as European Research Vessel Operators [ERVO] (2020) is the response of the European Commission (EC) to global marine challenges through research, technological development and innovation. These infrastructures (EMSO ERIC, Euro-Argo ERIC, ICOS-ERIC Marine, LifeWatch ERIC, and EMBRC-ERIC) include specialized vessels, fixed-point monitoring systems, Lagrangian floats, test facilities, genomics observatories, bio-sensing, and Virtual Research Environments (VREs), among others. Marine ecosystems are vital for life on Earth. Global climate change is progressing rapidly, and geo-hazards, such as earthquakes, volcanic eruptions, and tsunamis, cause large losses of human life and have massive worldwide socio-economic impacts. Enhancing our marine environmental monitoring and prediction capabilities will increase our ability to respond adequately to major challenges and efficiently. Collaboration among European marine RIs aligns with and has contributed to the OceanObs'19 Conference statement and the objectives of the UN Decade of Ocean Science for Sustainable Development (2021–2030). This collaboration actively participates and supports concrete actions to increase the quality and quantity of more integrated and sustained observations in the ocean worldwide. From an innovation perspective, the next decade will increasingly count on marine RIs to support the development of new technologies and their validation in the field, increasing market uptake and produce a shift in observing capabilities and strategies.
BibTeX:
@article{Danobeitia2020,
  author = {Dañobeitia, Juan Jose and Pouliquen, Sylvie and Johannessen, Truls and Basset, Alberto and Cannat, Mathilde and Pfeil, Benjamin Gerrit and Fredella, Maria Incoronata and Materia, Paola and Gourcuff, Claire and Magnifico, Giuseppe and Delory, Eric and del Rio Fernandez, Joaquin and Rodero, Ivan and Beranzoli, Laura and Nardello, Ilaria and Iudicone, Daniele and Carval, Thierry and Gonzalez Aranda, Juan M. and Petihakis, George and Blandin, Jerome and Kutsch, Werner Leo and Rintala, Janne-Markus and Gates, Andrew R. and Favali, Paolo},
  title = {Toward a Comprehensive and Integrated Strategy of the European Marine Research Infrastructures for Ocean Observations},
  journal = {Frontiers in Marine Science},
  publisher = {Frontiers Media S.A.},
  year = {2020},
  volume = {7},
  pages = {180},
  url = {https://www.frontiersin.org/article/10.3389/fmars.2020.00180/full},
  doi = {10.3389/fmars.2020.00180}
}
De Gruyter J, Weedon JT, Bazot S, Dauwe S, Fernandez-Garberí P-R, Geisen S, De La Motte LG, Heinesch B, Janssens IA, Leblans N, Manise T, Ogaya R, Löfvenius MO, Peñuelas J, Sigurdsson BD, Vincent G and Verbruggen E (2020), "Patterns of local, intercontinental and interseasonal variation of soil bacterial and eukaryotic microbial communities", FEMS Microbiology Ecology., mar, 2020. Vol. 96(3)
Abstract: Although ongoing research has revealed some of the main drivers behind global spatial patterns of microbial communities, spatio-temporal dynamics of these communities still remain largely unexplored. Here, we investigate spatio-temporal variability of both bacterial and eukaryotic soil microbial communities at local and intercontinental scales. We compare how temporal variation in community composition scales with spatial variation in community composition, and explore the extent to which bacteria, protists, fungi and metazoa have similar patterns of temporal community dynamics. All soil microbial groups displayed a strong correlation between spatial distance and community dissimilarity, which was related to the ratio of organism to sample size. Temporal changes were variable, ranging from equal to local between-sample variation, to as large as that between communities several thousand kilometers apart. Moreover, significant correlations were found between bacterial and protist communities, as well as between protist and fungal communities, indicating that these microbial groups change in tandem, potentially driven by interactions between them. We conclude that temporal variation can be considerable in soil microbial communities, and that future studies need to consider temporal variation in order to reliably capture all drivers of soil microbiome changes.
BibTeX:
@article{DeGruyter2020,
  author = {De Gruyter, Johan and Weedon, James T and Bazot, Stéphane and Dauwe, Steven and Fernandez-Garberí, Pere-Roc and Geisen, Stefan and De La Motte, Louis Gourlez and Heinesch, Bernard and Janssens, Ivan A and Leblans, Niki and Manise, Tanguy and Ogaya, Romà and Löfvenius, Mikaell Ottosson and Peñuelas, Josep and Sigurdsson, Bjarni D and Vincent, Gaëlle and Verbruggen, Erik},
  title = {Patterns of local, intercontinental and interseasonal variation of soil bacterial and eukaryotic microbial communities},
  journal = {FEMS Microbiology Ecology},
  year = {2020},
  volume = {96},
  number = {3},
  url = {https://academic.oup.com/femsec/article/doi/10.1093/femsec/fiaa018/5719567},
  doi = {10.1093/femsec/fiaa018}
}
Dobiʼnski W (2020), "Permafrost active layer", Earth-Science Reviews. Vol. 208(May)
Abstract: This article discusses the properties and occurrence of an active layer (AL) in the near-surface of the lithosphere in glacial and periglacial environments. This layer shows a seasonal variability in temperature, as a result of the climate. The AL, as classically understood, seasonally thaws and freezes, while in glacial environments it usually only reaches 0 °C. The definition of AL is currently not consistent with the definition of permafrost, even though both concepts usually appear linked. For these terms to be comparable, both should be defined based on temperature variability and not exclusively on phase change. Thus, the AL would be described not only as the upper section of perennially frozen ground presenting seasonal thaw-freeze cycles (# 1) but as a layer presenting a seasonal variation in temperature (# 2). Classical active layer can be thawed to a depth of approximately 2–8 cm, the thickest AL reaches over 20 m. In the particularly favorable conditions AL might be completely absent with the permafrost beginning at the ground surface. In glacial and sub-marine permafrost environments, the AL includes a layer of liquid water that seasonally accompanies the permafrost. Glaciers and ice sheets are usually devoid of the classical AL. In both cases, the AL is usually horizontal, but in specific terrains such as sea shore cliffs or karst environments, the AL may have a vertical course and may even be reversed. Both AL and permafrost are common in other frozen bodies in the solar system, differing mainly in their thermal character.
BibTeX:
@article{Dobinski2020,
  author = {Dobiʼnski, Wojciech},
  title = {Permafrost active layer},
  journal = {Earth-Science Reviews},
  year = {2020},
  volume = {208},
  number = {May},
  doi = {10.1016/j.earscirev.2020.103301}
}
Doney SC, Busch DS, Cooley SR and Kroeker KJ (2020), "The Impacts of Ocean Acidification on Marine Ecosystems and Reliant Human Communities", Annual Review of Environment and Resources., oct, 2020. Vol. 45(1) Annual Reviews.
Abstract: Rising atmospheric carbon dioxide (CO 2 ) levels, from fossil fuel combustion and deforestation, along with agriculture and land-use practices are causing wholesale increases in seawater CO 2 and inorganic carbon levels; reductions in pH; and alterations in acid-base chemistry of estuarine, coastal, and surface open-ocean waters. On the basis of laboratory experiments and field studies of naturally elevated CO 2 marine environments, widespread biological impacts of human-driven ocean acidification have been posited, ranging from changes in organism physiology and population dynamics to altered communities and ecosystems. Acidification, in conjunction with other climate change–related environmental stresses, particularly under future climate change and further elevated atmospheric CO 2 levels, potentially puts at risk many of the valuable ecosystem services that the ocean provides to society, such as fisheries, aquaculture, and shoreline protection. This review emphasizes both current scientific understanding and knowledge gaps, highlighting directions for future research and recognizing the information needs of policymakers and stakeholders. Expected final online publication date for the Annual Review of Environment and Resources, Volume 45 is October 19, 2020. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
BibTeX:
@article{Doney2020,
  author = {Doney, Scott C. and Busch, D. Shallin and Cooley, Sarah R. and Kroeker, Kristy J.},
  title = {The Impacts of Ocean Acidification on Marine Ecosystems and Reliant Human Communities},
  journal = {Annual Review of Environment and Resources},
  publisher = {Annual Reviews},
  year = {2020},
  volume = {45},
  number = {1},
  doi = {10.1146/annurev-environ-012320-083019}
}
Eller CB, Rowland L, Mencuccini M, Rosas T, Williams K, Harper A, Medlyn BE, Wagner Y, Klein T, Teodoro GS, Oliveira RS, Matos IS, Rosado BH, Fuchs K, Wohlfahrt G, Montagnani L, Meir P, Sitch S and Cox PM (2020), "Stomatal optimization based on xylem hydraulics (SOX) improves land surface model simulation of vegetation responses to climate", New Phytologist., jun, 2020. Vol. 226(6), pp. 1622-1637. Blackwell Publishing Ltd.
Abstract: Land surface models (LSMs) typically use empirical functions to represent vegetation responses to soil drought. These functions largely neglect recent advances in plant ecophysiology that link xylem hydraulic functioning with stomatal responses to climate. We developed an analytical stomatal optimization model based on xylem hydraulics (SOX) to predict plant responses to drought. Coupling SOX to the Joint UK Land Environment Simulator (JULES) LSM, we conducted a global evaluation of SOX against leaf- and ecosystem-level observations. SOX simulates leaf stomatal conductance responses to climate for woody plants more accurately and parsimoniously than the existing JULES stomatal conductance model. An ecosystem-level evaluation at 70 eddy flux sites shows that SOX decreases the sensitivity of gross primary productivity (GPP) to soil moisture, which improves the model agreement with observations and increases the predicted annual GPP by 30% in relation to JULES. SOX decreases JULES root-mean-square error in GPP by up to 45% in evergreen tropical forests, and can simulate realistic patterns of canopy water potential and soil water dynamics at the studied sites. SOX provides a parsimonious way to incorporate recent advances in plant hydraulics and optimality theory into LSMs, and an alternative to empirical stress factors.
BibTeX:
@article{Eller2020,
  author = {Eller, Cleiton B. and Rowland, Lucy and Mencuccini, Maurizio and Rosas, Teresa and Williams, Karina and Harper, Anna and Medlyn, Belinda E. and Wagner, Yael and Klein, Tamir and Teodoro, Grazielle S. and Oliveira, Rafael S. and Matos, Ilaine S. and Rosado, Bruno H.P. and Fuchs, Kathrin and Wohlfahrt, Georg and Montagnani, Leonardo and Meir, Patrick and Sitch, Stephen and Cox, Peter M.},
  title = {Stomatal optimization based on xylem hydraulics (SOX) improves land surface model simulation of vegetation responses to climate},
  journal = {New Phytologist},
  publisher = {Blackwell Publishing Ltd},
  year = {2020},
  volume = {226},
  number = {6},
  pages = {1622--1637},
  doi = {10.1111/nph.16419}
}
El-Madany TS, Carrara A, Martín MP, Moreno G, Kolle O, Pacheco-Labrador J, Weber U, Wutzler T, Reichstein M and Migliavacca M (2020), "Drought and heatwave impacts on semi-arid ecosystems' carbon fluxes along a precipitation gradient", Philosophical Transactions of the Royal Society B: Biological Sciences., oct, 2020. Vol. 375(1810), pp. 20190519.
Abstract: The inter-annual variability (IAV) of the terrestrial carbon cycle is tightly linked to the variability of semi-arid ecosystems. Thus, it is of utmost importance to understand what the main meteorological drivers for the IAV of such ecosystems are, and how they respond to extreme events such as droughts and heatwaves. To shed light onto these questions, we analyse the IAV of carbon fluxes, its relation with meteorological variables, and the impact of compound drought and heatwave on the carbon cycle of two similar ecosystems, along a precipitation gradient. A four-year long dataset from 2016 to 2019 was used for the FLUXNET sites ES-LMa and ES-Abr, located in central (39°56'25″ N 5°46'28″ W) and southeastern (38°42'6″ N 6°47'9″ W) Spain. We analyse the physiological impact of compound drought and heatwave on the dominant tree species, Quercus ilex. Our results show that the gross primary productivity of the wetter ecosystem was less sensitive to changes in soil water content, compared to the dryer site. Still, the wetter ecosystem was a source of CO 2 each year, owing to large ecosystem respiration during summer; while the dry site turned into a CO 2 sink during wet years. Overall, the impact of the summertime compound event on annual CO 2 fluxes was marginal at both sites, compared to drought events during spring or autumn. This highlights that drought timing is crucial to determine the annual carbon fluxes in these semi-arid ecosystems.
BibTeX:
@article{ElMadany2020,
  author = {El-Madany, Tarek S. and Carrara, Arnaud and Martín, M. Pilar and Moreno, Gerardo and Kolle, Olaf and Pacheco-Labrador, Javier and Weber, Ulrich and Wutzler, Thomas and Reichstein, Markus and Migliavacca, Mirco},
  title = {Drought and heatwave impacts on semi-arid ecosystems' carbon fluxes along a precipitation gradient},
  journal = {Philosophical Transactions of the Royal Society B: Biological Sciences},
  year = {2020},
  volume = {375},
  number = {1810},
  pages = {20190519},
  url = {https://royalsocietypublishing.org/doi/10.1098/rstb.2019.0519},
  doi = {10.1098/rstb.2019.0519}
}
Fersch B, Senatore A, Adler B, Arnault J, Mauder M, Schneider K, Völksch I and Kunstmann H (2020), "High-resolution fully coupled atmospheric-hydrological modeling: A cross-compartment regional water and energy cycle evaluation", Hydrology and Earth System Sciences. Vol. 24(5), pp. 2457-2481.
Abstract: The land surface and the atmospheric boundary layer are closely intertwined with respect to the exchange of water, trace gases, and energy. Nonlinear feedback and scaledependent mechanisms are obvious by observations and theories. Modeling instead is often narrowed to single compartments of the terrestrial system or bound to traditional viewpoints of definite scientific disciplines. Coupled terrestrial hydrometeorological modeling systems attempt to overcome these limitations to achieve a better integration of the processes relevant for regional climate studies and local-area weather prediction. This study examines the ability of the hydrologically enhanced version of the Weather Research and Forecasting model (WRF-Hydro) to reproduce the regional water cycle by means of a two-way coupled approach and assesses the impact of hydrological coupling with respect to a traditional regional atmospheric model setting. It includes the observation-based calibration of the hydrological model component (offline WRF-Hydro) and a comparison of the classic WRF and the fully coupled WRFHydro models both with identically calibrated parameter settings for the land surface model (Noah-Multiparametrization; Noah-MP). The simulations are evaluated based on extensive observations at the Terrestrial Environmental Observatories (TERENO) Pre-Alpine Observatory for the Ammer (600 km2) and Rott (55 km2) river catchments in southern Germany, covering a 5-month period (June-October 2016). The sensitivity of seven land surface parameters is tested using the Latin-Hypercube-One-factor-At-a-Time (LH-OAT) method, and six sensitive parameters are subsequently optimized for six different subcatchments, using the modelindependent Parameter Estimation and Uncertainty Analysis software (PEST). The calibration of the offline WRF-Hydro gives Nash-Sutcliffe efficiencies between 0.56 and 0.64 and volumetric efficiencies between 0.46 and 0.81 for the six subcatchments. The comparison of the classic WRF and fully coupled WRF-Hydro models, both using the calibrated parameters from the offline model, shows only tiny alterations for radiation and precipitation but considerable changes for moisture and heat fluxes. By comparison with TERENO Pre- Alpine Observatory measurements, the fully coupled model slightly outperforms the classic WRF model with respect to evapotranspiration, sensible and ground heat flux, the nearsurface mixing ratio, temperature, and boundary layer profiles of air temperature. The subcatchment-based water budgets show uniformly directed variations for evapotranspiration, infiltration excess and percolation, whereas soil moisture and precipitation change randomly.
BibTeX:
@article{Fersch2020,
  author = {Fersch, Benjamin and Senatore, Alfonso and Adler, Bianca and Arnault, Joel and Mauder, Matthias and Schneider, Katrin and Völksch, Ingo and Kunstmann, Harald},
  title = {High-resolution fully coupled atmospheric-hydrological modeling: A cross-compartment regional water and energy cycle evaluation},
  journal = {Hydrology and Earth System Sciences},
  year = {2020},
  volume = {24},
  number = {5},
  pages = {2457--2481},
  doi = {10.5194/hess-24-2457-2020}
}
Fisher JB, Lee B, Purdy AJ, Halverson GH, Dohlen MB, Cawse-Nicholson K, Wang A, Anderson RG, Aragon B, Arain MA, Baldocchi DD, Baker JM, Barral H, Bernacchi CJ, Bernhofer C, Biraud SC, Bohrer G, Brunsell N, Cappelaere B, Castro-Contreras S, Chun J, Conrad BJ, Cremonese E, Demarty J, Desai AR, De Ligne A, Foltýnová L, Goulden ML, Griffis TJ, Grünwald T, Johnson MS, Kang M, Kelbe D, Kowalska N, Lim JH, Maïnassara I, McCabe MF, Missik JEC, Mohanty BP, Moore CE, Morillas L, Morrison R, Munger JW, Posse G, Richardson AD, Russell ES, Ryu Y, Sanchez-Azofeifa A, Schmidt M, Schwartz E, Sharp I, Šigut L, Tang Y, Hulley G, Anderson M, Hain C, French A, Wood E and Hook S (2020), "ECOSTRESS: NASA's Next Generation Mission to Measure Evapotranspiration From the International Space Station", Water Resources Research. Vol. 56(4), pp. 1-20.
Abstract: The ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) was launched to the International Space Station on 29 June 2018 by the National Aeronautics and Space Administration (NASA). The primary science focus of ECOSTRESS is centered on evapotranspiration (ET), which is produced as Level-3 (L3) latent heat flux (LE) data products. These data are generated from the Level-2 land surface temperature and emissivity product (L2_LSTE), in conjunction with ancillary surface and atmospheric data. Here, we provide the first validation (Stage 1, preliminary) of the global ECOSTRESS clear-sky ET product (L3_ET_PT-JPL, Version 6.0) against LE measurements at 82 eddy covariance sites around the world. Overall, the ECOSTRESS ET product performs well against the site measurements (clear-sky instantaneous/time of overpass: r2 = 0.88; overall bias = 8%; normalized root-mean-square error, RMSE = 6%). ET uncertainty was generally consistent across climate zones, biome types, and times of day (ECOSTRESS samples the diurnal cycle), though temperate sites are overrepresented. The 70-m-high spatial resolution of ECOSTRESS improved correlations by 85%, and RMSE by 62%, relative to 1-km pixels. This paper serves as a reference for the ECOSTRESS L3 ET accuracy and Stage 1 validation status for subsequent science that follows using these data.
BibTeX:
@article{Fisher2020,
  author = {Fisher, Joshua B and Lee, Brian and Purdy, Adam J and Halverson, Gregory H and Dohlen, Matthew B and Cawse-Nicholson, Kerry and Wang, Audrey and Anderson, Ray G and Aragon, Bruno and Arain, M Altaf and Baldocchi, Dennis D and Baker, John M and Barral, Hélène and Bernacchi, Carl J and Bernhofer, Christian and Biraud, Sébastien C and Bohrer, Gil and Brunsell, Nathaniel and Cappelaere, Bernard and Castro-Contreras, Saulo and Chun, Junghwa and Conrad, Bryan J and Cremonese, Edoardo and Demarty, Jérôme and Desai, Ankur R and De Ligne, Anne and Foltýnová, Lenka and Goulden, Michael L and Griffis, Timothy J and Grünwald, Thomas and Johnson, Mark S and Kang, Minseok and Kelbe, Dave and Kowalska, Natalia and Lim, Jong Hwan and Maïnassara, Ibrahim and McCabe, Matthew F and Missik, Justine E C and Mohanty, Binayak P and Moore, Caitlin E and Morillas, Laura and Morrison, Ross and Munger, J William and Posse, Gabriela and Richardson, Andrew D and Russell, Eric S and Ryu, Youngryel and Sanchez-Azofeifa, Arturo and Schmidt, Marius and Schwartz, Efrat and Sharp, Iain and Šigut, Ladislav and Tang, Yao and Hulley, Glynn and Anderson, Martha and Hain, Christopher and French, Andrew and Wood, Eric and Hook, Simon},
  title = {ECOSTRESS: NASA's Next Generation Mission to Measure Evapotranspiration From the International Space Station},
  journal = {Water Resources Research},
  year = {2020},
  volume = {56},
  number = {4},
  pages = {1--20},
  doi = {10.1029/2019WR026058}
}
Flechard CR, Ibrom A, Skiba UM, de Vries W, van Oijen M, Cameron DR, Dise NB, Korhonen JFJ, Buchmann N, Legout A, Simpson D, Sanz MJ, Aubinet M, Loustau D, Montagnani L, Neirynck J, Janssens IA, Pihlatie M, Kiese R, Siemens J, Francez A-J, Augustin J, Varlagin A, Olejnik J, Juszczak R, Aurela M, Berveiller D, Chojnicki BH, Dämmgen U, Delpierre N, Djuricic V, Drewer J, Dufrêne E, Eugster W, Fauvel Y, Fowler D, Frumau A, Granier A, Gross P, Hamon Y, Helfter C, Hensen A, Horváth L, Kitzler B, Kruijt B, Kutsch WL, Lobo-do-Vale R, Lohila A, Longdoz B, Marek MV, Matteucci G, Mitosinkova M, Moreaux V, Neftel A, Ourcival J-M, Pilegaard K, Pita G, Sanz F, Schjoerring JK, Sebastià M-T, Tang YS, Uggerud H, Urbaniak M, van Dijk N, Vesala T, Vidic S, Vincke C, Weidinger T, Zechmeister-Boltenstern S, Butterbach-Bahl K, Nemitz E and Sutton MA (2020), "Carbon-nitrogen interactions in European forests and semi-natural vegetation; Part 1: Fluxes and budgets of carbon, nitrogen and greenhouse gases from ecosystem monitoring and modelling", Biogeosciences., mar, 2020. Vol. 17(6), pp. 1583-1620.
Abstract: 3 g N mâˆ'2 yrâˆ'1. Such large levels of Nr loss likely indicate that different stages of N saturation occurred at a number of sites. The joint analysis of the C and N budgets provided further hints that N saturation could be detected in altered patterns of forest growth. Net ecosystem productivity increased with Nr deposition up to 2–2.5 g N mâˆ'2 yrâˆ'1, with large scatter associated with a wide range in carbon sequestration efficiency (CSE, defined as the NEP ∕ GPP ratio). At elevated Ndep levels ( 2.5 g N mâˆ'2 yrâˆ'1), where inorganic Nr losses were also increasingly large, NEP levelled off and then decreased. The apparent increase in NEP at low to intermediate Ndep levels was partly the result of geographical cross-correlations between Ndep and climate, indicating that the actual mean dC∕dN response at individual sites was significantly lower than would be suggested by a simple, straightforward regression of NEP vs. Ndep.]]
BibTeX:
@article{Flechard2020a,
  author = {Flechard, Chris R and Ibrom, Andreas and Skiba, Ute M and de Vries, Wim and van Oijen, Marcel and Cameron, David R and Dise, Nancy B and Korhonen, Janne F J and Buchmann, Nina and Legout, Arnaud and Simpson, David and Sanz, Maria J and Aubinet, Marc and Loustau, Denis and Montagnani, Leonardo and Neirynck, Johan and Janssens, Ivan A and Pihlatie, Mari and Kiese, Ralf and Siemens, Jan and Francez, André-Jean and Augustin, Jürgen and Varlagin, Andrej and Olejnik, Janusz and Juszczak, Radosław and Aurela, Mika and Berveiller, Daniel and Chojnicki, Bogdan H and Dämmgen, Ulrich and Delpierre, Nicolas and Djuricic, Vesna and Drewer, Julia and Dufrêne, Eric and Eugster, Werner and Fauvel, Yannick and Fowler, David and Frumau, Arnoud and Granier, André and Gross, Patrick and Hamon, Yannick and Helfter, Carole and Hensen, Arjan and Horváth, László and Kitzler, Barbara and Kruijt, Bart and Kutsch, Werner L and Lobo-do-Vale, Raquel and Lohila, Annalea and Longdoz, Bernard and Marek, Michal V and Matteucci, Giorgio and Mitosinkova, Marta and Moreaux, Virginie and Neftel, Albrecht and Ourcival, Jean-Marc and Pilegaard, Kim and Pita, Gabriel and Sanz, Francisco and Schjoerring, Jan K and Sebastià, Maria-Teresa and Tang, Y Sim and Uggerud, Hilde and Urbaniak, Marek and van Dijk, Netty and Vesala, Timo and Vidic, Sonja and Vincke, Caroline and Weidinger, Tamás and Zechmeister-Boltenstern, Sophie and Butterbach-Bahl, Klaus and Nemitz, Eiko and Sutton, Mark A},
  title = {Carbon-nitrogen interactions in European forests and semi-natural vegetation; Part 1: Fluxes and budgets of carbon, nitrogen and greenhouse gases from ecosystem monitoring and modelling},
  journal = {Biogeosciences},
  year = {2020},
  volume = {17},
  number = {6},
  pages = {1583--1620},
  url = {https://www.biogeosciences.net/17/1583/2020/},
  doi = {10.5194/bg-17-1583-2020}
}
Flechard CR, van Oijen M, Cameron DR, de Vries W, Ibrom A, Buchmann N, Dise NB, Janssens IA, Neirynck J, Montagnani L, Varlagin A, Loustau D, Legout A, Ziembliʼnska K, Aubinet M, Aurela M, Chojnicki BH, Drewer J, Eugster W, Francez A-J, Juszczak R, Kitzler B, Kutsch WL, Lohila A, Longdoz B, Matteucci G, Moreaux V, Neftel A, Olejnik J, Sanz MJ, Siemens J, Vesala T, Vincke C, Nemitz E, Zechmeister-Boltenstern S, Butterbach-Bahl K, Skiba UM and Sutton MA (2020), "Carbon-nitrogen interactions in European forests and semi-natural vegetation; Part 2: Untangling climatic, edaphic, management and nitrogen deposition effects on carbon sequestration potentials", Biogeosciences., mar, 2020. Vol. 17(6), pp. 1621-1654.
Abstract: 2.5–3 g N mâˆ'2 yrâˆ'1) but accompanied by increasingly large ecosystem N losses by leaching and gaseous emissions. The reduced increase in productivity per unit N deposited at high Ndep levels implies that the forecast increased Nr emissions and increased Ndep levels in large areas of Asia may not positively impact the continent's forest CO2 sink. The large level of unexplained variability in observed carbon sequestration efficiency (CSE) across sites further adds to the uncertainty in the dC∕dN response.]]
BibTeX:
@article{Flechard2020,
  author = {Flechard, Chris R and van Oijen, Marcel and Cameron, David R and de Vries, Wim and Ibrom, Andreas and Buchmann, Nina and Dise, Nancy B and Janssens, Ivan A and Neirynck, Johan and Montagnani, Leonardo and Varlagin, Andrej and Loustau, Denis and Legout, Arnaud and Ziembliʼnska, Klaudia and Aubinet, Marc and Aurela, Mika and Chojnicki, Bogdan H and Drewer, Julia and Eugster, Werner and Francez, André-Jean and Juszczak, Radosław and Kitzler, Barbara and Kutsch, Werner L and Lohila, Annalea and Longdoz, Bernard and Matteucci, Giorgio and Moreaux, Virginie and Neftel, Albrecht and Olejnik, Janusz and Sanz, Maria J and Siemens, Jan and Vesala, Timo and Vincke, Caroline and Nemitz, Eiko and Zechmeister-Boltenstern, Sophie and Butterbach-Bahl, Klaus and Skiba, Ute M and Sutton, Mark A},
  title = {Carbon-nitrogen interactions in European forests and semi-natural vegetation; Part 2: Untangling climatic, edaphic, management and nitrogen deposition effects on carbon sequestration potentials},
  journal = {Biogeosciences},
  year = {2020},
  volume = {17},
  number = {6},
  pages = {1621--1654},
  url = {https://www.biogeosciences.net/17/1621/2020/},
  doi = {10.5194/bg-17-1621-2020}
}
Ford DA (2020), "Assessing the role and consistency of satellite observation products in global physical–biogeochemical ocean reanalysis", Ocean Science., jul, 2020. Vol. 16(4), pp. 875-893. Copernicus GmbH.
Abstract: textlessptextgreatertextless![CDATA[Abstract. As part of the European Space Agency's Climate Change Initiative, new sets of satellite observation products have been produced for essential climate variables including ocean colour, sea surface temperature, sea level, and sea ice. These new products have been assimilated into a global physical–biogeochemical ocean model to create a set of 13-year reanalyses at 1∘ resolution and 3-year reanalyses at 1∕4∘ resolution. In a series of experiments, the variables were assimilated individually and in combination in order to assess their consistency from a data assimilation perspective. The satellite products, and the reanalyses assimilating them, were found to be consistent in their representation of spatial features such as fronts, sea ice extent, and bloom activity. Assimilating multiple variables together often resulted in larger mean increments for a variable than assimilating it individually, providing information about model biases and compensating errors which could be addressed in the future development of the model and assimilation scheme. Sea surface fugacity of carbon dioxide had lower errors against independent observations in the higher-resolution simulations and was improved by assimilating ocean colour or sea ice concentration, but it was degraded by assimilating sea surface temperature or sea level anomaly. Phytoplankton biomass correlated more strongly with net air–sea heat fluxes in the reanalyses than chlorophyll concentration did, and the correlation was weakened by assimilating ocean colour data, suggesting that studies of phytoplankton bloom initiation based solely on chlorophyll data may not provide a full understanding of the underlying processes.]]textgreatertextless/ptextgreater
BibTeX:
@article{Ford2020,
  author = {Ford, David Andrew},
  title = {Assessing the role and consistency of satellite observation products in global physical–biogeochemical ocean reanalysis},
  journal = {Ocean Science},
  publisher = {Copernicus GmbH},
  year = {2020},
  volume = {16},
  number = {4},
  pages = {875--893},
  url = {https://os.copernicus.org/articles/16/875/2020/},
  doi = {10.5194/os-16-875-2020}
}
Fourrier M, Coppola L, Claustre H, D'Ortenzio F, Sauzède R and Gattuso J-P (2020), "A Regional Neural Network Approach to Estimate Water-Column Nutrient Concentrations and Carbonate System Variables in the Mediterranean Sea: CANYON-MED", Frontiers in Marine Science., aug, 2020. Vol. 7
Abstract: A regional neural network-based method, “CANYON-MED” is developed to estimate nutrients and carbonate system variables specifically in the Mediterranean Sea over the water column from pressure, temperature, salinity, and oxygen together with geolocation and date of sampling. Six neural network ensembles were developed, one for each variable (i.e., three macronutrients: nitrates (NO 3 - ), phosphates (PO 4 3 - ) and silicates (SiOH 4 ), and three carbonate system variables: pH on the total scale (pH T ), total alkalinity ( A T ), and dissolved inorganic carbon or total carbon ( C T ), trained using a specific quality-controlled dataset of reference “bottle” data in the Mediterranean Sea. This dataset is representative of the peculiar conditions of this semi-enclosed sea, as opposed to the global ocean. For each variable, the neural networks were trained on 80% of the data chosen randomly and validated using the remaining 20%. CANYON-MED retrieved the variables with good accuracies (Root Mean Squared Error): 0.78 μmol.kg –1 for NO 3 - , 0.043 μmol.kg –1 for PO 4 3 - and 0.71 μmol.kg –1 for Si(OH) 4 , 0.014 units for pH T , 13 μmol.kg –1 for A T and 12 μmol.kg –1 for C T . A second validation on the ANTARES independent time series confirmed the method's applicability in the Mediterranean Sea. After comparison to other existing methods to estimate nutrients and carbonate system variables, CANYON-MED stood out as the most robust, using the aforementioned inputs. The application of CANYON-MED on the Mediterranean Sea data from autonomous observing systems (integrated network of Biogeochemical-Argo floats, Eulerian moorings and ocean gliders measuring hydrological properties together with oxygen concentration) could have a wide range of applications. These include data quality control or filling gaps in time series, as well as biogeochemical data assimilation and/or the initialization and validation of regional biogeochemical models still lacking crucial reference data. Matlab and R code are available at https:// github.com/MarineFou/CANYON-MED/ .
BibTeX:
@article{Fourrier2020,
  author = {Fourrier, Marine and Coppola, Laurent and Claustre, Hervé and D'Ortenzio, Fabrizio and Sauzède, Raphaëlle and Gattuso, Jean-Pierre},
  title = {A Regional Neural Network Approach to Estimate Water-Column Nutrient Concentrations and Carbonate System Variables in the Mediterranean Sea: CANYON-MED},
  journal = {Frontiers in Marine Science},
  year = {2020},
  volume = {7},
  url = {https://www.frontiersin.org/articles/10.3389/fmars.2020.00620/full},
  doi = {10.3389/fmars.2020.00620}
}
Fu Z, Ciais P, Bastos A, Stoy PC, Yang H, Green JK, Wang B, Yu K, Huang Y, Knohl A, Šigut L, Gharun M, Cuntz M, Arriga N, Roland M, Peichl M, Migliavacca M, Cremonese E, Varlagin A, Brümmer C, Gourlez de la Motte L, Fares S, Buchmann N, El-Madany TS, Pitacco A, Vendrame N, Li Z, Vincke C, Magliulo E and Koebsch F (2020), "Sensitivity of gross primary productivity to climatic drivers during the summer drought of 2018 in Europe", Philosophical Transactions of the Royal Society B: Biological Sciences., oct, 2020. Vol. 375(1810), pp. 20190747.
Abstract: In summer 2018, Europe experienced a record drought, but it remains unknown how the drought affected ecosystem carbon dynamics. Using observations from 34 eddy covariance sites in different biomes across Europe, we studied the sensitivity of gross primary productivity (GPP) to environmental drivers during the summer drought of 2018 versus the reference summer of 2016. We found a greater drought-induced decline of summer GPP in grasslands (−38%) than in forests (−10%), which coincided with reduced evapotranspiration and soil water content (SWC). As compared to the ‘normal year' of 2016, GPP in different ecosystems exhibited more negative sensitivity to summer air temperature (Ta) but stronger positive sensitivity to SWC during summer drought in 2018, that is, a stronger reduction of GPP with soil moisture deficit. We found larger negative effects of Ta and vapour pressure deficit (VPD) but a lower positive effect of photosynthetic photon flux density on GPP in 2018 compared to 2016, which contributed to reduced summer GPP in 2018. Our results demonstrate that high temperature-induced increases in VPD and decreases in SWC aggravated drought impacts on GPP.
BibTeX:
@article{Fu2020,
  author = {Fu, Zheng and Ciais, Philippe and Bastos, Ana and Stoy, Paul C. and Yang, Hui and Green, Julia K. and Wang, Bingxue and Yu, Kailiang and Huang, Yuanyuan and Knohl, Alexander and Šigut, Ladislav and Gharun, Mana and Cuntz, Matthias and Arriga, Nicola and Roland, Marilyn and Peichl, Matthias and Migliavacca, Mirco and Cremonese, Edoardo and Varlagin, Andrej and Brümmer, Christian and Gourlez de la Motte, Louis and Fares, Silvano and Buchmann, Nina and El-Madany, Tarek S. and Pitacco, Andrea and Vendrame, Nadia and Li, Zhaolei and Vincke, Caroline and Magliulo, Enzo and Koebsch, Franziska},
  title = {Sensitivity of gross primary productivity to climatic drivers during the summer drought of 2018 in Europe},
  journal = {Philosophical Transactions of the Royal Society B: Biological Sciences},
  year = {2020},
  volume = {375},
  number = {1810},
  pages = {20190747},
  url = {https://royalsocietypublishing.org/doi/10.1098/rstb.2019.0747},
  doi = {10.1098/rstb.2019.0747}
}
Gallego MA, Timmermann A, Friedrich T and Zeebe RE (2020), "Anthropogenic Intensification of Surface Ocean Interannual pCO textlesssubtextgreater2textless/subtextgreater Variability", Geophysical Research Letters., jul, 2020. Vol. 47(13) Blackwell Publishing Ltd.
Abstract: We use several global coupled atmosphere-ocean-biogeochemistry models from the Coupled Model Intercomparison Project (CMIP5) to show that the global interannual variability of the sea surface pCO2 (calculated as 1σ) will increase by ∼64 ± 20% by 2040–2090 relative to the beginning of the industrial revolution under the RCP8.5 scenario. All models agree that the increase in variability is a consequence of a larger background pCO2 and a lower buffering capacity that enhance the response of pCO2 to the fluctuations of surface temperature (T) and dissolved inorganic carbon (DIC). The most skillful group of models under present-day conditions shows a future global decrease in DIC fluctuations that will weaken the pCO2 interannual variability (IAV). The remaining uncertainties in the projected evolution of pCO2 variability regionally highlight the need for continuous carbon monitoring programs which will contribute to a better understanding of the oceanic carbon sink's response to increased green house emissions.
BibTeX:
@article{Gallego2020,
  author = {Gallego, M. Angeles and Timmermann, Axel and Friedrich, Tobias and Zeebe, Richard E.},
  title = {Anthropogenic Intensification of Surface Ocean Interannual pCO textlesssubtextgreater2textless/subtextgreater Variability},
  journal = {Geophysical Research Letters},
  publisher = {Blackwell Publishing Ltd},
  year = {2020},
  volume = {47},
  number = {13},
  url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2020GL087104},
  doi = {10.1029/2020GL087104}
}
Gharun M, Hörtnagl L, Paul-Limoges E, Ghiasi S, Feigenwinter I, Burri S, Marquardt K, Etzold S, Zweifel R, Eugster W and Buchmann N (2020), "Physiological response of Swiss ecosystems to 2018 drought across plant types and elevation", Philosophical Transactions of the Royal Society B: Biological Sciences., oct, 2020. Vol. 375(1810), pp. 20190521.
Abstract: Using five eddy covariance flux sites (two forests and three grasslands), we investigated ecosystem physiological responses to the 2018 drought across elevational gradients in Switzerland. Flux measurements showed that at lower elevation sites (below 1000 m.a.s.l.; grassland and mixed forest) annual ecosystem productivity (GPP) declined by approximately 20% compared to the previous 2 years (2016 and 2017), which led to a reduced annual net ecosystem productivity (NEP). At the high elevation sites, however, GPP increased by approximately 14% and as a result NEP increased in the alpine and montane grasslands, but not in the subalpine coniferous forest. There, increased ecosystem respiration led to a reduced annual NEP, despite increased GPP and lengthening of the growing period. Among all ecosystems, the coniferous forest showed the most pronounced negative stomatal response to atmospheric dryness (i.e. vapour pressure deficit, VPD) that resulted in a decline in surface conductance and an increased water-use efficiency during drought. While increased temperature enhanced the water-use efficiency of both forests, de-coupling of GPP from evapotranspiration at the low-elevation grassland site negatively affected water-use efficiency due to non-stomatal reductions in photosynthesis. Our results show that hot droughts (such as in 2018) lead to different responses across plants types, and thus ecosystems. Particularly grasslands at lower elevations are the most vulnerable ecosystems to negative impacts of future drought in Switzerland.
BibTeX:
@article{Gharun2020,
  author = {Gharun, Mana and Hörtnagl, Lukas and Paul-Limoges, Eugénie and Ghiasi, Shiva and Feigenwinter, Iris and Burri, Susanne and Marquardt, Kristiina and Etzold, Sophia and Zweifel, Roman and Eugster, Werner and Buchmann, Nina},
  title = {Physiological response of Swiss ecosystems to 2018 drought across plant types and elevation},
  journal = {Philosophical Transactions of the Royal Society B: Biological Sciences},
  year = {2020},
  volume = {375},
  number = {1810},
  pages = {20190521},
  url = {https://royalsocietypublishing.org/doi/10.1098/rstb.2019.0521},
  doi = {10.1098/rstb.2019.0521}
}
Ghirardo A, Lindstein F, Koch K, Buegger F, Schloter M, Albert A, Michelsen A, Winkler JB, Schnitzler JP and Rinnan R (2020), "Origin of volatile organic compound emissions from subarctic tundra under global warming", Global Change Biology. Vol. 26(3), pp. 1908-1925.
Abstract: Warming occurs in the Arctic twice as fast as the global average, which in turn leads to a large enhancement in terpenoid emissions from vegetation. Volatile terpenoids are the main class of biogenic volatile organic compounds (VOCs) that play crucial roles in atmospheric chemistry and climate. However, the biochemical mechanisms behind the temperature-dependent increase in VOC emissions from subarctic ecosystems are largely unexplored. Using 13CO2-labeling, we studied the origin of VOCs and the carbon (C) allocation under global warming in the soil–plant–atmosphere system of contrasting subarctic heath tundra vegetation communities characterized by dwarf shrubs of the genera Salix or Betula. The projected temperature rise of the subarctic summer by 5°C was realistically simulated in sophisticated climate chambers. VOC emissions strongly depended on the plant species composition of the heath tundra. Warming caused increased VOC emissions and significant changes in the pattern of volatiles toward more reactive hydrocarbons. The 13C was incorporated to varying degrees in different monoterpene and sesquiterpene isomers. We found that de novo monoterpene biosynthesis contributed to 40%–44% (Salix) and 60%–68% (Betula) of total monoterpene emissions under the current climate, and that warming increased the contribution to 50%–58% (Salix) and 87%–95% (Betula). Analyses of above- and belowground 12/13C showed shifts of C allocation in the plant–soil systems and negative effects of warming on C sequestration by lowering net ecosystem exchange of CO2 and increasing C loss as VOCs. This comprehensive analysis provides the scientific basis for mechanistically understanding the processes controlling terpenoid emissions, required for modeling VOC emissions from terrestrial ecosystems and predicting the future chemistry of the arctic atmosphere. By changing the chemical composition and loads of VOCs into the atmosphere, the current data indicate that global warming in the Arctic may have implications for regional and global climate and for the delicate tundra ecosystems.
BibTeX:
@article{Ghirardo2020,
  author = {Ghirardo, Andrea and Lindstein, Frida and Koch, Kerstin and Buegger, Franz and Schloter, Michael and Albert, Andreas and Michelsen, Anders and Winkler, J Barbro and Schnitzler, Jörg Peter and Rinnan, Riikka},
  title = {Origin of volatile organic compound emissions from subarctic tundra under global warming},
  journal = {Global Change Biology},
  year = {2020},
  volume = {26},
  number = {3},
  pages = {1908--1925},
  doi = {10.1111/gcb.14935}
}
Gourlez de la Motte L, Beauclaire Q, Heinesch B, Cuntz M, Foltýnová L, Šigut L, Kowalska N, Manca G, Ballarin IG, Vincke C, Roland M, Ibrom A, Lousteau D, Siebicke L, Neiryink J and Longdoz B (2020), "Non-stomatal processes reduce gross primary productivity in temperate forest ecosystems during severe edaphic drought", Philosophical Transactions of the Royal Society B: Biological Sciences., oct, 2020. Vol. 375(1810), pp. 20190527.
Abstract: Severe drought events are known to cause important reductions of gross primary productivity ( GPP ) in forest ecosystems. However, it is still unclear whether this reduction originates from stomatal closure (Stomatal Origin Limitation) and/or non-stomatal limitations (Non-SOL). In this study, we investigated the impact of edaphic drought in 2018 on GPP and its origin (SOL, NSOL) using a dataset of 10 European forest ecosystem flux towers. In all stations where GPP reductions were observed during the drought, these were largely explained by declines in the maximum apparent canopy scale carboxylation rate V CMAX,APP (NSOL) when the soil relative extractable water content dropped below around 0.4. Concurrently, we found that the stomatal slope parameter ( G 1 , related to SOL) of the Medlyn et al . unified optimization model linking vegetation conductance and GPP remained relatively constant. These results strengthen the increasing evidence that NSOL should be included in stomatal conductance/photosynthesis models to faithfully simulate both GPP and water fluxes in forest ecosystems during severe drought.
BibTeX:
@article{GourlezdelaMotte2020,
  author = {Gourlez de la Motte, Louis and Beauclaire, Quentin and Heinesch, Bernard and Cuntz, Mathias and Foltýnová, Lenka and Šigut, Ladislav and Kowalska, Natalia and Manca, Giovanni and Ballarin, Ignacio Goded and Vincke, Caroline and Roland, Marilyn and Ibrom, Andreas and Lousteau, Denis and Siebicke, Lukas and Neiryink, Johan and Longdoz, Bernard},
  title = {Non-stomatal processes reduce gross primary productivity in temperate forest ecosystems during severe edaphic drought},
  journal = {Philosophical Transactions of the Royal Society B: Biological Sciences},
  year = {2020},
  volume = {375},
  number = {1810},
  pages = {20190527},
  url = {https://royalsocietypublishing.org/doi/10.1098/rstb.2019.0527},
  doi = {10.1098/rstb.2019.0527}
}
Graf A, Klosterhalfen A, Arriga N, Bernhofer C, Bogena H, Bornet F, Brüggemann N, Brümmer C, Buchmann N, Chi J, Chipeaux C, Cremonese E, Cuntz M, Dušek J, El-Madany TS, Fares S, Fischer M, Foltýnová L, Gharun M, Ghiasi S, Gielen B, Gottschalk P, Grünwald T, Heinemann G, Heinesch B, Heliasz M, Holst J, Hörtnagl L, Ibrom A, Ingwersen J, Jurasinski G, Klatt J, Knohl A, Koebsch F, Konopka J, Korkiakoski M, Kowalska N, Kremer P, Kruijt B, Lafont S, Léonard J, De Ligne A, Longdoz B, Loustau D, Magliulo V, Mammarella I, Manca G, Mauder M, Migliavacca M, Mölder M, Neirynck J, Ney P, Nilsson M, Paul-Limoges E, Peichl M, Pitacco A, Poyda A, Rebmann C, Roland M, Sachs T, Schmidt M, Schrader F, Siebicke L, Šigut L, Tuittila E-S, Varlagin A, Vendrame N, Vincke C, Völksch I, Weber S, Wille C, Wizemann H-D, Zeeman M and Vereecken H (2020), "Altered energy partitioning across terrestrial ecosystems in the European drought year 2018", Philosophical Transactions of the Royal Society B: Biological Sciences., oct, 2020. Vol. 375(1810), pp. 20190524.
Abstract: Drought and heat events, such as the 2018 European drought, interact with the exchange of energy between the land surface and the atmosphere, potentially affecting albedo, sensible and latent heat fluxes, as well as CO 2 exchange. Each of these quantities may aggravate or mitigate the drought, heat, their side effects on productivity, water scarcity and global warming. We used measurements of 56 eddy covariance sites across Europe to examine the response of fluxes to extreme drought prevailing most of the year 2018 and how the response differed across various ecosystem types (forests, grasslands, croplands and peatlands). Each component of the surface radiation and energy balance observed in 2018 was compared to available data per site during a reference period 2004–2017. Based on anomalies in precipitation and reference evapotranspiration, we classified 46 sites as drought affected. These received on average 9% more solar radiation and released 32% more sensible heat to the atmosphere compared to the mean of the reference period. In general, drought decreased net CO 2 uptake by 17.8%, but did not significantly change net evapotranspiration. The response of these fluxes differed characteristically between ecosystems; in particular, the general increase in the evaporative index was strongest in peatlands and weakest in croplands.
BibTeX:
@article{Graf2020,
  author = {Graf, Alexander and Klosterhalfen, Anne and Arriga, Nicola and Bernhofer, Christian and Bogena, Heye and Bornet, Frédéric and Brüggemann, Nicolas and Brümmer, Christian and Buchmann, Nina and Chi, Jinshu and Chipeaux, Christophe and Cremonese, Edoardo and Cuntz, Matthias and Dušek, Jiří and El-Madany, Tarek S. and Fares, Silvano and Fischer, Milan and Foltýnová, Lenka and Gharun, Mana and Ghiasi, Shiva and Gielen, Bert and Gottschalk, Pia and Grünwald, Thomas and Heinemann, Günther and Heinesch, Bernard and Heliasz, Michal and Holst, Jutta and Hörtnagl, Lukas and Ibrom, Andreas and Ingwersen, Joachim and Jurasinski, Gerald and Klatt, Janina and Knohl, Alexander and Koebsch, Franziska and Konopka, Jan and Korkiakoski, Mika and Kowalska, Natalia and Kremer, Pascal and Kruijt, Bart and Lafont, Sebastien and Léonard, Joël and De Ligne, Anne and Longdoz, Bernard and Loustau, Denis and Magliulo, Vincenzo and Mammarella, Ivan and Manca, Giovanni and Mauder, Matthias and Migliavacca, Mirco and Mölder, Meelis and Neirynck, Johan and Ney, Patrizia and Nilsson, Mats and Paul-Limoges, Eugénie and Peichl, Matthias and Pitacco, Andrea and Poyda, Arne and Rebmann, Corinna and Roland, Marilyn and Sachs, Torsten and Schmidt, Marius and Schrader, Frederik and Siebicke, Lukas and Šigut, Ladislav and Tuittila, Eeva-Stiina and Varlagin, Andrej and Vendrame, Nadia and Vincke, Caroline and Völksch, Ingo and Weber, Stephan and Wille, Christian and Wizemann, Hans-Dieter and Zeeman, Matthias and Vereecken, Harry},
  title = {Altered energy partitioning across terrestrial ecosystems in the European drought year 2018},
  journal = {Philosophical Transactions of the Royal Society B: Biological Sciences},
  year = {2020},
  volume = {375},
  number = {1810},
  pages = {20190524},
  url = {https://royalsocietypublishing.org/doi/10.1098/rstb.2019.0524},
  doi = {10.1098/rstb.2019.0524}
}
Griebel A, Metzen D, Pendall E, Burba G and Metzger S (2020), "Generating Spatially Robust Carbon Budgets From Flux Tower Observations", Geophysical Research Letters., feb, 2020. Vol. 47(3) Blackwell Publishing Ltd.
Abstract: Estimating global terrestrial productivity is typically achieved by rescaling individual flux tower measurements, traditionally assumed to represent homogeneous areas, using gridded remote sensing and climate data. Using 154 locations from the FLUXNET2015 database, we demonstrate that variations in spatial homogeneity and nonuniform sampling patterns introduce variability in carbon budget estimates that propagate to the biome scale. We propose a practical solution to quantify the variability of vegetation characteristics and uniformity of sampling patterns and, moreover, account for contributions of sampling variations over heterogeneous surfaces to carbon budgets from flux towers. Our proposed space-time-equitable budgets reduce uncertainty related to heterogeneities, allow for more accurate attribution of physiological variations in productivity trends, and provide more representative grid cell averages for linking fluxes with gridded data products.
BibTeX:
@article{Griebel2020,
  author = {Griebel, Anne and Metzen, Daniel and Pendall, Elise and Burba, George and Metzger, Stefan},
  title = {Generating Spatially Robust Carbon Budgets From Flux Tower Observations},
  journal = {Geophysical Research Letters},
  publisher = {Blackwell Publishing Ltd},
  year = {2020},
  volume = {47},
  number = {3},
  doi = {10.1029/2019GL085942}
}
Grunicke S, Queck R and Bernhofer C (2020), "Long-term investigation of forest canopy rainfall interception for a spruce stand", Agricultural and Forest Meteorology. Vol. 292-293(February), pp. 108125. Elsevier.
Abstract: The factors influencing the interception process such as the vegetation structure and the meteorological conditions, especially rainfall characteristics, are diverse and highly variable. Therefore, derivation of canopy parameters for interception modelling requires data from field experiments over a long period. In this study, we analyse long-term changes in canopy parameters and rainfall interception for an old-growth spruce stand (composed mainly of Picea abies at a continuous flux site started within EUROFLUX in 1996) within the Tharandter Wald, Southwest of Dresden, Germany. The 10-minute data from the continuous measurements of gross precipitation (P) and throughfall (TF) from 1997 to 2018 were used as follows: Rainfall events were separated by a minimum time of three hours without rainfall and divided into rainfall classes according to their total amount and intensity. Due to vegetation changes in the measuring period caused by two thinning operations, the complete study period was divided into three periods. Canopy parameters S (storage capacity), p (free throughfall coefficient) and Ps (canopy saturation point) were then generated applying a regression-based method using the relationship between P and TF. We generated parameter sets for the complete period, for the three periods reflecting the vegetation changes and for single years. These parameter sets were further tested using a regression model. The statistical analysis of the long-term data set showed that stand parameters and interception are largely influenced by vegetation changes. S and Ps decreased with each thinning. Interestingly, interception and rainfall only changed after the first thinning (increase in p, decrease in interception), indicating counter-acting factors after the second thinning, such as changes in meteorological conditions, rainfall patterns or thinning induced changes in the microclimate of the canopy. Generally, the reliability of the derived canopy parameters depends on the length of the dataset used for the regression analysis. However, the parameter sets that considered three periods produced the best model fit compared to parameter sets for the complete period or for single years. This clearly shows that model performance of statistical interception models depend on a reliable parameterisation that can be improved when taking into account changes in stand characteristics.
BibTeX:
@article{Grunicke2020,
  author = {Grunicke, Sandra and Queck, Ronald and Bernhofer, Christian},
  title = {Long-term investigation of forest canopy rainfall interception for a spruce stand},
  journal = {Agricultural and Forest Meteorology},
  publisher = {Elsevier},
  year = {2020},
  volume = {292-293},
  number = {February},
  pages = {108125},
  url = {https://doi.org/10.1016/j.agrformet.2020.108125},
  doi = {10.1016/j.agrformet.2020.108125}
}
Hari V, Rakovec O, Markonis Y, Hanel M and Kumar R (2020), "Increased future occurrences of the exceptional 2018–2019 Central European drought under global warming", Scientific Reports., dec, 2020. Vol. 10(1), pp. 12207.
BibTeX:
@article{Hari2020,
  author = {Hari, Vittal and Rakovec, Oldrich and Markonis, Yannis and Hanel, Martin and Kumar, Rohini},
  title = {Increased future occurrences of the exceptional 2018–2019 Central European drought under global warming},
  journal = {Scientific Reports},
  year = {2020},
  volume = {10},
  number = {1},
  pages = {12207},
  url = {http://www.nature.com/articles/s41598-020-68872-9},
  doi = {10.1038/s41598-020-68872-9}
}
Hartmann E, Schulz JP, Seibert R, Schmidt M, Zhang M, Luterbacher J and Tölle MH (2020), "Impact of environmental conditions on grass phenology in the regional climate model COSMO-CLM", Atmosphere. Vol. 11(12), pp. 1-19.
Abstract: Feedbacks of plant phenology to the regional climate system affect fluxes of energy, water, CO2, biogenic volatile organic compounds as well as canopy conductance, surface roughness length, and are influencing the seasonality of albedo. We performed simulations with the regional climate model COSMO-CLM (CCLM) at three locations in Germany covering the period 1999 to 2015 in order to study the sensitivity of grass phenology to different environmental conditions by implementing a new phenology module. We provide new evidence that the annually-recurring standard phenology of CCLM is improved by the new calculation of leaf area index (LAI) dependent upon surface temperature, day length, and water availability. Results with the new phenology implemented in the model show a significantly higher correlation with observations than simulations with the standard phenology. The interannual variability of LAI improves the representation of vegetation in years with extremely warm winter/spring (e.g., 2007) or extremely dry summer (e.g., 2003) and shows a more realistic growth period. The effect of the newly implemented phenology on atmospheric variables is small but tends to be positive. It should be used in future applications with an extension on more plant functional types.
BibTeX:
@article{Hartmann2020,
  author = {Hartmann, Eva and Schulz, Jan Peter and Seibert, Ruben and Schmidt, Marius and Zhang, Mingyue and Luterbacher, Jürg and Tölle, Merja H},
  title = {Impact of environmental conditions on grass phenology in the regional climate model COSMO-CLM},
  journal = {Atmosphere},
  year = {2020},
  volume = {11},
  number = {12},
  pages = {1--19},
  doi = {10.3390/atmos11121364}
}
Haverd V, Smith B, Canadell JG, Cuntz M, Mikaloff‐Fletcher S, Farquhar G, Woodgate W, Briggs PR and Trudinger CM (2020), " Higher than expected CO 2 fertilization inferred from leaf to global observations ", Global Change Biology., feb, 2020. Vol. 26(4), pp. 2390-2402. Wiley.
Abstract: Several lines of evidence point to an increase in the activity of the terrestrial biosphere over recent decades, impacting the global net land carbon sink (NLS) and its control on the growth of atmospheric carbon dioxide (ca). Global terrestrial gross primary production (GPP)—the rate of carbon fixation by photosynthesis—is esti- mated to have risen by (31 ± 5)% since 1900, but the relative contributions of differ- ent putative drivers to this increase are not well known. Here we identify the rising atmospheric CO2 concentration as the dominant driver. We reconcile leaf-level and global atmospheric constraints on trends in modeled biospheric activity to reveal a global CO2 fertilization effect on photosynthesis of 30% since 1900, or 47% for a doubling of ca above the pre-industrial level. Our historic value is nearly twice as high as current estimates (17 ± 4)% that do not use the full range of available constraints. Consequently, under a future low-emission scenario, we project a land carbon sink (174 PgC, 2006–2099) that is 57 PgC larger than if a lower CO2 fertilization effect comparable with current estimates is assumed. These findings suggest a larger ben- eficial role of the land carbon sink in modulating future excess anthropogenic CO2 consistent with the target of the Paris Agreement to stay below 2°C warming, and underscore the importance of preserving terrestrial carbon sinks.
BibTeX:
@article{Haverd2020,
  author = {Haverd, Vanessa and Smith, Benjamin and Canadell, Josep G and Cuntz, Matthias and Mikaloff‐Fletcher, Sara and Farquhar, Graham and Woodgate, William and Briggs, Peter R and Trudinger, Cathy M},
  title = { Higher than expected CO 2 fertilization inferred from leaf to global observations },
  journal = {Global Change Biology},
  publisher = {Wiley},
  year = {2020},
  volume = {26},
  number = {4},
  pages = {2390--2402},
  doi = {10.1111/gcb.14950}
}
Helbig M, Waddington JM, Alekseychik P, Amiro B, Aurela M, Barr AG, Black TA, Carey SK, Chen J, Chi J, Desai AR, Dunn A, Euskirchen ES, Flanagan LB, Friborg T, Garneau M, Grelle A, Harder S, Heliasz M, Humphreys ER, Ikawa H, Isabelle PE, Iwata H, Jassal R, Korkiakoski M, Kurbatova J, Kutzbach L, Lapshina E, Lindroth A, Löfvenius MO, Lohila A, Mammarella I, Marsh P, Moore PA, Maximov T, Nadeau DF, Nicholls EM, Nilsson MB, Ohta T, Peichl M, Petrone RM, Prokushkin A, Quinton WL, Roulet N, Runkle BRK, Sonnentag O, Strachan IB, Taillardat P, Tuittila ES, Tuovinen JP, Turner J, Ueyama M, Varlagin A, Vesala T, Wilmking M, Zyrianov V and Schulze C (2020), "The biophysical climate mitigation potential of boreal peatlands during the growing season", Environmental Research Letters. Vol. 15(10)
Abstract: Peatlands and forests cover large areas of the boreal biome and are critical for global climate regulation. They also regulate regional climate through heat and water vapour exchange with the atmosphere. Understanding how land-atmosphere interactions in peatlands differ from forests may therefore be crucial for modelling boreal climate system dynamics and for assessing climate benefits of peatland conservation and restoration. To assess the biophysical impacts of peatlands and forests on peak growing season air temperature and humidity, we analysed surface energy fluxes and albedo from 35 peatlands and 37 evergreen needleleaf forests - the dominant boreal forest type - and simulated air temperature and vapour pressure deficit (VPD) over hypothetical homogeneous peatland and forest landscapes. We ran an evapotranspiration model using land surface parameters derived from energy flux observations and coupled an analytical solution for the surface energy balance to an atmospheric boundary layer (ABL) model. We found that peatlands, compared to forests, are characterized by higher growing season albedo, lower aerodynamic conductance, and higher surface conductance for an equivalent VPD. This combination of peatland surface properties results in a ∼20% decrease in afternoon ABL height, a cooling (from 1.7 to 2.5 °C) in afternoon air temperatures, and a decrease in afternoon VPD (from 0.4 to 0.7 kPa) for peatland landscapes compared to forest landscapes. These biophysical climate impacts of peatlands are most pronounced at lower latitudes (∼45°N) and decrease toward the northern limit of the boreal biome (∼70°N). Thus, boreal peatlands have the potential to mitigate the effect of regional climate warming during the growing season. The biophysical climate mitigation potential of peatlands needs to be accounted for when projecting the future climate of the boreal biome, when assessing the climate benefits of conserving pristine boreal peatlands, and when restoring peatlands that have experienced peatland drainage and mining.
BibTeX:
@article{Helbig2020a,
  author = {Helbig, Manuel and Waddington, James M and Alekseychik, Pavel and Amiro, Brian and Aurela, Mika and Barr, Alan G and Black, T Andrew and Carey, Sean K and Chen, Jiquan and Chi, Jinshu and Desai, Ankur R and Dunn, Allison and Euskirchen, Eugenie S and Flanagan, Lawrence B and Friborg, Thomas and Garneau, Michelle and Grelle, Achim and Harder, Silvie and Heliasz, Michal and Humphreys, Elyn R and Ikawa, Hiroki and Isabelle, Pierre Erik and Iwata, Hiroki and Jassal, Rachhpal and Korkiakoski, Mika and Kurbatova, Juliya and Kutzbach, Lars and Lapshina, Elena and Lindroth, Anders and Löfvenius, Mikaell Ottosson and Lohila, Annalea and Mammarella, Ivan and Marsh, Philip and Moore, Paul A and Maximov, Trofim and Nadeau, Daniel F and Nicholls, Erin M and Nilsson, Mats B and Ohta, Takeshi and Peichl, Matthias and Petrone, Richard M and Prokushkin, Anatoly and Quinton, William L and Roulet, Nigel and Runkle, Benjamin R K and Sonnentag, Oliver and Strachan, Ian B and Taillardat, Pierre and Tuittila, Eeva Stiina and Tuovinen, Juha Pekka and Turner, Jessica and Ueyama, Masahito and Varlagin, Andrej and Vesala, Timo and Wilmking, Martin and Zyrianov, Vyacheslav and Schulze, Christopher},
  title = {The biophysical climate mitigation potential of boreal peatlands during the growing season},
  journal = {Environmental Research Letters},
  year = {2020},
  volume = {15},
  number = {10},
  doi = {10.1088/1748-9326/abab34}
}
Helbig M, Waddington JM, Alekseychik P, Amiro BD, Aurela M, Barr AG, Black TA, Blanken PD, Carey SK, Chen J, Chi J, Desai AR, Dunn A, Euskirchen ES, Flanagan LB, Forbrich I, Friborg T, Grelle A, Harder S, Heliasz M, Humphreys ER, Ikawa H, Isabelle PE, Iwata H, Jassal R, Korkiakoski M, Kurbatova J, Kutzbach L, Lindroth A, Löfvenius MO, Lohila A, Mammarella I, Marsh P, Maximov T, Melton JR, Moore PA, Nadeau DF, Nicholls EM, Nilsson MB, Ohta T, Peichl M, Petrone RM, Petrov R, Prokushkin A, Quinton WL, Reed DE, Roulet NT, Runkle BR, Sonnentag O, Strachan IB, Taillardat P, Tuittila ES, Tuovinen JP, Turner J, Ueyama M, Varlagin A, Wilmking M, Wofsy SC and Zyrianov V (2020), "Increasing contribution of peatlands to boreal evapotranspiration in a warming climate", Nature Climate Change., jun, 2020. Vol. 10(6), pp. 555-560. Nature Research.
Abstract: The response of evapotranspiration (ET) to warming is of critical importance to the water and carbon cycle of the boreal biome, a mosaic of land cover types dominated by forests and peatlands. The effect of warming-induced vapour pressure deficit (VPD) increases on boreal ET remains poorly understood because peatlands are not specifically represented as plant functional types in Earth system models. Here we show that peatland ET increases more than forest ET with increasing VPD using observations from 95 eddy covariance tower sites. At high VPD of more than 2 kPa, peatland ET exceeds forest ET by up to 30%. Future (2091–2100) mid-growing season peatland ET is estimated to exceed forest ET by over 20% in about one-third of the boreal biome for RCP4.5 and about two-thirds for RCP8.5. Peatland-specific ET responses to VPD should therefore be included in Earth system models to avoid biases in water and carbon cycle projections.
BibTeX:
@article{Helbig2020,
  author = {Helbig, Manuel and Waddington, James Michael and Alekseychik, Pavel and Amiro, Brian D. and Aurela, Mika and Barr, Alan G. and Black, T. Andrew and Blanken, Peter D. and Carey, Sean K. and Chen, Jiquan and Chi, Jinshu and Desai, Ankur R. and Dunn, Allison and Euskirchen, Eugenie S. and Flanagan, Lawrence B. and Forbrich, Inke and Friborg, Thomas and Grelle, Achim and Harder, Silvie and Heliasz, Michal and Humphreys, Elyn R. and Ikawa, Hiroki and Isabelle, Pierre Erik and Iwata, Hiroki and Jassal, Rachhpal and Korkiakoski, Mika and Kurbatova, Juliya and Kutzbach, Lars and Lindroth, Anders and Löfvenius, Mikaell Ottosson and Lohila, Annalea and Mammarella, Ivan and Marsh, Philip and Maximov, Trofim and Melton, Joe R. and Moore, Paul A. and Nadeau, Daniel F. and Nicholls, Erin M. and Nilsson, Mats B. and Ohta, Takeshi and Peichl, Matthias and Petrone, Richard M. and Petrov, Roman and Prokushkin, Anatoly and Quinton, William L. and Reed, David E. and Roulet, Nigel T. and Runkle, Benjamin R.K. and Sonnentag, Oliver and Strachan, Ian B. and Taillardat, Pierre and Tuittila, Eeva Stiina and Tuovinen, Juha Pekka and Turner, Jessica and Ueyama, Masahito and Varlagin, Andrej and Wilmking, Martin and Wofsy, Steven C. and Zyrianov, Vyacheslav},
  title = {Increasing contribution of peatlands to boreal evapotranspiration in a warming climate},
  journal = {Nature Climate Change},
  publisher = {Nature Research},
  year = {2020},
  volume = {10},
  number = {6},
  pages = {555--560},
  doi = {10.1038/s41558-020-0763-7}
}
Henley SF, Cavan EL, Fawcett SE, Kerr R, Monteiro T, Sherrell RM, Bowie AR, Boyd PW, Barnes DKA, Schloss IR, Marshall T, Flynn R and Smith S (2020), "Changing Biogeochemistry of the Southern Ocean and Its Ecosystem Implications", Frontiers in Marine Science., jul, 2020. Vol. 7, pp. 581. Frontiers Media SA.
Abstract: The Southern Ocean plays a critical role in regulating global climate as a major sink for atmospheric carbon dioxide (CO2), and in global ocean biogeochemistry by supplying nutrients to the global thermocline, thereby influencing global primary production and carbon export. Biogeochemical processes within the Southern Ocean regulate regional primary production and biological carbon uptake, primarily through iron supply, and support ecosystem functioning over a range of spatial and temporal scales. Here we assimilate existing knowledge and present new data to examine the biogeochemical cycles of iron, carbon and major nutrients, their key drivers and their responses to, and roles in, contemporary climate and environmental change. Projected increases in iron supply, coupled with increases in light availability to phytoplankton through increased near-surface stratification and longer ice-free periods, are very likely to increase primary production and carbon export around Antarctica. Biological carbon uptake is likely to increase for the Southern Ocean as a whole, whilst there is greater uncertainty around projections of primary production in the Sub-Antarctic and basin-wide changes in phytoplankton species composition, as well as their biogeochemical consequences. Phytoplankton, zooplankton, higher trophic level organisms and microbial communities are strongly influenced by Southern Ocean biogeochemistry, in particular through nutrient supply and ocean acidification. In turn, these organisms exert important controls on biogeochemistry through carbon storage and export, nutrient recycling and redistribution, and benthic-pelagic coupling. The key processes described in this paper are summarised in the graphical abstract. Climate-mediated changes in Southern Ocean biogeochemistry over the coming decades are very likely to impact primary production, sea-air CO2 exchange and ecosystem functioning within and beyond this vast and critically important ocean region.
BibTeX:
@article{Henley2020,
  author = {Henley, Sian F. and Cavan, Emma L. and Fawcett, Sarah E. and Kerr, Rodrigo and Monteiro, Thiago and Sherrell, Robert M. and Bowie, Andrew R. and Boyd, Philip W. and Barnes, David K. A. and Schloss, Irene R. and Marshall, Tanya and Flynn, Raquel and Smith, Shantelle},
  title = {Changing Biogeochemistry of the Southern Ocean and Its Ecosystem Implications},
  journal = {Frontiers in Marine Science},
  publisher = {Frontiers Media SA},
  year = {2020},
  volume = {7},
  pages = {581},
  url = {www.frontiersin.org},
  doi = {10.3389/fmars.2020.00581}
}
Hobeichi S, Abramowitz G and Evans J (2020), "Conserving Land–Atmosphere Synthesis Suite (CLASS)", Journal of Climate., mar, 2020. Vol. 33(5), pp. 1821-1844.
Abstract: Accurate estimates of terrestrial water and energy cycle components are needed to better understand climate processes and improve models' ability to simulate future change. Various observational estimates are available for the individual budget terms; however, these typically show inconsistencies when combined in a budget. In this work, a Conserving Land–Atmosphere Synthesis Suite (CLASS) of estimates of simultaneously balanced surface water and energy budget components is developed. Individual CLASS variable datasets, where possible, 1) combine a range of existing variable product estimates, and hence overcome the limitations of estimates from a single source; 2) are observationally constrained with in situ measurements; 3) have uncertainty estimates that are consistent with their agreement with in situ observations; and 4) are consistent with each other by being able to solve the water and energy budgets simultaneously. First, available datasets of a budget variable are merged by implementing a weighting method that accounts both for the ability of datasets to match in situ measurements and the error covariance between datasets. Then, the budget terms are adjusted by applying an objective variational data assimilation technique (DAT) that enforces the simultaneous closure of the surface water and energy budgets linked through the equivalence of evapotranspiration and latent heat. Comparing component estimates before and after applying the DAT against in situ measurements of energy fluxes and streamflow showed that modified estimates agree better with in situ observations across various metrics, but also revealed some inconsistencies between water budget terms in June over the higher latitudes. CLASS variable estimates are freely available via https://doi.org/10.25914/5c872258dc183.
BibTeX:
@article{Hobeichi2020,
  author = {Hobeichi, Sanaa and Abramowitz, Gab and Evans, Jason},
  title = {Conserving Land–Atmosphere Synthesis Suite (CLASS)},
  journal = {Journal of Climate},
  year = {2020},
  volume = {33},
  number = {5},
  pages = {1821--1844},
  url = {https://journals.ametsoc.org/jcli/article/33/5/1821/347131/Conserving-LandAtmosphere-Synthesis-Suite-CLASS},
  doi = {10.1175/JCLI-D-19-0036.1}
}
Horemans JA, Janssens IA, Gielen B, Roland M, Deckmyn G, Verstraeten A, Neirynck J and Ceulemans R (2020), "Weather, pollution and biotic factors drive net forest - atmosphere exchange of CO2 at different temporal scales in a temperate-zone mixed forest", AGRICULTURAL AND FOREST METEOROLOGY., sep, 2020. Vol. 291
Abstract: Understanding the drivers of net ecosystem exchange of carbon (NEE)
between forests and the atmosphere is crucial for the prediction of
future global carbon dynamics. We therefore analyzed the long-term
(1999-2014) ecosystem carbon fluxes of a mixed coniferous/deciduous
forest (Brasschaat forest) in the Campine ecoregion of Belgium. The
carbon uptake of this forest increased over the 16-year study period. By
consecutively performing time series decomposition and the statistical
technique of random forests, the correlative strength between multiple
meteorological drivers, tropospheric pollutants and biotic indices with
NEE was quantified at different time scales: i.e., long-term, seasonal
and weekly, and separately for day- and nighttime NEE fluxes. The
drivers that were most correlated with the trend in carbon sink capacity
were the increasing atmospheric CO2 level and soil recovery from
acidification. The radiation-saturated carbon uptake increased
remarkably and explained much of the long-term variability of daytime
NEE. When the long-term and seasonal variation were extracted the
remaining weekly variation in daytime NEE was most strongly correlated
with variation in the incoming radiation and cloudiness, and to a lesser
extent by variation in vapor pressure deficit. In contrast to daytime
NEE, nighttime NEE did not show a steady trend over time, but
fluctuated, peaking in 1999 and in 2011. The long-term variability in
nighttime NEE was most strongly correlated with the groundwater table
depth. Air temperature was highly correlated to the seasonal as well as
to the remaining weekly variation, i.e., after removal of the long-term
and seasonal variability, in nighttime NEE. Biotic drivers (e.g.,
quantum yield and radiation saturated carbon uptake) explained less of
the variation in NEE on a seasonal and short-term scale, but were more
important at the long term.
BibTeX:
@article{Horemans2020,
  author = {Horemans, Joanna A and Janssens, Ivan A and Gielen, Bert and Roland, Marilyn and Deckmyn, Gaby and Verstraeten, Arne and Neirynck, Johan and Ceulemans, Reinhart},
  title = {Weather, pollution and biotic factors drive net forest - atmosphere exchange of CO2 at different temporal scales in a temperate-zone mixed forest},
  journal = {AGRICULTURAL AND FOREST METEOROLOGY},
  year = {2020},
  volume = {291},
  doi = {10.1016/j.agrformet.2020.108059}
}
Hough M, McClure A, Bolduc B, Dorrepaal E, Saleska S, Klepac-Ceraj V and Rich V (2020), "Biotic and Environmental Drivers of Plant Microbiomes Across a Permafrost Thaw Gradient", Frontiers in Microbiology. Vol. 11(May), pp. 1-18.
Abstract: Plant-associated microbiomes are structured by environmental conditions and plant associates, both of which are being altered by climate change. The future structure of plant microbiomes will depend on the, largely unknown, relative importance of each. This uncertainty is particularly relevant for arctic peatlands, which are undergoing large shifts in plant communities and soil microbiomes as permafrost thaws, and are potentially appreciable sources of climate change feedbacks due to their soil carbon (C) storage. We characterized phyllosphere and rhizosphere microbiomes of six plant species, and bulk peat, across a permafrost thaw progression (from intact permafrost, to partially- and fully-thawed stages) via 16S rRNA gene amplicon sequencing. We tested the hypothesis that the relative influence of biotic versus environmental filtering (the role of plant species versus thaw-defined habitat) in structuring microbial communities would differ among phyllosphere, rhizosphere, and bulk peat. Using both abundance- and phylogenetic-based approaches, we found that phyllosphere microbial composition was more strongly explained by plant associate, with little influence of habitat, whereas in the rhizosphere, plant and habitat had similar influence. Network-based community analyses showed that keystone taxa exhibited similar patterns with stronger responses to drivers. However, plant associates appeared to have a larger influence on organisms belonging to families associated with methane-cycling than the bulk community. Putative methanogens were more strongly influenced by plant than habitat in the rhizosphere, and in the phyllosphere putative methanotrophs were more strongly influenced by plant than was the community at large. We conclude that biotic effects can be stronger than environmental filtering, but their relative importance varies among microbial groups. For most microbes in this system, biotic filtering was stronger aboveground than belowground. However, for putative methane-cyclers, plant associations have a stronger influence on community composition than environment despite major hydrological changes with thaw. This suggests that plant successional dynamics may be as important as hydrological changes in determining microbial relevance to C-cycling climate feedbacks. By partitioning the degree that plant versus environmental filtering drives microbiome composition and function we can improve our ability to predict the consequences of warming for C-cycling in other arctic areas undergoing similar permafrost thaw transitions.
BibTeX:
@article{Hough2020,
  author = {Hough, Moira and McClure, Amelia and Bolduc, Benjamin and Dorrepaal, Ellen and Saleska, Scott and Klepac-Ceraj, Vanja and Rich, Virginia},
  title = {Biotic and Environmental Drivers of Plant Microbiomes Across a Permafrost Thaw Gradient},
  journal = {Frontiers in Microbiology},
  year = {2020},
  volume = {11},
  number = {May},
  pages = {1--18},
  doi = {10.3389/fmicb.2020.00796}
}
Hrachowitz M, Stockinger M, Coenders-Gerrits M, van der Ent R, Bogena H, Lücke A and Stumpp C (2020), "Deforestation reduces the vegetation-accessible water storage in the unsaturated soil and affects catchment travel time distributions and young water fractions", Hydrology and Earth System Sciences Discussions. Vol. 2020, pp. 1-43.
BibTeX:
@article{Hrachowitz2020,
  author = {Hrachowitz, M and Stockinger, M and Coenders-Gerrits, M and van der Ent, R and Bogena, H and Lücke, A and Stumpp, C},
  title = {Deforestation reduces the vegetation-accessible water storage in the unsaturated soil and affects catchment travel time distributions and young water fractions},
  journal = {Hydrology and Earth System Sciences Discussions},
  year = {2020},
  volume = {2020},
  pages = {1--43},
  url = {https://hess.copernicus.org/preprints/hess-2020-293/},
  doi = {10.5194/hess-2020-293}
}
Huang J, Desai AR, Zhu J, Hartemink AE, Stoy PC, Loheide SP, Bogena HR, Zhang Y, Zhang Z and Arriaga F (2020), "Retrieving Heterogeneous Surface Soil Moisture at 100 m Across the Globe via Fusion of Remote Sensing and Land Surface Parameters", Frontiers in Water. Vol. 2(October)
BibTeX:
@article{Huang2020,
  author = {Huang, Jingyi and Desai, Ankur R and Zhu, Jun and Hartemink, Alfred E and Stoy, Paul C and Loheide, Steven P and Bogena, Heye R and Zhang, Yakun and Zhang, Zhou and Arriaga, Francisco},
  title = {Retrieving Heterogeneous Surface Soil Moisture at 100 m Across the Globe via Fusion of Remote Sensing and Land Surface Parameters},
  journal = {Frontiers in Water},
  year = {2020},
  volume = {2},
  number = {October},
  doi = {10.3389/frwa.2020.578367}
}
ICOS ERIC (2020), "ICOS Handbook" Helsinki , pp. 1-150. ICOS ERIC.
Abstract: This book gives a comprehensive overview of ICOS research infrastructure, for example, of its data processing and data life cycle, organisational structure and technical details about station requirements. It also describes the National Networks and the process for a country to participate in this research infrastructure. Novel in this edition, we have added those prospective member countries, Spain and Poland, that have announced their intention to join ICOS ERIC in 2020.
BibTeX:
@book{ICOS2020,
  author = {ERIC, ICOS},
  editor = {Ahlgren, Katri and Keski-Nisula, Mari},
  title = {ICOS Handbook},
  publisher = {ICOS ERIC},
  year = {2020},
  pages = {1--150},
  edition = {2020-2},
  url = {https://www.icos-cp.eu/sites/default/files/cmis/ICOS Handbook 2020.pdf}
}
Jakobi J, Huisman JA, Schrön M, Fiedler J, Brogi C, Vereecken H and Bogena HR (2020), "Error Estimation for Soil Moisture Measurements With Cosmic Ray Neutron Sensing and Implications for Rover Surveys", Frontiers in Water. Vol. 2(May), pp. 1-15.
Abstract: Cosmic ray neutron (CRN) sensing allows for non-invasive soil moisture measurements at the field scale and relies on the inverse correlation between aboveground measured epithermal neutron intensity (1 eV−100 keV) and environmental water content. The measurement uncertainty follows Poisson statistics and thus increases with decreasing neutron intensity, which corresponds to increasing soil moisture. In order to reduce measurement uncertainty, the neutron count rate is usually aggregated over 12 or 24 h time windows for stationary CRN probes. To obtain accurate soil moisture estimates with mobile CRN rover applications, the aggregation of neutron measurements is also necessary and should consider soil wetness and driving speed. To date, the optimization of spatial aggregation of mobile CRN observations in order to balance measurement accuracy and spatial resolution of soil moisture patterns has not been investigated in detail. In this work, we present and apply an easy-to-use method based on Gaussian error propagation theory for uncertainty quantification of soil moisture measurements obtained with CRN sensing. We used a 3 rd order Taylor expansion for estimating the soil moisture uncertainty from uncertainty in neutron counts and compared the results to a Monte Carlo approach with excellent agreement. Furthermore, we applied our method with selected aggregation times to investigate how CRN rover survey design affects soil moisture estimation uncertainty. We anticipate that the new approach can be used to improve the strategic planning and evaluation of CRN rover surveys based on uncertainty requirements.
BibTeX:
@article{Jakobi2020,
  author = {Jakobi, Jannis and Huisman, Johan A and Schrön, Martin and Fiedler, Justus and Brogi, Cosimo and Vereecken, Harry and Bogena, Heye R},
  title = {Error Estimation for Soil Moisture Measurements With Cosmic Ray Neutron Sensing and Implications for Rover Surveys},
  journal = {Frontiers in Water},
  year = {2020},
  volume = {2},
  number = {May},
  pages = {1--15},
  doi = {10.3389/frwa.2020.00010}
}
Janardanan R, Maksyutov S, Tsuruta A, Wang F, Tiwari YK, Valsala V, Ito A, Yoshida Y, Kaiser JW, Janssens-Maenhout G, Arshinov M, Sasakawa M, Tohjima Y, Worthy DEJ, Dlugokencky EJ, Ramonet M, Arduini J, Lavric JV, Piacentino S, Krummel PB, Langenfelds RL, Mammarella I and Matsunaga T (2020), "Country-Scale Analysis of Methane Emissions with a High-Resolution Inverse Model Using GOSAT and Surface Observations", Remote Sensing., jan, 2020. Vol. 12(3), pp. 375. MDPI AG.
Abstract: textlessptextgreaterWe employed a global high-resolution inverse model to optimize the CH4 emission using Greenhouse gas Observing Satellite (GOSAT) and surface observation data for a period from 2011–2017 for the two main source categories of anthropogenic and natural emissions. We used the Emission Database for Global Atmospheric Research (EDGAR v4.3.2) for anthropogenic methane emission and scaled them by country to match the national inventories reported to the United Nations Framework Convention on Climate Change (UNFCCC). Wetland and soil sink prior fluxes were simulated using the Vegetation Integrative Simulator of Trace gases (VISIT) model. Biomass burning prior fluxes were provided by the Global Fire Assimilation System (GFAS). We estimated a global total anthropogenic and natural methane emissions of 340.9 Tg CH4 yr−1 and 232.5 Tg CH4 yr−1, respectively. Country-scale analysis of the estimated anthropogenic emissions showed that all the top-emitting countries showed differences with their respective inventories to be within the uncertainty range of the inventories, confirming that the posterior anthropogenic emissions did not deviate from nationally reported values. Large countries, such as China, Russia, and the United States, had the mean estimated emission of 45.7 ± 8.6, 31.9 ± 7.8, and 29.8 ± 7.8 Tg CH4 yr−1, respectively. For natural wetland emissions, we estimated large emissions for Brazil (39.8 ± 12.4 Tg CH4 yr−1), the United States (25.9 ± 8.3 Tg CH4 yr−1), Russia (13.2 ± 9.3 Tg CH4 yr−1), India (12.3 ± 6.4 Tg CH4 yr−1), and Canada (12.2 ± 5.1 Tg CH4 yr−1). In both emission categories, the major emitting countries all had the model corrections to emissions within the uncertainty range of inventories. The advantages of the approach used in this study were: (1) use of high-resolution transport, useful for simulations near emission hotspots, (2) prior anthropogenic emissions adjusted to the UNFCCC reports, (3) combining surface and satellite observations, which improves the estimation of both natural and anthropogenic methane emissions over spatial scale of countries.textless/ptextgreater
BibTeX:
@article{Janardanan2020,
  author = {Janardanan, Rajesh and Maksyutov, Shamil and Tsuruta, Aki and Wang, Fenjuan and Tiwari, Yogesh K. and Valsala, Vinu and Ito, Akihiko and Yoshida, Yukio and Kaiser, Johannes W. and Janssens-Maenhout, Greet and Arshinov, Mikhail and Sasakawa, Motoki and Tohjima, Yasunori and Worthy, Douglas E. J. and Dlugokencky, Edward J. and Ramonet, Michel and Arduini, Jgor and Lavric, Jost V. and Piacentino, Salvatore and Krummel, Paul B. and Langenfelds, Ray L. and Mammarella, Ivan and Matsunaga, Tsuneo},
  title = {Country-Scale Analysis of Methane Emissions with a High-Resolution Inverse Model Using GOSAT and Surface Observations},
  journal = {Remote Sensing},
  publisher = {MDPI AG},
  year = {2020},
  volume = {12},
  number = {3},
  pages = {375},
  url = {https://www.mdpi.com/2072-4292/12/3/375},
  doi = {10.3390/rs12030375}
}
Jansen J, F. Thornton B, Cortés A, Snöälv J, Wik M, MacIntyre S and Crill PM (2020), "Drivers of diffusive CH4 emissions from shallow subarctic lakes on daily to multi-year timescales", Biogeosciences. Vol. 17(7), pp. 1911-1932.
Abstract: Lakes and reservoirs contribute to regional carbon budgets via significant emissions of climate forcing trace gases. Here, for improved modelling, we use 8 years of floating chamber measurements from three small, shallow subarctic lakes (2010-2017, n = 1306) to separate the contribution of physical and biogeochemical processes to the turbulence-driven, diffusion-limited flux of methane (CH4) on daily to multi-year timescales. Correlative data include surface water concentration measurements (2009-2017, n = 606), total water column storage (2010-2017, n = 237), and in situ meteorological observations. We used the last to compute near-surface turbulence based on similarity scaling and then applied the surface renewal model to compute gas transfer velocities. Chamber fluxes averaged 6.9±0.3 mg CH4 m-2 d-1 and gas transfer velocities (k600) averaged 4.0±0.1 cm h-1. Chamber-derived gas transfer velocities tracked the power-law wind speed relation of the model. Coefficients for the model and dissipation rates depended on shear production of turbulence, atmospheric stability, and exposure to wind. Fluxes increased with wind speed until daily average values exceeded 6.5 m s-1, at which point emissions were suppressed due to rapid water column degassing reducing the water-air concentration gradient. Arrhenius-type temperature functions of the CH4 flux (E′a = 0.90 ± 0.14eV) were robust (R2≥0.93, ptextless0.01) and also applied to the surface CH4 concentration ((E′a = 0.88 ± 0.09 eV). These results imply that emissions were strongly coupled to production and supply to the water column. Spectral analysis indicated that on timescales shorter than a month, emissions were driven by wind shear whereas on longer timescales variations in water temperature governed the flux. Long-term monitoring efforts are essential to identify distinct functional relations that govern flux variability on timescales of weather and climate change.
BibTeX:
@article{Jansen2020,
  author = {Jansen, Joachim and F. Thornton, Brett and Cortés, Alicia and Snöälv, Jo and Wik, Martin and MacIntyre, Sally and Crill, Patrick M},
  title = {Drivers of diffusive CH4 emissions from shallow subarctic lakes on daily to multi-year timescales},
  journal = {Biogeosciences},
  year = {2020},
  volume = {17},
  number = {7},
  pages = {1911--1932},
  doi = {10.5194/bg-17-1911-2020}
}
Jansen J, Thornton BF, Wik M, MacIntyre S and Crill PM (2020), "Temperature Proxies as a Solution to Biased Sampling of Lake Methane Emissions", Geophysical Research Letters. Vol. 47(14)
Abstract: Lake emissions of the climate forcing trace gas methane (CH4) are spatiotemporally variable, but biases in flux measurements arising from undersampling are poorly quantified. We use a multiyear data set (2009–2017) of ice-free CH4 emissions from three subarctic lakes obtained with bubble traps (n = 14,677), floating chambers (n = 1,306), and surface concentrations plus a gas transfer model (n = 535) to quantify these biases and evaluate corrections. Sampling primarily in warmer summer months, as is common, overestimates the ice-free season flux by a factor 1.4–1.8. Temperature proxies based on Arrhenius functions that closely fit measured fluxes (R2 ≥ 0.93) enable gap filling the colder months of the ice-free season and reduce sampling bias. Ebullition (activation energy 1.36 eV) expressed greater temperature sensitivity than diffusion (1.00 eV). Resolving seasonal and interannual variability in fluxes with proxies requires ∼135 sampling days for ebullition, and 22 and 14 days for diffusion via models and chambers, respectively.
BibTeX:
@article{Jansen2020a,
  author = {Jansen, Joachim and Thornton, Brett F and Wik, Martin and MacIntyre, Sally and Crill, Patrick M},
  title = {Temperature Proxies as a Solution to Biased Sampling of Lake Methane Emissions},
  journal = {Geophysical Research Letters},
  year = {2020},
  volume = {47},
  number = {14},
  doi = {10.1029/2020GL088647}
}
Janssens-Maenhout G, Pinty B, Dowell M, Zunker H, Andersson E, Balsamo G, Bézy J-L, Brunhes T, Bösch H, Bojkov B, Brunner D, Buchwitz M, Crisp D, Ciais P, Counet P, Dee D, Denier van der Gon H, Dolman H, Drinkwater M, Dubovik O, Engelen R, Fehr T, Fernandez V, Heimann M, Holmlund K, Houweling S, Husband R, Juvyns O, Kentarchos A, Landgraf J, Lang R, Löscher A, Marshall J, Meijer Y, Nakajima M, Palmer PI, Peylin P, Rayner P, Scholze M, Sierk B, Tamminen J and Veefkind P (2020), "Towards an operational anthropogenic CO2 emissions monitoring and verification support capacity", Bulletin of the American Meteorological Society., feb, 2020. Vol. preprint(2020)
Abstract: Under the Paris Agreement progress of emission reduction efforts is tracked on the basis of regular updates to national Greenhouse Gas (GHG) inventories, referred to as bottom-up estimates. However, only top-down atmospheric measurements can provide observation-based evidence of emission trends. Today there is no internationally agreed, operational capacity to monitor anthropogenic GHG emission trends using atmospheric measurements to complement national bottom-up inventories.
BibTeX:
@article{Janssens-Maenhout2020,
  author = {Janssens-Maenhout, G and Pinty, B and Dowell, M and Zunker, H and Andersson, E and Balsamo, G and Bézy, J.-L. and Brunhes, T and Bösch, H and Bojkov, B and Brunner, D and Buchwitz, M and Crisp, D and Ciais, P and Counet, P and Dee, D and Denier van der Gon, H and Dolman, H and Drinkwater, M and Dubovik, O and Engelen, R and Fehr, T and Fernandez, V and Heimann, M and Holmlund, K and Houweling, S and Husband, R and Juvyns, O and Kentarchos, A and Landgraf, J and Lang, R and Löscher, A and Marshall, J and Meijer, Y and Nakajima, M and Palmer, P I and Peylin, P and Rayner, P and Scholze, M and Sierk, B and Tamminen, J and Veefkind, P},
  title = {Towards an operational anthropogenic CO2 emissions monitoring and verification support capacity},
  journal = {Bulletin of the American Meteorological Society},
  year = {2020},
  volume = {preprint},
  number = {2020},
  url = {https://journals.ametsoc.org/bams/article/345576/Towards-an-operational-anthropogenic-CO2-emissions},
  doi = {10.1175/BAMS-D-19-0017.1}
}
Järveoja J, Nilsson MB, Crill PM and Peichl M (2020), "Bimodal diel pattern in peatland ecosystem respiration rebuts uniform temperature response", Nature Communications., dec, 2020. Vol. 11(1), pp. 4255.
BibTeX:
@article{Jaerveoja2020,
  author = {Järveoja, Järvi and Nilsson, Mats B. and Crill, Patrick M. and Peichl, Matthias},
  title = {Bimodal diel pattern in peatland ecosystem respiration rebuts uniform temperature response},
  journal = {Nature Communications},
  year = {2020},
  volume = {11},
  number = {1},
  pages = {4255},
  url = {http://www.nature.com/articles/s41467-020-18027-1},
  doi = {10.1038/s41467-020-18027-1}
}
Jiang T, Wang D, Meng B, Chi J, Laudon H and Liu J (2020), "The concentrations and characteristics of dissolved organic matter in high-latitude lakes determine its ambient reducing capacity", Water Research. Vol. 169, pp. 115217. Elsevier Ltd.
Abstract: The reducing capacity (RC) of natural organic matter plays an important role in the carbon cycle and biogeochemical fates of environmental contaminants in the aquatic system. However, the electron donation potentials of dissolved organic matter (DOM) from high-latitude lakes are still uncertain. In this study, we collected DOM samples from high-latitude lakes across the Arctic and boreal regions in Sweden and Norway to investigate the effects of the DOM concentration and characteristics on its ambient reducing capacity (ARC). Mercury (Hg(II)) abiotic reduction in darkness was used to determine the ARC. The results showed that the DOM in Arctic lakes is less terrestrial-dominant than in reference sites (i.e., forest lakes). Between the two categories of Arctic lakes, tundra lakes are more terrestrial-influenced compared to mountain lakes. Additionally, terrestrial-originated DOM is a main controlling factor for enhancing the ambient reducing capacity, whereas the DOM concentration, i.e., dissolved organic carbon (DOC), resulted in variations in the Hg/DOC ratios that also cause the variations of the observed ARC values. Thus, comparisons of the ARC values can be conducted while oxidant/DOC ratios are kept the same and reported through the method using heavy metals as a chemical probe. After correction for Hg/DOC ratio interference, the ambient reducing capacity of DOM followed the order: boreal forest lakes textgreaterArctic tundra lakes textgreaterArctic mountain lakes. This study highlights that the DOM concentration should also be considered when estimating the ARC as compared to the previous that mainly focusing on the properties of DOM such as its origins. As climate change is projected to be severe in high latitudes, this study demonstrates a significant connection between aquatic DOM geochemical reactivity and terrestrial inputs, which is crucial for a better prediction of the role of DOM in high-latitude lakes in the context of climate change.
BibTeX:
@article{Jiang2020,
  author = {Jiang, Tao and Wang, Dingyong and Meng, Bo and Chi, Jinshu and Laudon, Hjalmar and Liu, Jiang},
  title = {The concentrations and characteristics of dissolved organic matter in high-latitude lakes determine its ambient reducing capacity},
  journal = {Water Research},
  publisher = {Elsevier Ltd},
  year = {2020},
  volume = {169},
  pages = {115217},
  url = {https://doi.org/10.1016/j.watres.2019.115217},
  doi = {10.1016/j.watres.2019.115217}
}
Jung M, Schwalm C, Migliavacca M, Walther S, Camps-Valls G, Koirala S, Anthoni P, Besnard S, Bodesheim P, Carvalhais N, Chevallier F, Gans F, Goll DS, Haverd V, Köhler P, Ichii K, Jain AK, Liu J, Lombardozzi D, Nabel JEMS, Nelson JA, O&apos, Sullivan M, Pallandt M, Papale D, Peters W, Pongratz J, Rödenbeck C, Sitch S, Tramontana G, Walker A, Weber U and Reichstein M (2020), "Scaling carbon fluxes from eddy covariance sites to globe: synthesis and evaluation of the FLUXCOM approach", Biogeosciences., mar, 2020. Vol. 17(5), pp. 1343-1365.
Abstract: 0.94 at 1∘ spatial resolution) while the majority of DGVMs show, for 70 % of the land surface, values outside the FLUXCOM range. Global mean GPP magnitudes for 2008–2010 from FLUXCOM members vary within 106 and 130 PgC yrâˆ'1 with the largest uncertainty in the tropics. Seasonal variations in independent SIF estimates agree better with FLUXCOM GPP (mean global pixel-wise R2∼0.75) than with GPP from DGVMs (mean global pixel-wise R2∼0.6). Seasonal variations in FLUXCOM NEE show good consistency with atmospheric inversion-based net land carbon fluxes, particularly for temperate and boreal regions (R20.92). Interannual variability of global NEE in FLUXCOM is underestimated compared to inversions and DGVMs. The FLUXCOM version which also uses meteorological inputs shows a strong co-variation in interannual patterns with inversions (R2=0.87 for 2001–2010). Mean regional NEE from FLUXCOM shows larger uptake than inversion and DGVM-based estimates, particularly in the tropics with discrepancies of up to several hundred grammes of carbon per square metre per year. These discrepancies can only partly be reconciled by carbon loss pathways that are implicit in inversions but not captured by the flux tower measurements such as carbon emissions from fires and water bodies. We hypothesize that a combination of systematic biases in the underlying eddy covariance data, in particular in tall tropical forests, and a lack of site history effects on NEE in FLUXCOM are likely responsible for the too strong tropical carbon sink estimated by FLUXCOM. Furthermore, as FLUXCOM does not account for CO2 fertilization effects, carbon flux trends are not realistic. Overall, current FLUXCOM estimates of mean annual and seasonal cycles of GPP as well as seasonal NEE variations provide useful constraints of global carbon cycling, while interannual variability patterns from FLUXCOM are valuable but require cautious interpretation. Exploring the diversity of Earth observation data and of machine learning concepts along with improved quality and quantity of flux tower measurements will facilitate further improvements of the FLUXCOM approach overall.]]
BibTeX:
@article{Jung2020,
  author = {Jung, Martin and Schwalm, Christopher and Migliavacca, Mirco and Walther, Sophia and Camps-Valls, Gustau and Koirala, Sujan and Anthoni, Peter and Besnard, Simon and Bodesheim, Paul and Carvalhais, Nuno and Chevallier, Frédéric and Gans, Fabian and Goll, Daniel S and Haverd, Vanessa and Köhler, Philipp and Ichii, Kazuhito and Jain, Atul K and Liu, Junzhi and Lombardozzi, Danica and Nabel, Julia E M S and Nelson, Jacob A and O'Sullivan, Michael and Pallandt, Martijn and Papale, Dario and Peters, Wouter and Pongratz, Julia and Rödenbeck, Christian and Sitch, Stephen and Tramontana, Gianluca and Walker, Anthony and Weber, Ulrich and Reichstein, Markus},
  title = {Scaling carbon fluxes from eddy covariance sites to globe: synthesis and evaluation of the FLUXCOM approach},
  journal = {Biogeosciences},
  year = {2020},
  volume = {17},
  number = {5},
  pages = {1343--1365},
  url = {https://www.biogeosciences.net/17/1343/2020/},
  doi = {10.5194/bg-17-1343-2020}
}
Kaikkonen L, Enberg S, Blomster J, Luhtanen A-M, Autio R and Rintala J-M (2020), "Autumn to spring microbial community in the northern Baltic Sea: temporal variability in bacterial, viral and nanoflagellate abundance during the cold-water season", Polar Biology., jun, 2020.
BibTeX:
@article{Kaikkonen2020,
  author = {Kaikkonen, Laura and Enberg, Sara and Blomster, Jaanika and Luhtanen, Anne-Mari and Autio, Riitta and Rintala, Janne-Markus},
  title = {Autumn to spring microbial community in the northern Baltic Sea: temporal variability in bacterial, viral and nanoflagellate abundance during the cold-water season},
  journal = {Polar Biology},
  year = {2020},
  url = {http://link.springer.com/10.1007/s00300-020-02700-8},
  doi = {10.1007/s00300-020-02700-8}
}
Kammer J, Décuq C, Baisnée D, Ciuraru R, Lafouge F, Buysse P, Bsaibes S, Henderson B, Cristescu SM, Benabdallah R, Chandra V, Durand B, Fanucci O, Petit JE, Truong F, Bonnaire N, Sarda-Estève R, Gros V and Loubet B (2020), "Characterization of particulate and gaseous pollutants from a French dairy and sheep farm", Science of the Total Environment., apr, 2020. Vol. 712, pp. 135598. Elsevier BV.
Abstract: Agricultural activities highly contribute to atmospheric pollution, but the diversity and the magnitude of their emissions are still subject to large uncertainties. A field measurement campaign was conducted to characterize gaseous and particulate emissions from an experimental farm in France containing a sheep pen and a dairy stable. During the campaign, more than four hundred volatile organic compounds (VOCs) were characterized using an original combination of online and off-line measurements. Carbon dioxide (CO2) and ammonia (NH3) were the most concentrated compounds inside the buildings, followed by methanol, acetic acid and acetaldehyde. A CO2 mass balance model was used to estimate NH3 and VOC emission rates. To our knowledge, this study constitutes the first evaluation of emission rates for most of the identified VOCs. The measurements show that the dairy stable emitted more VOCs than the sheep pen. Despite strong VOC and NH3 emissions, the chemical composition of particles indicates that gaseous farm emissions do not affect the loading of fine particles inside the farm and is mainly explained by the low residence time inside the buildings. The experimental dataset obtained in this work will help to improve emissions inventories for agricultural activities.
BibTeX:
@article{Kammer2020,
  author = {Kammer, Julien and Décuq, Céline and Baisnée, Dominique and Ciuraru, Raluca and Lafouge, Florence and Buysse, Pauline and Bsaibes, Sandy and Henderson, Ben and Cristescu, Simona M and Benabdallah, Rachid and Chandra, Varunesh and Durand, Brigitte and Fanucci, Oliver and Petit, Jean Eudes and Truong, Francois and Bonnaire, Nicolas and Sarda-Estève, Roland and Gros, Valerie and Loubet, Benjamin},
  title = {Characterization of particulate and gaseous pollutants from a French dairy and sheep farm},
  journal = {Science of the Total Environment},
  publisher = {Elsevier BV},
  year = {2020},
  volume = {712},
  pages = {135598},
  doi = {10.1016/j.scitotenv.2019.135598}
}
Kannenberg SA, Bowling DR and Anderegg WR (2020), "Hot moments in ecosystem fluxes: High GPP anomalies exert outsized influence on the carbon cycle and are differentially driven by moisture availability across biomes", Environmental Research Letters., may, 2020. Vol. 15(5) Institute of Physics Publishing.
Abstract: The 'hot spot-hot moment' concept is a long-standing and popular framework often invoked to explain spatially or temporally variable rates of biogeochemical cycling. However, this concept has been rarely extended to ecosystem fluxes such as gross primary productivity (GPP), in part due to the lack of a quantitative definition of hot moments that can be applied to large flux datasets. Here, we develop a general statistical framework for quantifying hot moments in GPP and identify their spatial patterns and climatic drivers. Using 308 site-years of eddy covariance data from the FLUXNET2015 dataset spanning 32 U.S. sites, we found hot moments in GPP to comprise a disproportionate percentage of annual carbon (C) uptake relative to the frequency of their occurrence. For example, at five sites over 12% of annual C uptake occurred during the ∼2% most extreme half-hourly or hourly observations of GPP. Hot moments were most quantitatively important for the C cycle in short-stature, arid ecosystem such as grasslands, woody savannas, and open shrublands, where these positive anomalies in GPP were caused by increases in moisture availability. In contrast, hot moments were less important for annual C uptake in more mesic ecosystems, where their occurrence was largely determined by high temperature and light availability. Our results point to a need to consider how short-term spikes in environmental conditions exert an outsized influence on annual GPP, and how future shifts in these conditions could impact the terrestrial C cycle.
BibTeX:
@article{Kannenberg2020,
  author = {Kannenberg, Steven A. and Bowling, David R. and Anderegg, William R.L.},
  title = {Hot moments in ecosystem fluxes: High GPP anomalies exert outsized influence on the carbon cycle and are differentially driven by moisture availability across biomes},
  journal = {Environmental Research Letters},
  publisher = {Institute of Physics Publishing},
  year = {2020},
  volume = {15},
  number = {5},
  doi = {10.1088/1748-9326/ab7b97}
}
Kitz F, Spielmann FM, Hammerle A, Kolle O, Migliavacca M, Moreno G, Ibrom A, Krasnov D, Noe SM and Wohlfahrt G (2020), "Soil COS Exchange: A Comparison of Three European Ecosystems", Global Biogeochemical Cycles. Vol. 34(4)
Abstract: The potential of carbonyl sulfide (COS) flux measurements as an additional constraint for estimating the gross primary production depends, among other preconditions, on our understanding of the soil COS exchange and its contribution to the overall net ecosystem COS flux. We conducted soil chamber measurements of COS, with transparent chambers, in three different ecosystems across Europe. The in situ measurements were followed by laboratory measurements of soil samples collected at the study sites. The soil samples were exposed to UV radiation to investigate the role of photo-degradation for COS exchange. In situ and laboratory measurements revealed pronounced intersite and intrasite variability of COS exchange. In situ COS fluxes were primarily governed by radiation in the savannah-like grassland (SAV), soil temperature and intrasite heterogeneity in the deciduous broadleaf forest, and soil water content and intrasite heterogeneity in the evergreen needleleaf forest. The soil of the ecosystem with the highest light intensity incident on the soil surface, SAV, was a net source for COS, while the soils of the other two ecosystems were COS sinks. UV radiation increased COS emissions and/or reduced COS uptake from all soil samples under laboratory conditions. The impact of UV on the COS flux differed between soil samples, with a tendency toward a stronger response of the COS flux to UV radiation exposure in samples with higher soil organic matter content. Our results emphasize the importance of photo-degradation for the soil COS flux and stress the substantial spatial variability of soil COS exchange in ecosystems.
BibTeX:
@article{Kitz2020,
  author = {Kitz, Florian and Spielmann, Felix M and Hammerle, Albin and Kolle, Olaf and Migliavacca, Mirco and Moreno, Gerardo and Ibrom, Andreas and Krasnov, Dmitrii and Noe, Steffen M and Wohlfahrt, Georg},
  title = {Soil COS Exchange: A Comparison of Three European Ecosystems},
  journal = {Global Biogeochemical Cycles},
  year = {2020},
  volume = {34},
  number = {4},
  doi = {10.1029/2019GB006202}
}
Koebsch F, Gottschalk P, Beyer F, Wille C, Jurasinski G and Sachs T (2020), "The impact of occasional drought periods on vegetation spread and greenhouse gas exchange in rewetted fens", Philosophical Transactions of the Royal Society B: Biological Sciences., oct, 2020. Vol. 375(1810), pp. 20190685.
Abstract: Peatland rewetting aims at stopping the emissions of carbon dioxide (CO 2 ) and establishing net carbon sinks. However, in times of global warming, restoration projects must increasingly deal with extreme events such as drought periods. Here, we evaluate the effect of the European summer drought 2018 on vegetation development and the exchange of methane (CH 4 ) and CO 2 in two rewetted minerotrophic fens (Hütelmoor—Hte and Zarnekow—Zrk) including potential carry-over effects in the post-drought year. Drought was a major stress factor for the established vegetation but also promoted the rapid spread of new vegetation, which will likely gain a lasting foothold in Zrk. Accordingly, drought increased not only respiratory CO 2 losses but also photosynthetic CO 2 uptake. Altogether, the drought reduced the net CO 2 sink in Hte, while it stopped the persistent net CO 2 emissions of Zrk. In addition, the drought reduced CH 4 emissions in both fens, though this became most apparent in the post-drought year and suggests a lasting shift towards non-methanogenic organic matter decomposition. Occasional droughts can be beneficial for the restoration of the peatland carbon sink function if the newly grown vegetation increases CO 2 sequestration in the long term. Nonetheless, care must be taken to prevent extensive peat decay.
BibTeX:
@article{Koebsch2020a,
  author = {Koebsch, Franziska and Gottschalk, Pia and Beyer, Florian and Wille, Christian and Jurasinski, Gerald and Sachs, Torsten},
  title = {The impact of occasional drought periods on vegetation spread and greenhouse gas exchange in rewetted fens},
  journal = {Philosophical Transactions of the Royal Society B: Biological Sciences},
  year = {2020},
  volume = {375},
  number = {1810},
  pages = {20190685},
  url = {https://royalsocietypublishing.org/doi/10.1098/rstb.2019.0685},
  doi = {10.1098/rstb.2019.0685}
}
Koebsch F, Sonnentag O, Järveoja J, Peltoniemi M, Alekseychik P, Aurela M, Arslan AN, Dinsmore K, Gianelle D, Helfter C, Jackowicz-Korczynski M, Korrensalo A, Leith F, Linkosalmi M, Lohila A, Lund M, Maddison M, Mammarella I, Mander Ü, Minkkinen K, Pickard A, Pullens JWM, Tuittila ES, Nilsson MB and Peichl M (2020), "Refining the role of phenology in regulating gross ecosystem productivity across European peatlands", Global Change Biology., dec, 2020. Vol. 26(2), pp. 876-887. Wiley.
Abstract: The role of plant phenology as a regulator for gross ecosystem productivity (GEP) in peatlands is empirically not well constrained. This is because proxies to track vegetation development with daily coverage at the ecosystem scale have only recently become available and the lack of such data has hampered the disentangling of biotic and abiotic effects. This study aimed at unraveling the mechanisms that regulate the seasonal variation in GEP across a network of eight European peatlands. Therefore, we described phenology with canopy greenness derived from digital repeat photography and disentangled the effects of radiation, temperature and phenology on GEP with commonality analysis and structural equation modeling. The resulting relational network could not only delineate direct effects but also accounted for possible effect combinations such as interdependencies (mediation) and interactions (moderation). We found that peatland GEP was controlled by the same mechanisms across all sites: phenology constituted a key predictor for the seasonal variation in GEP and further acted as a distinct mediator for temperature and radiation effects on GEP. In particular, the effect of air temperature on GEP was fully mediated through phenology, implying that direct temperature effects representing the thermoregulation of photosynthesis were negligible. The tight coupling between temperature, phenology and GEP applied especially to high latitude and high altitude peatlands and during phenological transition phases. Our study highlights the importance of phenological effects when evaluating the future response of peatland GEP to climate change. Climate change will affect peatland GEP especially through changing temperature patterns during plant phenologically sensitive phases in high latitude and high altitude regions.
BibTeX:
@article{Koebsch2020,
  author = {Koebsch, Franziska and Sonnentag, Oliver and Järveoja, Järvi and Peltoniemi, Mikko and Alekseychik, Pavel and Aurela, Mika and Arslan, Ali Nadir and Dinsmore, Kerry and Gianelle, Damiano and Helfter, Carole and Jackowicz-Korczynski, Marcin and Korrensalo, Aino and Leith, Fraser and Linkosalmi, Maiju and Lohila, Annalea and Lund, Magnus and Maddison, Martin and Mammarella, Ivan and Mander, Ülo and Minkkinen, Kari and Pickard, Amy and Pullens, Johannes W M and Tuittila, Eeva Stiina and Nilsson, Mats B and Peichl, Matthias},
  title = {Refining the role of phenology in regulating gross ecosystem productivity across European peatlands},
  journal = {Global Change Biology},
  publisher = {Wiley},
  year = {2020},
  volume = {26},
  number = {2},
  pages = {876--887},
  doi = {10.1111/gcb.14905}
}
Korkiakoski M, Ojanen P, Penttilä T, Minkkinen K, Sarkkola S, Rainne J, Laurila T and Lohila A (2020), "Impact of partial harvest on CH4 and N2O balances of a drained boreal peatland forest", Agricultural and Forest Meteorology. Vol. 295(March), pp. 108168. Elsevier.
Abstract: Rotation forestry including clearcutting is a common method of practising forestry in Fennoscandia. Clearcutting in peatland forests markedly increases environmental loading: leaching of nutrients and methane (CH4) and nitrous oxide (N2O) fluxes from soil. Continuous cover forestry has been suggested as an alternative because it does not include clearcutting but partial harvesting. However, impacts of partial harvesting on greenhouse gas fluxes are not well understood and in peatlands have not been studied at all. We conducted a partial harvest by removing 70% of the total stem volume in a mature nutrient-rich peatland forest in Southern Finland. The aim was to investigate how partial harvesting a peatland forest affects CH4 and N2O balances, and how much different surface types contribute to the balances. We used automatic and manual chamber methods to measure fluxes from both harvest and uncut control site. Fluxes were measured from the forest floor, logging trails, and ditches. Fluxes from these surface types were upscaled to obtain net ecosystem-level fluxes during two post-harvest summers (June–August 2016 and 2017). After the harvest, forest floor CH4 fluxes did not change significantly at the harvested site compared to the control site. However, fluxes at logging trails increased significantly. N2O fluxes increased at the harvest site in the post-harvest years, but so did those at the control site as well. Upscaling CH4 fluxes to ecosystem-level indicated that despite their small area (2.4%), emissions from ditches could be large on ecosystem-scale, but their uncertainty was high, while the logging trail CH4 fluxes (20% of the total area) were small. In contrast, N2O fluxes from ditches were low, but the logging trail fluxes comprised 35–38% of the total surface balance. The overall conclusion is that partial harvesting did not cause considerable changes in CH4 and N2O fluxes from a forestry-drained peatland.
BibTeX:
@article{Korkiakoski2020,
  author = {Korkiakoski, Mika and Ojanen, Paavo and Penttilä, Timo and Minkkinen, Kari and Sarkkola, Sakari and Rainne, Juuso and Laurila, Tuomas and Lohila, Annalea},
  title = {Impact of partial harvest on CH4 and N2O balances of a drained boreal peatland forest},
  journal = {Agricultural and Forest Meteorology},
  publisher = {Elsevier},
  year = {2020},
  volume = {295},
  number = {March},
  pages = {108168},
  url = {https://doi.org/10.1016/j.agrformet.2020.108168},
  doi = {10.1016/j.agrformet.2020.108168}
}
Korrensalo A, Mehtätalo L, Alekseychik P, Uljas S, Mammarella I, Vesala T and Tuittila ES (2020), "Varying Vegetation Composition, Respiration and Photosynthesis Decrease Temporal Variability of the CO2 Sink in a Boreal Bog", Ecosystems., jun, 2020. Vol. 23(4), pp. 842-858. Springer.
Abstract: We quantified the role of spatially varying vegetation composition in seasonal and interannual changes in a boreal bog's CO2 uptake. We divided the spatially heterogeneous site into six microform classes based on plant species composition and measured their net ecosystem exchange (NEE) using chamber method over the growing seasons in 2012–2014. A nonlinear mixed-effects model was applied to assess how the contributions of microforms with different vegetation change temporally, and to upscale NEE to the ecosystem level to be compared with eddy covariance (EC) measurements. Both ecosystem respiration (R) and gross photosynthesis (PG) were the largest in high hummocks, 894–964 (R) and 969–1132 (PG) g CO2 m−2 growing season−1, and decreased toward the wetter microforms. NEE had a different spatial pattern than R and PG; the highest cumulative seasonal CO2 sink was found in lawns in all years (165–353 g CO2 m−2). Microforms with similar wetness but distinct vegetation had different NEE, highlighting the importance of vegetation composition in regulating CO2 sink. Chamber-based ecosystem-level NEE was smaller and varied less interannually than the EC-derived estimate, indicating a need for further research on the error sources of both methods. Lawns contributed more to ecosystem-level NEE (55–78%) than their areal cover within the site (21.5%). In spring and autumn, lawns had the highest NEE, whereas in midsummer differences among microforms were small. The contributions of all microforms to the ecosystem-level NEE varied seasonally and interannually, suggesting that spatially heterogeneous vegetation composition could make bog CO2 uptake temporally more stable.
BibTeX:
@article{Korrensalo2020,
  author = {Korrensalo, Aino and Mehtätalo, Lauri and Alekseychik, Pavel and Uljas, Salli and Mammarella, Ivan and Vesala, Timo and Tuittila, Eeva Stiina},
  title = {Varying Vegetation Composition, Respiration and Photosynthesis Decrease Temporal Variability of the CO2 Sink in a Boreal Bog},
  journal = {Ecosystems},
  publisher = {Springer},
  year = {2020},
  volume = {23},
  number = {4},
  pages = {842--858},
  doi = {10.1007/s10021-019-00434-1}
}
Kowalska N, Šigut L, Stojanović M, Fischer M, Kyselova I and Pavelka M (2020), "Analysis of floodplain forest sensitivity to drought", Philosophical Transactions of the Royal Society B: Biological Sciences., oct, 2020. Vol. 375(1810), pp. 20190518.
Abstract: Floodplain forests are very complex, productive ecosystems, capable of storing huge amounts of soil carbon. With the increasing occurrence of extreme events, they are today among the most threatened ecosystems. Our study's main goal was to assess the productivity of a floodplain forest located at Lanžhot in the Czech Republic from two perspectives: carbon uptake (using an eddy covariance method) and stem radius variations (using dendrometers). We aimed to determine which conditions allow for high ecosystem production and what role drought plays in reducing such production potential. Additionally, we were interested to determine the relative soil water content threshold indicating the onset and duration of this event. We hypothesized that summer drought in 2018 had the most significant negative effects on the overall annual carbon and water budgets. In contrast with our original hypothesis, we found that an exceptionally warm spring in 2018 caused a positive gross primary production (GPP) and evapotranspiration (ET) anomaly that consequently led in 2018 to the highest seasonal total GPP and ET from all of the investigated years (2015–2018). The results showed ring-porous species to be the most drought resistant. Relative soil water content threshold of approximately 0.45 was determined as indicating the onset of drought stress.
BibTeX:
@article{Kowalska2020,
  author = {Kowalska, Natalia and Šigut, Ladislav and Stojanović, Marko and Fischer, Milan and Kyselova, Ina and Pavelka, Marian},
  title = {Analysis of floodplain forest sensitivity to drought},
  journal = {Philosophical Transactions of the Royal Society B: Biological Sciences},
  year = {2020},
  volume = {375},
  number = {1810},
  pages = {20190518},
  url = {https://royalsocietypublishing.org/doi/10.1098/rstb.2019.0518},
  doi = {10.1098/rstb.2019.0518}
}
Kozii N, Haahti K, Tor-Ngern P, Chi J, Maher Hasselquist E, Laudon H, Launiainen S, Oren R, Peichl M, rgen Wallerman J and Hasselquist NJ (2020), "Partitioning growing season water balance within a forested boreal catchment using sap flux, eddy covariance, and a process-based model", Hydrology and Earth System Sciences., jun, 2020. Vol. 24(6), pp. 2999-3014. Copernicus GmbH.
Abstract: Although it is well known that evapotranspiration (ET) represents an important water flux at local to global scales, few studies have quantified the magnitude and relative importance of ET and its individual flux components in high-latitude forests. In this study, we combined empirical sapflux, throughfall, and eddy-covariance measurements with estimates from a process-based model to partition the water balance in a northern boreal forested catchment. This study was conducted within the Krycklan catchment, which has a rich history of hydrological measurements, thereby providing us with the unique opportunity to compare the absolute and relative magnitudes of ET and its flux components to other water balance components. During the growing season, ET represented ca. 85% of the incoming precipitation. Both empirical results and model estimates suggested that tree transpiration (T) and evaporation of intercepted water from the tree canopy (IC) represented 43% and 31% of ET, respectively, and together were equal to ca. 70%of incoming precipitation during the growing season. Understory evapotranspiration (ETu) was less important than T and IC during most of the study period, except for late autumn, when ETu was the largest ET flux component. Overall, our study highlights the importance of trees in regulating the water cycle of boreal catchments, implying that forest management impacts on stand structure as well as climate change effects on tree growth are likely to have large cascading effects on the way water moves through these forested landscapes.
BibTeX:
@article{Kozii2020,
  author = {Kozii, Nataliia and Haahti, Kersti and Tor-Ngern, Pantana and Chi, Jinshu and Maher Hasselquist, Eliza and Laudon, Hjalmar and Launiainen, Samuli and Oren, Ram and Peichl, Matthias and rgen Wallerman, J. and Hasselquist, Niles J.},
  title = {Partitioning growing season water balance within a forested boreal catchment using sap flux, eddy covariance, and a process-based model},
  journal = {Hydrology and Earth System Sciences},
  publisher = {Copernicus GmbH},
  year = {2020},
  volume = {24},
  number = {6},
  pages = {2999--3014},
  doi = {10.5194/hess-24-2999-2020}
}
Krich C, Runge J, Miralles DG, Migliavacca M, Perez-Priego O, El-Madany T, Carrara A and Mahecha MD (2020), "Estimating causal networks in biosphere-atmosphere interaction with the PCMCI approach", Biogeosciences., feb, 2020. Vol. 17(4), pp. 1033-1061. Copernicus GmbH.
Abstract: The dynamics of biochemical processes in terrestrial ecosystems are tightly coupled to local meteorological conditions. Understanding these interactions is an essential prerequisite for predicting, e.g. the response of the terrestrial carbon cycle to climate change. However, many empirical studies in this field rely on correlative approaches and only very few studies apply causal discovery methods. Here we explore the potential for a recently proposed causal graph discovery algorithm to reconstruct the causal dependency structure underlying biosphere-atmosphere interactions. Using artificial time series with known dependencies that mimic real-world biosphere-atmosphere interactions we address the influence of non-stationarities, i.e. periodicity and heteroscedasticity, on the estimation of causal networks. We then investigate the interpretability of the method in two case studies. Firstly, we analyse three replicated eddy covariance datasets from a Mediterranean ecosystem. Secondly, we explore global Normalised Difference Vegetation Index time series (GIMMS 3g), along with gridded climate data to study large-scale climatic drivers of vegetation greenness. We compare the retrieved causal graphs to simple cross-correlation-based approaches to test whether causal graphs are considerably more informative. Overall, the results confirm the capacity of the causal discovery method to extract time-lagged linear dependencies under realistic settings. For example, we find a complete decoupling of the net ecosystem exchange from meteorological variability during summer in the Mediterranean ecosystem. However, cautious interpretations are needed, as the violation of the method's assumptions due to non-stationarities increases the likelihood to detect false links. Overall, estimating directed biosphere-atmosphere networks helps unravel complex multidirectional process interactions. Other than classical correlative approaches, our findings are constrained to a few meaningful sets of relations, which can be powerful insights for the evaluation of terrestrial ecosystem models.
BibTeX:
@article{Krich2020,
  author = {Krich, Christopher and Runge, Jakob and Miralles, Diego G. and Migliavacca, Mirco and Perez-Priego, Oscar and El-Madany, Tarek and Carrara, Arnaud and Mahecha, Miguel D.},
  title = {Estimating causal networks in biosphere-atmosphere interaction with the PCMCI approach},
  journal = {Biogeosciences},
  publisher = {Copernicus GmbH},
  year = {2020},
  volume = {17},
  number = {4},
  pages = {1033--1061},
  doi = {10.5194/bg-17-1033-2020}
}
Kuhry P, Barta J, Blok D, Elberling B, Faucherre S, Hugelius G, Jørgensen CJ, Richter A, ŠantrÅ̄čková H and Weiss N (2020), "Lability classification of soil organic matter in the northern permafrost region", Biogeosciences. Vol. 17(2), pp. 361-379.
Abstract: The large stocks of soil organic carbon (SOC) in soils and deposits of the northern permafrost region are sensitive to global warming and permafrost thawing. The potential release of this carbon (C) as greenhouse gases to the atmosphere does not only depend on the total quantity of soil organic matter (SOM) affected by warming and thawing, but it also depends on its lability (i.e., the rate at which it will decay). In this study we develop a simple and robust classification scheme of SOM lability for the main types of soils and deposits in the northern permafrost region. The classification is based on widely available soil geochemical parameters and landscape unit classes, which makes it useful for upscaling to the entire northern permafrost region. We have analyzed the relationship between C content and C-textlessspan classCombining double low line"inline-formula"textgreaterCO2textless/spantextgreaterproduction rates of soil samples in two different types of laboratory incubation experiments. In one experiment, ca. 240 soil samples from four study areas were incubated using the same protocol (at 5 textlessspan classCombining double low line"inline-formula"textgreaterĝtextless/spantextgreaterC, aerobically) over a period of 1 year. Here we present C release rates measured on day 343 of incubation. These long-term results are compared to those obtained from short-term incubations of ca. 1000 samples (at 12 textlessspan classCombining double low line"inline-formula"textgreaterĝtextless/spantextgreaterC, aerobically) from an additional three study areas. In these experiments, C-textlessspan classCombining double low line"inline-formula"textgreaterCO2textless/spantextgreaterproduction rates were measured over the first 4 d of incubation. We have focused our analyses on the relationship between C-textlessspan classCombining double low line"inline-formula"textgreaterCO2textless/spantextgreaterproduction per gram dry weight per day (textlessspan classCombining double low line"inline-formula"textgreater$$textless/spantextgreatergC-textlessspan classCombining double low line"inline-formula"textgreaterCO2textless/spantextgreater gdwtextlessspan classCombining double low line"inline-formula"textgreater-1textless/spantextgreater dtextlessspan classCombining double low line"inline-formula"textgreater-1textless/spantextgreater) and C content (%C of dry weight) in the samples, but we show that relationships are consistent when using textlessspan classCombining double low line"inline-formula"textgreaterC ĝ• Ntextless/spantextgreaterratios or different production units such as textlessspan classCombining double low line"inline-formula"textgreater$$textless/spantextgreatergC per gram soil C per day (textlessspan classCombining double low line"inline-formula"textgreater$$textless/spantextgreatergC-textlessspan classCombining double low line"inline-formula"textgreaterCO2textless/spantextgreater gCtextlessspan classCombining double low line"inline-formula"textgreater-1textless/spantextgreater dtextlessspan classCombining double low line"inline-formula"textgreater-1textless/spantextgreater) or per cmtextlessspan classCombining double low line"inline-formula"textgreater3textless/spantextgreaterof soil per day (textlessspan classCombining double low line"inline-formula"textgreater$$textless/spantextgreatergC-textlessspan classCombining double low line"inline-formula"textgreaterCO2textless/spantextgreater cmtextlessspan classCombining double low line"inline-formula"textgreater-3textless/spantextgreater dtextlessspan classCombining double low line"inline-formula"textgreater-1textless/spantextgreater). C content of the samples is positively correlated to C-textlessspan classCombining double low line"inline-formula"textgreaterCO2textless/spantextgreaterproduction rates but explains less than 50 % of the observed variability when the full datasets are considered. A partitioning of the data into landscape units greatly reduces variance and provides consistent results between incubation experiments. These results indicate that relative SOM lability decreases in the order of Late Holocene eolian deposits to alluvial deposits and mineral soils (including peaty wetlands) to Pleistocene yedoma deposits to C-enriched pockets in cryoturbated soils to peat deposits. Thus, three of the most important SOC storage classes in the northern permafrost region (yedoma, cryoturbated soils and peatlands) show low relative SOM lability. Previous research has suggested that SOM in these pools is relatively undecomposed, and the reasons for the observed low rates of decomposition in our experiments need urgenttextlessspan idCombining double low line"page362"/textgreaterattention if we want to better constrain the magnitude of the thawing permafrost carbon feedback on global warming.
BibTeX:
@article{Kuhry2020,
  author = {Kuhry, Peter and Barta, Jiri and Blok, Daan and Elberling, Bo and Faucherre, Samuel and Hugelius, Gustaf and Jørgensen, Christian J and Richter, Andreas and ŠantrÅ̄čková, Hana and Weiss, Niels},
  title = {Lability classification of soil organic matter in the northern permafrost region},
  journal = {Biogeosciences},
  year = {2020},
  volume = {17},
  number = {2},
  pages = {361--379},
  doi = {10.5194/bg-17-361-2020}
}
L. Tunnicliffe R, L. Ganesan A, J. Parker R, Boesch H, Gedney N, Poulter B, Zhang Z, Walter D, Rigby M, Henne S, Young D and O'Doherty S (2020), "Quantifying sources of Brazil's CH4 emissions between 2010 and 2018 from satellite data", Atmospheric Chemistry and Physics. Vol. 20(21), pp. 13041-13067.
Abstract: Brazil's CH4 emissions over the period 2010- 2018 were derived for the three main sectors of activity: anthropogenic, wetland and biomass burning. Our inverse modelling estimates were derived from GOSAT (Greenhouse gases Observing SATellite) satellite measurements of XCH4 combined with surface data from Ragged Point, Barbados, and the high-resolution regional atmospheric transport model NAME (Numerical Atmospheric-dispersion Modelling Environment). We find that Brazil's mean emissions over 2010- 2018 are 33:63:6Tgyr1, which are comprised of 19:0 2:6Tgyr1 from anthropogenic (primarily related to agriculture and waste), 13:01:9Tgyr1 from wetlands and 1:7 0:3Tgyr1 from biomass burning sources. In addition, between the 2011-2013 and 2014-2018 periods, Brazil's mean emissions rose by 6:95:3Tgyr1 and this increase may have contributed to the accelerated global methane growth rate observed during the latter period. We find that wetland emissions from the western Amazon increased during the start of the 2015-2016 El Nino by 3:72:7Tgyr1 and this is likely driven by increased surface temperatures. We also find that our estimates of anthropogenic emissions are consistent with those reported by Brazil to the United Framework Convention on Climate Change. We show that satellite data are beneficial for constraining national-scale CH4 emissions, and, through a series of sensitivity studies and validation experiments using data not assimilated in the inversion, we demonstrate that (a) calibrated ground-based data are important to include alongside satellite data in a regional inversion and that (b) inversions must account for any offsets between the two data streams and their representations by models.
BibTeX:
@article{L.Tunnicliffe2020,
  author = {L. Tunnicliffe, Rachel and L. Ganesan, Anita and J. Parker, Robert and Boesch, Hartmut and Gedney, Nicola and Poulter, Benjamin and Zhang, Zhen and Walter, David and Rigby, Matthew and Henne, Stephan and Young, Dickon and O'Doherty, Simon},
  title = {Quantifying sources of Brazil's CH4 emissions between 2010 and 2018 from satellite data},
  journal = {Atmospheric Chemistry and Physics},
  year = {2020},
  volume = {20},
  number = {21},
  pages = {13041--13067},
  doi = {10.5194/acp-20-13041-2020}
}
Languille B, Gros V, Petit JE, Honoré C, Baudic A, Perrussel O, Foret G, Michoud V, Truong F, Bonnaire N, Sarda-Estève R, Delmotte M, Feron A, Maisonneuve F, Gaimoz C, Formenti P, Kotthaus S, Haeffelin M and Favez O (2020), "Wood burning: A major source of Volatile Organic Compounds during wintertime in the Paris region", Science of the Total Environment., apr, 2020. Vol. 711, pp. 135055. Elsevier BV.
Abstract: Wood burning is widely used for domestic heating and has been identified as a ubiquitous pollution source in urban areas, especially during cold months. The present study is based on a three and a half winter months field campaign in the Paris region measuring Volatile Organic Compounds (VOCs) by Proton Transfer Reaction Mass Spectrometry (PTR-MS) in addition to Black Carbon (BC). Several VOCs were identified as strongly wood burning-influenced (e.g., acetic acid, furfural), or traffic-influenced (e.g., toluene, C8-aromatics). Methylbutenone, benzenediol and butandione were identified for the first time as wood burning-related in ambient air. A Positive Matrix Factorization (PMF) analysis highlighted that wood burning is the most important source of VOCs during the winter season. (47%). Traffic was found to account for about 22% of the measured VOCs during the same period, whereas solvent use plus background accounted altogether for the remaining fraction. The comparison with the regional emission inventory showed good consistency for benzene and xylenes but revisions of the inventory should be considered for several VOCs such as acetic acid, C9-aromatics and methanol. Finally, complementary measurements acquired simultaneously at other sites in Île-de-France (the Paris region) enabled evaluation of spatial variabilities. The influence of traffic emissions on investigated pollutants displayed a clear negative gradient from roadside to suburban stations, whereas wood burning pollution was found to be fairly homogeneous over the region.
BibTeX:
@article{Languille2020,
  author = {Languille, Baptiste and Gros, Valérie and Petit, Jean Eudes and Honoré, Cécile and Baudic, Alexia and Perrussel, Olivier and Foret, Gilles and Michoud, Vincent and Truong, François and Bonnaire, Nicolas and Sarda-Estève, Roland and Delmotte, Marc and Feron, Anaïs and Maisonneuve, Franck and Gaimoz, Cécile and Formenti, Paola and Kotthaus, Simone and Haeffelin, Martial and Favez, Olivier},
  title = {Wood burning: A major source of Volatile Organic Compounds during wintertime in the Paris region},
  journal = {Science of the Total Environment},
  publisher = {Elsevier BV},
  year = {2020},
  volume = {711},
  pages = {135055},
  doi = {10.1016/j.scitotenv.2019.135055}
}
Lansu EM, van Heerwaarden CC, Stegehuis AI and Teuling AJ (2020), "Atmospheric Aridity and Apparent Soil Moisture Drought in European Forest During Heat Waves", Geophysical Research Letters., mar, 2020. Vol. 47(6) Blackwell Publishing Ltd.
Abstract: Land-atmosphere feedbacks, in particular the response of land evaporation to vapor pressure deficit (VPD) or the dryness of the air, remain poorly understood. Here we investigate the VPD response by analysis of a large database of eddy covariance flux observations and simulations using a conceptual model of the atmospheric boundary layer. Data analysis reveals that under high VPD and corresponding high temperatures, forest in particular reduces evaporation and emits more sensible heat. In contrast, grass increases evaporation and emits less sensible heat. Simulations show that this VPD feedback can induce significant temperature increases over forest of up to 2 K during heat wave conditions. It is inferred from the simulations that the effect of the VPD feedback corresponds to an apparent soil moisture depletion of more than 50%. This suggests that previous studies may have incorrectly attributed the effects of atmospheric aridity on temperature to soil dryness.
BibTeX:
@article{Lansu2020,
  author = {Lansu, Eva M. and van Heerwaarden, C. C. and Stegehuis, Annemiek I. and Teuling, Adriaan J.},
  title = {Atmospheric Aridity and Apparent Soil Moisture Drought in European Forest During Heat Waves},
  journal = {Geophysical Research Letters},
  publisher = {Blackwell Publishing Ltd},
  year = {2020},
  volume = {47},
  number = {6},
  doi = {10.1029/2020GL087091}
}
Le Quéré C, Jackson RB, Jones MW, Smith AJP, Abernethy S, Andrew RM, De-Gol AJ, Willis DR, Shan Y, Canadell JG, Friedlingstein P, Creutzig F and Peters GP (2020), "Temporary reduction in daily global CO2 emissions during the COVID-19 forced confinement", Nature Climate Change., jul, 2020. Vol. 10(7), pp. 647-653.
BibTeX:
@article{LeQuere2020,
  author = {Le Quéré, Corinne and Jackson, Robert B and Jones, Matthew W and Smith, Adam J P and Abernethy, Sam and Andrew, Robbie M and De-Gol, Anthony J and Willis, David R and Shan, Yuli and Canadell, Josep G and Friedlingstein, Pierre and Creutzig, Felix and Peters, Glen P},
  title = {Temporary reduction in daily global CO2 emissions during the COVID-19 forced confinement},
  journal = {Nature Climate Change},
  year = {2020},
  volume = {10},
  number = {7},
  pages = {647--653},
  url = {http://www.nature.com/articles/s41558-020-0797-x},
  doi = {10.1038/s41558-020-0797-x}
}
Lefèvre N, Tyaquiçã P, Veleda D, Perruche C and van Gennip SJ (2020), "Amazon River propagation evidenced by a CO2 decrease at 8°N, 38°W in September 2013", Journal of Marine Systems., nov, 2020. Vol. 211 Elsevier B.V..
Abstract: The surface fugacity of CO2 (fCO2) has been measured hourly at a mooring at 8°N, 38°W, using a spectrophotometric CO2 sensor, from June to October 2013. In September 2013, the fCO2 and the sea surface salinity (SSS) decrease significantly. The high precipitation due to the presence of the Intertropical Convergence Zone (ITCZ) and the propagation of low salinity waters from the Amazon River plume explain the decrease of SSS. Indeed, in fall, the retroflection of the North Brazil Current (NBC) feeds the North Equatorial Counter Current (NECC) and transports Amazon waters to the eastern part of the tropical Atlantic. Simulations from a three dimensional physical and biogeochemical model and observations at the mooring show that the Amazon plume reached the mooring in September 2013. The decrease of fCO2 is associated with a moderate peak of chlorophyll. Over the period of the CO2 observations, the site is a source of CO2 to the atmosphere of 0.65 ± 0.47 mmol m−2 day−1. Although the wind speed is at its lowest intensity in September 2013, the flux over the whole period would be about 14% higher without this month. Every month of September from 2006 to 2017, the model simulates a decrease of dissolved inorganic carbon corresponding to the SSS minimum.
BibTeX:
@article{Lefevre2020,
  author = {Lefèvre, Nathalie and Tyaquiçã, Pedro and Veleda, Doris and Perruche, Coralie and van Gennip, Simon Jan},
  title = {Amazon River propagation evidenced by a CO2 decrease at 8°N, 38°W in September 2013},
  journal = {Journal of Marine Systems},
  publisher = {Elsevier B.V.},
  year = {2020},
  volume = {211},
  doi = {10.1016/j.jmarsys.2020.103419}
}
Legge O, Johnson M, Hicks N, Jickells T, Diesing M, Aldridge J, Andrews J, Artioli Y, Bakker DC, Burrows MT, Carr N, Cripps G, Felgate SL, Fernand L, Greenwood N, Hartman S, Kröger S, Lessin G, Mahaffey C, Mayor DJ, Parker R, Queirós AM, Shutler JD, Silva T, Stahl H, Tinker J, Underwood GJ, Van Der Molen J, Wakelin S, Weston K and Williamson P (2020), "Carbon on the Northwest European Shelf: Contemporary Budget and Future Influences", Frontiers in Marine Science., mar, 2020. Vol. 7, pp. 143. Frontiers Media S.A..
Abstract: A carbon budget for the northwest European continental shelf seas (NWES) was synthesized using available estimates for coastal, pelagic and benthic carbon stocks and flows. Key uncertainties were identified and the effect of future impacts on the carbon budget were assessed. The water of the shelf seas contains between 210 and 230 Tmol of carbon and absorbs between 1.3 and 3.3 Tmol from the atmosphere annually. Off-shelf transport and burial in the sediments account for 60–100 and 0–40% of carbon outputs from the NWES, respectively. Both of these fluxes remain poorly constrained by observations and resolving their magnitudes and relative importance is a key research priority. Pelagic and benthic carbon stocks are dominated by inorganic carbon. Shelf sediments contain the largest stock of carbon, with between 520 and 1600 Tmol stored in the top 0.1 m of the sea bed. Coastal habitats such as salt marshes and mud flats contain large amounts of carbon per unit area but their total carbon stocks are small compared to pelagic and benthic stocks due to their smaller spatial extent. The large pelagic stock of carbon will continue to increase due to the rising concentration of atmospheric CO2, with associated pH decrease. Pelagic carbon stocks and flows are also likely to be significantly affected by increasing acidity and temperature, and circulation changes but the net impact is uncertain. Benthic carbon stocks will be affected by increasing temperature and acidity, and decreasing oxygen concentrations, although the net impact of these interrelated changes on carbon stocks is uncertain and a major knowledge gap. The impact of bottom trawling on benthic carbon stocks is unique amongst the impacts we consider in that it is widespread and also directly manageable, although its net effect on the carbon budget is uncertain. Coastal habitats are vulnerable to sea level rise and are strongly impacted by management decisions. Local, national and regional actions have the potential to protect or enhance carbon storage, but ultimately global governance, via controls on emissions, has the greatest potential to influence the long-term fate of carbon stocks in the northwestern European continental shelf.
BibTeX:
@article{Legge2020,
  author = {Legge, Oliver and Johnson, Martin and Hicks, Natalie and Jickells, Tim and Diesing, Markus and Aldridge, John and Andrews, Julian and Artioli, Yuri and Bakker, Dorothee C.E. and Burrows, Michael T. and Carr, Nealy and Cripps, Gemma and Felgate, Stacey L. and Fernand, Liam and Greenwood, Naomi and Hartman, Susan and Kröger, Silke and Lessin, Gennadi and Mahaffey, Claire and Mayor, Daniel J. and Parker, Ruth and Queirós, Ana M. and Shutler, Jamie D. and Silva, Tiago and Stahl, Henrik and Tinker, Jonathan and Underwood, Graham J.C. and Van Der Molen, Johan and Wakelin, Sarah and Weston, Keith and Williamson, Phillip},
  title = {Carbon on the Northwest European Shelf: Contemporary Budget and Future Influences},
  journal = {Frontiers in Marine Science},
  publisher = {Frontiers Media S.A.},
  year = {2020},
  volume = {7},
  pages = {143},
  url = {www.frontiersin.org},
  doi = {10.3389/fmars.2020.00143}
}
Lembrechts JJ, Aalto J, Ashcroft MB, De Frenne P, Kopecký M, Lenoir J, Luoto M, Maclean IM, Roupsard O, Fuentes-Lillo E, García RA, Pellissier L, Pitteloud C, Alatalo JM, Smith SW, Björk RG, Muffler L, Ratier Backes A, Cesarz S, Gottschall F, Okello J, Urban J, Plichta R, Svátek M, Phartyal SS, Wipf S, Eisenhauer N, Pușcaș M, Turtureanu PD, Varlagin A, Dimarco RD, Jump AS, Randall K, Dorrepaal E, Larson K, Walz J, Vitale L, Svoboda M, Finger Higgens R, Halbritter AH, Curasi SR, Klupar I, Koontz A, Pearse WD, Simpson E, Stemkovski M, Jessen Graae B, Vedel Sørensen M, Høye TT, Fernández Calzado MR, Lorite J, Carbognani M, Tomaselli M, Forte TG, Petraglia A, Haesen S, Somers B, Van Meerbeek K, Björkman MP, Hylander K, Merinero S, Gharun M, Buchmann N, Dolezal J, Matula R, Thomas AD, Bailey JJ, Ghosn D, Kazakis G, de Pablo MA, Kemppinen J, Niittynen P, Rew L, Seipel T, Larson C, Speed JD, Ardö J, Cannone N, Guglielmin M, Malfasi F, Bader MY, Canessa R, Stanisci A, Kreyling J, Schmeddes J, Teuber L, Aschero V, Čiliak M, Máliš F, De Smedt P, Govaert S, Meeussen C, Vangansbeke P, Gigauri K, Lamprecht A, Pauli H, Steinbauer K, Winkler M, Ueyama M, Nuñez MA, Ursu TM, Haider S, Wedegärtner RE, Smiljanic M, Trouillier M, Wilmking M, Altman J, Brůna J, Hederová L, Macek M, Man M, Wild J, Vittoz P, Pärtel M, Barančok P, Kanka R, Kollár J, Palaj A, Barros A, Mazzolari AC, Bauters M, Boeckx P, Benito Alonso JL, Zong S, Di Cecco V, Sitková Z, Tielbörger K, van den Brink L, Weigel R, Homeier J, Dahlberg CJ, Medinets S, Medinets V, De Boeck HJ, Portillo-Estrada M, Verryckt LT, Milbau A, Daskalova GN, Thomas HJ, Myers-Smith IH, Blonder B, Stephan JG, Descombes P, Zellweger F, Frei ER, Heinesch B, Andrews C, Dick J, Siebicke L, Rocha A, Senior RA, Rixen C, Jimenez JJ, Boike J, Pauchard A, Scholten T, Scheffers B, Klinges D, Basham EW, Zhang J, Zhang Z, Géron C, Fazlioglu F, Candan O, Sallo Bravo J, Hrbacek F, Laska K, Cremonese E, Haase P, Moyano FE, Rossi C and Nijs I (2020), "SoilTemp: A global database of near-surface temperature", Global Change Biology. Blackwell Publishing Ltd.
Abstract: Current analyses and predictions of spatially explicit patterns and processes in ecology most often rely on climate data interpolated from standardized weather stations. This interpolated climate data represents long-term average thermal conditions at coarse spatial resolutions only. Hence, many climate-forcing factors that operate at fine spatiotemporal resolutions are overlooked. This is particularly important in relation to effects of observation height (e.g. vegetation, snow and soil characteristics) and in habitats varying in their exposure to radiation, moisture and wind (e.g. topography, radiative forcing or cold-air pooling). Since organisms living close to the ground relate more strongly to these microclimatic conditions than to free-air temperatures, microclimatic ground and near-surface data are needed to provide realistic forecasts of the fate of such organisms under anthropogenic climate change, as well as of the functioning of the ecosystems they live in. To fill this critical gap, we highlight a call for temperature time series submissions to SoilTemp, a geospatial database initiative compiling soil and near-surface temperature data from all over the world. Currently, this database contains time series from 7,538 temperature sensors from 51 countries across all key biomes. The database will pave the way toward an improved global understanding of microclimate and bridge the gap between the available climate data and the climate at fine spatiotemporal resolutions relevant to most organisms and ecosystem processes.
BibTeX:
@article{Lembrechts2020,
  author = {Lembrechts, Jonas J. and Aalto, Juha and Ashcroft, Michael B. and De Frenne, Pieter and Kopecký, Martin and Lenoir, Jonathan and Luoto, Miska and Maclean, Ilya M.D. and Roupsard, Olivier and Fuentes-Lillo, Eduardo and García, Rafael A. and Pellissier, Loïc and Pitteloud, Camille and Alatalo, Juha M. and Smith, Stuart W. and Björk, Robert G. and Muffler, Lena and Ratier Backes, Amanda and Cesarz, Simone and Gottschall, Felix and Okello, Joseph and Urban, Josef and Plichta, Roman and Svátek, Martin and Phartyal, Shyam S. and Wipf, Sonja and Eisenhauer, Nico and Pușcaș, Mihai and Turtureanu, Pavel D. and Varlagin, Andrej and Dimarco, Romina D. and Jump, Alistair S. and Randall, Krystal and Dorrepaal, Ellen and Larson, Keith and Walz, Josefine and Vitale, Luca and Svoboda, Miroslav and Finger Higgens, Rebecca and Halbritter, Aud H. and Curasi, Salvatore R. and Klupar, Ian and Koontz, Austin and Pearse, William D. and Simpson, Elizabeth and Stemkovski, Michael and Jessen Graae, Bente and Vedel Sørensen, Mia and Høye, Toke T. and Fernández Calzado, M. Rosa and Lorite, Juan and Carbognani, Michele and Tomaselli, Marcello and Forte, T'ai G.W. and Petraglia, Alessandro and Haesen, Stef and Somers, Ben and Van Meerbeek, Koenraad and Björkman, Mats P. and Hylander, Kristoffer and Merinero, Sonia and Gharun, Mana and Buchmann, Nina and Dolezal, Jiri and Matula, Radim and Thomas, Andrew D. and Bailey, Joseph J. and Ghosn, Dany and Kazakis, George and de Pablo, Miguel A. and Kemppinen, Julia and Niittynen, Pekka and Rew, Lisa and Seipel, Tim and Larson, Christian and Speed, James D.M. and Ardö, Jonas and Cannone, Nicoletta and Guglielmin, Mauro and Malfasi, Francesco and Bader, Maaike Y. and Canessa, Rafaella and Stanisci, Angela and Kreyling, Juergen and Schmeddes, Jonas and Teuber, Laurenz and Aschero, Valeria and Čiliak, Marek and Máliš, František and De Smedt, Pallieter and Govaert, Sanne and Meeussen, Camille and Vangansbeke, Pieter and Gigauri, Khatuna and Lamprecht, Andrea and Pauli, Harald and Steinbauer, Klaus and Winkler, Manuela and Ueyama, Masahito and Nuñez, Martin A. and Ursu, Tudor Mihai and Haider, Sylvia and Wedegärtner, Ronja E.M. and Smiljanic, Marko and Trouillier, Mario and Wilmking, Martin and Altman, Jan and Brůna, Josef and Hederová, Lucia and Macek, Martin and Man, Matěj and Wild, Jan and Vittoz, Pascal and Pärtel, Meelis and Barančok, Peter and Kanka, Róbert and Kollár, Jozef and Palaj, Andrej and Barros, Agustina and Mazzolari, Ana C. and Bauters, Marijn and Boeckx, Pascal and Benito Alonso, José Luis and Zong, Shengwei and Di Cecco, Valter and Sitková, Zuzana and Tielbörger, Katja and van den Brink, Liesbeth and Weigel, Robert and Homeier, Jürgen and Dahlberg, C. Johan and Medinets, Sergiy and Medinets, Volodymyr and De Boeck, Hans J. and Portillo-Estrada, Miguel and Verryckt, Lore T. and Milbau, Ann and Daskalova, Gergana N. and Thomas, Haydn J.D. and Myers-Smith, Isla H. and Blonder, Benjamin and Stephan, Jörg G. and Descombes, Patrice and Zellweger, Florian and Frei, Esther R. and Heinesch, Bernard and Andrews, Christopher and Dick, Jan and Siebicke, Lukas and Rocha, Adrian and Senior, Rebecca A. and Rixen, Christian and Jimenez, Juan J. and Boike, Julia and Pauchard, Aníbal and Scholten, Thomas and Scheffers, Brett and Klinges, David and Basham, Edmund W. and Zhang, Jian and Zhang, Zhaochen and Géron, Charly and Fazlioglu, Fatih and Candan, Onur and Sallo Bravo, Jhonatan and Hrbacek, Filip and Laska, Kamil and Cremonese, Edoardo and Haase, Peter and Moyano, Fernando E. and Rossi, Christian and Nijs, Ivan},
  title = {SoilTemp: A global database of near-surface temperature},
  journal = {Global Change Biology},
  publisher = {Blackwell Publishing Ltd},
  year = {2020},
  doi = {10.1111/gcb.15123}
}
Leppä K, Korkiakoski M, Nieminen M, Laiho R, Hotanen JP, Kieloaho AJ, Korpela L, Laurila T, Lohila A, Minkkinen K, Mäkipää R, Ojanen P, Pearson M, Penttilä T, Tuovinen JP and Launiainen S (2020), "Vegetation controls of water and energy balance of a drained peatland forest: Responses to alternative harvesting practices", Agricultural and Forest Meteorology. Vol. 295(April), pp. 108198. Elsevier.
Abstract: We quantified the response of peatland water table level (WTL) and energy fluxes to harvesting of a drained peatland forest. Two alternative harvests (clear-cut and partial harvest) were carried out in a mixed-species ditch-drained peatland forest in southern Finland, where water and energy balance components were monitored for six pre-treatment and three post-treatment growing seasons. To explore the responses caused by harvestings, we applied a mechanistic multi-layer soil-plant-atmosphere transfer model. At the clear-cut site, the mean growing season WTL rose by 0.18 ± 0.02 m (error estimate based on measurement uncertainty), while net radiation, and sensible and latent heat fluxes decreased after harvest. On the contrary, we observed only minor changes in energy fluxes and mean WTL (0.05 ± 0.03 m increase) at the partial harvest site, although as much as 70% of the stand basal area was removed and leaf-area index was reduced to half. The small changes were mainly explained by increased water use of spruce undergrowth and field layer vegetation, as well as increased forest floor evaporation. The rapid establishment of field layer vegetation had a significant role in energy balance recovery at the clear-cut site. At partial harvest, chlorophyll fluorescence measurements and model-data comparison suggested the shade-adapted spruce undergrowth was suffering from light stress during the first post-harvest growing season. We conclude that in addition to stand basal area, species composition and stand structure need to be considered when controlling WTL in peatland forests with partial harvesting. Our results have important implications on the operational use of continuous cover forestry on drained peatlands. A continuously maintained tree cover with significant evapotranspiration capacity could enable optimizing WTL from both tree growth and environmental perspectives.
BibTeX:
@article{Leppae2020,
  author = {Leppä, Kersti and Korkiakoski, Mika and Nieminen, Mika and Laiho, Raija and Hotanen, Juha Pekka and Kieloaho, Antti Jussi and Korpela, Leila and Laurila, Tuomas and Lohila, Annalea and Minkkinen, Kari and Mäkipää, Raisa and Ojanen, Paavo and Pearson, Meeri and Penttilä, Timo and Tuovinen, Juha Pekka and Launiainen, Samuli},
  title = {Vegetation controls of water and energy balance of a drained peatland forest: Responses to alternative harvesting practices},
  journal = {Agricultural and Forest Meteorology},
  publisher = {Elsevier},
  year = {2020},
  volume = {295},
  number = {April},
  pages = {108198},
  url = {https://doi.org/10.1016/j.agrformet.2020.108198},
  doi = {10.1016/j.agrformet.2020.108198}
}
Leseurre C, Lo Monaco C, Reverdin G, Metzl N, Fin J, Olafsdottir S and Racapé V (2020), "Ocean carbonate system variability in the North Atlantic Subpolar surface water (1993-2017)", Biogeosciences., may, 2020. Vol. 17(9), pp. 2553-2577. Copernicus GmbH.
Abstract: The North Atlantic is one of the major ocean sinks for natural and anthropogenic atmospheric CO2. Given the variability of the circulation, convective processes or warming-cooling recognized in the high latitudes in this region, a better understanding of the CO2 sink temporal variability and associated acidification needs a close inspection of seasonal, interannual to multidecadal observations. In this study, we investigate the evolution of CO2 uptake and ocean acidification in the North Atlantic Subpolar Gyre (50-64_ N) using repeated observations collected over the last 3 decades in the framework of the long-term monitoring program SURATLANT (SURveillance de l'ATLANTique). Over the full period (1993-2017) pH decreases (-0:0017 yr-1) and fugacity of CO2 (fCO2) increases (C1.70 μatm yr-1). The trend of fCO2 in surface water is slightly less than the atmospheric rate (C1.96 μatm yr-1). This is mainly due to dissolved inorganic carbon (DIC) increase associated with the anthropogenic signal. However, over shorter periods (4-10 years) and depending on the season, we detect significant variability investigated in more detail in this study. Data obtained between 1993 and 1997 suggest a rapid increase in fCO2 in summer (up to C14 μatm yr-1) that was driven by a significant warming and an increase in DIC for a short period. Similar fCO2 trends are observed between 2001 and 2007 during both summer and winter, but, without significant warming detected, these trends are mainly explained by an increase in DIC and a decrease in alkalinity. This also leads to a pH decrease but with contrasting trends depending on the region and season (between -0:006 and -0:013 yr-1). Conversely, data obtained during the last decade (2008-2017) in summer show a cooling of surface waters and an increase in alkalinity, leading to a strong decrease in surface fCO2 (between -4:4 and -2:3 μatm yr-1; i.e., the ocean CO2 sink increases). Surprisingly, during summer, pH increases up to C0:0052 yr-1 in the southern subpolar gyre. Overall, our results show that, in addition to the accumulation of anthropogenic CO2, the temporal changes in the uptake of CO2 and ocean acidification in the North Atlantic Subpolar Gyre present significant multiannual variability, not clearly directly associated with the North Atlantic Oscillation (NAO). With such variability it is uncertain to predict the near-future evolution of air-sea CO2 fluxes and pH in this region. Thus, it is highly recommended to maintain long-term observations to monitor these properties in the next decade.
BibTeX:
@article{Leseurre2020,
  author = {Leseurre, Coraline and Lo Monaco, Claire and Reverdin, Gilles and Metzl, Nicolas and Fin, Jonathan and Olafsdottir, Solveig and Racapé, Virginie},
  title = {Ocean carbonate system variability in the North Atlantic Subpolar surface water (1993-2017)},
  journal = {Biogeosciences},
  publisher = {Copernicus GmbH},
  year = {2020},
  volume = {17},
  number = {9},
  pages = {2553--2577},
  doi = {10.5194/bg-17-2553-2020}
}
Levin I, Karstens U, Eritt M, Maier F, Arnold S, Rzesanke D, Hammer S, Ramonet M, Vítková G, Conil S, Heliasz M, Kubistin D and Lindauer M (2020), "A dedicated flask sampling strategy developed for Integrated Carbon Observation System (ICOS) stations based on CO<sub>2</sub> and CO measurements and Stochastic Time-Inverted Lagrangian Transport (STILT) footprint modelling", Atmospheric Chemistry and Physics., sep, 2020. Vol. 20(18), pp. 11161-11180.
BibTeX:
@article{Levin2020,
  author = {Levin, Ingeborg and Karstens, Ute and Eritt, Markus and Maier, Fabian and Arnold, Sabrina and Rzesanke, Daniel and Hammer, Samuel and Ramonet, Michel and Vítková, Gabriela and Conil, Sebastien and Heliasz, Michal and Kubistin, Dagmar and Lindauer, Matthias},
  title = {A dedicated flask sampling strategy developed for Integrated Carbon Observation System (ICOS) stations based on CO<sub>2</sub> and CO measurements and Stochastic Time-Inverted Lagrangian Transport (STILT) footprint modelling},
  journal = {Atmospheric Chemistry and Physics},
  year = {2020},
  volume = {20},
  number = {18},
  pages = {11161--11180},
  url = {https://acp.copernicus.org/articles/20/11161/2020/},
  doi = {10.5194/acp-20-11161-2020}
}
Levy P, Drewer J, Jammet M, Leeson S, Friborg T, Skiba U and van Oijen M (2020), "Inference of spatial heterogeneity in surface fluxes from eddy covariance data: A case study from a subarctic mire ecosystem", Agricultural and Forest Meteorology. Vol. 280(August 2019), pp. 107783. Elsevier.
Abstract: Horizontal heterogeneity causes difficulties in the eddy covariance technique for measuring surface fluxes, related to both advection and the confounding of temporal and spatial variability. Our aim here was to address this problem, using statistical modelling and footprint analysis, applied to a case study of fluxes of sensible heat and methane in a subarctic mire. We applied a new method to infer the spatial heterogeneity in fluxes of sensible heat and methane from a subarctic ecosystem in northern Sweden, where there were clear differences in surface types within the landscape. We inferred the flux from each of these surface types, using a Bayesian approach to estimate the parameters of a hierarchical model which includes coefficients for the different surface types. The approach is based on the variation in the flux observed at a single eddy covariance tower as the footprint changes over time. The method has applications wherever spatial heterogeneity is a concern in the interpretation of eddy covariance fluxes.
BibTeX:
@article{Levy2020,
  author = {Levy, Peter and Drewer, Julia and Jammet, Mathilde and Leeson, Sarah and Friborg, Thomas and Skiba, Ute and van Oijen, Marcel},
  title = {Inference of spatial heterogeneity in surface fluxes from eddy covariance data: A case study from a subarctic mire ecosystem},
  journal = {Agricultural and Forest Meteorology},
  publisher = {Elsevier},
  year = {2020},
  volume = {280},
  number = {August 2019},
  pages = {107783},
  url = {https://doi.org/10.1016/j.agrformet.2019.107783},
  doi = {10.1016/j.agrformet.2019.107783}
}
Li X, Wahlroos O, Haapanala S, Pumpanen J, Vasander H, Ojala A, Vesala T and Mammarella I (2020), "Carbon dioxide and methane fluxes from different surface types in a created urban wetland", Biogeosciences., jul, 2020. Vol. 17(13), pp. 3409-3425. Copernicus GmbH.
Abstract: Many wetlands have been drained due to urbanization, agriculture, forestry or other purposes, which has resulted in a loss of their ecosystem services. To protect receiving waters and to achieve services such as flood control and storm water quality mitigation, new wetlands are created in urbanized areas. However, our knowledge of greenhouse gas exchange in newly created wetlands in urban areas is currently limited. In this paper we present measurements carried out at a created urban wetland in Southern Finland in the boreal climate. We conducted measurements of ecosystem CO2 flux and CH4 flux (FCH4 ) at the created storm water wetland Gateway in Nummela, Vihti, Southern Finland, using the eddy covariance (EC) technique. The measurements were commenced the fourth year after construction and lasted for 1 full year and two subsequent growing seasons. Besides ecosystemscale fluxes measured by the EC tower, the diffusive CO2 and CH4 fluxes from the open-water areas (FwCO2 and FwCH4 , respectively) were modelled based on measurements of CO2 and CH4 concentration in the water. Fluxes from the vegetated areas were estimated by applying a simple mixing model using the above-mentioned fluxes and the footprintweighted fractional area. The half-hourly footprint-weighted contribution of diffusive fluxes from open water ranged from 0% to 25.5% in 2013. The annual net ecosystem exchange (NEE) of the studied wetland was 8.0 g C-CO2 m2 yr1, with the 95% confidence interval between 18:9 and 34.9 g C-CO2 m2 yr1, and FCH4 was 3.9 g C-CH4 m2 yr1, with the 95% confidence interval between 3.75 and 4.07 g C-CH4 m2 yr1. The ecosystem sequestered CO2 during summer months (June August), while the rest of the year it was a CO2 source. CH4 displayed strong seasonal dynamics, higher in summer and lower in winter, with a sporadic emission episode in the end of May 2013. Both CH4 and CO2 fluxes, especially those obtained from vegetated areas, exhibited strong diurnal cycles during summer with synchronized peaks around noon. The annual FwCO2 was 297.5 g C-CO2 m2 yr1 and FwCH4 was 1.73 g C-CH4 m2 yr1. The peak diffusive CH4 flux was 137.6 nmol C-CH4 m2 s1, which was synchronized with the FCH4 . Overall, during the monitored time period, the established storm water wetland had a climate-warming effect with 0.263 kgCO2-eqm2 yr1 of which 89% was contributed by CH4. The radiative forcing of the open-water areas exceeded that of the vegetation areas (1.194 and 0.111 kgCO2- eqm2 yr1, respectively), which implies that, when considering solely the climate impact of a created wetland over a 100-year horizon, it would be more beneficial to design and establish wetlands with large patches of emergent vegetation and to limit the areas of open water to the minimum necessitated by other desired ecosystem services.
BibTeX:
@article{Li2020,
  author = {Li, Xuefei and Wahlroos, Outi and Haapanala, Sami and Pumpanen, Jukka and Vasander, Harri and Ojala, Anne and Vesala, Timo and Mammarella, Ivan},
  title = {Carbon dioxide and methane fluxes from different surface types in a created urban wetland},
  journal = {Biogeosciences},
  publisher = {Copernicus GmbH},
  year = {2020},
  volume = {17},
  number = {13},
  pages = {3409--3425},
  doi = {10.5194/bg-17-3409-2020}
}
Li X and Xiao J (2020), "Global climatic controls on interannual variability of ecosystem productivity: Similarities and differences inferred from solar-induced chlorophyll fluorescence and enhanced vegetation index", Agricultural and Forest Meteorology. Elsevier B.V..
Abstract: Assessing how climate factors regulate the interannual variability (IAV) of ecosystem productivity globally is crucial for understanding the ecosystem-climate interactions and carbon-climate feedbacks under a changing climate. However, our understanding of global climatic controls on the IAV of ecosystem productivity has been limited by the lack of direct measurements of ecosystem productivity at the global scale. We used a long-term, fine-resolution solar-induced chlorophyll fluorescence (SIF) product (GOSIF) derived from SIF soundings measured by the Orbiting Carbon Observatory-2 (OCO-2) to investigate how climatic factors drive the IAV of global ecosystem productivity. We also examined how the results derived from SIF differed from those based on a satellite-derived measure of vegetation greenness and productivity - the enhanced vegetation index (EVI) derived from the Moderate Resolution Imaging Spectroradiometer (MODIS). Both productivity measures showed the dominant role of soil moisture in driving the IAV of global ecosystem productivity, particularly in arid and semi-arid areas. SIF was more sensitive to climate variability than was EVI. SIF was positively correlated with solar radiation in the humid regions, while no significant correlations were found between EVI and solar radiation. The stronger correlation of SIF with climate factors was also observed at the ecosystem level based on a number of eddy covariance flux sites, indicating that SIF had a higher ability in capturing the variations of gross primary productivity (GPP) than did EVI. The comparison between SIF and EVI also highlighted the biome-specific (depending on the tree cover) responses of ecosystem productivity to solar radiation under water stress. Our findings explicitly reveal the global climatic controls on the IAV of ecosystem productivity, and provide insight into the mechanistic differences between SIF and vegetation indices in characterizing ecosystem productivity.
BibTeX:
@article{Li2020a,
  author = {Li, Xing and Xiao, Jingfeng},
  title = {Global climatic controls on interannual variability of ecosystem productivity: Similarities and differences inferred from solar-induced chlorophyll fluorescence and enhanced vegetation index},
  journal = {Agricultural and Forest Meteorology},
  publisher = {Elsevier B.V.},
  year = {2020},
  doi = {10.1016/j.agrformet.2020.108018}
}
Lian X, Piao S, Li LZX, Li Y, Huntingford C, Ciais P, Cescatti A, Janssens IA, Peñuelas J, Buermann W, Chen A, Li X, Myneni RB, Wang X, Wang Y, Yang Y, Zeng Z, Zhang Y and McVicar TR (2020), "Summer soil drying exacerbated by earlier spring greening of northern vegetation", Science Advances., jan, 2020. Vol. 6(1), pp. eaax0255. American Association for the Advancement of Science (AAAS).
Abstract: Earlier vegetation greening under climate change raises evapotranspiration and thus lowers spring soil moisture, yet the extent and magnitude of this water deficit persistence into the following summer remain elusive. We provide observational evidence that increased foliage cover over the Northern Hemisphere, during 1982–2011, triggers an additional soil moisture deficit that is further carried over into summer. Climate model simulations independently support this and attribute the driving process to be larger increases in evapotranspiration than in precipitation. This extra soil drying is projected to amplify the frequency and intensity of summer heatwaves. Most feedbacks operate locally, except for a notable teleconnection where extra moisture transpired over Europe is transported to central Siberia. Model results illustrate that this teleconnection offsets Siberian soil moisture losses from local spring greening. Our results highlight that climate change adaptation planning must account for the extra summer water and heatwave stress inherited from warming-induced earlier greening.
BibTeX:
@article{Lian2020,
  author = {Lian, Xu and Piao, Shilong and Li, Laurent Z X and Li, Yue and Huntingford, Chris and Ciais, Philippe and Cescatti, Alessandro and Janssens, Ivan A and Peñuelas, Josep and Buermann, Wolfgang and Chen, Anping and Li, Xiangyi and Myneni, Ranga B and Wang, Xuhui and Wang, Yilong and Yang, Yuting and Zeng, Zhenzhong and Zhang, Yongqiang and McVicar, Tim R},
  title = {Summer soil drying exacerbated by earlier spring greening of northern vegetation},
  journal = {Science Advances},
  publisher = {American Association for the Advancement of Science (AAAS)},
  year = {2020},
  volume = {6},
  number = {1},
  pages = {eaax0255},
  doi = {10.1126/sciadv.aax0255}
}
Lin H, Tu C, Fang J, Gioli B, Loubet B, Gruening C, Zhou G, Beringer J, Huang J, Dušek J, Liddell M, Buysse P, Shi P, Song Q, Han S, Magliulo V, Li Y and Grace J (2020), "Forests buffer thermal fluctuation better than non-forests", Agricultural and Forest Meteorology. Elsevier B.V..
Abstract: With the increase in intensity and frequency of extreme climate events, interactions between vegetation and local climate are gaining more and more attention. Both the mean temperature and the temperature fluctuations of vegetation will exert thermal influence on local climate and the life of plants and animals. Many studies have focused on the pattern in the mean canopy surface temperature of vegetation, whereas there is still no systematic study of thermal buffer ability (TBA) of different vegetation types across global biomes. We developed a new method to measure TBA based on the rate of temperature increase, requiring only one radiometer. With this method, we compared TBA of ten vegetation types with contrasting structures, e.g. from grasslands to forests, using data from 133 sites globally. TBA ranged from 5.2 to 21.2 across these sites and biomes. Forests and wetlands buffer thermal fluctuation better than non-forests (grasslands, savannas, and croplands), and the TBA boundary between forests and non-forests was typically around 10. Notably, seriously disturbed and young planted forests displayed a greatly reduced TBA as low as that of non-forests at high latitudes. Canopy height was a primary controller of TBA of forests, while the TBA of grasslands and savannas were mainly determined by energy partition, water availability, and carbon sequestration rates. Our research suggests that both mean values and fluctuations in canopy surface temperature should be considered to predict the risk for plants under extreme events. Protecting mature forests, both at high and low latitudes, is critical to mitigate thermal fluctuation under extreme events.
BibTeX:
@article{Lin2020,
  author = {Lin, Hua and Tu, Chengyi and Fang, Junyong and Gioli, Beniamino and Loubet, Benjamin and Gruening, Carsten and Zhou, Guoyi and Beringer, Jason and Huang, Jianguo and Dušek, Jiří and Liddell, Michael and Buysse, Pauline and Shi, Peili and Song, Qinghai and Han, Shijie and Magliulo, Vincenzo and Li, Yingnian and Grace, John},
  title = {Forests buffer thermal fluctuation better than non-forests},
  journal = {Agricultural and Forest Meteorology},
  publisher = {Elsevier B.V.},
  year = {2020},
  doi = {10.1016/j.agrformet.2020.107994}
}
Lindroth A, Holst J, Linderson M-L, Aurela M, Biermann T, Heliasz M, Chi J, Ibrom A, Kolari P, Klemedtsson L, Krasnova A, Laurila T, Lehner I, Lohila A, Mammarella I, Mölder M, Löfvenius MO, Peichl M, Pilegaard K, Soosar K, Vesala T, Vestin P, Weslien P and Nilsson M (2020), "Effects of drought and meteorological forcing on carbon and water fluxes in Nordic forests during the dry summer of 2018", Philosophical Transactions of the Royal Society B: Biological Sciences., oct, 2020. Vol. 375(1810), pp. 20190516.
Abstract: The Nordic region was subjected to severe drought in 2018 with a particularly long-lasting and large soil water deficit in Denmark, Southern Sweden and Estonia. Here, we analyse the impact of the drought on carbon and water fluxes in 11 forest ecosystems of different composition: spruce, pine, mixed and deciduous. We assess the impact of drought on fluxes by estimating the difference (anomaly) between year 2018 and a reference year without drought. Unexpectedly, the evaporation was only slightly reduced during 2018 compared to the reference year at two sites while it increased or was nearly unchanged at all other sites. This occurred under a 40 to 60% reduction in mean surface conductance and the concurrent increase in evaporative demand due to the warm and dry weather. The anomaly in the net ecosystem productivity (NEP) was 93% explained by a multilinear regression with the anomaly in heterotrophic respiration and the relative precipitation deficit as independent variables. Most of the variation (77%) was explained by the heterotrophic component. Six out of 11 forests reduced their annual NEP with more than 50 g C m −2 yr −1 during 2018 as compared to the reference year. The NEP anomaly ranged between −389 and +74 g C m −2 yr −1 with a median value of −59 g C m −2 yr −1 .
BibTeX:
@article{Lindroth2020,
  author = {Lindroth, Anders and Holst, Jutta and Linderson, Maj-Lena and Aurela, Mika and Biermann, Tobias and Heliasz, Michal and Chi, Jinshu and Ibrom, Andreas and Kolari, Pasi and Klemedtsson, Leif and Krasnova, Alisa and Laurila, Tuomas and Lehner, Irene and Lohila, Annalea and Mammarella, Ivan and Mölder, Meelis and Löfvenius, Mikaell Ottosson and Peichl, Matthias and Pilegaard, Kim and Soosar, Kaido and Vesala, Timo and Vestin, Patrik and Weslien, Per and Nilsson, Mats},
  title = {Effects of drought and meteorological forcing on carbon and water fluxes in Nordic forests during the dry summer of 2018},
  journal = {Philosophical Transactions of the Royal Society B: Biological Sciences},
  year = {2020},
  volume = {375},
  number = {1810},
  pages = {20190516},
  url = {https://royalsocietypublishing.org/doi/10.1098/rstb.2019.0516},
  doi = {10.1098/rstb.2019.0516}
}
Liu N, Michelsen A and Rinnan R (2020), "Vegetation and soil responses to added carbon and nutrients remain six years after discontinuation of long-term treatments", Science of the Total Environment. Vol. 722, pp. 137885. Elsevier B.V..
Abstract: Global warming and increased nutrient availability in the Arctic have attracted wide attention. However, it is unknown how an increased supply of nitrogen (N), phosphorus (P) and/or labile carbon (C) – alone and in combinations – affects the concentrations and pools of C and nutrients in plants, soil and soil microorganisms, and whether the cessation of these additions allows the ecosystem to recover from amendments. Six treatments (control, C, N, P, NP and C + NP) were applied at a subarctic heath for 8–10 years. After being untreated for two years, amendments were re-applied to one half of the plots for four years while the other plot half received no amendments. When the plots were harvested, we could therefore compare responses in plots with nearly continuous 14–16-year amendments to those with six years with discontinued treatments. The responses to individual and combined nutrient additions were mostly similar in re-initiated and discontinued plots. Individual N addition strongly increased the C and N pools in the graminoids, thereby also increasing the C and N pools in litter and fine roots compared to the plots without added N. This contributed to the increased microbial biomass C and total C in soil. P addition alone increased C and N pools in vascular cryptogams, as well as PO43−, NH4+, dissolved organic carbon and dissolved organic nitrogen concentrations in soil compared to the plots without added P. Hence, plant functional groups showed differential responses to long-term N and P amendment, and after the initial nutrient additions for 8–10 years, the investigated subarctic tundra ecosystem had reached a new steady state that was resilient to further changes still six years after cessation of additions.
BibTeX:
@article{Liu2020,
  author = {Liu, Na and Michelsen, Anders and Rinnan, Riikka},
  title = {Vegetation and soil responses to added carbon and nutrients remain six years after discontinuation of long-term treatments},
  journal = {Science of the Total Environment},
  publisher = {Elsevier B.V.},
  year = {2020},
  volume = {722},
  pages = {137885},
  url = {https://doi.org/10.1016/j.scitotenv.2020.137885},
  doi = {10.1016/j.scitotenv.2020.137885}
}
Louarn G, Chabbi A and Gastal F (2020), "Nitrogen concentration in the upper leaves of the canopy is a reliable indicator of plant N nutrition in both pure and mixed grassland swards", Grass and Forage Science., jan, 2020. Vol. 75(1), pp. 127-133. Wiley.
Abstract: Effective indicators of plant nitrogen (N) nutrition are needed to improve N management in grasslands. This is particularly the case for mixtures that rely on N fixation by legumes as a major N input, because no reference tool such as the nitrogen nutrition index (NNI) exists under these conditions. The aims of this study were to test the reliability of a plant-based index, the N concentration of upper leaves in the canopy (Nup), as a possible alternative for NNI in both pure and mixed grasslands. Data were gathered from four experiments covering a range of pure and mixed grasslands under different N fertilization levels. A cross-validation of Nup predictions against NNI in pure stands, and against two NNI-derived indices in mixtures, was performed. The Nup values appeared to be linearly related to NNI in pure stands of both grasses and legumes. The relationship was identical for the two groups of species and explained up to 86% of NNI variability. In mixtures, Nup also displayed a linear relationship with the two other tested indices, explaining 65% and 78% of variability. The conclusions of the three indices diverged with respect to strongly unbalanced mixtures, where the assumptions regarding the computation of NNI-derived indices were not met. Excluding these situations, the overall relationship between Nup and NNI proved to be identical for mixtures and pure stands. The results suggest that Nup is a valid criterion for plant N nutrition which applies to a broad range of grassland species and to mixture conditions.
BibTeX:
@article{Louarn2020,
  author = {Louarn, Gaëtan and Chabbi, Abad and Gastal, François},
  title = {Nitrogen concentration in the upper leaves of the canopy is a reliable indicator of plant N nutrition in both pure and mixed grassland swards},
  journal = {Grass and Forage Science},
  publisher = {Wiley},
  year = {2020},
  volume = {75},
  number = {1},
  pages = {127--133},
  doi = {10.1111/gfs.12466}
}
Macovei VA, Hartman SE, Schuster U, Torres-Valdés S, Moore CM and Sanders RJ (2020), "Impact of physical and biological processes on temporal variations of the ocean carbon sink in the mid-latitude North Atlantic (2002–2016)", Progress in Oceanography., jan, 2020. Vol. 180, pp. 102223. Elsevier BV.
Abstract: The ocean is currently a significant net sink for anthropogenically remobilised CO2, taking up around 24% of global emissions. Numerical models predict a diversity of responses of the ocean carbon sink to increased atmospheric concentrations in a warmer world. Here, we tested the hypothesis that increased atmospheric forcing is causing a change in the ocean carbon sink using a high frequency observational dataset derived from underway pCO2 (carbon dioxide partial pressure) instruments on ships of opportunity (SOO) and a fixed-point mooring between 2002 and 2016. We calculated an average carbon flux of 0.013 Pg yrâˆ'1 into the ocean at the Porcupine Abyssal Plain (PAP) site, consistent with past estimates. In spite of the increase in atmospheric pCO2, monthly average seawater pCO2 did not show a statistically significant increasing trend, but a higher annual variability, likely due to the decreasing buffer capacity of the system. The increasing ΔpCO2 led to an increasing trend in the estimated CO2 flux into the ocean of 0.19 ± 0.03 mmol mâˆ'2 dayâˆ'1 per year across the entire 15 year time series, making the study area a stronger carbon sink. Seawater pCO2 variability is mostly influenced by temperature, alkalinity and dissolved inorganic carbon (DIC) changes, with 77% of the annual seawater pCO2 changes explained by these terms. DIC is in turn influenced by gas exchange and biological production. In an average year, the DIC drawdown by biological production, as determined from nitrate uptake, was higher than the DIC increase due to atmospheric CO2 dissolution into the surface ocean. This effect was enhanced in years with high nutrient input or shallow mixed layers. Using the rate of change of DIC and nitrate, we observed Redfieldian carbon consumption during the spring bloom at a C:N ratio of 6.2 ± 1.6. A comparison between SOO and PAP sustained observatory data revealed a strong agreement for pCO2 and DIC. This work demonstrates that the study area has continued to absorb atmospheric CO2 in recent years with this sink enhancing over time. Furthermore, the change in pCO2 per unit nitrate became larger as surface buffer capacity changed.
BibTeX:
@article{Macovei2020,
  author = {Macovei, Vlad A and Hartman, Susan E and Schuster, Ute and Torres-Valdés, Sinhué and Moore, C Mark and Sanders, Richard J},
  title = {Impact of physical and biological processes on temporal variations of the ocean carbon sink in the mid-latitude North Atlantic (2002–2016)},
  journal = {Progress in Oceanography},
  publisher = {Elsevier BV},
  year = {2020},
  volume = {180},
  pages = {102223},
  doi = {10.1016/j.pocean.2019.102223}
}
Maksyutov S, Oda T, Saito M, Janardanan R, Belikov D, Kaiser W, Zhuravlev R, Ganshin A, Valsala VK, Andrews A, Chmura L, Dlugokencky E, Haszpra L, Langenfelds RL, Machida T, Nakazawa T, Ramonet M, Sweeney C and Worthy D (2020), "Technical note: A high-resolution inverse modelling technique for estimating surface CO2 fluxes based on the NIES-TM-FLEXPART coupled transport model and its adjoint", Atmospheric Chemistry and Physics.
Abstract: 25 We developed a high-resolution surface flux inversion system based on the global Lagrangian-Eulerian coupled tracer transport model composed of National Institute for Environmental Studies Transport Model (NIES-TM) and FLEXible PARTicle dispersion model (FLEXPART). The inversion system is named NTFVAR (NIES-TM-FLEXPART-variational) as it applies variational optimisation to estimate surface fluxes. We tested the system by estimating optimized corrections to natural surface CO2 fluxes to achieve best fit to atmospheric CO2 data collected by the global in-situ network, as a 30 necessary step towards capability of estimating anthropogenic CO2 emissions. We employ the Lagrangian particle dispersion model (LPDM) FLEXPART to calculate the surface flux footprints of CO2 observations at a 0.1° × 0.1° spatial https://doi.org/10.5194/acp-2020-251 Preprint. Discussion started: 27 March 2020 c Author(s) 2020. CC BY 4.0 License. 2 resolution. The LPDM is coupled to a global atmospheric tracer transport model (NIES-TM). Our inversion technique uses an adjoint of the coupled transport model in an iterative optimization procedure. The flux error covariance operator is being implemented via implicit diffusion. Biweekly flux corrections to prior flux fields were estimated for the years 2010-2012 from in-situ CO2 data included in the Observation Package (ObsPack) dataset. High-resolution prior flux fields were prepared using Open-Data Inventory for Anthropogenic Carbon dioxide (ODIAC) for fossil fuel combustion, Global Fire 5 Assimilation System (GFAS) for biomass burning, the Vegetation Integrative SImulator for Trace gases (VISIT) model for terrestrial biosphere exchange and Ocean Tracer Transport Model (OTTM) for oceanic exchange. The terrestrial biospheric flux field was constructed using a vegetation mosaic map and separate simulation of CO2 fluxes at daily time step by the VISIT model for each vegetation type. The prior flux uncertainty for terrestrial biosphere was scaled proportionally to the monthly mean Gross Primary Production (GPP) by the Moderate Resolution Imaging 10 Spectroradiometer (MODIS) MOD17 product. The inverse system calculates flux corrections to the prior fluxes in the form of a relatively smooth field multiplied by high-resolution patterns of the prior flux uncertainties for land and ocean, following the coastlines and vegetation productivity gradients. The resulting flux estimates improve fit to the observations at continuous observations sites, reproducing both the seasonal variation and short-term concentration variability, including high CO2 concentration events associated with anthropogenic emissions. The use of high-resolution atmospheric transport 15 in global CO2 flux inversion has the advantage of better resolving the transport from the mix of the anthropogenic and biospheric sources in densely populated continental regions and shows potential for better separation between fluxes from terrestrial ecosystems and strong localised sources such as anthropogenic emissions and forest fires. Further improvements in the modelling system are needed as the posterior fit is better than that by the National Oceanic and Atmospheric Administration (NOAA) CarbonTracker only for a fraction of the monitoring sites, mostly at coastal and island locations 20 experiencing mix of background and local flux signals.
BibTeX:
@article{Maksyutov,
  author = {Maksyutov, Shamil and Oda, Tomohiro and Saito, Makoto and Janardanan, Rajesh and Belikov, Dmitry and Kaiser, W and Zhuravlev, Ruslan and Ganshin, Alexander and Valsala, Vinu K and Andrews, Arlyn and Chmura, Lukasz and Dlugokencky, Edward and Haszpra, László and Langenfelds, Ray L and Machida, Toshinobu and Nakazawa, Takakiyo and Ramonet, Michel and Sweeney, Colm and Worthy, Douglas},
  title = {Technical note: A high-resolution inverse modelling technique for estimating surface CO2 fluxes based on the NIES-TM-FLEXPART coupled transport model and its adjoint},
  journal = {Atmospheric Chemistry and Physics},
  year = {2020},
  url = {https://doi.org/10.5194/acp-2020-251},
  doi = {10.5194/acp-2020-251}
}
Martínez B, Gilabert MA, Sánchez-Ruiz S, Campos-Taberner M, García-Haro FJ, Brümmer C, Carrara A, Feig G, Grünwald T, Mammarella I and Tagesson T (2020), "Evaluation of the LSA-SAF gross primary production product derived from SEVIRI/MSG data (MGPP)", ISPRS Journal of Photogrammetry and Remote Sensing. Vol. 159(November 2019), pp. 220-236. Elsevier.
Abstract: The objective of this study is to describe a completely new 10-day gross primary production (GPP) product (MGPP LSA-411) based on data from the geostationary SEVIRI/MSG satellite within the LSA SAF (Land Surface Analysis SAF) as part of the SAF (Satellite Application Facility) network of EUMETSAT. The methodology relies on the Monteith approach. It considers that GPP is proportional to the absorbed photosynthetically active radiation APAR and the proportionality factor is known as the light use efficiency $$. A parameterization of this factor is proposed as the product of a $$max, corresponding to the canopy functioning under optimal conditions, and a coefficient quantifying the reduction of photosynthesis as a consequence of water stress. A three years data record (2015–2017) was used in an assessment against site-level eddy covariance (EC) tower GPP estimates and against other Earth Observation (EO) based GPP products. The site-level comparison indicated that the MGPP product performed better than the other EO based GPP products with 48% of the observations being below the optimal accuracy (absolute error textless1.0 g m−2 day−1) and 75% of these data being below the user requirement threshold (absolute error textless3.0 g m−2 day−1). The largest discrepancies between the MGPP product and the other GPP products were found for forests whereas small differences were observed for the other land cover types. The integration of this GPP product with the ensemble of LSA-SAF MSG products is conducive to meet user needs for a better understanding of ecosystem processes and for improved understanding of anthropogenic impact on ecosystem services.
BibTeX:
@article{Martinez2020,
  author = {Martínez, B and Gilabert, M A and Sánchez-Ruiz, S and Campos-Taberner, M and García-Haro, F J and Brümmer, C and Carrara, A and Feig, G and Grünwald, T and Mammarella, I and Tagesson, T},
  title = {Evaluation of the LSA-SAF gross primary production product derived from SEVIRI/MSG data (MGPP)},
  journal = {ISPRS Journal of Photogrammetry and Remote Sensing},
  publisher = {Elsevier},
  year = {2020},
  volume = {159},
  number = {November 2019},
  pages = {220--236},
  url = {https://doi.org/10.1016/j.isprsjprs.2019.11.010},
  doi = {10.1016/j.isprsjprs.2019.11.010}
}
McColl KA and Rigden AJ (2020), "Emergent Simplicity of Continental Evapotranspiration", Geophysical Research Letters., mar, 2020. Vol. 47(6) Blackwell Publishing Ltd.
Abstract: Evapotranspiration (ET) is challenging to model because it depends on heterogeneous land surface features—such as soil moisture, land cover type, and plant physiology—resulting in rising model complexity and substantial disagreement between models. We show that the evaporative fraction (ET as a proportion of available energy at the surface) can be estimated accurately across a broad range of conditions using a simple equation with no free parameters and no land surface information; only near-surface air temperature and specific humidity observations are required. The equation performs well when compared to eddy covariance measurements at 76 inland continental sites, with prediction errors comparable to errors in the eddy covariance measurements themselves, despite substantial variability in surface conditions across sites. This reveals an emergent simplicity to continental ET that has not been previously recognized, in which land-atmosphere coupling efficiently embeds land surface information in the near-surface atmospheric state on daily to monthly time scales.
BibTeX:
@article{McColl2020,
  author = {McColl, Kaighin A. and Rigden, Angela J.},
  title = {Emergent Simplicity of Continental Evapotranspiration},
  journal = {Geophysical Research Letters},
  publisher = {Blackwell Publishing Ltd},
  year = {2020},
  volume = {47},
  number = {6},
  doi = {10.1029/2020GL087101}
}
McKinley GA, Fay AR, Eddebbar YA, Gloege L and Lovenduski NS (2020), "External Forcing Explains Recent Decadal Variability of the Ocean Carbon Sink", AGU Advances., jun, 2020. Vol. 1(2) American Geophysical Union (AGU).
Abstract: The ocean has absorbed the equivalent of 39% of industrial‐age fossil carbon emissions, significantly modulating the growth rate of atmospheric CO2 and its associated impacts on climate. Despite the importance of the ocean carbon sink to climate, our understanding of the causes of its interannual‐to‐decadal variability remains limited. This hinders our ability to attribute its past behavior and project its future. A key period of interest is the 1990s, when the ocean carbon sink did not grow as expected. Previous explanations of this behavior have focused on variability internal to the ocean or associated with coupled atmosphere/ocean modes. Here, we use an idealized upper ocean box model to illustrate that two external forcings are sufficient to explain the pattern and magnitude of sink variability since the mid‐1980s. First, the global‐scale reduction in the decadal‐average ocean carbon sink in the 1990s is attributable to the slowed growth rate of atmospheric pCO2. The acceleration of atmospheric pCO2 growth after 2001 drove recovery of the sink. Second, the global sea surface temperature response to the 1991 eruption of Mt Pinatubo explains the timing of the global sink within the 1990s. These results are consistent with previous experiments using ocean hindcast models with variable atmospheric pCO2 and with and without climate variability. The fact that variability in the growth rate of atmospheric pCO2 directly imprints on the ocean sink implies that there will be an immediate reduction in ocean carbon uptake as atmospheric pCO2 responds to cuts in anthropogenic emissions.
BibTeX:
@article{McKinley2020,
  author = {McKinley, Galen A. and Fay, Amanda R. and Eddebbar, Yassir A. and Gloege, Lucas and Lovenduski, Nicole S.},
  title = {External Forcing Explains Recent Decadal Variability of the Ocean Carbon Sink},
  journal = {AGU Advances},
  publisher = {American Geophysical Union (AGU)},
  year = {2020},
  volume = {1},
  number = {2},
  url = {https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019AV000149 https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019AV000149 https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019AV000149},
  doi = {10.1029/2019av000149}
}
Melton JR, Arora VK, Wisernig-Cojoc E, Seiler C, Fortier M, Chan E and Teckentrup L (2020), "CLASSIC v1.0: The open-source community successor to the Canadian Land Surface Scheme (CLASS) and the Canadian Terrestrial Ecosystem Model (CTEM)-Part 1: Model framework and site-level performance", Geoscientific Model Development., jun, 2020. Vol. 13(6), pp. 2825-2850. Copernicus GmbH.
Abstract: Recent reports by the Global Carbon Project highlight large uncertainties around land surface processes such as land use change, strength of CO2 fertilization, nutrient limitation and supply, and response to variability in climate. Process-based land surface models are well suited to address these complex and emerging global change problems but will require extensive development and evaluation. The coupled Canadian Land Surface Scheme and Canadian Terrestrial Ecosystem Model (CLASS-CTEM) framework has been under continuous development by Environment and Climate Change Canada since 1987. As the open-source model of code development has revolutionized the software industry, scientific software is experiencing a similar evolution. Given the scale of the challenge facing land surface modellers, and the benefits of open-source, or community model, development, we have transitioned CLASS-CTEM from an internally developed model to an open-source community model, which we call the Canadian Land Surface Scheme including Biogeochemical Cycles (CLASSIC) v.1.0. CLASSIC contains many technical features specifically designed to encourage community use including software containerization for serial and parallel simulations, extensive benchmarking software and data (Automated Model Benchmarking; AMBER), self-documenting code, community standard formats for model inputs and outputs, amongst others. Here, we evaluate and benchmark CLASSIC against 31 FLUXNET sites where the model has been tailored to the site-level conditions and driven with observed meteorology. Future versions of CLASSIC will be developed using AMBER and these initial benchmark results to evaluate model performance over time. CLASSIC remains under active development and the code, site-level benchmarking data, software container, and AMBER are freely available for community use.
BibTeX:
@article{Melton2020,
  author = {Melton, Joe R. and Arora, Vivek K. and Wisernig-Cojoc, Eduard and Seiler, Christian and Fortier, Matthew and Chan, Ed and Teckentrup, Lina},
  title = {CLASSIC v1.0: The open-source community successor to the Canadian Land Surface Scheme (CLASS) and the Canadian Terrestrial Ecosystem Model (CTEM)-Part 1: Model framework and site-level performance},
  journal = {Geoscientific Model Development},
  publisher = {Copernicus GmbH},
  year = {2020},
  volume = {13},
  number = {6},
  pages = {2825--2850},
  doi = {10.5194/gmd-13-2825-2020}
}
Miettinen H, Pumpanen J, Rantakari M and Ojala A (2020), "Carbon dynamics in a Boreal land-stream-lake continuum during the spring freshet of two hydrologically contrasting years", Biogeochemistry., mar, 2020. Vol. 148(1), pp. 91-109. Springer.
Abstract: We studied in 2013 and 2014 the spring carbon dynamics in a Boreal landscape consisting of a lake and 15 inflowing streams and an outlet. The first year had weather and a hydrological regime typical of past years with a distinct spring freshet connected with the thaw of the average snowpack. The latter year had higher air temperatures which did not permit snow accumulation, despite similar winter precipitation. As such, there was hardly any spring freshet in 2014, and stream discharge peaked in January, i.e., the conditions resembled those predicted in the future climate. Despite the hydrological differences between the years, there were only small interannual differences in the stream CO2 and DOC concentrations. The relationship between the concentrations and discharge was stronger in the typical year. CO2 concentrations in medium-sized streams correlated negatively with the discharge, indicating dilution effect of melting snowpacks, while in large-sized streams the correlation was positive, suggesting stronger groundwater influence. The DOC pathway to these streams was through the subsurface soil layers, not the groundwater. The total amount of carbon transported into the lake was ca. 1.5-fold higher in the typical year than in the year with warm winter. In 2013, most of the lateral inputs took place during spring freshet. In 2014, the majority of inputs occurred earlier, during the winter months. The lateral CO2 signal was visible in the lake at 1.5 m depth. DOC dominated the carbon transport, and in both years, 12% of the input C was in inorganic form.
BibTeX:
@article{Miettinen2020,
  author = {Miettinen, H. and Pumpanen, J. and Rantakari, M. and Ojala, A.},
  title = {Carbon dynamics in a Boreal land-stream-lake continuum during the spring freshet of two hydrologically contrasting years},
  journal = {Biogeochemistry},
  publisher = {Springer},
  year = {2020},
  volume = {148},
  number = {1},
  pages = {91--109},
  doi = {10.1007/s10533-020-00648-9}
}
Mobilia M, Schmidt M and Longobardi A (2020), "Modelling actual evapotranspiration seasonal variability by meteorological data-based models", Hydrology. Vol. 7(3), pp. 1-27.
Abstract: This study aims at illustrating a methodology for predicting monthly scale actual evapotranspiration losses only based on meteorological data, which mimics the evapotranspiration intra-annual dynamic. For this purpose, micrometeorological data at the Rollesbroich and Bondone mountain sites, which are energy-limited systems, and the Sister site, a water-limited system, have been analyzed. Based on an observed intra-annual transition between dry and wet states governed by a threshold value of net radiation at each site, an approach that couples meteorological data-based potential evapotranspiration and actual evapotranspiration relationships has been proposed and validated against eddy covariance measurements, and further compared to two well-known actual evapotranspiration prediction models, namely the advection-aridity and the antecedent precipitation index models. The threshold approach improves the intra-annual actual evapotranspiration variability prediction, particularly during the wet state periods, and especially concerning the Sister site, where errors are almost four times smaller compared to the basic models. To further improve the prediction within the dry state periods, a calibration of the Priestley-Taylor advection coefficient was necessary. This led to an error reduction of about 80% in the case of the Sister site, of about 30% in the case of Rollesbroich, and close to 60% in the case of Bondone Mountain. For cases with a lack of measured data of net radiation and soil heat fluxes, which are essential for the implementation of the models, an application derived from empirical relationships is discussed. In addition, the study assessed whether this variation from meteorological data worsened the prediction performances of the models.
BibTeX:
@article{Mobilia2020,
  author = {Mobilia, Mirka and Schmidt, Marius and Longobardi, Antonia},
  title = {Modelling actual evapotranspiration seasonal variability by meteorological data-based models},
  journal = {Hydrology},
  year = {2020},
  volume = {7},
  number = {3},
  pages = {1--27},
  doi = {10.3390/HYDROLOGY7030050}
}
Montzka C, Brogi C, Mengen D, Matveeva M, Baum S, Schüttemeyer D, Bayat B, Bogena H, Coccia A, Masalias G, Graf V, Jakobi J, Jonard F, Ma Y, Mattia F, Palmisano D, Rascher U, Satalino G, Jagdhuber T, Fluhrer A, Schumacher M, Schmidt M and Vereecken H (2020), "Sarsense: A C- and L-Band SAR Rehearsal Campaign in Germany in Preparation for ROSE-L", In IGARSS 2020 - 2020 IEEE International Geoscience and Remote Sensing Symposium. , pp. 2137-2140.
Abstract: In summer 2019 the SARSense campaign was held in Jülich, Germany, to provide insights into the potentials and specifications of the ESA Copernicus candidate mission ROSE-L (Radar Observation System for Europe). ROSE-L will consist of two satellites that carry a polarimetric L-band SAR. Since the L-band signal can penetrate through many natural materials such as vegetation, dry snow and ice, the mission will provide additional information that cannot be gathered by the Copernicus Sentinel-1 C-band SAR mission. The overall objective of the SARSense 2019 campaign is to analyze the mission design concerning its potential for agricultural monitoring services including target applications such as soil moisture monitoring, irrigation management, crop type discrimination, food security and precision farming. The SARSense in situ measurements of soil moisture, soil temperature, vegetation properties, UAS-based multispectral and thermal mapping, as well as the airborne SAR observations are presented as well as strategies for soil moisture retrieval and first analysis.
BibTeX:
@inproceedings{Montzka2020,
  author = {Montzka, C and Brogi, C and Mengen, D and Matveeva, M and Baum, S and Schüttemeyer, D and Bayat, B and Bogena, H and Coccia, A and Masalias, G and Graf, V and Jakobi, J and Jonard, F and Ma, Y and Mattia, F and Palmisano, D and Rascher, U and Satalino, G and Jagdhuber, T and Fluhrer, A and Schumacher, M and Schmidt, M and Vereecken, H},
  title = {Sarsense: A C- and L-Band SAR Rehearsal Campaign in Germany in Preparation for ROSE-L},
  booktitle = {IGARSS 2020 - 2020 IEEE International Geoscience and Remote Sensing Symposium},
  year = {2020},
  pages = {2137--2140},
  doi = {10.1109/IGARSS39084.2020.9324090}
}
Moreaux V, Longdoz B, Berveiller D, Delpierre N, Dufrene E, Bonnefond J-M, Chipeaux C, Joffre R, Limousin J-M, Ourcival J-M, Klumpp K, Darsonville O, Brut A, Tallec T, Ceschia E, Panthou G and Loustau D (2020), "Environmental control of land-atmosphere CO2 fluxes from temperate ecosystems: a statistical approach based on homogenized time series from five land-use types", TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY., jun, 2020. Vol. 72(1), pp. 1-25.
BibTeX:
@article{Moreaux2020,
  author = {Moreaux, Virginie and Longdoz, Bernard and Berveiller, Daniel and Delpierre, Nicolas and Dufrene, Eric and Bonnefond, Jean-Marc and Chipeaux, Christophe and Joffre, Richard and Limousin, Jean-Marc and Ourcival, Jean-Marc and Klumpp, Katja and Darsonville, Olivier and Brut, Aurore and Tallec, Tiphaine and Ceschia, Eric and Panthou, Geremy and Loustau, Denis},
  title = {Environmental control of land-atmosphere CO2 fluxes from temperate ecosystems: a statistical approach based on homogenized time series from five land-use types},
  journal = {TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY},
  year = {2020},
  volume = {72},
  number = {1},
  pages = {1--25},
  doi = {10.1080/16000889.2020.1784689}
}
Moreaux V, Martel S, Bosc A, Picart D, Achat D, Moisy C, Aussenac R, Chipeaux C, Bonnefond J-M, Figueres S, Trichetl P, Vezy R, Badeau V, Longdoz B, Granier A, Roupsard O, Nicolas M, Pilegaard K, Matteucci G, Jolivet C, Black AT, Picard O and Loustau D (2020), "Energy, water and carbon exchanges in managed forest ecosystems: description, sensitivity analysis and evaluation of the INRAE GO plus model, version 3.0", GEOSCIENTIFIC MODEL DEVELOPMENT., dec, 2020. Vol. 13(12), pp. 5973-6009.
BibTeX:
@article{Moreaux2020a,
  author = {Moreaux, Virginie and Martel, Simon and Bosc, Alexandre and Picart, Delphine and Achat, David and Moisy, Christophe and Aussenac, Raphael and Chipeaux, Christophe and Bonnefond, Jean-Marc and Figueres, Soisick and Trichetl, Pierre and Vezy, Remi and Badeau, Vincent and Longdoz, Bernard and Granier, Andre and Roupsard, Olivier and Nicolas, Manuel and Pilegaard, Kim and Matteucci, Giorgio and Jolivet, Claudy and Black, Andrew T and Picard, Olivier and Loustau, Denis},
  title = {Energy, water and carbon exchanges in managed forest ecosystems: description, sensitivity analysis and evaluation of the INRAE GO plus model, version 3.0},
  journal = {GEOSCIENTIFIC MODEL DEVELOPMENT},
  year = {2020},
  volume = {13},
  number = {12},
  pages = {5973--6009},
  doi = {10.5194/gmd-13-5973-2020}
}
Müller M, Graf P, Meyer J, Pentina A, Brunner D, Perez-Cruz F, Hüglin C and Emmenegger L (2020), "Integration and calibration of non-dispersive infrared (NDIR) CO2 low-cost sensors and their operation in a sensor network covering Switzerland", Atmospheric Measurement Techniques., jul, 2020. Vol. 13(7), pp. 3815-3834.
Abstract: ∼85 %) impairs the LP8 measurements, and corresponding data filtering results in a significant loss during humid conditions. The LP8 sensors are not suitable for the detection of small regional gradients and long-term trends. However, with careful data processing, the sensors are able to resolve CO2 changes and differences with a magnitude larger than about 30 ppm. Thereby, the sensor can resolve the site-specific CO2 signal at most locations in Switzerland. A low-power network (LPN) using LoRaWAN allowed for reliable data transmission with low energy consumption and proved to be a key element of the Carbosense low-cost sensor network.]]textgreater
BibTeX:
@article{Mueller2020,
  author = {Müller, Michael and Graf, Peter and Meyer, Jonas and Pentina, Anastasia and Brunner, Dominik and Perez-Cruz, Fernando and Hüglin, Christoph and Emmenegger, Lukas},
  title = {Integration and calibration of non-dispersive infrared (NDIR) CO2 low-cost sensors and their operation in a sensor network covering Switzerland},
  journal = {Atmospheric Measurement Techniques},
  year = {2020},
  volume = {13},
  number = {7},
  pages = {3815--3834},
  url = {https://amt.copernicus.org/articles/13/3815/2020/},
  doi = {10.5194/amt-13-3815-2020}
}
Mund M, Herbst M, Knohl A, Matthäus B, Schumacher J, Schall P, Siebicke L, Tamrakar R and Ammer C (2020), "It is not just a ‘trade-off': indications for sink- and source-limitation to vegetative and regenerative growth in an old-growth beech forest", New Phytologist. Vol. 226(1), pp. 111-125.
Abstract: Controls on tree growth are key issues in plant physiology. The hypothesis of our study was that the interannual variability of wood and fruit production are primarily controlled directly by weather conditions (sink limitation), while carbon assimilation (source limitation) plays a secondary role. We analyzed the interannual variability of weather conditions, gross primary productivity (GPP) and net primary productivity (NPP) of wood and fruits of an old-growth, unmanaged Fagus sylvatica forest over 14 yr, including six mast years. In a multiple linear regression model, c. 71% of the annual variation in wood-NPP could be explained by mean air temperature in May, precipitation from April to May (positive influence) and fruit-NPP (negative influence). GPP of June to July solely explained c. 42% of the variation in wood-NPP. Fruit-NPP was positively related to summer precipitation 2 yr before (R2 = 0.85), and negatively to precipitation in May (R2 = 0.83) in the fruit years. GPP had no influence on fruit-NPP. Our results suggest a complex system of sink and source limitations to tree growth driven by weather conditions and going beyond a simple carbon-mediated ‘trade-off' between regenerative and vegetative growth.
BibTeX:
@article{Mund2020,
  author = {Mund, Martina and Herbst, Mathias and Knohl, Alexander and Matthäus, Bertrand and Schumacher, Jens and Schall, Peter and Siebicke, Lukas and Tamrakar, Rijan and Ammer, Christian},
  title = {It is not just a ‘trade-off': indications for sink- and source-limitation to vegetative and regenerative growth in an old-growth beech forest},
  journal = {New Phytologist},
  year = {2020},
  volume = {226},
  number = {1},
  pages = {111--125},
  doi = {10.1111/nph.16408}
}
Nelson JA, Pérez-Priego O, Zhou S, Poyatos R, Zhang Y, Blanken PD, Gimeno TE, Wohlfahrt G, Desai AR, Gioli B, Limousin JM, Bonal D, Paul-Limoges E, Scott RL, Varlagin A, Fuchs K, Montagnani L, Wolf S, Delpierre N, Berveiller D, Gharun M, Belelli Marchesini L, Gianelle D, Šigut L, Mammarella I, Siebicke L, Andrew Black T, Knohl A, Hörtnagl L, Magliulo V, Besnard S, Weber U, Carvalhais N, Migliavacca M, Reichstein M and Jung M (2020), "Ecosystem transpiration and evaporation: Insights from three water flux partitioning methods across FLUXNET sites", Global Change Biology. Vol. 26(12), pp. 6916-6930.
Abstract: We apply and compare three widely applicable methods for estimating ecosystem transpiration (T) from eddy covariance (EC) data across 251 FLUXNET sites globally. All three methods are based on the coupled water and carbon relationship, but they differ in assumptions and parameterizations. Intercomparison of the three daily T estimates shows high correlation among methods (R between.89 and.94), but a spread in magnitudes of T/ET (evapotranspiration) from 45% to 77%. When compared at six sites with concurrent EC and sap flow measurements, all three EC-based T estimates show higher correlation to sap flow-based T than EC-based ET. The partitioning methods show expected tendencies of T/ET increasing with dryness (vapor pressure deficit and days since rain) and with leaf area index (LAI). Analysis of 140 sites with high-quality estimates for at least two continuous years shows that T/ET variability was 1.6 times higher across sites than across years. Spatial variability of T/ET was primarily driven by vegetation and soil characteristics (e.g., crop or grass designation, minimum annual LAI, soil coarse fragment volume) rather than climatic variables such as mean/standard deviation of temperature or precipitation. Overall, T and T/ET patterns are plausible and qualitatively consistent among the different water flux partitioning methods implying a significant advance made for estimating and understanding T globally, while the magnitudes remain uncertain. Our results represent the first extensive EC data-based estimates of ecosystem T permitting a data-driven perspective on the role of plants' water use for global water and carbon cycling in a changing climate.
BibTeX:
@article{Nelson2020,
  author = {Nelson, Jacob A and Pérez-Priego, Oscar and Zhou, Sha and Poyatos, Rafael and Zhang, Yao and Blanken, Peter D and Gimeno, Teresa E and Wohlfahrt, Georg and Desai, Ankur R and Gioli, Beniamino and Limousin, Jean Marc and Bonal, Damien and Paul-Limoges, Eugénie and Scott, Russell L and Varlagin, Andrej and Fuchs, Kathrin and Montagnani, Leonardo and Wolf, Sebastian and Delpierre, Nicolas and Berveiller, Daniel and Gharun, Mana and Belelli Marchesini, Luca and Gianelle, Damiano and Šigut, Ladislav and Mammarella, Ivan and Siebicke, Lukas and Andrew Black, T and Knohl, Alexander and Hörtnagl, Lukas and Magliulo, Vincenzo and Besnard, Simon and Weber, Ulrich and Carvalhais, Nuno and Migliavacca, Mirco and Reichstein, Markus and Jung, Martin},
  title = {Ecosystem transpiration and evaporation: Insights from three water flux partitioning methods across FLUXNET sites},
  journal = {Global Change Biology},
  year = {2020},
  volume = {26},
  number = {12},
  pages = {6916--6930},
  doi = {10.1111/gcb.15314}
}
Nezami S, Khoramshahi E, Nevalainen O, Pölönen I and Honkavaara E (2020), "Tree species classification of drone hyperspectral and RGB imagery with deep learning convolutional neural networks", Remote Sensing. Vol. 12(7)
Abstract: Interest in drone solutions in forestry applications is growing. Using drones, datasets can be captured flexibly and at high spatial and temporal resolutions when needed. In forestry applications, fundamental tasks include the detection of individual trees, tree species classification, biomass estimation, etc. Deep neural networks (DNN) have shown superior results when comparing with conventional machine learning methods such as multi-layer perceptron (MLP) in cases of huge input data. The objective of this research is to investigate 3D convolutional neural networks (3D-CNN) to classify three major tree species in a boreal forest: pine, spruce, and birch. The proposed 3D-CNN models were employed to classify tree species in a test site in Finland. The classifiers were trained with a dataset of 3039 manually labelled trees. Then the accuracies were assessed by employing independent datasets of 803 records. To find the most efficient set of feature combination, we compare the performances of 3D-CNN models trained with hyperspectral (HS) channels, Red-Green-Blue (RGB) channels, and canopy height model (CHM), separately and combined. It is demonstrated that the proposed 3D-CNN model with RGB and HS layers produces the highest classification accuracy. The producer accuracy of the best 3D-CNN classifier on the test dataset were 99.6%, 94.8%, and 97.4% for pines, spruces, and birches, respectively. The best 3D-CNN classifier produced ˜5% better classification accuracy than the MLP with all layers. Our results suggest that the proposed method provides excellent classification results with acceptable performance metrics for HS datasets. Our results show that pine class was detectable in most layers. Spruce was most detectable in RGB data, while birch was most detectable in the HS layers. Furthermore, the RGB datasets provide acceptable results for many low-accuracy applications.
BibTeX:
@article{Nezami2020,
  author = {Nezami, Somayeh and Khoramshahi, Ehsan and Nevalainen, Olli and Pölönen, Ilkka and Honkavaara, Eija},
  title = {Tree species classification of drone hyperspectral and RGB imagery with deep learning convolutional neural networks},
  journal = {Remote Sensing},
  year = {2020},
  volume = {12},
  number = {7},
  doi = {10.3390/rs12071070}
}
Nickless A, Scholes RJ, Vermeulen A, Beck J, López-Ballesteros A, Ardö J, Karstens U, Rigby M, Kasurinen V, Pantazatou K, Jorch V and Kutsch W (2020), "Greenhouse gas observation network design for Africa", Tellus B: Chemical and Physical Meteorology. Vol. 72(1), pp. 1-30. Taylor & Francis.
BibTeX:
@article{Nickless2020,
  author = {Nickless, Alecia and Scholes, Robert J and Vermeulen, Alex and Beck, Johannes and López-Ballesteros, Ana and Ardö, Jonas and Karstens, Ute and Rigby, Matthew and Kasurinen, Ville and Pantazatou, Karolina and Jorch, Veronika and Kutsch, Werner},
  title = {Greenhouse gas observation network design for Africa},
  journal = {Tellus B: Chemical and Physical Meteorology},
  publisher = {Taylor & Francis},
  year = {2020},
  volume = {72},
  number = {1},
  pages = {1--30},
  url = {https://www.tandfonline.com/doi/abs/10.1080/16000889.2020.1824486},
  doi = {10.1080/16000889.2020.1824486}
}
Olid C, Klaminder J, Monteux S, Johansson M and Dorrepaal E (2020), "Decade of experimental permafrost thaw reduces turnover of young carbon and increases losses of old carbon, without affecting the net carbon balance", Global Change Biology., oct, 2020. Vol. 26(10), pp. 5886-5898.
BibTeX:
@article{Olid2020,
  author = {Olid, Carolina and Klaminder, Jonatan and Monteux, Sylvain and Johansson, Margareta and Dorrepaal, Ellen},
  title = {Decade of experimental permafrost thaw reduces turnover of young carbon and increases losses of old carbon, without affecting the net carbon balance},
  journal = {Global Change Biology},
  year = {2020},
  volume = {26},
  number = {10},
  pages = {5886--5898},
  url = {https://onlinelibrary.wiley.com/doi/10.1111/gcb.15283},
  doi = {10.1111/gcb.15283}
}
Ouyang Z, Qi D, Chen L, Takahashi T, Zhong W, DeGrandpre MD, Chen B, Gao Z, Nishino S, Murata A, Sun H, Robbins LL, Jin M and Cai WJ (2020), "Sea-ice loss amplifies summertime decadal CO2 increase in the western Arctic Ocean", Nature Climate Change., jul, 2020. Vol. 10(7), pp. 678-684. Nature Research.
Abstract: Rapid climate warming and sea-ice loss have induced major changes in the sea surface partial pressure of CO2 (pCO2). However, the long-term trends in the western Arctic Ocean are unknown. Here we show that in 1994–2017, summer pCO2 in the Canada Basin increased at twice the rate of atmospheric increase. Warming and ice loss in the basin have strengthened the pCO2 seasonal amplitude, resulting in the rapid decadal increase. Consequently, the summer air–sea CO2 gradient has reduced rapidly, and may become near zero within two decades. In contrast, there was no significant pCO2 increase on the Chukchi Shelf, where strong and increasing biological uptake has held pCO2 low, and thus the CO2 sink has increased and may increase further due to the atmospheric CO2 increase. Our findings elucidate the contrasting physical and biological drivers controlling sea surface pCO2 variations and trends in response to climate change in the Arctic Ocean.
BibTeX:
@article{Ouyang2020,
  author = {Ouyang, Zhangxian and Qi, Di and Chen, Liqi and Takahashi, Taro and Zhong, Wenli and DeGrandpre, Michael D. and Chen, Baoshan and Gao, Zhongyong and Nishino, Shigeto and Murata, Akihiko and Sun, Heng and Robbins, Lisa L. and Jin, Meibing and Cai, Wei Jun},
  title = {Sea-ice loss amplifies summertime decadal CO2 increase in the western Arctic Ocean},
  journal = {Nature Climate Change},
  publisher = {Nature Research},
  year = {2020},
  volume = {10},
  number = {7},
  pages = {678--684},
  url = {https://www.nature.com/articles/s41558-020-0784-2},
  doi = {10.1038/s41558-020-0784-2}
}
Papale D (2020), "Ideas and perspectives: enhancing the impact of the FLUXNET network of eddy covariance sites", Biogeosciences. Vol. 17(22), pp. 5587-5598.
Abstract: In the last 20 years, the FLUXNET network provided unique measurements of CO2, energy and other greenhouse gas exchanges between ecosystems and atmosphere measured with the eddy covariance technique. These data have been widely used in different and heterogeneous applications, and FLUXNET became a reference source of information not only for ecological studies but also in modeling and remote sensing applications. The data are, in general, collected, processed and shared by regional networks or by single sites, and for this reason it is difficult for users interested in analyses involving multiple sites to easily access a coherent and standardized dataset. For this reason, periodic FLUXNET collections have been released in the last 15 years, every 5 to 10 years, with data standardized and shared under the same data use policy. However, the new tools available for data analysis and the need to constantly monitor the relations between ecosystem behavior and climate change require a reorganization of FLUXNET in order to increase the data interoperability, reduce the delay in the data sharing and facilitate the data use, all this while keeping in mind the great effort made by the site teams to collect these unique data and respecting the different regional and national network organizations and data policies. Here a proposal for a new organization of FLUXNET is presented with the aim of stimulating a discussion for the needed developments. In this new scheme, the regional and national networks become the pillars of the global initiative, organizing clusters and becoming responsible for the processing, preparation and distribution of datasets that users will be able to access in real time and with a machine-to-machine tool, obtaining always the most updated collection possible but keeping a high standardization and common data policy. This will also lead to an increase in the FAIRness (Findability, Accessibility, Interoperability and Reusability) of the FLUXNET data that will ensure a larger impact of the unique data produced and a proper data management and traceability.
BibTeX:
@article{Papale2020,
  author = {Papale, Dario},
  title = {Ideas and perspectives: enhancing the impact of the FLUXNET network of eddy covariance sites},
  journal = {Biogeosciences},
  year = {2020},
  volume = {17},
  number = {22},
  pages = {5587--5598},
  doi = {10.5194/bg-17-5587-2020}
}
Pastorello G, Trotta C, Canfora E, Chu H, Christianson D, Cheah Y-W, Poindexter C, Chen J, Elbashandy A, Humphrey M, Isaac P, Polidori D, Ribeca A, van Ingen C, Zhang L, Amiro B, Ammann C, Arain MA, Ardö J, Arkebauer T, Arndt SK, Arriga N, Aubinet M, Aurela M, Baldocchi D, Barr A, Beamesderfer E, Marchesini LB, Bergeron O, Beringer J, Bernhofer C, Berveiller D, Billesbach D, Black TA, Blanken PD, Bohrer G, Boike J, Bolstad PV, Bonal D, Bonnefond J-M, Bowling DR, Bracho R, Brodeur J, Brümmer C, Buchmann N, Burban B, Burns SP, Buysse P, Cale P, Cavagna M, Cellier P, Chen S, Chini I, Christensen TR, Cleverly J, Collalti A, Consalvo C, Cook BD, Cook D, Coursolle C, Cremonese E, Curtis PS, D'Andrea E, da Rocha H, Dai X, Davis KJ, De Cinti B, de Grandcourt A, De Ligne A, De Oliveira RC, Delpierre N, Desai AR, Di Bella CM, di Tommasi P, Dolman H, Domingo F, Dong G, Dore S, Duce P, Dufrêne E, Dunn A, Dušek J, Eamus D, Eichelmann U, ElKhidir HAM, Eugster W, Ewenz CM, Ewers B, Famulari D, Fares S, Feigenwinter I, Feitz A, Fensholt R, Filippa G, Fischer M, Frank J, Galvagno M, Gharun M, Gianelle D, Gielen B, Gioli B, Gitelson A, Goded I, Goeckede M, Goldstein AH, Gough CM, Goulden ML, Graf A, Griebel A, Gruening C, Grünwald T, Hammerle A, Han S, Han X, Hansen BU, Hanson C, Hatakka J, He Y, Hehn M, Heinesch B, Hinko-Najera N, Hörtnagl L, Hutley L, Ibrom A, Ikawa H, Jackowicz-Korczynski M, Janouš D, Jans W, Jassal R, Jiang S, Kato T, Khomik M, Klatt J, Knohl A, Knox S, Kobayashi H, Koerber G, Kolle O, Kosugi Y, Kotani A, Kowalski A, Kruijt B, Kurbatova J, Kutsch WL, Kwon H, Launiainen S, Laurila T, Law B, Leuning R, Li Y, Liddell M, Limousin J-M, Lion M, Liska AJ, Lohila A, López-Ballesteros A, López-Blanco E, Loubet B, Loustau D, Lucas-Moffat A, Lüers J, Ma S, Macfarlane C, Magliulo V, Maier R, Mammarella I, Manca G, Marcolla B, Margolis HA, Marras S, Massman W, Mastepanov M, Matamala R, Matthes JH, Mazzenga F, McCaughey H, McHugh I, McMillan AMS, Merbold L, Meyer W, Meyers T, Miller SD, Minerbi S, Moderow U, Monson RK, Montagnani L, Moore CE, Moors E, Moreaux V, Moureaux C, Munger JW, Nakai T, Neirynck J, Nesic Z, Nicolini G, Noormets A, Northwood M, Nosetto M, Nouvellon Y, Novick K, Oechel W, Olesen JE, Ourcival J-M, Papuga SA, Parmentier F-J, Paul-Limoges E, Pavelka M, Peichl M, Pendall E, Phillips RP, Pilegaard K, Pirk N, Posse G, Powell T, Prasse H, Prober SM, Rambal S, Rannik Ü, Raz-Yaseef N, Reed D, de Dios VR, Restrepo-Coupe N, Reverter BR, Roland M, Sabbatini S, Sachs T, Saleska SR, Sánchez-Cañete EP, Sanchez-Mejia ZM, Schmid HP, Schmidt M, Schneider K, Schrader F, Schroder I, Scott RL, Sedlák P, Serrano-Ortíz P, Shao C, Shi P, Shironya I, Siebicke L, Šigut L, Silberstein R, Sirca C, Spano D, Steinbrecher R, Stevens RM, Sturtevant C, Suyker A, Tagesson T, Takanashi S, Tang Y, Tapper N, Thom J, Tiedemann F, Tomassucci M, Tuovinen J-P, Urbanski S, Valentini R, van der Molen M, van Gorsel E, van Huissteden K, Varlagin A, Verfaillie J, Vesala T, Vincke C, Vitale D, Vygodskaya N, Walker JP, Walter-Shea E, Wang H, Weber R, Westermann S, Wille C, Wofsy S, Wohlfahrt G, Wolf S, Woodgate W, Li Y, Zampedri R, Zhang J, Zhou G, Zona D, Agarwal D, Biraud S, Torn M and Papale D (2020), "The FLUXNET2015 dataset and the ONEFlux processing pipeline for eddy covariance data", Scientific Data., dec, 2020. Vol. 7(1), pp. 225.
BibTeX:
@article{Pastorello2020,
  author = {Pastorello, Gilberto and Trotta, Carlo and Canfora, Eleonora and Chu, Housen and Christianson, Danielle and Cheah, You-Wei and Poindexter, Cristina and Chen, Jiquan and Elbashandy, Abdelrahman and Humphrey, Marty and Isaac, Peter and Polidori, Diego and Ribeca, Alessio and van Ingen, Catharine and Zhang, Leiming and Amiro, Brian and Ammann, Christof and Arain, M Altaf and Ardö, Jonas and Arkebauer, Timothy and Arndt, Stefan K and Arriga, Nicola and Aubinet, Marc and Aurela, Mika and Baldocchi, Dennis and Barr, Alan and Beamesderfer, Eric and Marchesini, Luca Belelli and Bergeron, Onil and Beringer, Jason and Bernhofer, Christian and Berveiller, Daniel and Billesbach, Dave and Black, Thomas Andrew and Blanken, Peter D and Bohrer, Gil and Boike, Julia and Bolstad, Paul V and Bonal, Damien and Bonnefond, Jean-Marc and Bowling, David R and Bracho, Rosvel and Brodeur, Jason and Brümmer, Christian and Buchmann, Nina and Burban, Benoit and Burns, Sean P and Buysse, Pauline and Cale, Peter and Cavagna, Mauro and Cellier, Pierre and Chen, Shiping and Chini, Isaac and Christensen, Torben R and Cleverly, James and Collalti, Alessio and Consalvo, Claudia and Cook, Bruce D and Cook, David and Coursolle, Carole and Cremonese, Edoardo and Curtis, Peter S and D'Andrea, Ettore and da Rocha, Humberto and Dai, Xiaoqin and Davis, Kenneth J and De Cinti, Bruno and de Grandcourt, Agnes and De Ligne, Anne and De Oliveira, Raimundo C and Delpierre, Nicolas and Desai, Ankur R and Di Bella, Carlos Marcelo and di Tommasi, Paul and Dolman, Han and Domingo, Francisco and Dong, Gang and Dore, Sabina and Duce, Pierpaolo and Dufrêne, Eric and Dunn, Allison and Dušek, JiÅ™í and Eamus, Derek and Eichelmann, Uwe and ElKhidir, Hatim Abdalla M and Eugster, Werner and Ewenz, Cacilia M and Ewers, Brent and Famulari, Daniela and Fares, Silvano and Feigenwinter, Iris and Feitz, Andrew and Fensholt, Rasmus and Filippa, Gianluca and Fischer, Marc and Frank, John and Galvagno, Marta and Gharun, Mana and Gianelle, Damiano and Gielen, Bert and Gioli, Beniamino and Gitelson, Anatoly and Goded, Ignacio and Goeckede, Mathias and Goldstein, Allen H and Gough, Christopher M and Goulden, Michael L and Graf, Alexander and Griebel, Anne and Gruening, Carsten and Grünwald, Thomas and Hammerle, Albin and Han, Shijie and Han, Xingguo and Hansen, Birger Ulf and Hanson, Chad and Hatakka, Juha and He, Yongtao and Hehn, Markus and Heinesch, Bernard and Hinko-Najera, Nina and Hörtnagl, Lukas and Hutley, Lindsay and Ibrom, Andreas and Ikawa, Hiroki and Jackowicz-Korczynski, Marcin and Janouš, Dalibor and Jans, Wilma and Jassal, Rachhpal and Jiang, Shicheng and Kato, Tomomichi and Khomik, Myroslava and Klatt, Janina and Knohl, Alexander and Knox, Sara and Kobayashi, Hideki and Koerber, Georgia and Kolle, Olaf and Kosugi, Yoshiko and Kotani, Ayumi and Kowalski, Andrew and Kruijt, Bart and Kurbatova, Julia and Kutsch, Werner L and Kwon, Hyojung and Launiainen, Samuli and Laurila, Tuomas and Law, Bev and Leuning, Ray and Li, Yingnian and Liddell, Michael and Limousin, Jean-Marc and Lion, Marryanna and Liska, Adam J and Lohila, Annalea and López-Ballesteros, Ana and López-Blanco, Efrén and Loubet, Benjamin and Loustau, Denis and Lucas-Moffat, Antje and Lüers, Johannes and Ma, Siyan and Macfarlane, Craig and Magliulo, Vincenzo and Maier, Regine and Mammarella, Ivan and Manca, Giovanni and Marcolla, Barbara and Margolis, Hank A and Marras, Serena and Massman, William and Mastepanov, Mikhail and Matamala, Roser and Matthes, Jaclyn Hatala and Mazzenga, Francesco and McCaughey, Harry and McHugh, Ian and McMillan, Andrew M S and Merbold, Lutz and Meyer, Wayne and Meyers, Tilden and Miller, Scott D and Minerbi, Stefano and Moderow, Uta and Monson, Russell K and Montagnani, Leonardo and Moore, Caitlin E and Moors, Eddy and Moreaux, Virginie and Moureaux, Christine and Munger, J William and Nakai, Taro and Neirynck, Johan and Nesic, Zoran and Nicolini, Giacomo and Noormets, Asko and Northwood, Matthew and Nosetto, Marcelo and Nouvellon, Yann and Novick, Kimberly and Oechel, Walter and Olesen, Jørgen Eivind and Ourcival, Jean-Marc and Papuga, Shirley A and Parmentier, Frans-Jan and Paul-Limoges, Eugenie and Pavelka, Marian and Peichl, Matthias and Pendall, Elise and Phillips, Richard P and Pilegaard, Kim and Pirk, Norbert and Posse, Gabriela and Powell, Thomas and Prasse, Heiko and Prober, Suzanne M and Rambal, Serge and Rannik, Üllar and Raz-Yaseef, Naama and Reed, David and de Dios, Victor Resco and Restrepo-Coupe, Natalia and Reverter, Borja R and Roland, Marilyn and Sabbatini, Simone and Sachs, Torsten and Saleska, Scott R and Sánchez-Cañete, Enrique P and Sanchez-Mejia, Zulia M and Schmid, Hans Peter and Schmidt, Marius and Schneider, Karl and Schrader, Frederik and Schroder, Ivan and Scott, Russell L and Sedlák, Pavel and Serrano-Ortíz, Penélope and Shao, Changliang and Shi, Peili and Shironya, Ivan and Siebicke, Lukas and Šigut, Ladislav and Silberstein, Richard and Sirca, Costantino and Spano, Donatella and Steinbrecher, Rainer and Stevens, Robert M and Sturtevant, Cove and Suyker, Andy and Tagesson, Torbern and Takanashi, Satoru and Tang, Yanhong and Tapper, Nigel and Thom, Jonathan and Tiedemann, Frank and Tomassucci, Michele and Tuovinen, Juha-Pekka and Urbanski, Shawn and Valentini, Riccardo and van der Molen, Michiel and van Gorsel, Eva and van Huissteden, Ko and Varlagin, Andrej and Verfaillie, Joseph and Vesala, Timo and Vincke, Caroline and Vitale, Domenico and Vygodskaya, Natalia and Walker, Jeffrey P and Walter-Shea, Elizabeth and Wang, Huimin and Weber, Robin and Westermann, Sebastian and Wille, Christian and Wofsy, Steven and Wohlfahrt, Georg and Wolf, Sebastian and Woodgate, William and Li, Yuelin and Zampedri, Roberto and Zhang, Junhui and Zhou, Guoyi and Zona, Donatella and Agarwal, Deb and Biraud, Sebastien and Torn, Margaret and Papale, Dario},
  title = {The FLUXNET2015 dataset and the ONEFlux processing pipeline for eddy covariance data},
  journal = {Scientific Data},
  year = {2020},
  volume = {7},
  number = {1},
  pages = {225},
  url = {http://www.nature.com/articles/s41597-020-0534-3},
  doi = {10.1038/s41597-020-0534-3}
}
Patzner MS, Mueller CW, Malusova M, Baur M, Nikeleit V, Scholten T, Hoeschen C, Byrne JM, Borch T, Kappler A and Bryce C (2020), "Iron mineral dissolution releases iron and associated organic carbon during permafrost thaw", Nature Communications. Vol. 11(1), pp. 1-11. Springer US.
Abstract: It has been shown that reactive soil minerals, specifically iron(III) (oxyhydr)oxides, can trap organic carbon in soils overlying intact permafrost, and may limit carbon mobilization and degradation as it is observed in other environments. However, the use of iron(III)-bearing minerals as terminal electron acceptors in permafrost environments, and thus their stability and capacity to prevent carbon mobilization during permafrost thaw, is poorly understood. We have followed the dynamic interactions between iron and carbon using a space-for-time approach across a thaw gradient in Abisko (Sweden), where wetlands are expanding rapidly due to permafrost thaw. We show through bulk (selective extractions, EXAFS) and nanoscale analysis (correlative SEM and nanoSIMS) that organic carbon is bound to reactive Fe primarily in the transition between organic and mineral horizons in palsa underlain by intact permafrost (41.8 ± 10.8 mg carbon per g soil, 9.9 to 14.8% of total soil organic carbon). During permafrost thaw, water-logging and O2 limitation lead to reducing conditions and an increase in abundance of Fe(III)-reducing bacteria which favor mineral dissolution and drive mobilization of both iron and carbon along the thaw gradient. By providing a terminal electron acceptor, this rusty carbon sink is effectively destroyed along the thaw gradient and cannot prevent carbon release with thaw.
BibTeX:
@article{Patzner2020,
  author = {Patzner, Monique S and Mueller, Carsten W and Malusova, Miroslava and Baur, Moritz and Nikeleit, Verena and Scholten, Thomas and Hoeschen, Carmen and Byrne, James M and Borch, Thomas and Kappler, Andreas and Bryce, Casey},
  title = {Iron mineral dissolution releases iron and associated organic carbon during permafrost thaw},
  journal = {Nature Communications},
  publisher = {Springer US},
  year = {2020},
  volume = {11},
  number = {1},
  pages = {1--11},
  url = {http://dx.doi.org/10.1038/s41467-020-20102-6},
  doi = {10.1038/s41467-020-20102-6}
}
Penuelas J, Janssens IA, Ciais P, Obersteiner M and Sardans J (2020), "Anthropogenic global shifts in biospheric N and P concentrations and ratios and their impacts on biodiversity, ecosystem productivity, food security, and human health", Global Change Biology., feb, 2020. Vol. 26(4), pp. 1962-1985. Wiley.
Abstract: The availability of carbon (C) from high levels of atmospheric carbon dioxide (CO2 ) and anthropogenic release of nitrogen (N) is increasing, but these increases are not paralleled by increases in levels of phosphorus (P). The current unstoppable changes in the stoichiometries of C and N relative to P have no historical precedent. We describe changes in P and N fluxes over the last five decades that have led to asymmetrical increases in P and N inputs to the biosphere. We identified widespread and rapid changes in N:P ratios in air, soil, water, and organisms and important consequences to the structure, function, and biodiversity of ecosystems. A mass-balance approach found that the combined limited availability of P and N was likely to reduce C storage by natural ecosystems during the remainder of the 21st Century, and projected crop yields of the Millennium Ecosystem Assessment indicated an increase in nutrient deficiency in developing regions if access to P fertilizer is limited. Imbalances of the N:P ratio would likely negatively affect human health, food security, and global economic and geopolitical stability, with feedbacks and synergistic effects on drivers of global environmental change, such as increasing levels of CO2 , climatic warming, and increasing pollution. We summarize potential solutions for avoiding the negative impacts of global imbalances of N:P ratios on the environment, biodiversity, climate change, food security, and human health.
BibTeX:
@article{Penuelas2020,
  author = {Penuelas, Josep and Janssens, Ivan A and Ciais, Philippe and Obersteiner, Michael and Sardans, Jordi},
  title = {Anthropogenic global shifts in biospheric N and P concentrations and ratios and their impacts on biodiversity, ecosystem productivity, food security, and human health},
  journal = {Global Change Biology},
  publisher = {Wiley},
  year = {2020},
  volume = {26},
  number = {4},
  pages = {1962--1985},
  doi = {10.1111/gcb.14981}
}
Perryman CR, McCalley CK, Malhotra A, Fahnestock MF, Kashi NN, Bryce JG, Giesler R and Varner RK (2020), "Thaw Transitions and Redox Conditions Drive Methane Oxidation in a Permafrost Peatland", Journal of Geophysical Research: Biogeosciences. Vol. 125(3), pp. 1-15.
Abstract: Permafrost peatlands are a significant source of methane (CH4) emissions to the atmosphere and could emit more CH4 with continued permafrost thaw. Aerobic methane-oxidizing bacteria may attenuate a substantial fraction of CH4 emissions in thawing permafrost peatlands; however, the impact of permafrost thaw on CH4 oxidation is uncertain. We measured potential CH4 oxidation rates (hereafter, CH4 oxidation) and their predictors using laboratory incubations and in situ porewater redox chemistry across a permafrost thaw gradient of eight thaw stages at Stordalen Mire, a permafrost peatland complex in northernmost Sweden. Methane oxidation rates increased across a gradient of permafrost thaw and differed in transitional thaw stages relative to end-member stages. Oxidation was consistently higher in submerged fens than in bogs or palsas across a range of CH4 concentrations. We also observed that CH4 oxidation increased with decreasing in situ redox potential and was highest in sites with lower redox potential (Eh textless10 mV) and high water table. Our results suggest that redox potential can be used as an important predictor of CH4 oxidation, especially in thawed permafrost peatlands. Our results also highlight the importance of considering transitional thaw stages when characterizing landscape-scale CH4 dynamics, because these transitional areas have different rates and controls of CH4 oxidation relative to intact or completely thawed permafrost areas. As permafrost thaw increases the total area of semiwet and wet thaw stages in permafrost peatlands, CH4 oxidation represents an important control on CH4 emissions to the atmosphere.
BibTeX:
@article{Perryman2020,
  author = {Perryman, Clarice R and McCalley, Carmody K and Malhotra, Avni and Fahnestock, M Florencia and Kashi, Natalie N and Bryce, Julia G and Giesler, Reiner and Varner, Ruth K},
  title = {Thaw Transitions and Redox Conditions Drive Methane Oxidation in a Permafrost Peatland},
  journal = {Journal of Geophysical Research: Biogeosciences},
  year = {2020},
  volume = {125},
  number = {3},
  pages = {1--15},
  doi = {10.1029/2019JG005526}
}
Peters RL, von Arx G, Nievergelt D, Ibrom A, Stillhard J, Trotsiuk V, Mazurkiewicz A and Babst F (2020), "Axial changes in wood functional traits have limited net effects on stem biomass increment in European beech (Fagus sylvatica)", Tree physiology. Vol. 40(4), pp. 498-510.
Abstract: During the growing season, trees allocate photoassimilates to increase their aboveground woody biomass in the stem (ABIstem). This 'carbon allocation' to structural growth is a dynamic process influenced by internal and external (e.g., climatic) drivers. While radial variability in wood formation and its resulting structure have been intensively studied, their variability along tree stems and subsequent impacts on ABIstem remain poorly understood. We collected wood cores from mature trees within a fixed plot in a well-studied temperate Fagus sylvatica L. forest. For a subset of trees, we performed regular interval sampling along the stem to elucidate axial variability in ring width (RW) and wood density ($$), and the resulting effects on tree- and plot-level ABIstem. Moreover, we measured wood anatomical traits to understand the anatomical basis of $$ and the coupling between changes in RW and $$ during drought. We found no significant axial variability in $$ because an increase in the vessel-to-fiber ratio with smaller RW compensated for vessel tapering towards the apex. By contrast, temporal variability in RW varied significantly along the stem axis, depending on the growing conditions. Drought caused a more severe growth decrease, and wetter summers caused a disproportionate growth increase at the stem base compared with the top. Discarding this axial variability resulted in a significant overestimation of tree-level ABIstem in wetter and cooler summers, but this bias was reduced to ˜2% when scaling ABIstem to the plot level. These results suggest that F. sylvatica prioritizes structural carbon sinks close to the canopy when conditions are unfavorable. The different axial variability in RW and $$ thereby indicates some independence of the processes that drive volume growth and wood structure along the stem. This refines our knowledge of carbon allocation dynamics in temperate diffuse-porous species and contributes to reducing uncertainties in determining forest carbon fixation.
BibTeX:
@article{Peters2020a,
  author = {Peters, Richard L and von Arx, Georg and Nievergelt, Daniel and Ibrom, Andreas and Stillhard, Jonas and Trotsiuk, Volodymyr and Mazurkiewicz, Aleksandra and Babst, Flurin},
  title = {Axial changes in wood functional traits have limited net effects on stem biomass increment in European beech (Fagus sylvatica)},
  journal = {Tree physiology},
  year = {2020},
  volume = {40},
  number = {4},
  pages = {498--510},
  doi = {10.1093/treephys/tpaa002}
}
Peters W, Bastos A, Ciais P and Vermeulen A (2020), "A historical, geographical and ecological perspective on the 2018 European summer drought", Philosophical Transactions of the Royal Society B: Biological Sciences., oct, 2020. Vol. 375(1810), pp. 20190505.
BibTeX:
@article{Peters2020,
  author = {Peters, Wouter and Bastos, Ana and Ciais, Philippe and Vermeulen, Alex},
  title = {A historical, geographical and ecological perspective on the 2018 European summer drought},
  journal = {Philosophical Transactions of the Royal Society B: Biological Sciences},
  year = {2020},
  volume = {375},
  number = {1810},
  pages = {20190505},
  url = {https://royalsocietypublishing.org/doi/10.1098/rstb.2019.0505},
  doi = {10.1098/rstb.2019.0505}
}
Piao S, Wang X, Wang K, Li X, Bastos A, Canadell JG, Ciais P, Friedlingstein P and Sitch S (2020), "Interannual variation of terrestrial carbon cycle: Issues and perspectives", Global Change Biology., nov, 2020. Vol. 26(1), pp. 300-318. Wiley.
Abstract: With accumulation of carbon cycle observations and model developments over the past decades, exploring interannual variation (IAV) of terrestrial carbon cycle offers the opportunity to better understand climate–carbon cycle relationships. However, despite growing research interest, uncertainties remain on some fundamental issues, such as the contributions of different regions, constituent fluxes and climatic factors to carbon cycle IAV. Here we overviewed the literature on carbon cycle IAV about current understanding of these issues. Observations and models of the carbon cycle unanimously show the dominance of tropical land ecosystems to the signal of global carbon cycle IAV, where tropical semiarid ecosystems contribute as much as the combination of all other tropical ecosystems. Vegetation photosynthesis contributes more than ecosystem respiration to IAV of the global net land carbon flux, but large uncertainties remain on the contribution of fires and other disturbance fluxes. Climatic variations are the major drivers to the IAV of net land carbon flux. Although debate remains on whether the dominant driver is temperature or moisture variability, their interaction,that is, the dependence of carbon cycle sensitivity to temperature on moisture conditions, is emerging as key regulators of the carbon cycle IAV. On timescales from the interannual to the centennial, global carbon cycle variability will be increasingly contributed by northern land ecosystems and oceans. Therefore, both improving Earth system models (ESMs) with the progressive understanding on the fast processes manifested at interannual timescale and expanding carbon cycle observations at broader spatial and longer temporal scales are critical to better prediction on evolution of the carbon–climate system.
BibTeX:
@article{Piao2020,
  author = {Piao, Shilong and Wang, Xuhui and Wang, Kai and Li, Xiangyi and Bastos, Ana and Canadell, Josep G and Ciais, Philippe and Friedlingstein, Pierre and Sitch, Stephen},
  title = {Interannual variation of terrestrial carbon cycle: Issues and perspectives},
  journal = {Global Change Biology},
  publisher = {Wiley},
  year = {2020},
  volume = {26},
  number = {1},
  pages = {300--318},
  doi = {10.1111/gcb.14884}
}
Piilo SR, Korhola A, Heiskanen L, Tuovinen JP, Aurela M, Juutinen S, Marttila H, Saari M, Tuittila ES, Turunen J and Väliranta MM (2020), "Spatially varying peatland initiation, Holocene development, carbon accumulation patterns and radiative forcing within a subarctic fen", Quaternary Science Reviews. Vol. 248
Abstract: High latitude peatlands act as globally important carbon (C) sinks and are in constant interaction with the atmosphere. Their C storage formed during the Holocene. In the course of time, the aggregate effect of the C fluxes on radiative forcing (RF) typically changes from warming to cooling, but the timing of this shift varies among different peatlands. Here we investigated Holocene peatland development, including vegetation history, vertical peat growth and the lateral expansion of a patterned subarctic fen in northern Finland by means of multiple sampling points. We modelled the Holocene RF by combining knowledge on past vegetation communities based on plant macrofossil stratigraphies and present in situ C flux measurements. The peatland initiated at ca. 9500 calibrated years Before Present (cal yr BP), and its lateral expansion was greatest between ca. 9000 and 7000 cal yr BP. After the early expansion, vertical peat growth proceeded very differently in different parts of the peatland, regulated by internal and external factors. The pronounced surface microtopography, with high strings and wet flarks, started to form only after ca. 1000 cal yr BP. C accumulation within the peatland recorded a high degree of spatial variability throughout its history, including the recent past. We applied two flux scenarios with different interpretation of the initial peatland development phases to estimate the RF induced by C fluxes of the fen. After ca. 4000 cal yr BP, at the latest, the peatland RF has been negative (cooling), mainly driven by C uptake and biomass production, while methane emissions had a lesser role in the total RF. Interestingly, these scenarios suggest that the greatest cooling effect took place around ca. 1000 cal yr BP, after which the surface microtopography established. The study demonstrated that despite the high spatial heterogeneity and idiosyncratic behaviour of the peatland, the RF of the studied fen followed the general development pattern of more southern peatlands. Holocene climate variations and warm phases did not seem to induce any distinctive and consistent peatland-scale patterns in C accumulation, whereas our data suggests that the changes in vegetation related to autogenic succession were reflected in the C accumulation patterns and RF more clearly.
BibTeX:
@article{Piilo2020,
  author = {Piilo, Sanna R and Korhola, Atte and Heiskanen, Lauri and Tuovinen, Juha Pekka and Aurela, Mika and Juutinen, Sari and Marttila, Hannu and Saari, Markus and Tuittila, Eeva Stiina and Turunen, Jukka and Väliranta, Minna M},
  title = {Spatially varying peatland initiation, Holocene development, carbon accumulation patterns and radiative forcing within a subarctic fen},
  journal = {Quaternary Science Reviews},
  year = {2020},
  volume = {248},
  doi = {10.1016/j.quascirev.2020.106596}
}
Pilegaard K and Ibrom A (2020), "Net carbon ecosystem exchange during 24 years in the SorøBeech Forest–relations to phenology and climate", Tellus, Series B: Chemical and Physical Meteorology. Vol. 72(1), pp. 1-17. Taylor & Francis.
Abstract: The carbon sequestration of plants through photosynthesis is responsible for removal of a substantial amount of the man-made CO2 emissions to the atmosphere. In recent years this so-called land-sink has removed about 30% of the man-made emissions to the atmosphere, with forests being the most important sinks. The land-sink is, however, vulnerable to changes in the environment, such as the atmospheric composition, climate change, and extreme events like storms and droughts. It is therefore important to study the effects of such change on terrestrial ecosystems to provide the basis for predicting the future of the sink. We here report the results of continuous CO2 flux measurements over a Danish beech forest during the years 1996–2019. Over the years the forest acted as a sink of CO2 with a net carbon sequestration ranging from about zero to 400 g C m–2 yr−1. We found significant trends in net ecosystem exchange (NEE) (increasing in absolute terms with 15 g C m–2 yr2), gross ecosystem exchange (GEE) (increasing with 25 g C m–2 yr–2), and ecosystem respiration (RE) (increasing with 10 g C m–2 yr–2). A prolonged growing season explained 73% of the increase in NEE. The increasing CO2 concentration in the atmosphere and a subsequent increase in photosynthetic capacity together with warming are the most likely main causes of the increased carbon uptake. The severe drought in the summer of 2018 resulted in a reduction of the annual NEE of 25%.
BibTeX:
@article{Pilegaard2020,
  author = {Pilegaard, Kim and Ibrom, Andreas},
  title = {Net carbon ecosystem exchange during 24 years in the SorøBeech Forest–relations to phenology and climate},
  journal = {Tellus, Series B: Chemical and Physical Meteorology},
  publisher = {Taylor & Francis},
  year = {2020},
  volume = {72},
  number = {1},
  pages = {1--17},
  url = {https://doi.org/10.1080/16000889.2020.1822063},
  doi = {10.1080/16000889.2020.1822063}
}
Pioli S, Sarneel J, Thomas HJD, Domene X, Andrés P, Hefting M, Reitz T, Laudon H, Sandén T, Piscová V, Aurela M and Brusetti L (2020), "Linking plant litter microbial diversity to microhabitat conditions, environmental gradients and litter mass loss: Insights from a European study using standard litter bags", Soil Biology and Biochemistry. Vol. 144(November 2019)
Abstract: Plant litter decomposition is a key process for carbon dynamics and nutrient cycling in terrestrial ecosystems. The interaction between litter properties, climatic conditions and soil attributes, influences the activity of microorganisms responsible for litter mineralization. So far, studies using standardized litters to investigate the response of bacterial and fungal communities under different environmental conditions are scarce, especially along wide geographic ranges. We used a standardized protocol to investigate the diversity of bacteria and fungi in plant litter with the aim of: (i) comparing the microbial communities of native and exotic litters with the community of local soil along a European transect from northern Finland to southern Italy, (ii) defining whether and to what extent, litter types with different traits represent selective substrates for microbial communities, (iii) disentangling the abiotic drivers of microbial diversity, and (iv) correlating the microbial diversity and species co-occurrences patterns with litter mass loss. We buried native litter and three exotic standardized litters (Deschampsia cespitosa, rooibos tea and green tea) at 12 European study sites. We determined litter mass loss after 94 days. We used an automated molecular DNA-based fingerprinting (ARISA) to profile the bacterial and fungal communities of each litter type and soil (180 samples in total). Microbial communities in native and exotic litters differed from local soil assemblages. Green tea and D. cespitosa litter represented more selective substrates compared to native litter and rooibos. Soil moisture and soil temperature were the major drivers of microbial community structure at larger scales, though with varying patterns according to litter type. Soil attributes (i.e. moisture and C/N ratios) better explained the differences in microbial abundances than litter type. Green tea degraded faster than all other litter types and accounted for the largest number of positive co-occurrences among microbial taxa. Litter mass loss was positively correlated with fungal evenness and with the percentage of positive co-occurrences between fungi. Our findings suggest that the microbial community at larger scales reflects the complex interplay between litter type and soil attributes, with the latter exerting a major influence. Mass loss patterns are in part determined by inter- and intra-kingdom interactions and fungal diversity.
BibTeX:
@article{Pioli2020,
  author = {Pioli, Silvia and Sarneel, Judith and Thomas, Haydn J D and Domene, Xavier and Andrés, Pilar and Hefting, Mariet and Reitz, Thomas and Laudon, Hjalmar and Sandén, Taru and Piscová, Veronika and Aurela, Mika and Brusetti, Lorenzo},
  title = {Linking plant litter microbial diversity to microhabitat conditions, environmental gradients and litter mass loss: Insights from a European study using standard litter bags},
  journal = {Soil Biology and Biochemistry},
  year = {2020},
  volume = {144},
  number = {November 2019},
  doi = {10.1016/j.soilbio.2020.107778}
}
Portillo-Estrada M, Ariza-Carricondo C and Ceulemans R (2020), "Outburst of senescence-related VOC emissions from a bioenergy poplar plantation", Plant Physiology and Biochemistry., mar, 2020. Vol. 148, pp. 324-332. Elsevier Masson SAS.
Abstract: Leaf senescence is a catabolic process that emits volatile organic compounds (VOCs). In densely planted monocultures these VOC emissions occur in outbursts that might be relevant for the local air quality since these VOCs are typically oxygenated. The VOC emissions of a high-density poplar (Populus) bioenergy plantation were monitored along with meteorological parameters, CO2 and H2O exchanges, canopy greenness, and leaf area index during the second half of the year 2015. The emissions of 25 VOCs peaked at the beginning of September, coinciding with the onset of senescence. Together these VOC emissions amounted to a total of 2.85 mmol m−2, translated into 98.3 mg C m−2. The emission peak was mainly composed of oxygenated VOCs as methanol, acetic acid, and lipoxygenase products that are all typical for catabolic processes. So, the senescence process of the poplar plantation was very well reflected in the peak of VOC emissions.
BibTeX:
@article{Portillo-Estrada2020,
  author = {Portillo-Estrada, Miguel and Ariza-Carricondo, Cristina and Ceulemans, Reinhart},
  title = {Outburst of senescence-related VOC emissions from a bioenergy poplar plantation},
  journal = {Plant Physiology and Biochemistry},
  publisher = {Elsevier Masson SAS},
  year = {2020},
  volume = {148},
  pages = {324--332},
  doi = {10.1016/j.plaphy.2020.01.024}
}
Prendin AL, Carrer M, Karami M, Hollesen J, Bjerregaard Pedersen N, Pividori M, Treier UA, Westergaard-Nielsen A, Elberling B and Normand S (2020), "Immediate and carry-over effects of insect outbreaks on vegetation growth in West Greenland assessed from cells to satellite", Journal of Biogeography. Vol. 47(1), pp. 87-100.
Abstract: Aim: Tundra ecosystems are highly vulnerable to climate change, and climate–growth responses of Arctic shrubs are variable and altered by microsite environmental conditions and biotic factors. With warming and drought during the growing season, insect-driven defoliation is expected to increase in frequency and severity with potential broad-scale impacts on tundra ecosystem functioning. Here we provide the first broad-scale reconstruction of spatio-temporal dynamics of past insect outbreaks by assessing their effects on shrub growth along a typical Greenlandic fjord climate gradient from the inland ice to the sea. Location: Nuuk Fjord (64°30′N/51°23′W) and adjacent areas, West Greenland. Taxa: Great brocade (Eurois occulta L.) and grey willow (Salix glauca L.). Methods: We combined dendro-anatomical and remote sensing analyses. Time series of ring width (RW) and wood-anatomical traits were obtained from chronologies of textgreater40 years established from 153 individuals of S. glauca collected at nine sites. We detected anomalies in satellite-based Normalized Difference Vegetation Index (NDVI) related to defoliation and reconstructed past changes in photosynthetic activity across the region. Results: We identified outbreaks as distinctive years with reduced RW, cell-wall thickness and vessel size, without being directly related to climate but matching with years of parallel reduction in NDVI. The two subsequent years after the defoliation showed a significant increase in RW. The reconstructed spatio-temporal dynamics of these events indicate substantial regional variation in outbreak intensity linked to the climate variability across the fjord system. Main conclusions: Our results highlight the ability of S. glauca to cope with severe insect defoliation by changing carbon investment and xylem conductivity leading to high resilience and rapid recovery after the disturbance. Our multiproxy approach allows us to pinpoint biotic drivers of narrow ring formation and to provide new broad-scale insight on the C-budget and vegetation productivity of shrub communities in a widespread arctic ecosystem.
BibTeX:
@article{Prendin2020,
  author = {Prendin, Angela Luisa and Carrer, Marco and Karami, Mojtaba and Hollesen, Jørgen and Bjerregaard Pedersen, Nanna and Pividori, Mario and Treier, Urs A and Westergaard-Nielsen, Andreas and Elberling, Bo and Normand, Signe},
  title = {Immediate and carry-over effects of insect outbreaks on vegetation growth in West Greenland assessed from cells to satellite},
  journal = {Journal of Biogeography},
  year = {2020},
  volume = {47},
  number = {1},
  pages = {87--100},
  doi = {10.1111/jbi.13644}
}
Rahmati M, Groh J, Graf A, Pütz T, Vanderborght J and Vereecken H (2020), "On the impact of increasing drought on the relationship between soil water content and evapotranspiration of a grassland", Vadose Zone Journal. Vol. 19(1), pp. 1-20.
Abstract: Weighable lysimeters were used to study the relation between soil water content (SWC) and the actual evapotranspiration (ETa) of grassland under two different climate regimes of Rollesbroich and Selhausen but for an identical soil from Rollesbroich. All components of the water balance were determined from 2012 until 2018. Budyko analysis was used to characterize the hydrological status of the studied sites. Wavelet analysis was also applied to study the power spectrum of ETa, vegetation-height-adjusted reference evapotranspiration (ETcrop), and water stress index (WSI) defined as ETa/ETcrop, as well as SWC at three different depths and the coherence between SWC and ETa and WSI. The Budyko analysis showed that 2018 resulted in a shift of both locations towards more water-limited conditions, although Rollesbroich remained an energy-limited system. Based on the power spectrum analysis, the annual timescale is the dominant scale for the temporal variability of ETa, ETcrop, and SWC. The results also showed that increasing dryness at the energy-limited site led to more temporal variability of SWC at all depths at the annual timescale. Wavelet coherence analysis showed a reduction of the phase shift between SWC and ETa at an annual scale caused by the increase in dryness during the measurement period. We found that phase shifts between SWC and ETa and SWC and WSI were stronger at the water-limited site than at the energy-limited site. The wavelet coherence analysis also showed that from 2014 to 2018, the control of ETa and WSI on SWC increased due to higher dryness of soil.
BibTeX:
@article{Rahmati2020,
  author = {Rahmati, Mehdi and Groh, Jannis and Graf, Alexander and Pütz, Thomas and Vanderborght, Jan and Vereecken, Harry},
  title = {On the impact of increasing drought on the relationship between soil water content and evapotranspiration of a grassland},
  journal = {Vadose Zone Journal},
  year = {2020},
  volume = {19},
  number = {1},
  pages = {1--20},
  doi = {10.1002/vzj2.20029}
}
Ramonet M, Ciais P, Apadula F, Bartyzel J, Bastos A, Bergamaschi P, Blanc PE, Brunner D, Caracciolo di Torchiarolo L, Calzolari F, Chen H, Chmura L, Colomb A, Conil S, Cristofanelli P, Cuevas E, Curcoll R, Delmotte M, di Sarra A, Emmenegger L, Forster G, Frumau A, Gerbig C, Gheusi F, Hammer S, Haszpra L, Hatakka J, Hazan L, Heliasz M, Henne S, Hensen A, Hermansen O, Keronen P, Kivi R, Komínková K, Kubistin D, Laurent O, Laurila T, Lavric JV, Lehner I, Lehtinen KEJ, Leskinen A, Leuenberger M, Levin I, Lindauer M, Lopez M, Myhre CL, Mammarella I, Manca G, Manning A, Marek MV, Marklund P, Martin D, Meinhardt F, Mihalopoulos N, Mölder M, Morgui JA, Necki J, O'Doherty S, O'Dowd C, Ottosson M, Philippon C, Piacentino S, Pichon JM, Plass-Duelmer C, Resovsky A, Rivier L, Rodó X, Sha MK, Scheeren HA, Sferlazzo D, Spain TG, Stanley KM, Steinbacher M, Trisolino P, Vermeulen A, Vítková G, Weyrauch D, Xueref-Remy I, Yala K and Yver Kwok C (2020), "The fingerprint of the summer 2018 drought in Europe on ground-based atmospheric CO 2 measurements", Philosophical Transactions of the Royal Society B: Biological Sciences., oct, 2020. Vol. 375(1810), pp. 20190513.
Abstract: During the summer of 2018, a widespread drought developed over Northern and Central Europe. The increase in temperature and the reduction of soil moisture have influenced carbon dioxide (CO 2 ) exchange between the atmosphere and terrestrial ecosystems in various ways, such as a reduction of photosynthesis, changes in ecosystem respiration, or allowing more frequent fires. In this study, we characterize the resulting perturbation of the atmospheric CO 2 seasonal cycles. 2018 has a good coverage of European regions affected by drought, allowing the investigation of how ecosystem flux anomalies impacted spatial CO 2 gradients between stations. This density of stations is unprecedented compared to previous drought events in 2003 and 2015, particularly thanks to the deployment of the Integrated Carbon Observation System (ICOS) network of atmospheric greenhouse gas monitoring stations in recent years. Seasonal CO 2 cycles from 48 European stations were available for 2017 and 2018. Earlier data were retrieved for comparison from international databases or national networks. Here, we show that the usual summer minimum in CO 2 due to the surface carbon uptake was reduced by 1.4 ppm in 2018 for the 10 stations located in the area most affected by the temperature anomaly, mostly in Northern Europe. Notwithstanding, the CO 2 transition phases before and after July were slower in 2018 compared to 2017, suggesting an extension of the growing season, with either continued CO 2 uptake by photosynthesis and/or a reduction in respiration driven by the depletion of substrate for respiration inherited from the previous months due to the drought. For stations with sufficiently long time series, the CO 2 anomaly observed in 2018 was compared to previous European droughts in 2003 and 2015. Considering the areas most affected by the temperature anomalies, we found a higher CO 2 anomaly in 2003 (+3 ppm averaged over 4 sites), and a smaller anomaly in 2015 (+1 ppm averaged over 11 sites) compared to 2018.
BibTeX:
@article{Ramonet2020,
  author = {Ramonet, M. and Ciais, P. and Apadula, F. and Bartyzel, J. and Bastos, A. and Bergamaschi, P. and Blanc, P. E. and Brunner, D. and Caracciolo di Torchiarolo, L. and Calzolari, F. and Chen, H. and Chmura, L. and Colomb, A. and Conil, S. and Cristofanelli, P. and Cuevas, E. and Curcoll, R. and Delmotte, M. and di Sarra, A. and Emmenegger, L. and Forster, G. and Frumau, A. and Gerbig, C. and Gheusi, F. and Hammer, S. and Haszpra, L. and Hatakka, J. and Hazan, L. and Heliasz, M. and Henne, S. and Hensen, A. and Hermansen, O. and Keronen, P. and Kivi, R. and Komínková, K. and Kubistin, D. and Laurent, O. and Laurila, T. and Lavric, J. V. and Lehner, I. and Lehtinen, K. E. J. and Leskinen, A. and Leuenberger, M. and Levin, I. and Lindauer, M. and Lopez, M. and Myhre, C. Lund and Mammarella, I. and Manca, G. and Manning, A. and Marek, M. V. and Marklund, P. and Martin, D. and Meinhardt, F. and Mihalopoulos, N. and Mölder, M. and Morgui, J. A. and Necki, J. and O'Doherty, S. and O'Dowd, C. and Ottosson, M. and Philippon, C. and Piacentino, S. and Pichon, J. M. and Plass-Duelmer, C. and Resovsky, A. and Rivier, L. and Rodó, X. and Sha, M. K. and Scheeren, H. A. and Sferlazzo, D. and Spain, T. G. and Stanley, K. M. and Steinbacher, M. and Trisolino, P. and Vermeulen, A. and Vítková, G. and Weyrauch, D. and Xueref-Remy, I. and Yala, K. and Yver Kwok, C.},
  title = {The fingerprint of the summer 2018 drought in Europe on ground-based atmospheric CO 2 measurements},
  journal = {Philosophical Transactions of the Royal Society B: Biological Sciences},
  year = {2020},
  volume = {375},
  number = {1810},
  pages = {20190513},
  url = {https://royalsocietypublishing.org/doi/10.1098/rstb.2019.0513},
  doi = {10.1098/rstb.2019.0513}
}
Randazzo NA, Michalak AM and Desai AR (2020), "Synoptic Meteorology Explains Temperate Forest Carbon Uptake", Journal of Geophysical Research: Biogeosciences., feb, 2020. Vol. 125(2) Blackwell Publishing Ltd.
Abstract: While substantial attention has been paid to the effects of both global climate oscillations and local meteorological conditions on the interannual variability of ecosystem carbon exchange, the relationship between the interannual variability of synoptic meteorology and ecosystem carbon exchange has not been well studied. Here we use a clustering algorithm to identify a summertime cyclonic precipitation system northwest of the Great Lakes to determine (a) the association at a daily scale between the occurrence of this system and the local meteorology and net ecosystem exchange at three Great Lakes region forested eddy covariance sites and (b) the association between the seasonal prevalence of this system and the summertime net ecosystem exchange of these sites. We find that temperature, in addition to precipitation and cloud cover, is an important explanatory factor for the suppression of net ecosystem productivity that occurs during these cyclonic events in this region. In addition, the prevalence of this cyclonic system can explain a significant proportion of the interannual variability in summertime forest ecosystem exchange in this region. This explanatory power is not due to a simple accumulation of low-productivity days that cooccur with this meteorological event, but rather a broader association between the frequency of these events and several aspects of prevailing seasonal conditions. This work demonstrates the usefulness of conceptualizing meteorology in terms of synoptic systems for explaining the interannual variability of regional carbon fluxes.
BibTeX:
@article{Randazzo2020,
  author = {Randazzo, Nina A. and Michalak, Anna M. and Desai, Ankur R.},
  title = {Synoptic Meteorology Explains Temperate Forest Carbon Uptake},
  journal = {Journal of Geophysical Research: Biogeosciences},
  publisher = {Blackwell Publishing Ltd},
  year = {2020},
  volume = {125},
  number = {2},
  doi = {10.1029/2019JG005476}
}
Rannik Ü, Vesala T, Peltola O, Novick KA, Aurela M, Järvi L, Montagnani L, Mölder M, Peichl M, Pilegaard K and Mammarella I (2020), "Impact of coordinate rotation on eddy covariance fluxes at complex sites", Agricultural and Forest Meteorology. Vol. 287(December 2019), pp. 107940. Elsevier.
Abstract: The choice of coordinate system to calculate eddy covariance fluxes becomes particularly relevant at complex measurement sites. The traditional way is to perform double rotation (DR) of the coordinate system i.e., to calculate turbulent fluxes in a coordinate system that is aligned with the flow streamlines within the flux averaging period (e.g., Kaimal and Finnigan, 1994). The second approach, the so-called planar-fitted (PF) coordinate system, averages the flow over a longer period of time, in practice a month or more. The PF method allows to derive an intercept coefficient of the vertical wind speed which can be attributed to the offset of the sonic anemometer or the average vertical flow related to meteorological conditions. We evaluated the variants of the PF methods using data from a variety of sites ranging from complex urban and forest sites to nearly ideal forest and peatland sites. At complex sites, we found that the intercept of the vertical wind speed derived from the PF method is a function of wind direction, time of day and/or stability. The sector-wise PF (SPF) method frequently led to insignificant statistical relationships. We tested a continuous PF (CPF) method where the relationship establishing the coordinate frame was represented as the continuous function in the form of Fourier series. The method enabled to obtain the PF with lower uncertainty as compared to the SPF method, by selecting necessary number of harmonics for each site based on confidence intervals of estimated parameters. Therefore, we recommend to use the CPF method in cases when the number of observations in some wind direction interval is low or the obtained SPF is insignificant due to large variance in measurements. We also showed that significant systematic difference can exist in cumulative turbulent fluxes between the DR and PF methods over a longer period of time. Derived vertical advection of carbon dioxide exhibited large variability with wind direction due to topography at complex sites and therefore, without considering horizontal advection, cannot be used to improve the net ecosystem exchange estimation during nocturnal, low turbulence conditions.
BibTeX:
@article{Rannik2020,
  author = {Rannik, Üllar and Vesala, Timo and Peltola, Olli and Novick, Kimberly A and Aurela, Mika and Järvi, Leena and Montagnani, Leonardo and Mölder, Meelis and Peichl, Matthias and Pilegaard, Kim and Mammarella, Ivan},
  title = {Impact of coordinate rotation on eddy covariance fluxes at complex sites},
  journal = {Agricultural and Forest Meteorology},
  publisher = {Elsevier},
  year = {2020},
  volume = {287},
  number = {December 2019},
  pages = {107940},
  url = {https://doi.org/10.1016/j.agrformet.2020.107940},
  doi = {10.1016/j.agrformet.2020.107940}
}
Räsänen M, Merbold L, Vakkari V, Aurela M, Laakso L, Beukes JP, Van Zyl PG, Josipovic M, Feig G, Pellikka P, Rinne J and Katul GG (2020), "Root-zone soil moisture variability across African savannas: From pulsed rainfall to land-cover switches", Ecohydrology. Vol. 13(5), pp. 1-20.
Abstract: The main source of soil moisture variability in savanna ecosystems is pulsed rainfall. Rainfall pulsing impacts water-stress durations, soil moisture switching between wet-to-dry and dry-to-wet states, and soil moisture spectra as well as derived measures from it such as soil moisture memory. Rainfall pulsing is also responsible for rapid changes in grassland leaf area and concomitant changes in evapotranspirational (ET) losses, which then impact soil moisture variability. With the use of a hierarchy of models and soil moisture measurements, temporal variability in root-zone soil moisture and water-stress periods are analysed at four African sites ranging from grass to miombo savannas. The normalized difference vegetation index (NDVI) and potential ET (PET)-adjusted ET model predict memory timescale and dry persistence in agreement with measurements. The model comparisons demonstrate that dry persistence and mean annual dry periods must account for seasonal and interannual changes in maximum ET represented by NDVI and to a lesser extent PET. Interestingly, the precipitation intensity and soil moisture memory were linearly related across three savannas with ET/infiltration ∼ 1.0. This relation and the variability of length and timing of dry periods are also discussed.
BibTeX:
@article{Raesaenen2020,
  author = {Räsänen, Matti and Merbold, Lutz and Vakkari, Ville and Aurela, Mika and Laakso, Lauri and Beukes, J Paul and Van Zyl, Pieter G and Josipovic, Miroslav and Feig, Gregor and Pellikka, Petri and Rinne, Janne and Katul, Gabriel G},
  title = {Root-zone soil moisture variability across African savannas: From pulsed rainfall to land-cover switches},
  journal = {Ecohydrology},
  year = {2020},
  volume = {13},
  number = {5},
  pages = {1--20},
  doi = {10.1002/eco.2213}
}
Rasmussen LH, Michelsen A, Ladegaard-Pedersen P, Nielsen CS and Elberling B (2020), "Arctic soil water chemistry in dry and wet tundra subject to snow addition, summer warming and herbivory simulation", Soil Biology and Biochemistry. Vol. 141(May 2019), pp. 107676. Elsevier Ltd.
Abstract: Multiple and rapid environmental changes in the Arctic have major consequences for the entire ecosystem. Soil water chemistry is one component with important implications for understanding climate feedbacks, plant growth, microbial turnover and net greenhouse gas emissions. Here we assess the contrasting growing season soil water chemistry in a Low arctic Greenlandic mesic tundra heath and a fen, which have been subjected to factorial treatments of summer warming using open top chambers (OTCs), snow addition using snow fences, which increase soil temperature in late winter, and shrub removal mimicking herbivory attack. Dissolved Organic Carbon (DOC) and plant nutrients, including NO3−, NH4+, PO42+ and total dissolved N were measured during multiple growing seasons (2013–2016) to quantify the treatment effects on nutrient availability in two dominating, but contrasting, vegetation types. Ambient nutrient concentrations in the mesic tundra heath decreased throughout the growing season and increased during senescence, while concentrations were highest during peak growing season in the fen. The content of NH4+ and DOC were highest in the fen, whereas NO3− was highest in the mesic tundra heath. The fen had no seasonal pattern. Summer warming in the mesic tundra heath did not change the availability of nutrients, but in combination with shrub removal, both NO3− and DOC concentrations increased, likely due to reduced plant uptake. Shrub removal alone increased NO3− in one growing season, and, combined with snow addition, increased DOC. Significant effects of shrub removal were mostly found in 2016. Snow addition combined with summer warming increased DOC and total N concentrations and highlights the potential loss of dissolved C from the ecosystem. In the fen, shrub removal alone and combined with summer warming decreased DOC. Snow addition alone and in combination with summer warming similarly decreased DOC. In the mesic tundra heath, shrub removal caused higher soil water contents in all years. In the dry and warm 2016, it meant textless10% soil water content in controls and 15–20% in shrub removal plots during the peak growing season, which may have relieved soil moisture limitation on mineralization rates in the latter. We conclude that soil water chemistry is vegetation-specific, and that treatment effects are surprisingly limited when comparing multiple years with contrasting precipitation patterns. Herbivory may have larger impact in very dry, warm summers and, together with extreme weather events, exert similar or larger effects than four years of temperature manipulations. The effects of summer warming or increased winter snow depend on ecosystem type and moisture status of the soil. The combination of multi-year and multi-site studies therefore seem important for understanding future biogeochemical dynamics in Arctic landscapes.
BibTeX:
@article{Rasmussen2020,
  author = {Rasmussen, Laura H and Michelsen, Anders and Ladegaard-Pedersen, Pernille and Nielsen, Cecilie S and Elberling, Bo},
  title = {Arctic soil water chemistry in dry and wet tundra subject to snow addition, summer warming and herbivory simulation},
  journal = {Soil Biology and Biochemistry},
  publisher = {Elsevier Ltd},
  year = {2020},
  volume = {141},
  number = {May 2019},
  pages = {107676},
  url = {https://doi.org/10.1016/j.soilbio.2019.107676},
  doi = {10.1016/j.soilbio.2019.107676}
}
Ravn NR, Elberling B and Michelsen A (2020), "Arctic soil carbon turnover controlled by experimental snow addition, summer warming and shrub removal", Soil Biology and Biochemistry. Vol. 142(April 2019), pp. 107698. Elsevier Ltd.
Abstract: Northern latitude tundra heaths have accumulated large amounts of organic carbon (C) in the soil. Changes in climatic conditions such as temperature and winter precipitation might affect the C balance and potentially change these tundra ecosystems from being C sinks to sources of CO2 emitted to the atmosphere. However, studies on C fluxes with single and combined winter snow and summer warming effects are scarce. This study investigates gross ecosystem production (GEP), ecosystem respiration (ER), net ecosystem production (NEP) and carbon isotopic composition of CO2 emitted from a dry heath in arctic Greenland one and two years following field manipulations of summer temperature, shrub abundance and winter snow depth. Our aims were to quantify climatic change effects on CO2 fluxes and the growing season carbon balance of the ecosystem and to investigate shifts in $$13C of emitted CO2 potentially due changes in emission from old soil C versus recently fixed carbon. Ecosystem CO2 fluxes and $$13C-CO2 were measured using closed chambers, and soil CO2 concentrations and $$13C were measured depth-specifically using gas probes. We found a significant increase of CO2 emissions in all treatments during both years. Growing season NEP increased by 38 and 73% with 1 m enhanced winter snow depth, by 113 and 144% with summer warming and by 61 and 320% with total shrub removal in 2013 and 2014, respectively. The snow effect can be explained by the delay in the onset of growth as indicated by early season reduced vegetation greenness. The effect of warming was a result of an increase of ER by 39 and 32%, and the effect of shrub removal was mainly due to a reduction in GEP by 34 and 48%, in 2013 and 2014, respectively. Furthermore, the $$13C of the carbon source of CO2 emitted from warmed plots increased significantly two years after the experiment was initiated. This might indicate increased decomposition of 13C enriched soil organic matter and hence increased mineralization of the old carbon stock in the soil under warmed conditions. The increase of NEP, the additive response of all treatments, and the indications of increased emission of carbon from old stocks due to warming (or warming-induced drying), demonstrate the risk of a relatively fast feedback to climate warming during the snow-free season.
BibTeX:
@article{Ravn2020,
  author = {Ravn, Nynne R and Elberling, Bo and Michelsen, Anders},
  title = {Arctic soil carbon turnover controlled by experimental snow addition, summer warming and shrub removal},
  journal = {Soil Biology and Biochemistry},
  publisher = {Elsevier Ltd},
  year = {2020},
  volume = {142},
  number = {April 2019},
  pages = {107698},
  url = {https://doi.org/10.1016/j.soilbio.2019.107698},
  doi = {10.1016/j.soilbio.2019.107698}
}
Reichenau TG, Korres W, Schmidt M, Graf A, Welp G, Meyer N, Stadler A, Brogi C and Schneider K (2020), "A comprehensive dataset of vegetation states, fluxes of matter and energy, weather, agricultural management, and soil properties from intensively monitored crop sites in western Germany", In Earth System Science Data. Vol. 12(4), pp. 2333-2364.
Abstract: The development and validation of hydroecological land-surface models to simulate agricultural areas require extensive data on weather, soil properties, agricultural management, and vegetation states and fluxes. However, these comprehensive data are rarely available since measurement, quality control, documentation, and compilation of the different data types are costly in terms of time and money. Here, we present a comprehensive dataset, which was collected at four agricultural sites within the Rur catchment in western Germany in the framework of the Transregional Collaborative Research Centre 32 (TR32) "Patterns in Soil-Vegetation-Atmosphere Systems: Monitoring, Modeling and Data Assimilation". Vegetation-related data comprise fresh and dry biomass (green and brown, predominantly per organ), plant height, green and brown leaf area index, phenological development state, nitrogen and carbon content (overall textgreater17 000 entries), and masses of harvest residues and regrowth of vegetation after harvest or before planting of the main crop (textgreater250 entries). Vegetation data including LAI were collected in frequencies of 1 to 3 weeks in the years 2015 until 2017, mostly during overflights of the Sentinel 1 and Radarsat 2 satellites. In addition, fluxes of carbon, energy, and water (textgreater180 000 half-hourly records) measured using the eddy covariance technique are included. Three flux time series have simultaneous data from two different heights. Data on agricultural management include sowing and harvest dates as well as information on cultivation, fertilization, and agrochemicals (27 management periods). The dataset also includes gap-filled weather data (textgreater200 000 hourly records) and soil parameters (particle size distributions, carbon and nitrogen content; textgreater800 records). These data can also be useful for development and validation of remote-sensing products. The dataset is hosted at the TR32 database (https://www.tr32db.uni-koeln.de/data.php?dataID=1889, last access: 29 September 2020) and has the DOI https://doi.org/10.5880/TR32DB.39 (Reichenau et al., 2020).
BibTeX:
@book{Reichenau2020,
  author = {Reichenau, Tim G and Korres, Wolfgang and Schmidt, Marius and Graf, Alexander and Welp, Gerhard and Meyer, Nele and Stadler, Anja and Brogi, Cosimo and Schneider, Karl},
  title = {A comprehensive dataset of vegetation states, fluxes of matter and energy, weather, agricultural management, and soil properties from intensively monitored crop sites in western Germany},
  booktitle = {Earth System Science Data},
  year = {2020},
  volume = {12},
  number = {4},
  pages = {2333--2364},
  doi = {10.5194/essd-12-2333-2020}
}
Reichl BG and Deike L (2020), "Contribution of Sea‐State Dependent Bubbles to Air‐Sea Carbon Dioxide Fluxes", Geophysical Research Letters., may, 2020. Vol. 47(9) Blackwell Publishing Ltd.
Abstract: Breaking surface ocean waves produce bubbles that are important for air-sea gas exchanges, particularly during high winds. In this study we estimate air-sea CO2 fluxes globally using a new approach that considers the surface wave contribution to gas fluxes. We estimate that 40% of the net air-sea CO2 flux is via bubbles, with annual, seasonal, and regional variability. When compared to traditional gas-flux parameterization methods that consider the wind speed alone, we find high-frequency (daily to weekly) differences in the predicted gas flux using the sea-state dependent method at spatial scales related to atmospheric weather (10 to 100 km). Seasonal net differences in the air-sea CO2 flux due to the sea-state dependence can exceed 20%, with the largest values associated with North Atlantic and North Pacific winter storms. These results confirm that bubbles are important for global gas-flux dynamics and that sea-state dependent parameterizations may improve performance of global coupled models.
BibTeX:
@article{Reichl2020,
  author = {Reichl, B. G. and Deike, L.},
  title = {Contribution of Sea‐State Dependent Bubbles to Air‐Sea Carbon Dioxide Fluxes},
  journal = {Geophysical Research Letters},
  publisher = {Blackwell Publishing Ltd},
  year = {2020},
  volume = {47},
  number = {9},
  url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2020GL087267},
  doi = {10.1029/2020GL087267}
}
Reyer CPO, Silveyra Gonzalez R, Dolos K, Hartig F, Hauf Y, Noack M, Lasch-Born P, Rötzer T, Pretzsch H, Meesenburg H, Fleck S, Wagner M, Bolte A, Sanders TGM, Kolari P, Mäkelä A, Vesala T, Mammarella I, Pumpanen J, Collalti A, Collalti A, Trotta C, Matteucci G, D'Andrea E, Foltýnová L, Krejza J, Ibrom A, Pilegaard K, Loustau D, Bonnefond JM, Berbigier P, Picart D, Lafont S, Dietze M, Cameron D, Vieno M, Tian H, Palacios-Orueta A, Cicuendez V, Recuero L, Wiese K, Büchner M, Lange S, Volkholz J, Kim H, Horemans JA, Bohn F, Steinkamp J, Chikalanov A, Weedon GP, Sheffield J, Babst F, Babst F, Vega Del Valle I, Suckow F, Martel S, Mahnken M, Gutsch M and Frieler K (2020), "The PROFOUND Database for evaluating vegetation models and simulating climate impacts on European forests", Earth System Science Data. Vol. 12(2), pp. 1295-1320.
Abstract: Process-based vegetation models are widely used to predict local and global ecosystem dynamics and climate change impacts. Due to their complexity, they require careful parameterization and evaluation to ensure that projections are accurate and reliable. The PROFOUND Database (PROFOUND DB) provides a wide range of empirical data on European forests to calibrate and evaluate vegetation models that simulate climate impacts at the forest stand scale. A particular advantage of this database is its wide coverage of multiple data sources at different hierarchical and temporal scales, together with environmental driving data as well as the latest climate scenarios. Specifically, the PROFOUND DB provides general site descriptions, soil, climate, CO2, nitrogen deposition, tree and forest stand level, and remote sensing data for nine contrasting forest stands distributed across Europe. Moreover, for a subset of five sites, time series of carbon fluxes, atmospheric heat conduction and soil water are also available. The climate and nitrogen deposition data contain several datasets for the historic period and a wide range of future climate change scenarios following the Representative Concentration Pathways (RCP2.6, RCP4.5, RCP6.0, RCP8.5). We also provide pre-industrial climate simulations that allow for model runs aimed at disentangling the contribution of climate change to observed forest productivity changes. The PROFOUND DB is available freely as a "SQLite"relational database or "ASCII"flat file version (at https://doi.org/10.5880/PIK.2020.006/; Reyer et al., 2020). The data policies of the individual contributing datasets are provided in the metadata of each data file. The PROFOUND DB can also be accessed via the ProfoundData R package (https://CRAN.R-project.org/package=ProfoundData; Silveyra Gonzalez et al., 2020), which provides basic functions to explore, plot and extract the data for model set-up, calibration and evaluation.
BibTeX:
@article{Reyer2020,
  author = {Reyer, Christopher P O and Silveyra Gonzalez, Ramiro and Dolos, Klara and Hartig, Florian and Hauf, Ylva and Noack, Matthias and Lasch-Born, Petra and Rötzer, Thomas and Pretzsch, Hans and Meesenburg, Henning and Fleck, Stefan and Wagner, Markus and Bolte, Andreas and Sanders, Tanja G M and Kolari, Pasi and Mäkelä, Annikki and Vesala, Timo and Mammarella, Ivan and Pumpanen, Jukka and Collalti, Alessio and Collalti, Alessio and Trotta, Carlo and Matteucci, Giorgio and D'Andrea, Ettore and Foltýnová, Lenka and Krejza, Jan and Ibrom, Andreas and Pilegaard, Kim and Loustau, Denis and Bonnefond, Jean Marc and Berbigier, Paul and Picart, Delphine and Lafont, Sébastien and Dietze, Michael and Cameron, David and Vieno, Massimo and Tian, Hanqin and Palacios-Orueta, Alicia and Cicuendez, Victor and Recuero, Laura and Wiese, Klaus and Büchner, Matthias and Lange, Stefan and Volkholz, Jan and Kim, Hyungjun and Horemans, Joanna A and Bohn, Friedrich and Steinkamp, Jörg and Chikalanov, Alexander and Weedon, Graham P and Sheffield, Justin and Babst, Flurin and Babst, Flurin and Vega Del Valle, Iliusi and Suckow, Felicitas and Martel, Simon and Mahnken, Mats and Gutsch, Martin and Frieler, Katja},
  title = {The PROFOUND Database for evaluating vegetation models and simulating climate impacts on European forests},
  journal = {Earth System Science Data},
  year = {2020},
  volume = {12},
  number = {2},
  pages = {1295--1320},
  doi = {10.5194/essd-12-1295-2020}
}
Rinne J, Tuovinen J-P, Klemedtsson L, Aurela M, Holst J, Lohila A, Weslien P, Vestin P, Łakomiec P, Peichl M, Tuittila E-S, Heiskanen L, Laurila T, Li X, Alekseychik P, Mammarella I, Ström L, Crill P and Nilsson MB (2020), "Effect of the 2018 European drought on methane and carbon dioxide exchange of northern mire ecosystems", Philosophical Transactions of the Royal Society B: Biological Sciences., oct, 2020. Vol. 375(1810), pp. 20190517.
Abstract: We analysed the effect of the 2018 European drought on greenhouse gas (GHG) exchange of five North European mire ecosystems. The low precipitation and high summer temperatures in Fennoscandia led to a lowered water table in the majority of these mires. This lowered both carbon dioxide (CO 2 ) uptake and methane (CH 4 ) emission during 2018, turning three out of the five mires from CO 2 sinks to sources. The calculated radiative forcing showed that the drought-induced changes in GHG fluxes first resulted in a cooling effect lasting 15–50 years, due to the lowered CH 4 emission, which was followed by warming due to the lower CO 2 uptake.
BibTeX:
@article{Rinne2020,
  author = {Rinne, J. and Tuovinen, J.-P. and Klemedtsson, L. and Aurela, M. and Holst, J. and Lohila, A. and Weslien, P. and Vestin, P. and Łakomiec, P. and Peichl, M. and Tuittila, E.-S. and Heiskanen, L. and Laurila, T. and Li, X. and Alekseychik, P. and Mammarella, I. and Ström, L. and Crill, P. and Nilsson, M. B.},
  title = {Effect of the 2018 European drought on methane and carbon dioxide exchange of northern mire ecosystems},
  journal = {Philosophical Transactions of the Royal Society B: Biological Sciences},
  year = {2020},
  volume = {375},
  number = {1810},
  pages = {20190517},
  url = {https://royalsocietypublishing.org/doi/10.1098/rstb.2019.0517},
  doi = {10.1098/rstb.2019.0517}
}
Rocher-Ros G, Harms TK, Sponseller RA, Väisänen M, Mörth CM and Giesler R (2020), "Metabolism overrides photo-oxidation in CO2 dynamics of Arctic permafrost streams", Limnology and Oceanography. , pp. 1-13.
Abstract: Global warming is enhancing the mobilization of organic carbon (C) from Arctic soils into streams, where it can be mineralized to CO2 and released to the atmosphere. Abiotic photo-oxidation might drive C mineralization, but this process has not been quantitatively integrated with biological processes that also influence CO2 dynamics in aquatic ecosystems. We measured CO2 concentrations and the isotopic composition of dissolved inorganic C ($$13CDIC) at diel resolution in two Arctic streams, and coupled this with whole-system metabolism estimates to assess the effect of biotic and abiotic processes on stream C dynamics. CO2 concentrations consistently decreased from night to day, a pattern counter to the hypothesis that photo-oxidation is the dominant source of CO2. Instead, the observed decrease in CO2 during daytime was explained by photosynthetic rates, which were strongly correlated with diurnal changes in $$13CDIC values. However, on days when modeled photosynthetic rates were near zero, there was still a significant diel change in $$13CDIC values, suggesting that metabolic estimates are partly masked by O2 consumption from photo-oxidation. Our results suggest that 6–12 mmol CO2-C m−2 d−1 may be generated from photo-oxidation, a range that corresponds well to previous laboratory measurements. Moreover, ecosystem respiration rates were 10 times greater than published photo-oxidation rates for these Arctic streams, and accounted for 33–80% of total CO2 evasion. Our results suggest that metabolic activity is the dominant process for CO2 production in Arctic streams. Thus, future aquatic CO2 emissions may depend on how biotic processes respond to the ongoing environmental change.
BibTeX:
@article{RocherRos2020,
  author = {Rocher-Ros, Gerard and Harms, Tamara K and Sponseller, Ryan A and Väisänen, Maria and Mörth, Carl Magnus and Giesler, Reiner},
  title = {Metabolism overrides photo-oxidation in CO2 dynamics of Arctic permafrost streams},
  journal = {Limnology and Oceanography},
  year = {2020},
  pages = {1--13},
  doi = {10.1002/lno.11564}
}
Rocher-Ros G, Sponseller RA, Bergström AK, Myrstener M and Giesler R (2020), "Stream metabolism controls diel patterns and evasion of CO2 in Arctic streams", Global Change Biology. Vol. 26(3), pp. 1400-1413.
Abstract: Streams play an important role in the global carbon (C) cycle, accounting for a large portion of CO2 evaded from inland waters despite their small areal coverage. However, the relative importance of different terrestrial and aquatic processes driving CO2 production and evasion from streams remains poorly understood. In this study, we measured O2 and CO2 continuously in streams draining tundra-dominated catchments in northern Sweden, during the summers of 2015 and 2016. From this, we estimated daily metabolic rates and CO2 evasion simultaneously and thus provide insight into the role of stream metabolism as a driver of C dynamics in Arctic streams. Our results show that aquatic biological processes regulate CO2 concentrations and evasion at multiple timescales. Photosynthesis caused CO2 concentrations to decrease by as much as 900 ppm during the day, with the magnitude of this diel variation being strongest at the low-turbulence streams. Diel patterns in CO2 concentrations in turn influenced evasion, with up to 45% higher rates at night. Throughout the summer, CO2 evasion was sustained by aquatic ecosystem respiration, which was one order of magnitude higher than gross primary production. Furthermore, in most cases, the contribution of stream respiration exceeded CO2 evasion, suggesting that some stream reaches serve as net sources of CO2, thus creating longitudinal heterogeneity in C production and loss within this stream network. Overall, our results provide the first link between stream metabolism and CO2 evasion in the Arctic and demonstrate that stream metabolic processes are key drivers of the transformation and fate of terrestrial organic matter exported from these landscapes.
BibTeX:
@article{RocherRos2020a,
  author = {Rocher-Ros, Gerard and Sponseller, Ryan A and Bergström, Ann Kristin and Myrstener, Maria and Giesler, Reiner},
  title = {Stream metabolism controls diel patterns and evasion of CO2 in Arctic streams},
  journal = {Global Change Biology},
  year = {2020},
  volume = {26},
  number = {3},
  pages = {1400--1413},
  doi = {10.1111/gcb.14895}
}
Rödenbeck C, Zaehle S, Keeling R and Heimann M (2020), "The European carbon cycle response to heat and drought as seen from atmospheric CO 2 data for 1999–2018", Philosophical Transactions of the Royal Society B: Biological Sciences., oct, 2020. Vol. 375(1810), pp. 20190506.
Abstract: In 2018, central and northern parts of Europe experienced heat and drought conditions over many months from spring to autumn, strongly affecting both natural ecosystems and crops. Besides their impact on nature and society, events like this can be used to study the impact of climate variations on the terrestrial carbon cycle, which is an important determinant of the future climate trajectory. Here, variations in the regional net ecosystem exchange (NEE) of CO 2 between terrestrial ecosystems and the atmosphere were quantified from measurements of atmospheric CO 2 mole fractions. Over Europe, several observational records have been maintained since at least 1999, giving us the opportunity to assess the 2018 anomaly in the context of at least two decades of variations, including the strong climate anomaly in 2003. In addition to an atmospheric inversion with temporally explicitly estimated anomalies, we use an inversion based on empirical statistical relations between anomalies in the local NEE and anomalies in local climate conditions. For our analysis period 1999–2018, we find that higher-than-usual NEE in hot and dry summers may tend to arise in Central Europe from enhanced ecosystem respiration due to the elevated temperatures, and in Southern Europe from reduced photosynthesis due to the reduced water availability. Despite concerns in the literature, the level of agreement between regression-based NEE anomalies and temporally explicitly estimated anomalies indicates that the atmospheric CO 2 measurements from the relatively dense European station network do provide information about the year-to-year variations of Europe's carbon sources and sinks, at least in summer.
BibTeX:
@article{Roedenbeck2020,
  author = {Rödenbeck, C. and Zaehle, S. and Keeling, R. and Heimann, M.},
  title = {The European carbon cycle response to heat and drought as seen from atmospheric CO 2 data for 1999–2018},
  journal = {Philosophical Transactions of the Royal Society B: Biological Sciences},
  year = {2020},
  volume = {375},
  number = {1810},
  pages = {20190506},
  url = {https://royalsocietypublishing.org/doi/10.1098/rstb.2019.0506},
  doi = {10.1098/rstb.2019.0506}
}
Saarela T, Rissanen AJ, Ojala A, Pumpanen J, Aalto SL, Tiirola M, Vesala T and Jäntti H (2020), "CH4 oxidation in a boreal lake during the development of hypolimnetic hypoxia", Aquatic Sciences., apr, 2020. Vol. 82(2) Springer.
Abstract: Freshwater ecosystems represent a significant natural source of methane (CH4). CH4 produced through anaerobic decomposition of organic matter (OM) in lake sediment and water column can be either oxidized to carbon dioxide (CO2) by methanotrophic microbes or emitted to the atmosphere. While the role of CH4 oxidation as a CH4 sink is widely accepted, neither the magnitude nor the drivers behind CH4 oxidation are well constrained. In this study, we aimed to gain more specific insight into CH4 oxidation in the water column of a seasonally stratified, typical boreal lake, particularly under hypoxic conditions. We used 13CH4 incubations to determine the active CH4 oxidation sites and the potential CH4 oxidation rates in the water column, and we measured environmental variables that could explain CH4 oxidation in the water column. During hypolimnetic hypoxia, 91% of available CH4 was oxidized in the active CH4 oxidation zone, where the potential CH4 oxidation rates gradually increased from the oxycline to the hypolimnion. Our results showed that in warm springs, which become more frequent, early thermal stratification with cold well-oxygenated hypolimnion delays the period of hypolimnetic hypoxia and limits CH4 production. Thus, the delayed development of hypolimnetic hypoxia may partially counteract the expected increase in the lacustrine CH4 emissions caused by the increasing organic carbon load from forested catchments.
BibTeX:
@article{Saarela2020,
  author = {Saarela, Taija and Rissanen, Antti J. and Ojala, Anne and Pumpanen, Jukka and Aalto, Sanni L. and Tiirola, Marja and Vesala, Timo and Jäntti, Helena},
  title = {CH4 oxidation in a boreal lake during the development of hypolimnetic hypoxia},
  journal = {Aquatic Sciences},
  publisher = {Springer},
  year = {2020},
  volume = {82},
  number = {2},
  doi = {10.1007/s00027-019-0690-8}
}
Saunois M, Stavert AR, Poulter B, Bousquet P, Canadell JG, Jackson RB, Raymond PA, Dlugokencky EJ, Houweling S, Patra PK, Ciais P, Arora VK, Bastviken D, Bergamaschi P, Blake DR, Brailsford G, Bruhwiler L, Carlson KM, Carrol M, Castaldi S, Chandra N, Crevoisier C, Crill PM, Covey K, Curry CL, Etiope G, Frankenberg C, Gedney N, Hegglin MI, Höglund-Isaksson L, Hugelius G, Ishizawa M, Ito A, Janssens-Maenhout G, Jensen KM, Joos F, Kleinen T, Krummel PB, Langenfelds RL, Laruelle GG, Liu L, Machida T, Maksyutov S, McDonald KC, McNorton J, Miller PA, Melton JR, Morino I, Müller J, Murguia-Flores F, Naik V, Niwa Y, Noce S, O'Doherty S, Parker RJ, Peng C, Peng S, Peters GP, Prigent C, Prinn R, Ramonet M, Regnier P, Riley WJ, Rosentreter JA, Segers A, Simpson IJ, Shi H, Smith SJ, Steele LP, Thornton BF, Tian H, Tohjima Y, Tubiello FN, Tsuruta A, Viovy N, Voulgarakis A, Weber TS, van Weele M, van der Werf GR, Weiss RF, Worthy D, Wunch D, Yin Y, Yoshida Y, Zhang W, Zhang Z, Zhao Y, Zheng B, Zhu Q, Zhu Q and Zhuang Q (2020), "The Global Methane Budget 2000–2017", Earth System Science Data., jul, 2020. Vol. 12(3), pp. 1561-1623.
BibTeX:
@article{Saunois2020,
  author = {Saunois, Marielle and Stavert, Ann R. and Poulter, Ben and Bousquet, Philippe and Canadell, Josep G. and Jackson, Robert B. and Raymond, Peter A. and Dlugokencky, Edward J. and Houweling, Sander and Patra, Prabir K. and Ciais, Philippe and Arora, Vivek K. and Bastviken, David and Bergamaschi, Peter and Blake, Donald R. and Brailsford, Gordon and Bruhwiler, Lori and Carlson, Kimberly M. and Carrol, Mark and Castaldi, Simona and Chandra, Naveen and Crevoisier, Cyril and Crill, Patrick M. and Covey, Kristofer and Curry, Charles L. and Etiope, Giuseppe and Frankenberg, Christian and Gedney, Nicola and Hegglin, Michaela I. and Höglund-Isaksson, Lena and Hugelius, Gustaf and Ishizawa, Misa and Ito, Akihiko and Janssens-Maenhout, Greet and Jensen, Katherine M. and Joos, Fortunat and Kleinen, Thomas and Krummel, Paul B. and Langenfelds, Ray L. and Laruelle, Goulven G. and Liu, Licheng and Machida, Toshinobu and Maksyutov, Shamil and McDonald, Kyle C. and McNorton, Joe and Miller, Paul A. and Melton, Joe R. and Morino, Isamu and Müller, Jurek and Murguia-Flores, Fabiola and Naik, Vaishali and Niwa, Yosuke and Noce, Sergio and O'Doherty, Simon and Parker, Robert J. and Peng, Changhui and Peng, Shushi and Peters, Glen P. and Prigent, Catherine and Prinn, Ronald and Ramonet, Michel and Regnier, Pierre and Riley, William J. and Rosentreter, Judith A. and Segers, Arjo and Simpson, Isobel J. and Shi, Hao and Smith, Steven J. and Steele, L. Paul and Thornton, Brett F. and Tian, Hanqin and Tohjima, Yasunori and Tubiello, Francesco N. and Tsuruta, Aki and Viovy, Nicolas and Voulgarakis, Apostolos and Weber, Thomas S. and van Weele, Michiel and van der Werf, Guido R. and Weiss, Ray F. and Worthy, Doug and Wunch, Debra and Yin, Yi and Yoshida, Yukio and Zhang, Wenxin and Zhang, Zhen and Zhao, Yuanhong and Zheng, Bo and Zhu, Qing and Zhu, Qiuan and Zhuang, Qianlai},
  title = {The Global Methane Budget 2000–2017},
  journal = {Earth System Science Data},
  year = {2020},
  volume = {12},
  number = {3},
  pages = {1561--1623},
  url = {https://essd.copernicus.org/articles/12/1561/2020/},
  doi = {10.5194/essd-12-1561-2020}
}
Schindler D and Kolbe S (2020), "Assessment of the response of a scots pine tree to effective wind loading", Forests. Vol. 11(2)
Abstract: The parameterization of hybrid-mechanistic storm damage models is largely based on the results of tree pulling tests. The tree pulling tests are used for imitating the quasi-static wind load associated with the mean wind speed. The combined effect of dynamic and quasi-static wind loads associated with wind load maxima is considered by either linearly increasing the quasi-static wind load by a gust factor or by using a turning moment coefficient determined from the relationship between maxima of wind-induced tree response and wind speed. To improve the joint use of information on dynamic and quasi-static wind loading, we present a new method that uses the coupled components of momentum flux time series and time series of stem orientation of a plantation-grown Scots pine tree. First, non-oscillatory tree motion components, which respond to wind excitation, are isolated from oscillatory components that are not coupled to the wind. The non-oscillatory components are detected by applying a sequence of time series decomposition methods including biorthogonal decomposition and singular spectrum analysis. Then, the wind-excited tree response components are subjected to dynamic time warping, which maximizes the coincidence between the processed data. The strong coincidence of the time-warped data allows for the estimation of the wind-induced tree response as a function of the effective wind load using simple linear regression. The slope of the regression line represents the rate of change in the tree response as the effective wind load changes. Because of the strength of the relationship, we argue that the method described is an improvement for the analysis of storm damage in forests and to individual trees.
BibTeX:
@article{Schindler2020,
  author = {Schindler, Dirk and Kolbe, Sven},
  title = {Assessment of the response of a scots pine tree to effective wind loading},
  journal = {Forests},
  year = {2020},
  volume = {11},
  number = {2},
  doi = {10.3390/f11020145}
}
Schneuwly J and Ammann C (2020), "Large regional differences of soil water limitation effect on ozone induced yield loss for wheat and potato in Switzerland", Science of the Total Environment., may, 2020. Vol. 718 Elsevier B.V..
Abstract: The accumulated stomatal ozone (O3) uptake over a threshold (Phytotoxic Ozone Dose POD6), calculated by an ozone deposition model, has been shown to be the most appropriate metric to quantify negative effects of O3 on food crops. In this study we used data of 13 sites in different regions of Switzerland with multiple years of O3 measurements to quantify the stomatal O3 uptake and the related yield loss of wheat and potato. Flux patterns for different years were calculated with the DO3SE model to disentangle the influence of contrasting seasonal environmental conditions. Regional and inter-annual differences in meteorological conditions led to considerable variations in soil water conditions and the POD6 values for wheat. Potato stomatal uptake was much less influenced by soil water and showed a more even distribution of POD6 values across sites and years. The estimated nationally and temporally average yield loss was 3.2 ± 1.2% for wheat and 2.4 ± 0.8% for potato, calculated based on an area weighting. It was found that soil water deficit, observed frequently in the western part of Switzerland, had a large attenuation effect on stomatal O3 uptake by wheat and on corresponding yield losses. This highlights the importance of including soil moisture limitation in O3 uptake modelling even in moist climatic regions. The comparison of modelled evapotranspiration with water flux measurements over a wheat field showed a reasonable agreement concerning the temporal pattern and the magnitude. But it is also concluded that the DO3SE soil moisture module will need further testing and adaptation to improve accuracy of the model in dryer conditions.
BibTeX:
@article{Schneuwly2020,
  author = {Schneuwly, Jérôme and Ammann, Christof},
  title = {Large regional differences of soil water limitation effect on ozone induced yield loss for wheat and potato in Switzerland},
  journal = {Science of the Total Environment},
  publisher = {Elsevier B.V.},
  year = {2020},
  volume = {718},
  doi = {10.1016/j.scitotenv.2019.135257}
}
Schrader F, Erisman JW and Brümmer C (2020), "Towards a coupled paradigm of NH3-CO2 biosphere–atmosphere exchange modelling", Global Change Biology. Vol. 26(9), pp. 4654-4663.
Abstract: Stomatal conductance, one of the major plant physiological controls within NH3 biosphere–atmosphere exchange models, is commonly estimated from semi-empirical multiplicative schemes or simple light- and temperature-response functions. However, due to their inherent parameterization on meteorological proxy variables, instead of a direct measure of stomatal opening, they are unfit for the use in climate change scenarios and of limited value for interpreting field-scale measurements. Alternatives based on H2O flux measurements suffer from uncertainties in the partitioning of evapotranspiration at humid sites, as well as a potential decoupling of transpiration from stomatal opening in the presence of hygroscopic particles on leaf surfaces. We argue that these problems may be avoided by directly deriving stomatal conductance from CO2 fluxes instead. We reanalysed a data set of NH3 flux measurements based on CO2-derived stomatal conductance, confirming the hypothesis that the increasing relevance of stomatal exchange with the onset of vegetation activity caused a rapid decrease of observed NH3 deposition velocities. Finally, we argue that developing more mechanistic representations of NH3 biosphere–atmosphere exchange can be of great benefit in many applications. These range from model-based flux partitioning, over deposition monitoring using low-cost samplers and inferential modelling, to a direct response of NH3 exchange to climate change.
BibTeX:
@article{Schrader2020,
  author = {Schrader, Frederik and Erisman, Jan Willem and Brümmer, Christian},
  title = {Towards a coupled paradigm of NH3-CO2 biosphere–atmosphere exchange modelling},
  journal = {Global Change Biology},
  year = {2020},
  volume = {26},
  number = {9},
  pages = {4654--4663},
  doi = {10.1111/gcb.15184}
}
Schuldt B, Buras A, Arend M, Vitasse Y, Beierkuhnlein C, Damm A, Gharun M, Grams TE, Hauck M, Hajek P, Hartmann H, Hiltbrunner E, Hoch G, Holloway-Phillips M, Körner C, Larysch E, Lübbe T, Nelson DB, Rammig A, Rigling A, Rose L, Ruehr NK, Schumann K, Weiser F, Werner C, Wohlgemuth T, Zang CS and Kahmen A (2020), "A first assessment of the impact of the extreme 2018 summer drought on Central European forests", Basic and Applied Ecology., jun, 2020. Vol. 45, pp. 86-103. Elsevier GmbH.
Abstract: In 2018, Central Europe experienced one of the most severe and long-lasting summer drought and heat wave ever recorded. Before 2018, the 2003 millennial drought was often invoked as the example of a “hotter drought”, and was classified as the most severe event in Europe for the last 500 years. First insights now confirm that the 2018 drought event was climatically more extreme and had a greater impact on forest ecosystems of Austria, Germany and Switzerland than the 2003 drought. Across this region, mean growing season air temperature from April to October was more than 3.3°C above the long-term average, and 1.2 °C warmer than in 2003. Here, we present a first impact assessment of the severe 2018 summer drought and heatwave on Central European forests. In response to the 2018 event, most ecologically and economically important tree species in temperate forests of Austria, Germany and Switzerland showed severe signs of drought stress. These symptoms included exceptionally low foliar water potentials crossing the threshold for xylem hydraulic failure in many species and observations of widespread leaf discoloration and premature leaf shedding. As a result of the extreme drought stress, the 2018 event caused unprecedented drought-induced tree mortality in many species throughout the region. Moreover, unexpectedly strong drought-legacy effects were detected in 2019. This implies that the physiological recovery of trees was impaired after the 2018 drought event, leaving them highly vulnerable to secondary drought impacts such as insect or fungal pathogen attacks. As a consequence, mortality of trees triggered by the 2018 events is likely to continue for several years. Our assessment indicates that many common temperate European forest tree species are more vulnerable to extreme summer drought and heat waves than previously thought. As drought and heat events are likely to occur more frequently with the progression of climate change, temperate European forests might approach the point for a substantial ecological and economic transition. Our assessment also highlights the urgent need for a pan-European ground-based monitoring network suited to track individual tree mortality, supported by remote sensing products with high spatial and temporal resolution to track, analyse and forecast these transitions.
BibTeX:
@article{Schuldt2020,
  author = {Schuldt, Bernhard and Buras, Allan and Arend, Matthias and Vitasse, Yann and Beierkuhnlein, Carl and Damm, Alexander and Gharun, Mana and Grams, Thorsten E.E. and Hauck, Markus and Hajek, Peter and Hartmann, Henrik and Hiltbrunner, Erika and Hoch, Günter and Holloway-Phillips, Meisha and Körner, Christian and Larysch, Elena and Lübbe, Torben and Nelson, Daniel B. and Rammig, Anja and Rigling, Andreas and Rose, Laura and Ruehr, Nadine K. and Schumann, Katja and Weiser, Frank and Werner, Christiane and Wohlgemuth, Thomas and Zang, Christian S. and Kahmen, Ansgar},
  title = {A first assessment of the impact of the extreme 2018 summer drought on Central European forests},
  journal = {Basic and Applied Ecology},
  publisher = {Elsevier GmbH},
  year = {2020},
  volume = {45},
  pages = {86--103},
  doi = {10.1016/j.baae.2020.04.003}
}
Seco R, Holst T, Sillesen Matzen M, Westergaard-Nielsen A, Li T, Simin T, Jansen J, Crill P, Friborg T, Rinne J and Rinnan R (2020), "Volatile organic compound fluxes in a subarctic peatland and lake", Atmospheric Chemistry and Physics. Vol. 20(21), pp. 13399-13416.
Abstract: Ecosystems exchange climate-relevant trace gases with the atmosphere, including volatile organic compounds (VOCs) that are a small but highly reactive part of the carbon cycle. VOCs have important ecological functions and implications for atmospheric chemistry and climate.We measured the ecosystem-level surface-atmosphere VOC fluxes using the eddy covariance technique at a shallow subarctic lake and an adjacent graminoid-dominated fen in northern Sweden during two contrasting periods: the peak growing season (mid-July) and the senescent period post-growing season (September-October). In July, the fen was a net source of methanol, acetaldehyde, acetone, dimethyl sulfide, isoprene, and monoterpenes. All of these VOCs showed a diel cycle of emission with maxima around noon and isoprene dominated the fluxes (93±22 $$molm-2 d-1, mean±SE). Isoprene emission was strongly stimulated by temperature and presented a steeper response to temperature (Q10 = 14:5) than that typically assumed in biogenic emission models, supporting the high temperature sensitivity of arctic vegetation. In September, net emissions of methanol and isoprene were drastically reduced, while acetaldehyde and acetone were deposited to the fen, with rates of up to-6:7±2:8 $$molm-2 d-1 for acetaldehyde. Remarkably, the lake was a sink for acetaldehyde and acetone during both periods, with average fluxes up to -19±1:3 $$molm-2 d-1 of acetone in July and up to-8:5± 2:3 $$molm-2 d-1 of acetaldehyde in September. The deposition of both carbonyl compounds correlated with their atmospheric mixing ratios, with deposition velocities of-0:23± 0:01 and-0:68±0:03 cm s-1 for acetone and acetaldehyde, respectively. Even though these VOC fluxes represented less than 0.5%and less than 5%of the CO2 and CH4 net carbon ecosystem exchange, respectively, VOCs alter the oxidation capacity of the atmosphere. Thus, understanding the response of their emissions to climate change is important for accurate prediction of the future climatic conditions in this rapidly warming area of the planet.
BibTeX:
@article{Seco2020,
  author = {Seco, Roger and Holst, Thomas and Sillesen Matzen, Mikkel and Westergaard-Nielsen, Andreas and Li, Tao and Simin, Tihomir and Jansen, Joachim and Crill, Patrick and Friborg, Thomas and Rinne, Janne and Rinnan, Riikka},
  title = {Volatile organic compound fluxes in a subarctic peatland and lake},
  journal = {Atmospheric Chemistry and Physics},
  year = {2020},
  volume = {20},
  number = {21},
  pages = {13399--13416},
  doi = {10.5194/acp-20-13399-2020}
}
Seelmann K, Steinhoff T, Aßmann S and Körtzinger A (2020), "Enhance Ocean Carbon Observations: Successful Implementation of a Novel Autonomous Total Alkalinity Analyzer on a Ship of Opportunity", Frontiers in Marine Science. Vol. 7(December), pp. 1-18.
Abstract: Over recent decades, observations based on merchant vessels (Ships of Opportunity—SOOP) equipped with sensors measuring the CO2 partial pressure (pCO2) in the surface seawater formed the backbone of the global ocean carbon observation system. However, the restriction to pCO2 measurements alone is one severe shortcoming of the current SOOP observatory. Full insight into the marine inorganic carbon system requires the measurement of at least two of the four measurable variables which are pCO2, total alkalinity (TA), dissolved inorganic carbon (DIC), and pH. One workaround is to estimate TA values based on established temperature-salinity parameterizations, but this leads to higher uncertainties and the possibility of regional and/or seasonal biases. Therefore, autonomous SOOP-based TA measurements are of great interest. Our study describes the implementation of a novel autonomous analyzer for seawater TA, the CONTROS HydroFIAⓇ TA system (-4H-JENA engineering GmbH, Germany) for unattended routine TA measurements on a SOOP line operating in the North Atlantic. We present the installation in detail and address major issues encountered with autonomous measurements using this analyzer, e.g., automated cleaning and stabilization routines, and waste handling. Another issue during long-term deployments is the provision of reference seawater in large-volume containers for quality assurance measurements and drift correction. Hence, a stable large-volume seawater storage had to be found. We tested several container types with respect to their suitability to store seawater over a time period of 30 days without significant changes in TA. Only one gas sampling bag made of polyvinylidene fluoride (PVDF) satisfied the high stability requirement. In order to prove the performance of the entire setup, we compared the autonomous TA measurements with TA from discrete samples taken during the first two trans-Atlantic crossings. Although the measurement accuracy in unattended mode (about ± 5 $$mol kgˆ-1) slightly deteriorated compared to our previous system characterization, its overall uncertainty fulfilled requirements for autonomous TA measurements on SOOP lines. A comparison with predicted TA values based on an established and often used parameterization pointed at regional and seasonal limitations of such TA predictions. Consequently, TA observations with better coverage of spatiotemporal variability are needed, which is now possible with the method described here.
BibTeX:
@article{Seelmann2020,
  author = {Seelmann, Katharina and Steinhoff, Tobias and Aßmann, Steffen and Körtzinger, Arne},
  title = {Enhance Ocean Carbon Observations: Successful Implementation of a Novel Autonomous Total Alkalinity Analyzer on a Ship of Opportunity},
  journal = {Frontiers in Marine Science},
  year = {2020},
  volume = {7},
  number = {December},
  pages = {1--18},
  doi = {10.3389/fmars.2020.571301}
}
Sgrigna G, Baldacchini C, Dreveck S, Cheng Z and Calfapietra C (2020), "Relationships between air particulate matter capture efficiency and leaf traits in twelve tree species from an Italian urban-industrial environment", Science of the Total Environment., may, 2020. Vol. 718 Elsevier B.V..
Abstract: Air pollution in the urban environment is widely recognized as one of the most harmful threats for human health. International organizations such as the United Nations and the European Commission are highlighting the potential role of nature in mitigating air pollution and are now funding the implementation of Nature-Based Solutions, especially at the city level. Over the past few decades, the attention of the scientific community has grown around the role of urban forest in air pollution mitigation. Nevertheless, the understanding on Particulate Matter (PM) retention mechanisms by tree leaves is still limited. In this study, twelve tree species were sampled within an urban park of an industrial city. Two techniques were used for leaf analysis: Vacuum/Filtration and Scanning Electron Microscopy coupled with Energy Dispersive X-ray spectroscopy, in order to obtain a quali-quantitative analysis of the different PM size fractions. Results showed that deposited PM loads vary significantly among species. Different leaf traits, including micro and macromorphological characteristics, were observed, measured and ranked, with the final aim to relate them with PM load. Even if no significant correlation between each single leaf characteristic and PM deposition was observed (p textgreater 0.05), multivariate analysis revealed relationships between clusters of leaf traits and deposited PM. Thus, by assigning a score to each trait, an Accumulation index (Ai) was calculated, which was significantly related to the leaf deposited PM load (p ≤ 0.05).
BibTeX:
@article{Sgrigna2020,
  author = {Sgrigna, G. and Baldacchini, C. and Dreveck, S. and Cheng, Z. and Calfapietra, C.},
  title = {Relationships between air particulate matter capture efficiency and leaf traits in twelve tree species from an Italian urban-industrial environment},
  journal = {Science of the Total Environment},
  publisher = {Elsevier B.V.},
  year = {2020},
  volume = {718},
  doi = {10.1016/j.scitotenv.2020.137310}
}
Shutler JD, Wanninkhof R, Nightingale PD, Woolf DK, Bakker DC, Watson A, Ashton I, Holding T, Chapron B, Quilfen Y, Fairall C, Schuster U, Nakajima M and Donlon CJ (2020), "Satellites will address critical science priorities for quantifying ocean carbon", Frontiers in Ecology and the Environment., feb, 2020. Vol. 18(1), pp. 27-35. Wiley Blackwell.
Abstract: The ability to routinely quantify global carbon dioxide (CO2) absorption by the oceans has become crucial: it provides a powerful constraint for establishing global and regional carbon (C) budgets, and enables identification of the ecological impacts and risks of this uptake on the marine environment. Advances in understanding, technology, and international coordination have made it possible to measure CO2 absorption by the oceans to a greater degree of accuracy than is possible in terrestrial landscapes. These advances, combined with new satellite-based Earth observation capabilities, increasing public availability of data, and cloud computing, provide important opportunities for addressing critical knowledge gaps. Furthermore, Earth observation in synergy with in-situ monitoring can provide the large-scale ocean monitoring that is necessary to support policies to protect ocean ecosystems at risk, and motivate societal shifts toward meeting C emissions targets; however, sustained effort will be needed.
BibTeX:
@article{Shutler2020,
  author = {Shutler, Jamie D and Wanninkhof, Rik and Nightingale, Philip D and Woolf, David K and Bakker, Dorothee CE and Watson, Andy and Ashton, Ian and Holding, Thomas and Chapron, Bertrand and Quilfen, Yves and Fairall, Chris and Schuster, Ute and Nakajima, Masakatsu and Donlon, Craig J},
  title = {Satellites will address critical science priorities for quantifying ocean carbon},
  journal = {Frontiers in Ecology and the Environment},
  publisher = {Wiley Blackwell},
  year = {2020},
  volume = {18},
  number = {1},
  pages = {27--35},
  url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/fee.2129},
  doi = {10.1002/fee.2129}
}
Silfver T, Heiskanen L, Aurela M, Myller K, Karhu K, Meyer N, Tuovinen JP, Oksanen E, Rousi M and Mikola J (2020), "Insect herbivory dampens Subarctic birch forest C sink response to warming", Nature Communications. Vol. 11(1), pp. 1-9. Springer US.
Abstract: Climate warming is anticipated to make high latitude ecosystems stronger C sinks through increasing plant production. This effect might, however, be dampened by insect herbivores whose damage to plants at their background, non-outbreak densities may more than double under climate warming. Here, using an open-air warming experiment among Subarctic birch forest field layer vegetation, supplemented with birch plantlets, we show that a 2.3 °C air and 1.2 °C soil temperature increase can advance the growing season by 1–4 days, enhance soil N availability, leaf chlorophyll concentrations and plant growth up to 400%, 160% and 50% respectively, and lead up to 122% greater ecosystem CO2 uptake potential. However, comparable positive effects are also found when insect herbivory is reduced, and the effect of warming on C sink potential is intensified under reduced herbivory. Our results confirm the expected warming-induced increase in high latitude plant growth and CO2 uptake, but also reveal that herbivorous insects may significantly dampen the strengthening of the CO2 sink under climate warming.
BibTeX:
@article{Silfver2020,
  author = {Silfver, Tarja and Heiskanen, Lauri and Aurela, Mika and Myller, Kristiina and Karhu, Kristiina and Meyer, Nele and Tuovinen, Juha Pekka and Oksanen, Elina and Rousi, Matti and Mikola, Juha},
  title = {Insect herbivory dampens Subarctic birch forest C sink response to warming},
  journal = {Nature Communications},
  publisher = {Springer US},
  year = {2020},
  volume = {11},
  number = {1},
  pages = {1--9},
  url = {http://dx.doi.org/10.1038/s41467-020-16404-4},
  doi = {10.1038/s41467-020-16404-4}
}
Silyakova A, Jansson P, Serov P, Ferré B, Pavlov AK, Hattermann T, Graves CA, Platt SM, Myhre CL, Gründger F and Niemann H (2020), "Physical controls of dynamics of methane venting from a shallow seep area west of Svalbard", Continental Shelf Research., feb, 2020. Vol. 194, pp. 104030. Elsevier BV.
Abstract: We investigate methane seepage on the shallow shelf west of Svalbard during three consecutive years, using discrete sampling of the water column, echosounder-based gas flux estimates, water mass properties, and numerical dispersion modelling. The results reveal three distinct hydrographic conditions in spring and summer, showing that the methane content in the water column is controlled by a combination of free gas seepage intensity and lateral water mass movements, which disperse and displace dissolved methane horizontally away from the seeps. Horizontal dispersion and displacement of dissolved methane are promoted by eddies originating from the West Spitsbergen Current and passing over the shallow shelf, a process that is more intense in winter and spring than in the summer season. Most of the methane injected from seafloor seeps resides in the bottom layer even when the water column is well mixed, implying that the controlling effect of water column stratification on vertical methane transport is small. Only small concentrations of methane are found in surface waters, and thus the escape of methane into the atmosphere above the site of seepage is also small. The magnitude of the sea to air methane flux is controlled by wind speed, rather than by the concentration of dissolved methane in the surface ocean.
BibTeX:
@article{Silyakova2020,
  author = {Silyakova, Anna and Jansson, Pär and Serov, Pavel and Ferré, Benedicte and Pavlov, Alexey K and Hattermann, Tore and Graves, Carolyn A and Platt, Stephen M and Myhre, Cathrine Lund and Gründger, Friederike and Niemann, Helge},
  title = {Physical controls of dynamics of methane venting from a shallow seep area west of Svalbard},
  journal = {Continental Shelf Research},
  publisher = {Elsevier BV},
  year = {2020},
  volume = {194},
  pages = {104030},
  doi = {10.1016/j.csr.2019.104030}
}
Simioni G, Marie G, Davi H, Martin-St Paul N and Huc R (2020), "Natural forest dynamics have more influence than climate change on the net ecosystem production of a mixed Mediterranean forest", Ecological Modelling., jan, 2020. Vol. 416, pp. 108921. Elsevier BV.
Abstract: Climate models predict increased drought conditions for the Mediterranean region, putting forests under increasing risk from direct or indirect effects of droughts. On the other hand, increasing CO2 and longer growing seasons could compensate the negative impacts of more intense droughts on forest productivity and carbon sequestration. Furthermore, large areas of Mediterranean forests are relatively young and unmanaged, and maturing usually tends to decrease carbon sequestration. We conducted a simulation study to explore the interplay between climate, CO2, and maturing, on forest net primary production (NPP) and net ecosystem production (NEP) over the 2000–2100 period. We used the Not Only Tree/Grass (NOTG) model, which is individual-based, process-oriented, and spatially explicit. We applied the model to the Font-Blanche experimental site, a typical mixed Mediterranean forest dominated by Aleppo pines and holm oaks. Simulations under three climate scenarios (current, moderate change, severe change) suggest that NPP could be enhanced by climate change, both due to higher CO2 and longer growing seasons. On the other hand NEP would only be temporarily enhanced by climate change. The largest effect, however, was a decrease of NEP over time for all scenarios, due to forest maturing, with heterotrophic respiration progressively catching up with NPP. This implies that, regardless of climate change, the sink capacity of large unmanaged forest areas in southern Europe could strongly diminish during the 21st century.
BibTeX:
@article{Simioni2020,
  author = {Simioni, Guillaume and Marie, Guillaume and Davi, Hendrik and Martin-St Paul, Nicolas and Huc, Roland},
  title = {Natural forest dynamics have more influence than climate change on the net ecosystem production of a mixed Mediterranean forest},
  journal = {Ecological Modelling},
  publisher = {Elsevier BV},
  year = {2020},
  volume = {416},
  pages = {108921},
  doi = {10.1016/j.ecolmodel.2019.108921}
}
Simmonds PG, Rigby M, Manning AJ, Park S, Stanley KM, McCulloch A, Henne S, Graziosi F, Maione M, Arduini J, Reimann S, Vollmer MK, Mühle J, O'Doherty S, Young D, Krummel PB, Fraser PJ, Weiss RF, Salameh PK, Harth CM, Park M-K, Park H, Arnold T, Rennick C, Steele LP, Mitrevski B, Wang RHJ and Prinn RG (2020), "The increasing atmospheric burden of the greenhouse gas sulfur hexafluoride (SF6)", Atmospheric Chemistry and Physics., jun, 2020. Vol. 20(12), pp. 7271-7290.
BibTeX:
@article{Simmonds2020,
  author = {Simmonds, Peter G. and Rigby, Matthew and Manning, Alistair J. and Park, Sunyoung and Stanley, Kieran M. and McCulloch, Archie and Henne, Stephan and Graziosi, Francesco and Maione, Michela and Arduini, Jgor and Reimann, Stefan and Vollmer, Martin K. and Mühle, Jens and O'Doherty, Simon and Young, Dickon and Krummel, Paul B. and Fraser, Paul J. and Weiss, Ray F. and Salameh, Peter K. and Harth, Christina M. and Park, Mi-Kyung and Park, Hyeri and Arnold, Tim and Rennick, Chris and Steele, L. Paul and Mitrevski, Blagoj and Wang, Ray H. J. and Prinn, Ronald G.},
  title = {The increasing atmospheric burden of the greenhouse gas sulfur hexafluoride (SF6)},
  journal = {Atmospheric Chemistry and Physics},
  year = {2020},
  volume = {20},
  number = {12},
  pages = {7271--7290},
  url = {https://acp.copernicus.org/articles/20/7271/2020/},
  doi = {10.5194/acp-20-7271-2020}
}
Smith NE, Kooijmans LMJ, Koren G, van Schaik E, van der Woude AM, Wanders N, Ramonet M, Xueref-Remy I, Siebicke L, Manca G, Brümmer C, Baker IT, Haynes KD, Luijkx IT and Peters W (2020), "Spring enhancement and summer reduction in carbon uptake during the 2018 drought in northwestern Europe", Philosophical Transactions of the Royal Society B: Biological Sciences., oct, 2020. Vol. 375(1810), pp. 20190509.
Abstract: We analysed gross primary productivity (GPP), total ecosystem respiration (TER) and the resulting net ecosystem exchange (NEE) of carbon dioxide (CO 2 ) by the terrestrial biosphere during the summer of 2018 through observed changes across the Integrated Carbon Observation System (ICOS) network, through biosphere and inverse modelling, and through remote sensing. Highly correlated yet independently-derived reductions in productivity from sun-induced fluorescence, vegetative near-infrared reflectance, and GPP simulated by the Simple Biosphere model version 4 (SiB4) suggest a 130–340 TgC GPP reduction in July–August–September (JAS) of 2018. This occurs over an area of 1.6 × 10 6 km 2 with anomalously low precipitation in northwestern and central Europe. In this drought-affected area, reduced GPP, TER, NEE and soil moisture at ICOS ecosystem sites are reproduced satisfactorily by the SiB4 model. We found that, in contrast to the preceding 5 years, low soil moisture is the main stress factor across the affected area. SiB4's NEE reduction by 57 TgC for JAS coincides with anomalously high atmospheric CO 2 observations in 2018, and this is closely matched by the NEE anomaly derived by CarbonTracker Europe (52 to 83 TgC). Increased NEE during the spring (May–June) of 2018 (SiB4 −52 TgC; CTE −46 to −55 TgC) largely offset this loss, as ecosystems took advantage of favourable growth conditions.
BibTeX:
@article{Smith2020,
  author = {Smith, Naomi E. and Kooijmans, Linda M. J. and Koren, Gerbrand and van Schaik, Erik and van der Woude, Auke M. and Wanders, Niko and Ramonet, Michel and Xueref-Remy, Irène and Siebicke, Lukas and Manca, Giovanni and Brümmer, Christian and Baker, Ian T. and Haynes, Katherine D. and Luijkx, Ingrid T. and Peters, Wouter},
  title = {Spring enhancement and summer reduction in carbon uptake during the 2018 drought in northwestern Europe},
  journal = {Philosophical Transactions of the Royal Society B: Biological Sciences},
  year = {2020},
  volume = {375},
  number = {1810},
  pages = {20190509},
  url = {https://royalsocietypublishing.org/doi/10.1098/rstb.2019.0509},
  doi = {10.1098/rstb.2019.0509}
}
Song C, Luan J, Xu X, Ma M, Aurela M, Lohila A, Mammarella I, Alekseychik P, Tuittila ES, Gong W, Chen X, Meng X and Yuan W (2020), "A Microbial Functional Group-Based CH4 Model Integrated Into a Terrestrial Ecosystem Model: Model Structure, Site-Level Evaluation, and Sensitivity Analysis", Journal of Advances in Modeling Earth Systems. Vol. 12(4)
Abstract: Wetlands are one of the most important terrestrial ecosystems for land-atmosphere CH4 exchange. A new process-based, biophysical model to quantify CH4 emissions from natural wetlands was developed and integrated into a terrestrial ecosystem model (Integrated Biosphere Simulator). The new model represents a multisubstance system (CH4, O2, CO2, and H2) and describes CH4 production, oxidation, and three transport processes (diffusion, plant-mediated transport, and ebullition). The new model uses several critical microbial mechanisms to represent the interaction of anaerobic fermenters and homoacetogens, hydrogenotrophic, and acetoclastic methanogens, and methanotrophs in CH4 production and oxidation. We applied the model to 24 different wetlands globally to compare the simulated CH4 emissions to observations and conducted a sensitivity analysis. The results indicated that (1) for most sites, the model was able to capture the magnitude and variation of observed CH4 emissions under varying environmental conditions; (2) the parameters that regulate dissolved organic carbon and acetate production, and acetoclastic methanogenesis had the significant impact on simulated CH4 emissions; (3) the representation of the process components of CH4 cycling showed that CH4 oxidation was about half or more of CH4 production, and plant-mediated transport was the dominant pathway at most sites; and (4) the seasonality of simulated CH4 emissions can be controlled by soil temperature, water table position, or combinations thereof.
BibTeX:
@article{Song2020,
  author = {Song, Chaoqing and Luan, Junwei and Xu, Xiaofeng and Ma, Minna and Aurela, Mika and Lohila, Annalea and Mammarella, Ivan and Alekseychik, Pavel and Tuittila, Eeva Stiina and Gong, Wei and Chen, Xiuzhi and Meng, Xianhong and Yuan, Wenping},
  title = {A Microbial Functional Group-Based CH4 Model Integrated Into a Terrestrial Ecosystem Model: Model Structure, Site-Level Evaluation, and Sensitivity Analysis},
  journal = {Journal of Advances in Modeling Earth Systems},
  year = {2020},
  volume = {12},
  number = {4},
  doi = {10.1029/2019MS001867}
}
Song R, Muller JP, Kharbouche S, Yin F, Woodgate W, Kitchen M, Roland M, Arriga N, Meyer W, Koerber G, Bonal D, Burban B, Knohl A, Siebicke L, Buysse P, Loubet B, Leonardo M, Lerebourg C and Gobron N (2020), "Validation of space-based albedo products from upscaled tower-based measurements over heterogeneous and homogeneous landscapes", Remote Sensing. Vol. 12(5)
Abstract: Surface albedo is a fundamental radiative parameter as it controls the Earth's energy budget and directly affects the Earth's climate. Satellite observations have long been used to capture the temporal and spatial variations of surface albedo because of their continuous global coverage. However, space-based albedo products are often affected by errors in the atmospheric correction, multi-angular bi-directional reflectance distribution function (BRDF) modelling, as well as spectral conversions. To validate space-based albedo products, an in situ tower albedometer is often used to provide continuous "ground truth" measurements of surface albedo over an extended area. Since space-based albedo and tower-measured albedo are produced at different spatial scales, the can be directly compared only for specific homogeneous land surfaces. However, most land surfaces are inherently heterogeneous with surface properties that vary over a wide range of spatial scales. In this work, tower-measured albedo products, including both directional hemispherical reflectance (DHR) and bi-hemispherical reflectance (BHR), are upscaled to coarse satellite spatial resolutions using a new method. This strategy uses high-resolution satellite derived surface albedos to fill the gaps between the albedometer's field-of-view (FoV) and coarse satellite scales. The high-resolution surface albedo is generated from a combination of surface reflectance retrieved from high-resolution Earth Observation (HR-EO) data and moderate resolution imaging spectroradiometer (MODIS) BRDF climatology over a larger area. We implemented a recently developed atmospheric correction method, the Sensor Invariant Atmospheric Correction (SIAC), to retrieve surface reflectance from HR-EO (e.g., Sentinel-2 and Landsat-8) top-of-atmosphere (TOA) reflectance measurements. This SIAC processing provides an estimated uncertainty for the retrieved surface spectral reflectance at the HR-EO pixel level and shows excellent agreement with the standard Landsat 8 Surface Reflectance Code (LaSRC) in retrieving Landsat-8 surface reflectance. Atmospheric correction of Sentinel-2 data is vastly improved by SIAC when compared against the use of in situ AErosol RObotic NETwork (AERONET) data. Based on this, we can trace the uncertainty of tower-measured albedo during its propagation through high-resolution EO measurements up to coarse satellite scales. These upscaled albedo products can then be compared with space-based albedo products over heterogeneous land surfaces. In this study, both tower-measured albedo and upscaled albedo products are examined at Ground Based Observation for Validation (GbOV) stations (https://land.copernicus.eu/global/gbov/), and used to compare with satellite observations, including Copernicus Global Land Service (CGLS) based on ProbaV and VEGETATION 2 data, MODIS and multi-angle imaging spectroradiometer (MISR).
BibTeX:
@article{Song2020a,
  author = {Song, Rui and Muller, Jan Peter and Kharbouche, Said and Yin, Feng and Woodgate, William and Kitchen, Mark and Roland, Marilyn and Arriga, Nicola and Meyer, Wayne and Koerber, Georgia and Bonal, Damien and Burban, Benoit and Knohl, Alexander and Siebicke, Lukas and Buysse, Pauline and Loubet, Benjamin and Leonardo, Montagnani and Lerebourg, Christophe and Gobron, Nadine},
  title = {Validation of space-based albedo products from upscaled tower-based measurements over heterogeneous and homogeneous landscapes},
  journal = {Remote Sensing},
  year = {2020},
  volume = {12},
  number = {5},
  doi = {10.3390/rs12050833}
}
Spank U, Hehn M, Keller P, Koschorreck M and Bernhofer C (2020), "A Season of Eddy-Covariance Fluxes Above an Extensive Water Body Based on Observations from a Floating Platform", Boundary-Layer Meteorology., dec, 2020. Vol. 174(3), pp. 433-464. Springer Science and Business Media LLC.
Abstract: The eddy-covariance (EC) technique is used to determine mass and energy fluxes between the Earth's surface and the lower atmosphere at high temporal resolution. Despite the frequent and successful use of the EC technique at terrestrial sites, its application over water surfaces is rare. We present one season of EC measurements conducted on the Rappbode Reservoir, Germany's largest drinking water reservoir. A floating observation platform in the centre of the reservoir is used for observations of fluxes that were unaffected by surrounding land surfaces and therefore representative of the actual water–atmosphere exchange. The temporal patterns of sensible heat flux are inverted compared to land sites, since the maxima and the minima occur at night and day respectively. The latent heat flux and the evaporation are unexpectedly low for a site where evaporation is not limited by the availability of water. The daily totals in summer and autumn are only 50% and 75% of the potential evaporation assessed by the FAO grass-reference evaporation, respectively. Measurement uncertainties and the effects of the energy balance closure are ruled out as potential factors, so that low values appear to be a general feature of large water surfaces. The observed carbon dioxide fluxes are characterized by distinctive diurnal variations in a typical range for lakes and reservoirs. However, the methane fluxes are low compared to other inland waters.
BibTeX:
@article{Spank2020,
  author = {Spank, Uwe and Hehn, Markus and Keller, Philipp and Koschorreck, Matthias and Bernhofer, Christian},
  title = {A Season of Eddy-Covariance Fluxes Above an Extensive Water Body Based on Observations from a Floating Platform},
  journal = {Boundary-Layer Meteorology},
  publisher = {Springer Science and Business Media LLC},
  year = {2020},
  volume = {174},
  number = {3},
  pages = {433--464},
  doi = {10.1007/s10546-019-00490-z}
}
Stocker M, Darroch L, Krahl R, Habermann T, Devaraju A, Schwardmann U, D'Onofrio C and Häggström I (2020), "Persistent Identification of Instruments", Data Science Journal., may, 2020. Vol. 19
BibTeX:
@article{Stocker2020,
  author = {Stocker, Markus and Darroch, Louise and Krahl, Rolf and Habermann, Ted and Devaraju, Anusuriya and Schwardmann, Ulrich and D'Onofrio, Claudio and Häggström, Ingemar},
  title = {Persistent Identification of Instruments},
  journal = {Data Science Journal},
  year = {2020},
  volume = {19},
  url = {http://datascience.codata.org/articles/10.5334/dsj-2020-018/},
  doi = {10.5334/dsj-2020-018}
}
Sulpis O, Lauvset SK and Hagens M (2020), "Current estimates of K<sub>1</sub>* and K<sub>2</sub>* appear inconsistent with measured CO<sub>2</sub> system parameters in cold oceanic regions", Ocean Science., jul, 2020. Vol. 16(4), pp. 847-862. Copernicus GmbH.
Abstract: textlessptextgreatertextless![CDATA[Abstract. Seawater absorption of anthropogenic atmospheric carbon dioxide (CO2) has led to a range of changes in carbonate chemistry, collectively referred to as ocean acidification. Stoichiometric dissociation constants used to convert measured carbonate system variables (pH, pCO2, dissolved inorganic carbon, total alkalinity) into globally comparable parameters are crucial for accurately quantifying these changes. The temperature and salinity coefficients of these constants have generally been experimentally derived under controlled laboratory conditions. Here, we use field measurements of carbonate system variables taken from the Global Ocean Data Analysis Project version 2 and the Surface Ocean CO2 Atlas data products to evaluate the temperature dependence of the carbonic acid stoichiometric dissociation constants. By applying a novel iterative procedure to a large dataset of 948 surface-water, quality-controlled samples where four carbonate system variables were independently measured, we show that the set of equations published by Lueker et al. (2000), currently preferred by the ocean acidification community, overestimates the stoichiometric dissociation constants at temperatures below about 8 ∘C. We apply these newly derived temperature coefficients to high-latitude Argo float and cruise data to quantify the effects on surface-water pCO2 and calcite saturation states. These findings highlight the critical implications of uncertainty in stoichiometric dissociation constants for future projections of ocean acidification in polar regions and the need to improve knowledge of what causes the CO2 system inconsistencies in cold waters.]]textgreatertextless/ptextgreater
BibTeX:
@article{Sulpis2020,
  author = {Sulpis, Olivier and Lauvset, Siv K. and Hagens, Mathilde},
  title = {Current estimates of K<sub>1</sub>* and K<sub>2</sub>* appear inconsistent with measured CO<sub>2</sub> system parameters in cold oceanic regions},
  journal = {Ocean Science},
  publisher = {Copernicus GmbH},
  year = {2020},
  volume = {16},
  number = {4},
  pages = {847--862},
  url = {https://os.copernicus.org/articles/16/847/2020/},
  doi = {10.5194/os-16-847-2020}
}
Super I, Dellaert SNC, Visschedijk AJH and Denier van der Gon HAC (2020), "Uncertainty analysis of a European high-resolution emission inventory of CO2 and CO to support inverse modelling and network design", Atmospheric Chemistry and Physics., feb, 2020. Vol. 20(3), pp. 1795-1816.
BibTeX:
@article{Super2020,
  author = {Super, Ingrid and Dellaert, Stijn N. C. and Visschedijk, Antoon J. H. and Denier van der Gon, Hugo A. C.},
  title = {Uncertainty analysis of a European high-resolution emission inventory of CO2 and CO to support inverse modelling and network design},
  journal = {Atmospheric Chemistry and Physics},
  year = {2020},
  volume = {20},
  number = {3},
  pages = {1795--1816},
  url = {https://acp.copernicus.org/articles/20/1795/2020/},
  doi = {10.5194/acp-20-1795-2020}
}
Tagesson T, Schurgers G, Horion S, Ciais P, Tian F, Brandt M, Ahlström A, Wigneron JP, Ardö J, Olin S, Fan L, Wu Z and Fensholt R (2020), "Recent divergence in the contributions of tropical and boreal forests to the terrestrial carbon sink", Nature Ecology and Evolution., jan, 2020. Vol. 4(2), pp. 202-209. Springer Science and Business Media LLC.
Abstract: Anthropogenic land use and land cover changes (LULCC) have a large impact on the global terrestrial carbon sink, but this effect is not well characterized according to biogeographical region. Here, using state-of-the-art Earth observation data and a dynamic global vegetation model, we estimate the impact of LULCC on the contribution of biomes to the terrestrial carbon sink between 1992 and 2015. Tropical and boreal forests contributed equally, and with the largest share of the mean global terrestrial carbon sink. CO2 fertilization was found to be the main driver increasing the terrestrial carbon sink from 1992 to 2015, but the net effect of all drivers (CO2 fertilization and nitrogen deposition, LULCC and meteorological forcing) caused a reduction and an increase, respectively, in the terrestrial carbon sink for tropical and boreal forests. These diverging trends were not observed when applying a conventional LULCC dataset, but were also evident in satellite passive microwave estimates of aboveground biomass. These datasets thereby converge on the conclusion that LULCC have had a greater impact on tropical forests than previously estimated, causing an increase and decrease of the contributions of boreal and tropical forests, respectively, to the growing terrestrial carbon sink.
BibTeX:
@article{Tagesson2020,
  author = {Tagesson, Torbern and Schurgers, Guy and Horion, Stéphanie and Ciais, Philippe and Tian, Feng and Brandt, Martin and Ahlström, Anders and Wigneron, Jean Pierre and Ardö, Jonas and Olin, Stefan and Fan, Lei and Wu, Zhendong and Fensholt, Rasmus},
  title = {Recent divergence in the contributions of tropical and boreal forests to the terrestrial carbon sink},
  journal = {Nature Ecology and Evolution},
  publisher = {Springer Science and Business Media LLC},
  year = {2020},
  volume = {4},
  number = {2},
  pages = {202--209},
  doi = {10.1038/s41559-019-1090-0}
}
Thompson RL, Broquet G, Gerbig C, Koch T, Lang M, Monteil G, Munassar S, Nickless A, Scholze M, Ramonet M, Karstens U, van Schaik E, Wu Z and Rödenbeck C (2020), "Changes in net ecosystem exchange over Europe during the 2018 drought based on atmospheric observations", Philosophical Transactions of the Royal Society B: Biological Sciences., oct, 2020. Vol. 375(1810), pp. 20190512.
Abstract: The 2018 drought was one of the worst European droughts of the twenty-first century in terms of its severity, extent and duration. The effects of the drought could be seen in a reduction in harvest yields in parts of Europe, as well as an unprecedented browning of vegetation in summer. Here, we quantify the effect of the drought on net ecosystem exchange (NEE) using five independent regional atmospheric inversion frameworks. Using a network of atmospheric CO 2 mole fraction observations, we estimate NEE with at least monthly and 0.5° × 0.5° resolution for 2009–2018. We find that the annual NEE in 2018 was likely more positive (less CO 2 uptake) in the temperate region of Europe by 0.09 ± 0.06 Pg C yr −1 (mean ± s.d.) compared to the mean of the last 10 years of −0.08 ± 0.17 Pg C yr −1 , making the region close to carbon neutral in 2018. Similarly, we find a positive annual NEE anomaly for the northern region of Europe of 0.02 ± 0.02 Pg C yr −1 compared the 10-year mean of −0.04 ± 0.05 Pg C yr −1 . In both regions, this was largely owing to a reduction in the summer CO 2 uptake. The positive NEE anomalies coincided spatially and temporally with negative anomalies in soil water. These anomalies were exceptional for the 10-year period of our study.
BibTeX:
@article{Thompson2020,
  author = {Thompson, R. L. and Broquet, G. and Gerbig, C. and Koch, T. and Lang, M. and Monteil, G. and Munassar, S. and Nickless, A. and Scholze, M. and Ramonet, M. and Karstens, U. and van Schaik, E. and Wu, Z. and Rödenbeck, C.},
  title = {Changes in net ecosystem exchange over Europe during the 2018 drought based on atmospheric observations},
  journal = {Philosophical Transactions of the Royal Society B: Biological Sciences},
  year = {2020},
  volume = {375},
  number = {1810},
  pages = {20190512},
  url = {https://royalsocietypublishing.org/doi/10.1098/rstb.2019.0512},
  doi = {10.1098/rstb.2019.0512}
}
Tian X, Minunno F, Cao T, Peltoniemi M, Kalliokoski T and Mäkelä A (2020), "Extending the range of applicability of the semi‐empirical ecosystem flux model PRELES for varying forest types and climate", Global Change Biology., may, 2020. Vol. 26(5), pp. 2923-2943. Blackwell Publishing Ltd.
Abstract: Applications of ecosystem flux models on large geographical scales are often limited by model complexity and data availability. Here we calibrated and evaluated a semi-empirical ecosystem flux model, PREdict Light-use efficiency, Evapotranspiration and Soil water (PRELES), for various forest types and climate conditions, based on eddy covariance data from 55 sites. A Bayesian approach was adopted for model calibration and uncertainty quantification. We applied the site-specific calibrations and multisite calibrations to nine plant functional types (PFTs) to obtain the site-specific and PFT-specific parameter vectors for PRELES. A systematically designed cross-validation was implemented to evaluate calibration strategies and the risks in extrapolation. The combination of plant physiological traits and climate patterns generated significant variation in vegetation responses and model parameters across but not within PFTs, implying that applying the model without PFT-specific parameters is risky. But within PFT, the multisite calibrations performed as accurately as the site-specific calibrations in predicting gross primary production (GPP) and evapotranspiration (ET). Moreover, the variations among sites within one PFT could be effectively simulated by simply adjusting the parameter of potential light-use efficiency (LUE), implying significant convergence of simulated vegetation processes within PFT. The hierarchical modelling of PRELES provides a compromise between satellite-driven LUE and physiologically oriented approaches for extrapolating the geographical variation of ecosystem productivity. Although measurement errors of eddy covariance and remotely sensed data propagated a substantial proportion of uncertainty or potential biases, the results illustrated that PRELES could reliably capture daily variations of GPP and ET for contrasting forest types on large geographical scales if PFT-specific parameterizations were applied.
BibTeX:
@article{Tian2020,
  author = {Tian, Xianglin and Minunno, Francesco and Cao, Tianjian and Peltoniemi, Mikko and Kalliokoski, Tuomo and Mäkelä, Annikki},
  title = {Extending the range of applicability of the semi‐empirical ecosystem flux model PRELES for varying forest types and climate},
  journal = {Global Change Biology},
  publisher = {Blackwell Publishing Ltd},
  year = {2020},
  volume = {26},
  number = {5},
  pages = {2923--2943},
  url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.14992},
  doi = {10.1111/gcb.14992}
}
Tiemoko DT, Yoroba F, Paris J-D, Diawara A, Berchet A, Pison I, Riandet A and Ramonet M (2020), "Source–Receptor Relationships and Cluster Analysis of CO2, CH4, and CO Concentrations in West Africa: The Case of Lamto in Côte d'Ivoire", Atmosphere., aug, 2020. Vol. 11(9), pp. 903.
Abstract: The contribution in terms of long-range transport of CO2, CH4, and CO concentrations to measurements at Lamto (5°02′ W–6°13′ N) was analyzed for the 2014–2017 period using the FLEXPART model that calculates the retro-plumes of air masses arriving at the station. The identification of the source-receptor relationships was also studied with a clustering technique applied on those retro-plumes. This clustering technique enabled us to distinguish four categories of air mass transports arriving at Lamto site described as follows: oceanic and maritime origin (≈37% of the retro-plumes), continental origin (≈21%), and two hybrid clusters (≈42%). The results show that continental emission sources contribute significantly to the increases in concentrations of CO2, CH4, and CO and explain ≈40% of their variance. These emission sources are predominantly from north and north-east directions of the measurement point, and where densely populated and economically developed areas are located. In addition, the transport of air masses from these directions lead to the accumulation of CO2, CH4, and CO. Furthermore, the ratios ΔCO/ΔCH4 and ΔCO/ΔCO2 observed in the groups associated with Harmattan flows clearly show an influence of combustion processes on the continent. Thus, the grouping based on FLEXPART footprints shows an advantage compared to the use of simple trajectories for analyzing source–receptor relationships.
BibTeX:
@article{Tiemoko2020,
  author = {Tiemoko, Dro Touré and Yoroba, Fidèle and Paris, Jean-Daniel and Diawara, Adama and Berchet, Antoine and Pison, Isabelle and Riandet, Aurélie and Ramonet, Michel},
  title = {Source–Receptor Relationships and Cluster Analysis of CO2, CH4, and CO Concentrations in West Africa: The Case of Lamto in Côte d'Ivoire},
  journal = {Atmosphere},
  year = {2020},
  volume = {11},
  number = {9},
  pages = {903},
  url = {https://www.mdpi.com/2073-4433/11/9/903},
  doi = {10.3390/atmos11090903}
}
Tramontana G, Migliavacca M, Jung M, Reichstein M, Keenan TF, Camps-Valls G, Ogee J, Verrelst J and Papale D (2020), "Partitioning net carbon dioxide fluxes into photosynthesis and respiration using neural networks", Global Change Biology. Vol. 26(9), pp. 5235-5253.
Abstract: The eddy covariance (EC) technique is used to measure the net ecosystem exchange (NEE) of CO2 between ecosystems and the atmosphere, offering a unique opportunity to study ecosystem responses to climate change. NEE is the difference between the total CO2 release due to all respiration processes (RECO), and the gross carbon uptake by photosynthesis (GPP). These two gross CO2 fluxes are derived from EC measurements by applying partitioning methods that rely on physiologically based functional relationships with a limited number of environmental drivers. However, the partitioning methods applied in the global FLUXNET network of EC observations do not account for the multiple co-acting factors that modulate GPP and RECO flux dynamics. To overcome this limitation, we developed a hybrid data-driven approach based on combined neural networks (NNC-part). NNC-part incorporates process knowledge by introducing a photosynthetic response based on the light-use efficiency (LUE) concept, and uses a comprehensive dataset of soil and micrometeorological variables as fluxes drivers. We applied the method to 36 sites from the FLUXNET2015 dataset and found a high consistency in the results with those derived from other standard partitioning methods for both GPP (R2 textgreater.94) and RECO (R2 textgreater.8). High consistency was also found for (a) the diurnal and seasonal patterns of fluxes and (b) the ecosystem functional responses. NNC-part performed more realistic than the traditional methods for predicting additional patterns of gross CO2 fluxes, such as: (a) the GPP response to VPD, (b) direct effects of air temperature on GPP dynamics, (c) hysteresis in the diel cycle of gross CO2 fluxes, (d) the sensitivity of LUE to the diffuse to direct radiation ratio, and (e) the post rain respiration pulse after a long dry period. In conclusion, NNC-part is a valid data-driven approach to provide GPP and RECO estimates and complementary to the existing partitioning methods.
BibTeX:
@article{Tramontana2020,
  author = {Tramontana, Gianluca and Migliavacca, Mirco and Jung, Martin and Reichstein, Markus and Keenan, Trevor F and Camps-Valls, Gustau and Ogee, Jerome and Verrelst, Jochem and Papale, Dario},
  title = {Partitioning net carbon dioxide fluxes into photosynthesis and respiration using neural networks},
  journal = {Global Change Biology},
  year = {2020},
  volume = {26},
  number = {9},
  pages = {5235--5253},
  doi = {10.1111/gcb.15203}
}
Trotsiuk V, Hartig F, Cailleret M, Babst F, Forrester DI, Baltensweiler A, Buchmann N, Bugmann H, Gessler A, Gharun M, Minunno F, Rigling A, Rohner B, Stillhard J, Thürig E, Waldner P, Ferretti M, Eugster W and Schaub M (2020), "Assessing the response of forest productivity to climate extremes in Switzerland using model–data fusion", Global Change Biology., apr, 2020. Vol. 26(4), pp. 2463-2476.
BibTeX:
@article{Trotsiuk2020,
  author = {Trotsiuk, Volodymyr and Hartig, Florian and Cailleret, Maxime and Babst, Flurin and Forrester, David I. and Baltensweiler, Andri and Buchmann, Nina and Bugmann, Harald and Gessler, Arthur and Gharun, Mana and Minunno, Francesco and Rigling, Andreas and Rohner, Brigitte and Stillhard, Jonas and Thürig, Esther and Waldner, Peter and Ferretti, Marco and Eugster, Werner and Schaub, Marcus},
  title = {Assessing the response of forest productivity to climate extremes in Switzerland using model–data fusion},
  journal = {Global Change Biology},
  year = {2020},
  volume = {26},
  number = {4},
  pages = {2463--2476},
  url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.15011},
  doi = {10.1111/gcb.15011}
}
Ueyama M, Ichii K, Kobayashi H, Kumagai T, Beringer J, Merbold L, Euskirchen ES, Hirano T, Belelli Marchesini L, Baldocchi D, Saitoh TM, Mizoguchi Y, Ono K, Kim J, Varlagin A, Kang M, Shimizu T, Kosugi Y, Bret-Harte MS(D, Machimura T, Matsuura Y, Ohta T, Takagi K, Takanashi S and Yasuda Y (2020), "Inferring CO2 fertilization effect based on global monitoring land-atmosphere exchange with a theoretical model", Environmental Research Letters., feb, 2020. IOP Publishing.
Abstract: Rising atmospheric CO2 concentration ([CO2]) enhances photosynthesis and reduces transpiration 8 70 9 at the leaf, ecosystem, and global scale via the CO2 fertilization effect. The CO2 fertilization effect 10 71 is among the most important processes for predicting the terrestrial carbon budget and future 11 72 12 climate, yet it has been elusive to quantify. For evaluating the CO2 fertilization effect on land 13 73 photosynthesis and transpiration, we developed a technique that isolated this effect from other 14 74 15 confounding effects, such as changes in climate, using a noisy time series of observed land- 16 75 atmosphere CO2 and water vapor exchange. Here, we evaluate the magnitude of this effect from 17 76 18 2000 to 2014 globally based on constraint optimization of gross primary productivity (GPP) and 19 77 evapotranspiration in a canopy photosynthesis model over 104 global eddy-covariance stations. 20 21 78 We found a consistent increase of GPP (0.138 ± 0.007 % ppm-1; percentile per rising ppm of 22 79 [CO2]) and a concomitant decrease in transpiration (-0.073 ± 0.006 % ppm-1) due to rising [CO2]. 23 80 24 Enhanced GPP from CO2 fertilization after the baseline year 2000 is, on average, 1.2% of global 25 81 GPP, 12.4 g C m-2 yr-1 or 1.8 Pg C yr-1 at the years from 2001 to 2014. Our result demonstrates 26 82 27 that the current increase in [CO2] could potentially explain the recent land CO2 sink at the global 28 83 scale
BibTeX:
@article{Ueyama2020,
  author = {Ueyama, Masahito and Ichii, Kazuhito and Kobayashi, Hideki and Kumagai, Tomo'omi and Beringer, Jason and Merbold, Lutz and Euskirchen, Eugenie S and Hirano, Takashi and Belelli Marchesini, Luca and Baldocchi, Dennis and Saitoh, Taku M. and Mizoguchi, Yasuko and Ono, Keisuke and Kim, Joon and Varlagin, Andrej and Kang, Minseok and Shimizu, Takanori and Kosugi, Yoshiko and Bret-Harte, Marion Syndonia (Donie) and Machimura, Takashi and Matsuura, Yojiro and Ohta, Takeshi and Takagi, Kentaro and Takanashi, Satoru and Yasuda, Yukio},
  title = {Inferring CO2 fertilization effect based on global monitoring land-atmosphere exchange with a theoretical model},
  journal = {Environmental Research Letters},
  publisher = {IOP Publishing},
  year = {2020},
  doi = {10.1088/1748-9326/ab79e5}
}
Väisänen M, Krab EJ, Monteux S, Teuber LM, Gavazov K, Weedon JT, Keuper F and Dorrepaal E (2020), "Meshes in mesocosms control solute and biota exchange in soils: A step towards disentangling (a)biotic impacts on the fate of thawing permafrost", Applied Soil Ecology. Vol. 151(February), pp. 103537. Elsevier.
Abstract: Environmental changes feedback to climate through their impact on soil functions such as carbon (C) and nutrient sequestration. Abiotic conditions and the interactions between above- and belowground biota drive soil responses to environmental change but these (a)biotic interactions are challenging to study. Nonetheless, better understanding of these interactions would improve predictions of future soil functioning and the soil-climate feedback and, in this context, permafrost soils are of particular interest due to their vast soil C-stores. We need new tools to isolate abiotic (microclimate, chemistry) and biotic (roots, fauna, microorganisms) components and to identify their respective roles in soil processes. We developed a new experimental setup, in which we mimic thermokarst (permafrost thaw-induced soil subsidence) by fitting thawed permafrost and vegetated active layer sods side by side into mesocosms deployed in a subarctic tundra over two growing seasons. In each mesocosm, the two sods were separated from each other by barriers with different mesh sizes to allow varying degrees of physical connection and, consequently, (a)biotic exchange between active layer and permafrost. We demonstrate that our mesh-approach succeeded in controlling 1) lateral exchange of solutes between the two soil types, 2) colonization of permafrost by microbes but not by soil fauna, and 3) ingrowth of roots into permafrost. In particular, experimental thermokarst induced a ˜60% decline in permafrost nitrogen (N) content, a shift in soil bacteria and a rapid buildup of root biomass (+33.2 g roots m−2 soil). This indicates that cascading plant-soil-microbe linkages are at the heart of biogeochemical cycling in thermokarst events. We propose that this novel setup can be used to explore the effects of (a)biotic ecosystem components on focal biogeochemical processes in permafrost soils and beyond.
BibTeX:
@article{Vaeisaenen2020,
  author = {Väisänen, Maria and Krab, Eveline J and Monteux, Sylvain and Teuber, Laurenz M and Gavazov, Konstantin and Weedon, James T and Keuper, Frida and Dorrepaal, Ellen},
  title = {Meshes in mesocosms control solute and biota exchange in soils: A step towards disentangling (a)biotic impacts on the fate of thawing permafrost},
  journal = {Applied Soil Ecology},
  publisher = {Elsevier},
  year = {2020},
  volume = {151},
  number = {February},
  pages = {103537},
  url = {https://doi.org/10.1016/j.apsoil.2020.103537},
  doi = {10.1016/j.apsoil.2020.103537}
}
Van Der Graaf SC, Kranenburg R, Segers AJ, Schaap M and Willem Erisman J (2020), "Satellite-derived leaf area index and roughness length information for surface-atmosphere exchange modelling: A case study for reactive nitrogen deposition in north-western Europe using LOTOS-EUROS v2.0", Geoscientific Model Development., may, 2020. Vol. 13(5), pp. 2451-2474. Copernicus GmbH.
Abstract: The nitrogen cycle has been continuously disrupted by human activity over the past century, resulting in almost a tripling of the total reactive nitrogen fixation in Europe. Consequently, excessive amounts of reactive nitrogen (textlessspan classCombining double low line"inline-formula"textgreaterNrtextless/spantextgreater) have manifested in the environment, leading to a cascade of adverse effects, such as acidification and eutrophication of terrestrial and aquatic ecosystems, and particulate matter formation. Chemistry transport models (CTMs) are frequently used as tools to simulate the complex chain of processes that determine atmospheric textlessspan classCombining double low line"inline-formula"textgreaterNrtextless/spantextgreater flows. In these models, the parameterization of the atmosphere-biosphere exchange of textlessspan classCombining double low line"inline-formula"textgreaterNrtextless/spantextgreater is largely based on few surface exchange measurement and is therefore known to be highly uncertain. In addition to this, the input parameters that are used here are often fixed values, only linked to specific land use classes. In an attempt to improve this, a combination of multiple satellite products is used to derive updated, time-variant leaf area index (LAI) and roughness length (textlessspan classCombining double low line"inline-formula"textgreatertextlessitextgreaterztextless/itextgreater0textless/spantextgreater) input maps. As LAI, we use the Moderate Resolution Imaging Spectroradiometer (MODIS) MCD15A2H product. The monthly textlessspan classCombining double low line"inline-formula"textgreatertextlessitextgreaterztextless/itextgreater0textless/spantextgreater input maps presented in this paper are a function of satellite-derived normalized difference vegetation index (NDVI) values (MYD13A3 product) for short vegetation types (such as grass and arable land) and a combination of satellite-derived forest canopy height and LAI for forests. The use of these growth-dependent satellite products allows us to represent the growing season more realistically. For urban areas, the textlessspan classCombining double low line"inline-formula"textgreatertextlessitextgreaterztextless/itextgreater0textless/spantextgreater values are updated, too, and linked to a population density map. The approach to derive these dynamic textlessspan classCombining double low line"inline-formula"textgreatertextlessitextgreaterztextless/itextgreater0textless/spantextgreater estimates can be linked to any land use map and is as such transferable to other models. We evaluated the sensitivity of the modelled textlessspan classCombining double low line"inline-formula"textgreaterNrtextless/spantextgreater deposition fields in LOng Term Ozone Simulation - EURopean Operational Smog (LOTOS-EUROS) v2.0 to the abovementioned changes in LAI and textlessspan classCombining double low line"inline-formula"textgreatertextlessitextgreaterztextless/itextgreater0textless/spantextgreater inputs, focusing on Germany, the Netherlands and Belgium. We computed textlessspan classCombining double low line"inline-formula"textgreatertextlessitextgreaterztextless/itextgreater0textless/spantextgreater values from FLUXNET sites and compared these to the default and updated textlessspan classCombining double low line"inline-formula"textgreatertextlessitextgreaterztextless/itextgreater0textless/spantextgreater values in LOTOS-EUROS. The root mean square difference (RMSD) for both short vegetation and forest sites improved. Comparing all sites, the RMSD decreased from 0.76 (default textlessspan classCombining double low line"inline-formula"textgreatertextlessitextgreaterztextless/itextgreater0textless/spantextgreater) to 0.60 (updated textlessspan classCombining double low line"inline-formula"textgreatertextlessitextgreaterztextless/itextgreater0textless/spantextgreater). The implementation of these updated LAI and textlessspan classCombining double low line"inline-formula"textgreatertextlessitextgreaterztextless/itextgreater0textless/spantextgreater input maps led to local changes in the total textlessspan classCombining double low line"inline-formula"textgreaterNrtextless/spantextgreater deposition of up to textlessspan classCombining double low line"inline-formula"textgreaterĝˆ1/430textless/spantextgreater % and a general shift from wet to dry deposition. The most distinct changes are observed in land-use-specific deposition fluxes. These fluxes may show relatively large deviations, locally affecting estimated critical load exceedances for specific natural ecosystems.
BibTeX:
@article{VanDerGraaf2020,
  author = {Van Der Graaf, Shelley C. and Kranenburg, Richard and Segers, Arjo J. and Schaap, Martijn and Willem Erisman, Jan},
  title = {Satellite-derived leaf area index and roughness length information for surface-atmosphere exchange modelling: A case study for reactive nitrogen deposition in north-western Europe using LOTOS-EUROS v2.0},
  journal = {Geoscientific Model Development},
  publisher = {Copernicus GmbH},
  year = {2020},
  volume = {13},
  number = {5},
  pages = {2451--2474},
  doi = {10.5194/gmd-13-2451-2020}
}
Verreyken B, Amelynck C, Brioude J, Muller JF, Schoon N, Kumps N, Colomb A, Metzger JM, Lee CF, Koenig TK, Volkamer R and Stavrakou T (2020), "Characterisation of African biomass burning plumes and impacts on the atmospheric composition over the south-west Indian Ocean", Atmospheric Chemistry and Physics. Vol. 20(23), pp. 14821-14845.
Abstract: We present an investigation of biomass burning (BB) plumes originating from Africa and Madagascar based on measurements of a suite of volatile organic compounds (VOCs), carbon monoxide (CO), ozone (O3) and nitrogen dioxide (NO2) obtained during the dry season of 2018 and 2019 at the high-Altitude Maïdo observatory (21.1 S, 55.4 E, 2160ma:s:l:), located on the remote island of La Réunion in the south-west Indian Ocean (SWIO). Biomass burning plume episodes were identified from increased acetonitrile (CH3CN) mixing ratios. Enhancement ratios (EnRs) relative to CO were calculated from in situ measurements for CH3CN, acetone (CH3COCH3), formic acid (HCOOH), acetic acid (CH3COOH), benzene (C6H6), methanol (CH3OH) and O3. We compared the EnRs to emission ratios (ERs) relative to CO reported in the literature in order to estimate loss or production of these compounds during transport. For CH3CN and CH3COOH, the calculated EnRs are similar to the ERs. For C6H6 and CH3OH, the EnR is lower than the ER, indicating a net sink of these compounds which was found to be in line with the expected atmospheric lifetime. For CH3COCH3 and HCOOH, the calculated EnRs are larger than the ERs. The discrepancy reaches an order of magnitude for HCOOH (18 34 pptvppbv1 compared to 1.8 4.5 pptvppbv1). This points to significant secondary production of HCOOH during transport. The Copernicus Atmospheric Monitoring Service (CAMS) global model simulations reproduce the temporal variation of CO mixing ratios well at the observatory but underestimate O3 and NO2 mixing ratios in the plumes by on average 16 ppbv and 60 pptv respectively. This discrepancy between modelled and measured O3 mixing ratios was attributed to (i) large uncertainties in VOC and NOx (NOCNO2) emissions due to BB in CAMS and (ii) misrepresentation of NOx recycling in the model during transport. Finally, transport of pyrogenically emitted CO is calculated with FLEXPART in order to (i) determine the mean plume age during the intrusions at the observatory and (ii) estimate the impact of BB on the pristine marine boundary layer (MBL). By multiplying the excess CO in the MBL with inferred EnRs at the observatory, we calculated the expected impact of BB on CH3CN, CH3COCH3, CH3OH and C6H6 concentrations in the MBL. These excesses constitute increases of 20 % 150% compared to background measurements in the SWIO MBL reported in the literature.
BibTeX:
@article{Verreyken2020,
  author = {Verreyken, Bert and Amelynck, Crist and Brioude, Jerome and Muller, Jean Francois and Schoon, Niels and Kumps, Nicolas and Colomb, Aurelie and Metzger, Jean Marc and Lee, Christopher F and Koenig, Theodore K and Volkamer, Rainer and Stavrakou, Trissevgeni},
  title = {Characterisation of African biomass burning plumes and impacts on the atmospheric composition over the south-west Indian Ocean},
  journal = {Atmospheric Chemistry and Physics},
  year = {2020},
  volume = {20},
  number = {23},
  pages = {14821--14845},
  doi = {10.5194/acp-20-14821-2020}
}
Vestin P, Mölder M, Kljun N, Cai Z, Hasan A, Holst J, Klemedtsson L and Lindroth A (2020), "Impacts of Clear-Cutting of a Boreal Forest on Carbon Dioxide, Methane and Nitrous Oxide Fluxes", Forests., sep, 2020. Vol. 11(9), pp. 961.
Abstract: The 2015 Paris Agreement encourages stakeholders to implement sustainable forest management policies to mitigate anthropogenic emissions of greenhouse gases (GHG). The net effects of forest management on the climate and the environment are, however, still not completely understood, partially as a result of a lack of long-term measurements of GHG fluxes in managed forests. During the period 2010–2013, we simultaneously measured carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) fluxes using the flux-gradient technique at two clear-cut plots of different degrees of wetness, located in central Sweden. The measurements started approx. one year after clear-cutting, directly following soil scarification and planting. The study focused on robust inter-plot comparisons, spatial and temporal dynamics of GHG fluxes, and the determination of the global warming potential of a clear-cut boreal forest. The clear-cutting resulted in significant emissions of GHGs at both the wet and the dry plot. The degree of wetness determined, directly or indirectly, the relative contribution of each GHG to the total budgets. Faster establishment of vegetation on the wet plot reduced total emissions of CO2 as compared to the dry plot but this was partially offset by higher CH4 emissions. Waterlogging following clear-cutting likely caused both plots to switch from sinks to sources of CH4. In addition, there were periods with N2O uptake at the wet plot, although both plots were net sources of N2O on an annual basis. We observed clear diel patters in CO2, CH4 and N2O fluxes during the growing season at both plots, with the exception of CH4 at the dry plot. The total three-year carbon budgets were 4107 gCO2-equivalent m−2 and 5274 gCO2-equivalent m−2 at the wet and the dry plots, respectively. CO2 contributed 91.8% to the total carbon budget at the wet plot and 98.2% at the dry plot. For the only full year with N2O measurements, the total GHG budgets were 1069.9 gCO2-eqvivalents m−2 and 1695.7 gCO2-eqvivalents m−2 at the wet and dry plot, respectively. At the wet plot, CH4 contributed 3.7%, while N2O contributed 7.3%. At the dry plot, CH4 and N2O contributed 1.5% and 7.6%, respectively. Our results emphasize the importance of considering the effects of the three GHGs on the climate for any forest management policy aiming at enhancing the mitigation potential of forests.
BibTeX:
@article{Vestin2020,
  author = {Vestin, Patrik and Mölder, Meelis and Kljun, Natascha and Cai, Zhanzhang and Hasan, Abdulghani and Holst, Jutta and Klemedtsson, Leif and Lindroth, Anders},
  title = {Impacts of Clear-Cutting of a Boreal Forest on Carbon Dioxide, Methane and Nitrous Oxide Fluxes},
  journal = {Forests},
  year = {2020},
  volume = {11},
  number = {9},
  pages = {961},
  url = {https://www.mdpi.com/1999-4907/11/9/961},
  doi = {10.3390/f11090961}
}
Vezy R, le Maire G, Christina M, Georgiou S, Imbach P, Hidalgo HG, Alfaro EJ, Blitz-Frayret C, Charbonnier F, Lehner P, Loustau D and Roupsard O (2020), "DynACof: A process-based model to study growth, yield and ecosystem services of coffee agroforestry systems", Environmental Modelling and Software., feb, 2020. Vol. 124, pp. 104609. Elsevier BV.
Abstract: The DynACof model was designed to model coffee agroforestry systems and study the trade-offs to e.g. optimize the system facing climate changes. The model simulates net primary productivity (NPP), growth, yield, mortality, energy and water balance of coffee agroforestry systems according to shade tree species and management. Several plot-scale ecosystem services are simulated by the model, such as production, canopy cooling effect, or potential C sequestration. DynACof uses metamodels derived from a detailed 3D process-based model (MAESPA) to account for complex spatial effects, while running fast. It also includes a coffee flower bud and fruit cohort module to better distribute fruit carbon demand over the year, a key feature to obtain a realistic competition between sinks. The model was parameterized and evaluated using a highly comprehensive database on a coffee agroforestry experimental site in Costa Rica. The fluxes simulated by the model were close to the measurements over a 5-year period (nRMSE = 26.27 for gross primary productivity; 28.22 for actual evapo-transpiration, 53.91 for sensible heat flux and 15.26 for net radiation), and DynACof satisfactorily simulated the yield, NPP, mortality and carbon stock for each coffee organ type over a 35-year rotation.
BibTeX:
@article{Vezy2020,
  author = {Vezy, Rémi and le Maire, Guerric and Christina, Mathias and Georgiou, Selena and Imbach, Pablo and Hidalgo, Hugo G and Alfaro, Eric J and Blitz-Frayret, Céline and Charbonnier, Fabien and Lehner, Peter and Loustau, Denis and Roupsard, Olivier},
  title = {DynACof: A process-based model to study growth, yield and ecosystem services of coffee agroforestry systems},
  journal = {Environmental Modelling and Software},
  publisher = {Elsevier BV},
  year = {2020},
  volume = {124},
  pages = {104609},
  doi = {10.1016/j.envsoft.2019.104609}
}
Vitale D, Fratini G, Bilancia M, Nicolini G, Sabbatini S and Papale D (2020), "A robust data cleaning procedure for eddy covariance flux measurements", Biogeosciences., mar, 2020. Vol. 17(6), pp. 1367-1391.
BibTeX:
@article{Vitale2020,
  author = {Vitale, Domenico and Fratini, Gerardo and Bilancia, Massimo and Nicolini, Giacomo and Sabbatini, Simone and Papale, Dario},
  title = {A robust data cleaning procedure for eddy covariance flux measurements},
  journal = {Biogeosciences},
  year = {2020},
  volume = {17},
  number = {6},
  pages = {1367--1391},
  url = {https://www.biogeosciences.net/17/1367/2020/},
  doi = {10.5194/bg-17-1367-2020}
}
Waliser D, Gleckler PJ, Ferraro R, Taylor KE, Ames S, Biard J, Bosilovich MG, Brown O, Chepfer H, Cinquini L, Durack PJ, Eyring V, Mathieu P-P, Lee T, Pinnock S, Potter GL, Rixen M, Saunders R, Schulz J, Thépaut J-N and Tuma M (2020), "Observations for Model Intercomparison Project (Obs4MIPs): status for CMIP6", Geoscientific Model Development., jul, 2020. Vol. 13(7), pp. 2945-2958.
Abstract: textlessptextgreatertextless![CDATA[Abstract. The Observations for Model Intercomparison Project (Obs4MIPs) was initiated in 2010 to facilitate the use of observations in climate model evaluation and research, with a particular target being the Coupled Model Intercomparison Project (CMIP), a major initiative of the World Climate Research Programme (WCRP). To this end, Obs4MIPs (1) targets observed variables that can be compared to CMIP model variables; (2) utilizes dataset formatting specifications and metadata requirements closely aligned with CMIP model output; (3) provides brief technical documentation for each dataset, designed for nonexperts and tailored towards relevance for model evaluation, including information on uncertainty, dataset merits, and limitations; and (4) disseminates the data through the Earth System Grid Federation (ESGF) platforms, making the observations searchable and accessible via the same portals as the model output. Taken together, these characteristics of the organization and structure of obs4MIPs should entice a more diverse community of researchers to engage in the comparison of model output with observations and to contribute to a more comprehensive evaluation of the climate models. At present, the number of obs4MIPs datasets has grown to about 80; many are undergoing updates, with another 20 or so in preparation, and more than 100 are proposed and under consideration. A partial list of current global satellite-based datasets includes humidity and temperature profiles; a wide range of cloud and aerosol observations; ocean surface wind, temperature, height, and sea ice fraction; surface and top-of-atmosphere longwave and shortwave radiation; and ozone (O3), methane (CH4), and carbon dioxide (CO2) products. A partial list of proposed products expected to be useful in analyzing CMIP6 results includes the following: alternative products for the above quantities, additional products for ocean surface flux and chlorophyll products, a number of vegetation products (e.g., FAPAR, LAI, burned area fraction), ice sheet mass and height, carbon monoxide (CO), and nitrogen dioxide (NO2). While most existing obs4MIPs datasets consist of monthly-mean gridded data over the global domain, products with higher time resolution (e.g., daily) and/or regional products are now receiving more attention. Along with an increasing number of datasets, obs4MIPs has implemented a number of capability upgrades including (1) an updated obs4MIPs data specifications document that provides additional search facets and generally improves congruence with CMIP6 specifications for model datasets, (2) a set of six easily understood indicators that help guide users as to a dataset's maturity and suitability for application, and (3) an option to supply supplemental information about a dataset beyond what can be found in the standard metadata. With the maturation of the obs4MIPs framework, the dataset inclusion process, and the dataset formatting guidelines and resources, the scope of the observations being considered is expected to grow to include gridded in situ datasets as well as datasets with a regional focus, and the ultimate intent is to judiciously expand this scope to any observation dataset that has applicability for evaluation of the types of Earth system models used in CMIP.]]textgreatertextless/ptextgreater
BibTeX:
@article{Waliser2020,
  author = {Waliser, Duane and Gleckler, Peter J. and Ferraro, Robert and Taylor, Karl E. and Ames, Sasha and Biard, James and Bosilovich, Michael G. and Brown, Otis and Chepfer, Helene and Cinquini, Luca and Durack, Paul J. and Eyring, Veronika and Mathieu, Pierre-Philippe and Lee, Tsengdar and Pinnock, Simon and Potter, Gerald L. and Rixen, Michel and Saunders, Roger and Schulz, Jörg and Thépaut, Jean-Noël and Tuma, Matthias},
  title = {Observations for Model Intercomparison Project (Obs4MIPs): status for CMIP6},
  journal = {Geoscientific Model Development},
  year = {2020},
  volume = {13},
  number = {7},
  pages = {2945--2958},
  url = {https://gmd.copernicus.org/articles/13/2945/2020/},
  doi = {10.5194/gmd-13-2945-2020}
}
Walker AP, De Kauwe MG, Bastos A, Belmecheri S, Georgiou K, Keeling RF, McMahon SM, Medlyn BE, Moore DJP, Norby RJ, Zaehle S, Anderson‐Teixeira KJ, Battipaglia G, Brienen RJW, Cabugao KG, Cailleret M, Campbell E, Canadell JG, Ciais P, Craig ME, Ellsworth DS, Farquhar GD, Fatichi S, Fisher JB, Frank DC, Graven H, Gu L, Haverd V, Heilman K, Heimann M, Hungate BA, Iversen CM, Joos F, Jiang M, Keenan TF, Knauer J, Körner C, Leshyk VO, Leuzinger S, Liu Y, MacBean N, Malhi Y, McVicar TR, Penuelas J, Pongratz J, Powell AS, Riutta T, Sabot MEB, Schleucher J, Sitch S, Smith WK, Sulman B, Taylor B, Terrer C, Torn MS, Treseder KK, Trugman AT, Trumbore SE, Mantgem PJ, Voelker SL, Whelan ME and Zuidema PA (2020), "Integrating the evidence for a terrestrial carbon sink caused by increasing atmospheric CO 2", New Phytologist., oct, 2020. , pp. nph.16866.
BibTeX:
@article{Walker2020,
  author = {Walker, Anthony P. and De Kauwe, Martin G. and Bastos, Ana and Belmecheri, Soumaya and Georgiou, Katerina and Keeling, Ralph F. and McMahon, Sean M. and Medlyn, Belinda E. and Moore, David J. P. and Norby, Richard J. and Zaehle, Sönke and Anderson‐Teixeira, Kristina J. and Battipaglia, Giovanna and Brienen, Roel J. W. and Cabugao, Kristine G. and Cailleret, Maxime and Campbell, Elliott and Canadell, Josep G. and Ciais, Philippe and Craig, Matthew E. and Ellsworth, David S. and Farquhar, Graham D. and Fatichi, Simone and Fisher, Joshua B. and Frank, David C. and Graven, Heather and Gu, Lianhong and Haverd, Vanessa and Heilman, Kelly and Heimann, Martin and Hungate, Bruce A. and Iversen, Colleen M. and Joos, Fortunat and Jiang, Mingkai and Keenan, Trevor F. and Knauer, Jürgen and Körner, Christian and Leshyk, Victor O. and Leuzinger, Sebastian and Liu, Yao and MacBean, Natasha and Malhi, Yadvinder and McVicar, Tim R. and Penuelas, Josep and Pongratz, Julia and Powell, A. Shafer and Riutta, Terhi and Sabot, Manon E. B. and Schleucher, Juergen and Sitch, Stephen and Smith, William K. and Sulman, Benjamin and Taylor, Benton and Terrer, César and Torn, Margaret S. and Treseder, Kathleen K. and Trugman, Anna T. and Trumbore, Susan E. and Mantgem, Phillip J. and Voelker, Steve L. and Whelan, Mary E. and Zuidema, Pieter A.},
  title = {Integrating the evidence for a terrestrial carbon sink caused by increasing atmospheric CO 2},
  journal = {New Phytologist},
  year = {2020},
  pages = {nph.16866},
  url = {https://onlinelibrary.wiley.com/doi/10.1111/nph.16866},
  doi = {10.1111/nph.16866}
}
Wang S, Garcia M, Ibrom A and Bauer-Gottwein P (2020), "Temporal interpolation of land surface fluxes derived from remote sensing - Results with an unmanned aerial system", Hydrology and Earth System Sciences. Vol. 24(7), pp. 3643-3661.
Abstract: Remote sensing imagery can provide snapshots of rapidly changing land surface variables, e.g. evapotranspiration (ET), land surface temperature (Ts), net radiation (Rn), soil moisture (-), and gross primary productivity (GPP), for the time of sensor overpass. However, discontinuous data acquisitions limit the applicability of remote sensing for water resources and ecosystem management. Methods to interpolate between remote sensing snapshot data and to upscale them from an instantaneous to a daily timescale are needed. We developed a dynamic soil-vegetation-atmosphere transfer model to interpolate land surface state variables that change rapidly between remote sensing observations. The "Soil-Vegetation, Energy, water, and CO2 traNsfer" (SVEN) model, which combines the snapshot version of the remote sensing Priestley-Taylor Jet Propulsion Laboratory ET model and light use efficiency GPP models, now incorporates a dynamic component for the ground heat flux based on the "force-restore" method and a water balance "bucket" model to estimate and canopy wetness at a half-hourly time step. A case study was conducted to demonstrate the method using optical and thermal data from an unmanned aerial system at a willow plantation flux site (Risoe, Denmark). Based on model parameter calibration with the snapshots of land surface variables at the time of flight, SVEN interpolated UAS-based snapshots to continuous records of Ts, Rn , ET, and GPP for the 2016 growing season with forcing from continuous climatic data and the normalized difference vegetation index (NDVI). Validation with eddy covariance and other in situ observations indicates that SVEN can estimate daily land surface fluxes between remote sensing acquisitions with normalized root mean square deviations of the simulated daily Ts, Rn , LE, and GPP of 11.77 %, 6.65 %, 19.53 %, 14.77 %, and 12.97% respectively. In this deciduous tree plantation, this study demonstrates that temporally sparse optical and thermal remote sensing observations can be used to calibrate soil and vegetation parameters of a simple land surface modelling scheme to estimate "lowpersistence" or rapidly changing land surface variables with the use of few forcing variables. This approach can also be applied with remotely-sensed data from other platforms to fill temporal gaps, e.g. cloud-induced data gaps in satellite observations.
BibTeX:
@article{Wang2020,
  author = {Wang, Sheng and Garcia, Monica and Ibrom, Andreas and Bauer-Gottwein, Peter},
  title = {Temporal interpolation of land surface fluxes derived from remote sensing - Results with an unmanned aerial system},
  journal = {Hydrology and Earth System Sciences},
  year = {2020},
  volume = {24},
  number = {7},
  pages = {3643--3661},
  doi = {10.5194/hess-24-3643-2020}
}
Watson AJ, Schuster U, Shutler JD, Holding T, Ashton IGC, Landschützer P, Woolf DK and Goddijn-Murphy L (2020), "Revised estimates of ocean-atmosphere CO2 flux are consistent with ocean carbon inventory", Nature Communications., dec, 2020. Vol. 11(1), pp. 4422.
BibTeX:
@article{Watson2020,
  author = {Watson, Andrew J. and Schuster, Ute and Shutler, Jamie D. and Holding, Thomas and Ashton, Ian G. C. and Landschützer, Peter and Woolf, David K. and Goddijn-Murphy, Lonneke},
  title = {Revised estimates of ocean-atmosphere CO2 flux are consistent with ocean carbon inventory},
  journal = {Nature Communications},
  year = {2020},
  volume = {11},
  number = {1},
  pages = {4422},
  url = {http://www.nature.com/articles/s41467-020-18203-3},
  doi = {10.1038/s41467-020-18203-3}
}
Westergaard-Nielsen A, Balstr m T, Treier UA, Normand S and Elberling B (2020), "Estimating meltwater retention and associated nitrate redistribution during snowmelt in an Arctic tundra landscape", Environmental Research Letters. Vol. 15(3) IOP Publishing.
Abstract: Nitrogen availability in Arctic ecosystems is a key driver for biological activity, including plant, growth and thereby directly linked to the greening of the Arctic. Here, we model the redistribution of meltwater following spring snowmelt as well as the accumulation of meltwater and dissolved nitrate at landscape scale. By combining snow mapping with unmanned aerial systems, snow chemistry, and hydrological modelling, we argue that the majority of nitrate in the snowpack is flushed out of the landscape due to the limited storage capacity of meltwater in the early growing season frozen soil. We illustrate how landscape micro-topography is a crucial parameter to quantify storage capacity of meltwater at landscape scale and thereby the associated pool of soluble compounds such as nitrate. This pool will be available for plants and may be important for plant diversity and growth rates in the wettest part of the landscape. This study illustrates that the evenly distributed nitrate input during the Arctic winter may be redistributed during the initial snowmelt and lead to marked differences in biologically available nitrate at the onset of the growing season, but also that the majority of deposited nitrate in snow is lost from the terrestrial to the aquatic environment during snowmelt.
BibTeX:
@article{WestergaardNielsen2020,
  author = {Westergaard-Nielsen, Andreas and Balstr m, Thomas and Treier, Urs A and Normand, Signe and Elberling, Bo},
  title = {Estimating meltwater retention and associated nitrate redistribution during snowmelt in an Arctic tundra landscape},
  journal = {Environmental Research Letters},
  publisher = {IOP Publishing},
  year = {2020},
  volume = {15},
  number = {3},
  doi = {10.1088/1748-9326/ab57b1}
}
Wester-Larsen L, Kramshøj M, Albers CN and Rinnan R (2020), "Biogenic Volatile Organic Compounds in Arctic Soil: A Field Study of Concentrations and Variability With Vegetation Cover", Journal of Geophysical Research: Biogeosciences. Vol. 125(7), pp. 1-15.
Abstract: Soil biogenic volatile organic compounds (sBVOCs) contribute to ecosystem emissions and play an important role in the soil ecosystem. Most previous studies on sBVOCs have looked at emissions from excavated soil in the laboratory or in situ emissions from areas with bare soil, using chambers. So far, however, the actual BVOC concentrations in the soil have rarely been considered. Herein, we sought to explore the relationships between the vegetation cover in a low Arctic heath ecosystem in Western Greenland and the BVOC concentration in the soil below. In situ measurements were performed at 15-cm depth in areas dominated by Cassiope tetragona, Empetrum nigrum, Salix glauca, and Betula nana and along a 36-m-long transect with mixed vegetation cover during the growing seasons of 2015–2017. sBVOC concentrations varied between the different vegetation covers, with higher concentrations below Cassiope and Betula compared to Empetrum. Furthermore, sBVOC concentrations differed along the transect, and this variation was also partly related to differences in the vegetation cover. Moreover, we demonstrate that installation of a soil probe, for sampling soil air, changes the composition and magnitude of sBVOCs up to 1 day after the installation.
BibTeX:
@article{WesterLarsen2020,
  author = {Wester-Larsen, Lærke and Kramshøj, Magnus and Albers, Christian N and Rinnan, Riikka},
  title = {Biogenic Volatile Organic Compounds in Arctic Soil: A Field Study of Concentrations and Variability With Vegetation Cover},
  journal = {Journal of Geophysical Research: Biogeosciences},
  year = {2020},
  volume = {125},
  number = {7},
  pages = {1--15},
  doi = {10.1029/2019JG005551}
}
Wiekenkamp I, Huisman JA, Bogena HR and Vereecken H (2020), "Effects of deforestation on water flow in the vadose zone", Water (Switzerland). Vol. 12(1)
Abstract: The effects of land use change on the occurrence and frequency of preferential flow (fast water flow through a small fraction of the pore space) and piston flow (slower water flow through a large fraction of the pore space) are still not fully understood. In this study, we used a five year high resolution soil moisture monitoring dataset in combination with a response time analysis to identify factors that control preferential and piston flow before and after partial deforestation in a small headwater catchment. The sensor response times at 5, 20 and 50 cm depths were classified into one of four classes: (1) non-sequential preferential flow, (2) velocity based preferential flow, (3) sequential (piston) flow, and (4) no response. The results of this analysis showed that partial deforestation increased sequential flow occurrence and decreased the occurrence of no flow in the deforested area. Similar precipitation conditions (total precipitation) after deforestation caused more sequential flow in the deforested area, which was attributed to higher antecedent moisture conditions and the lack of interception. At the same time, an increase in preferential flow occurrence was also observed for events with identical total precipitation. However, as the events in the treatment period (after deforestation) generally had lower total, maximum, and mean precipitation, this effect was not observed in the overall occurrence of preferential flow. The results of this analysis demonstrate that the combination of a sensor response time analysis and a soil moisture dataset that includes pre-and post-deforestation conditions can offer new insights in preferential and sequential flow conditions after land use change.
BibTeX:
@article{Wiekenkamp2020,
  author = {Wiekenkamp, Inge and Huisman, Johan Alexander and Bogena, Heye Reemt and Vereecken, Harry},
  title = {Effects of deforestation on water flow in the vadose zone},
  journal = {Water (Switzerland)},
  year = {2020},
  volume = {12},
  number = {1},
  doi = {10.3390/w12010035}
}
Wigneron JP, Fan L, Ciais P, Bastos A, Brandt M, Chave J, Saatchi S, Baccini A and Fensholt R (2020), "Tropical forests did not recover from the strong 2015–2016 El Niño event", Science Advances., feb, 2020. Vol. 6(6), pp. eaay4603. American Association for the Advancement of Science (AAAS).
Abstract: Severe drought and extreme heat associated with the 2015–2016 El Niño event have led to large carbon emissions from the tropical vegetation to the atmosphere. With the return to normal climatic conditions in 2017, tropical forest aboveground carbon (AGC) stocks are expected to partly recover due to increased productivity, but the intensity and spatial distribution of this recovery are unknown. We used low-frequency microwave satellite data (L-VOD) to feature precise monitoring of AGC changes and show that the AGC recovery of tropical ecosystems was slow and that by the end of 2017, AGC had not reached predrought levels of 2014. From 2014 to 2017, tropical AGC stocks decreased by 1.31.51.2 Pg C due to persistent AGC losses in Africa (âˆ'0.9âˆ'0.8âˆ'1.1 Pg C) and America (âˆ'0.5âˆ'0.4âˆ'0.6 Pg C). Pantropically, drylands recovered their carbon stocks to pre–El Niño levels, but African and American humid forests did not, suggesting carryover effects from enhanced forest mortality.
BibTeX:
@article{Wigneron2020,
  author = {Wigneron, Jean Pierre and Fan, Lei and Ciais, Philippe and Bastos, Ana and Brandt, Martin and Chave, Jérome and Saatchi, Sassan and Baccini, Alessandro and Fensholt, Rasmus},
  title = {Tropical forests did not recover from the strong 2015–2016 El Niño event},
  journal = {Science Advances},
  publisher = {American Association for the Advancement of Science (AAAS)},
  year = {2020},
  volume = {6},
  number = {6},
  pages = {eaay4603},
  doi = {10.1126/sciadv.aay4603}
}
Wimart-Rousseau C, Lajaunie-Salla K, Marrec P, Wagener T, Raimbault P, Lagadec V, Lafont M, Garcia N, Diaz F, Pinazo C, Yohia C, Garcia F, Xueref-Remy I, Blanc P-E, Armengaud A and Lefèvre D (2020), "Temporal variability of the carbonate system and air-sea CO2 exchanges in a Mediterranean human-impacted coastal site", Estuarine, Coastal and Shelf Science., may, 2020. Vol. 236, pp. 106641.
BibTeX:
@article{WimartRousseau2020,
  author = {Wimart-Rousseau, Cathy and Lajaunie-Salla, Katixa and Marrec, Pierre and Wagener, Thibaut and Raimbault, Patrick and Lagadec, Véronique and Lafont, Michel and Garcia, Nicole and Diaz, Frédéric and Pinazo, Christel and Yohia, Christophe and Garcia, Fabrice and Xueref-Remy, Irène and Blanc, Pierre-Eric and Armengaud, Alexandre and Lefèvre, Dominique},
  title = {Temporal variability of the carbonate system and air-sea CO2 exchanges in a Mediterranean human-impacted coastal site},
  journal = {Estuarine, Coastal and Shelf Science},
  year = {2020},
  volume = {236},
  pages = {106641},
  url = {https://linkinghub.elsevier.com/retrieve/pii/S0272771419305542},
  doi = {10.1016/j.ecss.2020.106641}
}
Wintjen P, Ammann C, Schrader F and Brümmer C (2020), "Correcting high-frequency losses of reactive nitrogen flux measurements", Atmospheric Measurement Techniques. Vol. 13(6), pp. 2923-2948.
Abstract: Flux measurements of reactive nitrogen compounds are of increasing importance to assess the impact of unintended emissions on sensitive ecosystems and to evaluate the efficiency of mitigation strategies. Therefore, it is necessary to determine the exchange of reactive nitrogen gases with the highest possible accuracy. This study gives insight into the performance of flux correction methods and their usability for reactive nitrogen gases. The eddy-covariance (EC) technique is today widely used in experimental field studies to measure land surface-atmosphere exchange of a variety of trace gases. In recent years, applying the EC technique to reactive nitrogen compounds has become more important since atmospheric nitrogen deposition influences the productivity and biodiversity of (semi)natural ecosystems and their carbon dioxide (CO2) exchange. Fluxes, which are calculated by EC, have to be corrected for setup-specific effects like attenuation in the high-frequency range. However, common methods for correcting such flux losses are mainly optimized for inert greenhouse gases like CO2 and methane or water vapor. In this study, we applied a selection of correction methods to measurements of total reactive nitrogen ($$Nr) conducted in different ecosystems using the Total Reactive Atmospheric Nitrogen Converter (TRANC) coupled to a chemiluminescence detector (CLD). Average flux losses calculated by methods using measured cospectra and ogives were approximately 26 %-38% for a seminatural peatland and about 16 %-22% for a mixed forest. The investigation of the different methods showed that damping factors calculated with measured heat and gas flux cospectra using an empirical spectral transfer function were most reliable. Flux losses of 6Nr with this method were on the upper end of the median damping range, i.e., 38% for the peatland site and 22% for the forest site. Using modified Kaimal cospectra for damping estimation worked well for the forest site but underestimated damping for the peatland site by about 12 %. Correction factors of methods based on power spectra or on site-specific and instrumental parameters were mostly below 10 %. Power spectra of $$Nr were heavily affected-likely by white noise-and deviated substantially at lower frequencies from the respective temperature (power) spectra. Our study supports the use of an empirical method for estimating flux losses of 6Nr or any reactive nitrogen compound and the use of locally measured cospectra.
BibTeX:
@article{Wintjen2020,
  author = {Wintjen, Pascal and Ammann, Christof and Schrader, Frederik and Brümmer, Christian},
  title = {Correcting high-frequency losses of reactive nitrogen flux measurements},
  journal = {Atmospheric Measurement Techniques},
  year = {2020},
  volume = {13},
  number = {6},
  pages = {2923--2948},
  doi = {10.5194/amt-13-2923-2020}
}
Xiao M, Yu Z, Kong D, Gu X, Mammarella I, Montagnani L, Arain MA, Merbold L, Magliulo V, Lohila A, Buchmann N, Wolf S, Gharun M, Hörtnagl L, Beringer J and Gioli B (2020), "Stomatal response to decreased relative humidity constrains the acceleration of terrestrial evapotranspiration", Environmental Research Letters. Vol. 15(9)
Abstract: Terrestrial evapotranspiration (ET) is thermodynamically expected to increase with increasing atmospheric temperature; however, the actual constraints on the intensification of ET remain uncertain due to a lack of direct observations. Based on the FLUXNET2015 Dataset, we found that relative humidity (RH) is a more important driver of ET than temperature. While actual ET decrease at reduced RH, potential ET increases, consistently with the complementary relationship (CR) framework stating that the fraction of energy not used for actual ET is dissipated as increased sensible heat flux that in turn increases potential ET. In this study, we proposed an improved CR formulation requiring no parameter calibration and assessed its reliability in estimating ET both at site-level with the FLUXNET2015 Dataset and at basin-level. Using the ERA-Interim meteorological dataset for 1979-2017 to calculate ET, we found that the global terrestrial ET showed an increasing trend until 1998, while the trend started to decline afterwards. Such decline was largely associated with a reduced RH, inducing water stress conditions that triggered stomatal closure to conserve water. For the first time, this study quantified the global-scale implications of changes in RH on terrestrial ET, indicating that the temperature-driven acceleration of the terrestrial water cycle will be likely constrained by terrestrial vegetation feedbacks.
BibTeX:
@article{Xiao2020,
  author = {Xiao, Mingzhong and Yu, Zhongbo and Kong, Dongdong and Gu, Xihui and Mammarella, Ivan and Montagnani, Leonardo and Arain, M Altaf and Merbold, Lutz and Magliulo, Vincenzo and Lohila, Annalea and Buchmann, Nina and Wolf, Sebastian and Gharun, Mana and Hörtnagl, Lukas and Beringer, Jason and Gioli, Beniamino},
  title = {Stomatal response to decreased relative humidity constrains the acceleration of terrestrial evapotranspiration},
  journal = {Environmental Research Letters},
  year = {2020},
  volume = {15},
  number = {9},
  doi = {10.1088/1748-9326/ab9967}
}
Yang S, Zhang J, Zhang S, Wang J, Bai Y, Yao F and Guo H (2020), "The potential of remote sensing-based models on global water-use efficiency estimation: An evaluation and intercomparison of an ecosystem model (BESS) and algorithm (MODIS) using site level and upscaled eddy covariance data", Agricultural and Forest Meteorology., jun, 2020. Vol. 287 Elsevier B.V..
Abstract: Ecosystem water-use efficiency (WUE) is a critical indicator to investigate the interaction between the terrestrial ecosystem carbon and water cycles. WUE, estimated from gross primary productivity (GPP) and evapotranspiration (ET) based on remote sensing (RS)-based ecosystem models and algorithms (e.g., MODIS (MODerate resolution Imaging Spectroradiometer), BESS (Breathing Earth System Simulator)), have been used to quantify the spatiotemporal dynamics of WUE and its responses to environmental changes. However, few studies have assessed the ability of RS-based ecosystem models and algorithms on global WUE estimation. In this study, we evaluated 8-day and annual WUE from MODIS and BESS among different sites, land cover types and climate zones using the FLUXNET2015 dataset as reference, and conducted spatial intercomparisons of annual WUE between MODIS, BESS and an upscaled FLUXNET dataset (MTE). The site level evaluation results showed that BESS WUE had better performance than MODIS WUE at both 8-day and annual scales. Among different land cover types and climate zones, MODIS and BESS WUE performed unsatisfactorily, especially for MODIS WUE in open shrublands and savannas and for BESS WUE in closed shrublands. Additionally, both MODIS and BESS WUE performed poorly in the hot semi-arid climate zone. The spatial intercomparisons over 2001-2011 revealed that BESS WUE had similar spatial patterns of annual WUE and linear trends with MTE WUE over the globe, except at the high latitudes. However, the spatiotemporal patterns of MODIS WUE were different from those of MTE and BESS WUE, particularly in the (sub) tropical arid and semi-arid regions. Our evaluations results suggested that coupling carbon and water cycles into RS-based models could improve their performance on global WUE estimation. Moreover, the performance of MODIS and BESS on global WUE estimation should be further improved, especially for their performance on temporal variation and their performance at the (semi) arid areas and the high latitudes.
BibTeX:
@article{Yang2020,
  author = {Yang, Shanshan and Zhang, Jiahua and Zhang, Sha and Wang, Jingwen and Bai, Yun and Yao, Fengmei and Guo, Huadong},
  title = {The potential of remote sensing-based models on global water-use efficiency estimation: An evaluation and intercomparison of an ecosystem model (BESS) and algorithm (MODIS) using site level and upscaled eddy covariance data},
  journal = {Agricultural and Forest Meteorology},
  publisher = {Elsevier B.V.},
  year = {2020},
  volume = {287},
  doi = {10.1016/j.agrformet.2020.107959}
}
Yu L, Harris E, Henne S, Eggleston S, Steinbacher M, Emmenegger L, Zellweger C and Mohn J (2020), "The isotopic composition of atmospheric nitrous oxide observed at the high-altitude research station Jungfraujoch, Switzerland", Atmospheric Chemistry and Physics., jun, 2020. Vol. 20(11), pp. 6495-6519.
BibTeX:
@article{Yu2020,
  author = {Yu, Longfei and Harris, Eliza and Henne, Stephan and Eggleston, Sarah and Steinbacher, Martin and Emmenegger, Lukas and Zellweger, Christoph and Mohn, Joachim},
  title = {The isotopic composition of atmospheric nitrous oxide observed at the high-altitude research station Jungfraujoch, Switzerland},
  journal = {Atmospheric Chemistry and Physics},
  year = {2020},
  volume = {20},
  number = {11},
  pages = {6495--6519},
  url = {https://acp.copernicus.org/articles/20/6495/2020/},
  doi = {10.5194/acp-20-6495-2020}
}
Zhang H, Goll DS, Wang YP, Ciais P, Wieder WR, Abramoff R, Huang Y, Guenet B, Prescher AK, Viscarra Rossel RA, Barré P, Chenu C, Zhou G and Tang X (2020), "Microbial dynamics and soil physicochemical properties explain large-scale variations in soil organic carbon", Global Change Biology., feb, 2020. Vol. 26(4), pp. 2668-2685. Wiley.
Abstract: First-order organic matter decomposition models are used within most Earth System Models (ESMs) to project future global carbon cycling; these models have been criticized for not accurately representing mechanisms of soil organic carbon (SOC) stabilization and SOC response to climate change. New soil biogeochemical models have been developed, but their evaluation is limited to observations from laboratory incubations or few field experiments. Given the global scope of ESMs, a comprehensive evaluation of such models is essential using in situ observations of a wide range of SOC stocks over large spatial scales before their introduction to ESMs. In this study, we collected a set of in situ observations of SOC, litterfall and soil properties from 206 sites covering different forest and soil types in Europe and China. These data were used to calibrate the model MIMICS (The MIcrobial-MIneral Carbon Stabilization model), which we compared to the widely used first-order model CENTURY. We show that, compared to CENTURY, MIMICS more accurately estimates forest SOC concentrations and the sensitivities of SOC to variation in soil temperature, clay content and litter input. The ratios of microbial biomass to total SOC predicted by MIMICS agree well with independent observations from globally distributed forest sites. By testing different hypotheses regarding (using alternative process representations) the physicochemical constraints on SOC deprotection and microbial turnover in MIMICS, the errors of simulated SOC concentrations across sites were further decreased. We show that MIMICS can resolve the dominant mechanisms of SOC decomposition and stabilization and that it can be a reliable tool for predictions of terrestrial SOC dynamics under future climate change. It also allows us to evaluate at large scale the rapidly evolving understanding of SOC formation and stabilization based on laboratory and limited filed observation.
BibTeX:
@article{Zhang2020a,
  author = {Zhang, Haicheng and Goll, Daniel S and Wang, Ying Ping and Ciais, Philippe and Wieder, William R and Abramoff, Rose and Huang, Yuanyuan and Guenet, Bertrand and Prescher, Anne Katrin and Viscarra Rossel, Raphael A and Barré, Pierre and Chenu, Claire and Zhou, Guoyi and Tang, Xuli},
  title = {Microbial dynamics and soil physicochemical properties explain large-scale variations in soil organic carbon},
  journal = {Global Change Biology},
  publisher = {Wiley},
  year = {2020},
  volume = {26},
  number = {4},
  pages = {2668--2685},
  doi = {10.1111/gcb.14994}
}
Zhang H, Väliranta M, Piilo S, Amesbury MJ, Aquino‐López MA, Roland TP, Salminen‐Paatero S, Paatero J, Lohila A and Tuittila E (2020), "Decreased carbon accumulation feedback driven by climate‐induced drying of two southern boreal bogs over recent centuries", Global Change Biology., feb, 2020. Vol. 26(4), pp. 2435-2448. Wiley.
Abstract: pNorthern boreal peatlands are important ecosystems in modulating global biogeochemical cycles, yet their biological communities and related carbon dynamics are highly sensitive to changes in climate. Despite this, the strength and recent direction of these feedbacks are still unclear. The response of boreal peatlands to climate warming has received relatively little attention compared with other northern peatland types, despite forming a large northern hemisphere‐wide ecosystem. Here we studied the response of two ombrotrophic boreal peatlands to climate variability over the last ic/i. 200 years for which local meteorological data are available. We used remains from plants and testate amoebae to study historical changes in peatland biological communities. These data were supplemented by peat property (bulk density, carbon and nitrogen content), sup14/supC, sup210/supPb and sup137/supCs analyses and were used to infer changes in peatland hydrology and carbon dynamics. In total, six peat cores, three per study site, were studied that represent different microhabitats: low hummock, high lawn and low lawn. The data show a consistent drying trend over recent centuries, represented mainly as a change from wet habitat iSphagnum/i spp. to dry habitat iS. fuscum/i. Summer temperature and precipitation appeared to be important drivers shaping peatland community and surface moisture conditions. Data from the driest microhabitat studied, low hummock, revealed a clear and strong negative linear correlation (Rsup2/sup = 0.5031, ip/i 0.001) between carbon accumulation rate and peat surface moisture conditions: under dry conditions, less carbon was accumulated. This suggests that at the dry end of the moisture gradient, availability of water regulates carbon accumulation. It can be further linked to the decreased abundance of mixotrophic testate amoebae under drier conditions (Rsup2/sup = 0.4207, ip/i 0.001). Our study implies that if effective precipitation decreases in the future, the carbon uptake capacity of boreal bogs may be threatened./p
BibTeX:
@article{Zhang2020,
  author = {Zhang, Hui and Väliranta, Minna and Piilo, Sanna and Amesbury, Matthew J and Aquino‐López, Marco A and Roland, Thomas P and Salminen‐Paatero, Susanna and Paatero, Jussi and Lohila, Annalea and Tuittila, Eeva‐Stiina},
  title = {Decreased carbon accumulation feedback driven by climate‐induced drying of two southern boreal bogs over recent centuries},
  journal = {Global Change Biology},
  publisher = {Wiley},
  year = {2020},
  volume = {26},
  number = {4},
  pages = {2435--2448},
  doi = {10.1111/gcb.15005}
}
Zhang W, Yu G, Chen Z, Zhang L, Wang Q, Zhang Y, He H, Han L, Chen S, Han S, Li Y, Sha L, Shi P, Wang H, Wang Y, Xiang W, Yan J, Zhang Y, Zona D, Arain MA, Maximov T, Oechel W and Kosugi Y (2020), "Attribute parameter characterized the seasonal variation of gross primary productivity (αGPP): Spatiotemporal variation and influencing factors", Agricultural and Forest Meteorology., jan, 2020. Vol. 280 Elsevier B.V..
Abstract: The seasonal dynamic of gross primary productivity (GPP) has influences on the annual GPP (AGPP) of the terrestrial ecosystem. However, the spatiotemporal variation of the seasonal dynamic of GPP and its effects on spatial and temporal variations of AGPP are still poorly addressed. In this study, we developed a parameter, αGPP, defined as the ratio of mean daily GPP (GPPmean) to the maximum daily GPP (GPPmax) during the growing season, to analyze the seasonal dynamic of GPP based on Weibull function. The αGPP was a comprehensive parameter characterizing the shape, scale, and location of the seasonal dynamic curve of GPP. We calculated αGPP based on the data of GPP for 942 site-years from 115 flux sites in the Northern Hemisphere, and analyzed the spatiotemporal variation and influencing factors of the αGPP. We found that the αGPP of terrestrial ecosystems in the Northern Hemisphere ranged from 0.47 to 0.85, with an average of 0.62 ± 0.06. The αGPP varied significantly both among different climatic zones and different ecosystem types. The αGPP was stable on the interannual scale, while decreased as latitude increased, which was consistent across different ecosystem types. The spatial pattern of the seasonal dynamic of astronomical radiation was the dominating factor of the spatial pattern of αGPP, that was, the spatial pattern of the seasonal dynamic of astronomical radiation determined that of the seasonal dynamic of GPP by controlling that of seasonal dynamics of total radiation and temperature. In addition, we assessed the spatial variation of AGPP preliminarily based on αGPP and other seasonal dynamic parameters of GPP, indicating that the understanding of the spatiotemporal variation of αGPP could provide a new approach for studying the spatial and temporal variations of AGPP and estimating AGPP based on the seasonal dynamic of GPP.
BibTeX:
@article{Zhang2020b,
  author = {Zhang, Weikang and Yu, Guirui and Chen, Zhi and Zhang, Leiming and Wang, Qiufeng and Zhang, Yangjian and He, Honglin and Han, Lang and Chen, Shiping and Han, Shijie and Li, Yingnian and Sha, Liqing and Shi, Peili and Wang, Huimin and Wang, Yanfen and Xiang, Wenhua and Yan, Junhua and Zhang, Yiping and Zona, Donatella and Arain, M. Altaf and Maximov, Trofim and Oechel, Walter and Kosugi, Yoshiko},
  title = {Attribute parameter characterized the seasonal variation of gross primary productivity (αGPP): Spatiotemporal variation and influencing factors},
  journal = {Agricultural and Forest Meteorology},
  publisher = {Elsevier B.V.},
  year = {2020},
  volume = {280},
  doi = {10.1016/j.agrformet.2019.107774}
}
Zhang Y, Bastos A, Maignan F, Goll D, Boucher O, Li L, Cescatti A, Vuichard N, Chen X, Ammann C, Altaf Arain M, Andrew Black T, Chojnicki B, Kato T, Mammarella I, Montagnani L, Roupsard O, Sanz MJ, Siebicke L, Urbaniak M, Primo Vaccari F, Wohlfahrt G, Woodgate W and Ciais P (2020), "Modeling the impacts of diffuse light fraction on photosynthesis in ORCHIDEE (v5453) land surface model", Geoscientific Model Development. Vol. 13(11), pp. 5401-5423.
Abstract: Aerosol- and cloud-induced changes in diffuse light have important impacts on the global land carbon cycle, as they alter light distribution and photosynthesis in vegetation canopies. However, this effect remains poorly represented or evaluated in current land surface models. Here, we add a light partitioning module and a new canopy light transmission module to the ORCHIDEE (Organising Carbon and Hydrology In Dynamic Ecosystems) land surface model (trunk version, v5453) and use the revised model, ORCHIDEE- DF, to estimate the fraction of diffuse light and its effect on gross primary production (GPP) in a multilayer canopy. We evaluate the new parameterizations using flux observations from 159 eddy covariance sites over the globe. Our results show that, compared with the original model, ORCHIDEE-DF improves the GPP simulation under sunny conditions and captures the observed higher photosynthesis under cloudier conditions in most plant functional types (PFTs). Our results also indicate that the larger GPP under cloudy conditions compared with sunny conditions is mainly driven by increased diffuse light in the morning and in the afternoon as well as by a decreased vapor pressure deficit (VPD) and decreased air temperature at midday. The observations show that the strongest positive effects of diffuse light on photosynthesis are found in the range from 5 to 20 °C and at a VPDtextless1 kPa. This effect is found to decrease when the VPD becomes too large or the temperature falls outside of the abovementioned range, which is likely due to the increasing stomatal resistance to leaf CO2 uptake. ORCHIDEE-DF underestimates the diffuse light effect at low temperature in all PFTs and overestimates this effect at high temperature and at a high VPD in grasslands and croplands. The new model has the potential to better investigate the impact of large-scale aerosol changes and long-term changes in cloudiness on the terrestrial carbon budget, both in the historical period and in the context of future air quality policies and/or climate engineering.
BibTeX:
@article{Zhang2020e,
  author = {Zhang, Yuan and Bastos, Ana and Maignan, Fabienne and Goll, Daniel and Boucher, Olivier and Li, Laurent and Cescatti, Alessandro and Vuichard, Nicolas and Chen, Xiuzhi and Ammann, Christof and Altaf Arain, M and Andrew Black, T and Chojnicki, Bogdan and Kato, Tomomichi and Mammarella, Ivan and Montagnani, Leonardo and Roupsard, Olivier and Sanz, Maria J and Siebicke, Lukas and Urbaniak, Marek and Primo Vaccari, Francesco and Wohlfahrt, Georg and Woodgate, Will and Ciais, Philippe},
  title = {Modeling the impacts of diffuse light fraction on photosynthesis in ORCHIDEE (v5453) land surface model},
  journal = {Geoscientific Model Development},
  year = {2020},
  volume = {13},
  number = {11},
  pages = {5401--5423},
  doi = {10.5194/gmd-13-5401-2020}
}
Zhang Y, Commane R, Zhou S, Williams AP and Gentine P (2020), "Light limitation regulates the response of autumn terrestrial carbon uptake to warming", Nature Climate Change., aug, 2020. Nature Research.
Abstract: Global warming is projected to shift the phenology and increase the productivity of northern ecosystems1–6. Both changes will further feed back to climate through biophysical and biogeochemical processes and are critical for future prediction7,8. However, it remains unclear whether warming and the extended growing season, especially in autumn, would lead to increased net ecosystem carbon uptake9,10. Here we analyse satellite observations, field measurements and model simulations and show a prevalent radiation limitation on carbon uptake in northern ecosystems, especially in autumn. By comparing the start and end of the growing season estimated from vegetation indices and from solar-induced chlorophyll fluorescence (a proxy for gross primary production11,12 (GPP)), we find a greater change in greenness-based start and end of season than that from GPP, mostly caused by the radiation limitation on photosynthesis. This radiation limitation explains the contrasting responses of autumn net carbon exchanges to warming, using both eddy covariance measurements and model simulations from Coupled Model Intercomparison Project Phase 5. Regions with weak radiation limitation benefit more from warming and enhanced vegetation greenness in autumn, where GPP increases can outweigh the warming-induced respiration carbon losses. With continued warming, radiation limitation will increase and exert a strong upper bound on northern ecosystems to act as carbon sinks.
BibTeX:
@article{Zhang2020c,
  author = {Zhang, Yao and Commane, Róisín and Zhou, Sha and Williams, A. Park and Gentine, Pierre},
  title = {Light limitation regulates the response of autumn terrestrial carbon uptake to warming},
  journal = {Nature Climate Change},
  publisher = {Nature Research},
  year = {2020},
  doi = {10.1038/s41558-020-0806-0}
}
Zhang Z, Zhang Y, Porcar-Castell A, Joiner J, Guanter L, Yang X, Migliavacca M, Ju W, Sun Z, Chen S, Martini D, Zhang Q, Li Z, Cleverly J, Wang H and Goulas Y (2020), "Reduction of structural impacts and distinction of photosynthetic pathways in a global estimation of GPP from space-borne solar-induced chlorophyll fluorescence", Remote Sensing of Environment., apr, 2020. Vol. 240 Elsevier Inc..
Abstract: Quantifying global photosynthesis remains a challenge due to a lack of accurate remote sensing proxies. Solar-induced chlorophyll fluorescence (SIF) has been shown to be a good indicator of photosynthetic activity across various spatial scales. However, a global and spatially challenging estimate of terrestrial gross primary production (GPP) based on satellite SIF remains unresolved due to the confounding effects of species-specific physical and physiological traits and external factors, such as canopy structure or photosynthetic pathway (C3 or C4). Here we analyze an ensemble of far-red SIF data from OCO-2 satellite and ground observations at multiple sites, using the spectral invariant theory to reduce the effects of canopy structure and to retrieve a structure-corrected total canopy SIF emission (SIFtotal). We find that the relationships between observed canopy-leaving SIF and ecosystem GPP vary significantly among biomes. In contrast, the relationships between SIFtotal and GPP converge around two unique models, one for C3 and one for C4 plants. We show that the two single empirical models can be used to globally scale satellite SIF observations to terrestrial GPP. We obtain an independent estimate of global terrestrial GPP of 129.56 ± 6.54 PgC/year for the 2015–2017 period, which is consistent with the state-of-the-art data- and process-oriented models. The new GPP product shows improved sensitivity to previously undetected ‘hotspots' of productivity, being able to resolve the double-peak in GPP due to rotational cropping systems. We suggest that the direct scheme to estimate GPP presented here, which is based on satellite SIF, may open up new possibilities to resolve the dynamics of global terrestrial GPP across space and time.
BibTeX:
@article{Zhang2020d,
  author = {Zhang, Zhaoying and Zhang, Yongguang and Porcar-Castell, Albert and Joiner, Joanna and Guanter, Luis and Yang, Xi and Migliavacca, Mirco and Ju, Weimin and Sun, Zhigang and Chen, Shiping and Martini, David and Zhang, Qian and Li, Zhaohui and Cleverly, James and Wang, Hezhou and Goulas, Yves},
  title = {Reduction of structural impacts and distinction of photosynthetic pathways in a global estimation of GPP from space-borne solar-induced chlorophyll fluorescence},
  journal = {Remote Sensing of Environment},
  publisher = {Elsevier Inc.},
  year = {2020},
  volume = {240},
  doi = {10.1016/j.rse.2020.111722}
}
Zweifel R, Etzold S, Sterck F, Gessler A, Anfodillo T, Mencuccini M, von Arx G, Lazzarin M, Haeni M, Feichtinger L, Meusburger K, Knuesel S, Walthert L, Salmon Y, Bose AK, Schoenbeck L, Hug C, De Girardi N, Giuggiola A, Schaub M and Rigling A (2020), "Determinants of legacy effects in pine trees – implications from an irrigation‐stop experiment", New Phytologist., aug, 2020. Vol. 227(4), pp. 1081-1096.
BibTeX:
@article{Zweifel2020,
  author = {Zweifel, Roman and Etzold, Sophia and Sterck, Frank and Gessler, Arthur and Anfodillo, Tommaso and Mencuccini, Maurizio and von Arx, Georg and Lazzarin, Martina and Haeni, Matthias and Feichtinger, Linda and Meusburger, Katrin and Knuesel, Simon and Walthert, Lorenz and Salmon, Yann and Bose, Arun K. and Schoenbeck, Leonie and Hug, Christian and De Girardi, Nicolas and Giuggiola, Arnaud and Schaub, Marcus and Rigling, Andreas},
  title = {Determinants of legacy effects in pine trees – implications from an irrigation‐stop experiment},
  journal = {New Phytologist},
  year = {2020},
  volume = {227},
  number = {4},
  pages = {1081--1096},
  url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/nph.16582},
  doi = {10.1111/nph.16582}
}
Acosta M, Dušek J, Chamizo S, Serrano-Ortiz P and Pavelka M (2019), "Autumnal fluxes of CH4 and CO2 from Mediterranean reed wetland based on eddy covariance and chamber methods", Catena., dec, 2019. Vol. 183, pp. 104191. Elsevier BV.
Abstract: Atmospheric methane (CH4) and carbon dioxide (CO2) concentration have been increasing during the last several centuries due to changes in agricultural practices and other anthropogenic activities. Both greenhouse gases (GHGs), have a significant impact on the Earth's radiative balance. GHG effluxes of CH4 and CO2 were measured in a warm Mediterranean wetland in south of Spain. The dominant vegetation cover at the site was by common reed (Phragmites australis) and the measurements were done during short measurement campaign in early autumn 2015. Gas-flux measurements were carried out applying two methods, the eddy covariance (EC) technique and the chamber method (CM). These two methods representing different ecosystem subsets, with EC representing the plant/ecosystem subset and CM representing the water/soil subset. In our measurement campaigns using CM, CH4 emissions ranged from 7.2 to 17.7 mg CH4-C mâˆ'2 dâˆ'1 and CO2 emissions from 0.53 to 1.27 g CO2-C mâˆ'2 dâˆ'1. When using EC, the average fluxes of CH4 and CO2 were 31.4 mg CH4-C mâˆ'2 dâˆ'1 and 1.32 g CO2-C mâˆ'2 dâˆ'1, respectively. Relationships between gas fluxes (CO2 and CH4) measured by the EC method were quite closely correlated with photosynthetically active solar radiation. Our results showed higher CO2 carbon released from the water/soil ecosystem subset in comparison to plants subset. On the other hand, the estimated CH4 carbon balance for the plant/ecosystem subset was about twice that of the water/soil ecosystem subset. Overall, we showed that EC and CM methods cover different areas making EC advantageous for integrated measurements over larger areas, while the CM approach is suitable for local and spatially well constrained flux measurements. Hence, EC and CM methods should be seen as complementary rather than fully comparable methods.
BibTeX:
@article{Acosta2019,
  author = {Acosta, Manuel and Dušek, JiÅ™í and Chamizo, S and Serrano-Ortiz, Penelope and Pavelka, Marian},
  title = {Autumnal fluxes of CH4 and CO2 from Mediterranean reed wetland based on eddy covariance and chamber methods},
  journal = {Catena},
  publisher = {Elsevier BV},
  year = {2019},
  volume = {183},
  pages = {104191},
  doi = {10.1016/j.catena.2019.104191}
}
Agustí-Panareda A, Diamantakis M, Massart S, Chevallier F, Muñoz-Sabater J, Barré J, Curcoll R, Engelen R, Langerock B, Law RM, Loh Z, Morguí JA, Parrington M, Peuch VH, Ramonet M, Roehl C, Vermeulen AT, Warneke T and Wunch D (2019), "Modelling CO2 weather-why horizontal resolution matters", Atmospheric Chemistry and Physics., jun, 2019. Vol. 19(11), pp. 7347-7376.
Abstract: Climate change mitigation efforts require information on the current greenhouse gas atmospheric concentrations and their sources and sinks. Carbon dioxide (CO2) is the most abundant anthropogenic greenhouse gas. Its variability in the atmosphere is modulated by the synergy between weather and CO2 surface fluxes, often referred to as CO2 weather. It is interpreted with the help of global or regional numerical transport models, with horizontal resolutions ranging from a few hundreds of kilometres to a few kilometres. Changes in the model horizontal resolution affect not only atmospheric transport but also the representation of topography and surface CO2 fluxes. This paper assesses the impact of horizontal resolution on the simulated atmospheric CO2 variability with a numerical weather prediction model. The simulations are performed using the Copernicus Atmosphere Monitoring Service (CAMS) CO2 forecasting system at different resolutions from 9 to 80 km and are evaluated using in situ atmospheric surface measurements and atmospheric column-mean observations of CO2, as well as radiosonde and SYNOP observations of the winds. The results indicate that both diurnal and day-to-day variability of atmospheric CO2 are generally better represented at high resolution, as shown by a reduction in the errors in simulated wind and CO2. Mountain stations display the largest improvements at high resolution as they directly benefit from the more realistic orography. In addition, the CO2 spatial gradients are generally improved with increasing resolution for both stations near the surface and those observing the total column, as the overall inter-station error is also reduced in magnitude. However, close to emission hotspots, the high resolution can also lead to a deterioration of the simulation skill, highlighting uncertainties in the high-resolution fluxes that are more diffuse at lower resolutions. We conclude that increasing horizontal resolution matters for modelling CO2 weather because it has the potential to bring together improvements in the surface representation of both winds and CO2 fluxes, as well as an expected reduction in numerical errors of transport. Modelling applications like atmospheric inversion systems to estimate surface fluxes will only be able to benefit fully from upgrades in horizontal resolution if the topography, winds and prior flux distribution are also upgraded accordingly. It is clear from the results that an additional increase in resolution might reduce errors even further. However, the horizontal resolution sensitivity tests indicate that the change in the CO2 and wind modelling error with resolution is not linear, making it difficult to quantify the improvement beyond the tested resolutions. Finally, we show that the high-resolution simulations are useful for the assessment of the small-scale variability of CO2 which cannot be represented in coarser-resolution models. These representativeness errors need to be considered when assimilating in situ data and high-resolution satellite data such as Greenhouse gases Observing Satellite (GOSAT), Orbiting Carbon Observatory-2 (OCO-2), the Chinese Carbon Dioxide Observation Satellite Mission (TanSat) and future missions such as the Geostationary Carbon Observatory (GeoCarb) and the Sentinel satellite constellation for CO2. For these reasons, the high-resolution CO2 simulations provided by the CAMS in real time can be useful to estimate such small-scale variability in real time, as well as providing boundary conditions for regional modelling studies and supporting field experiments.
BibTeX:
@article{Agusti-Panareda2019,
  author = {Agustí-Panareda, Anna and Diamantakis, Michail and Massart, Sébastien and Chevallier, Frédéric and Muñoz-Sabater, Joaquín and Barré, Jérôme and Curcoll, Roger and Engelen, Richard and Langerock, Bavo and Law, Rachel M and Loh, Zoë and Morguí, Josep Anton and Parrington, Mark and Peuch, Vincent Henri and Ramonet, Michel and Roehl, Coleen and Vermeulen, Alex T and Warneke, Thorsten and Wunch, Debra},
  title = {Modelling CO2 weather-why horizontal resolution matters},
  journal = {Atmospheric Chemistry and Physics},
  year = {2019},
  volume = {19},
  number = {11},
  pages = {7347--7376},
  url = {https://www.atmos-chem-phys.net/19/7347/2019/},
  doi = {10.5194/acp-19-7347-2019}
}
Alice Courtois E, Stahl C, Burban B, Van Den Berge J, Berveiller D, Bréchet L, Larned Soong J, Arriga N, Peñuelas J and August Janssens I (2019), "Automatic high-frequency measurements of full soil greenhouse gas fluxes in a tropical forest", Biogeosciences., feb, 2019. Vol. 16(3), pp. 785-796. Copernicus GmbH.
Abstract: Measuring in situ soil fluxes of carbon dioxide (CO 2 ), methane (CH 4 ), and nitrous oxide (N 2 O) continuously at high frequency requires appropriate technology. We tested the combination of a commercial automated soil CO 2 flux chamber system (LI-8100A) with a CH 4 and N 2 O analyzer (Picarro G2308) in a tropical rainforest for 4 months. A chamber closure time of 2 min was sufficient for a reliable estimation of CO 2 and CH 4 fluxes (100% and 98.5% of fluxes were above minimum detectable flux - MDF, respectively). This closure time was generally not suitable for a reliable estimation of the low N 2 O fluxes in this ecosystem but was sufficient for detecting rare major peak events. A closure time of 25 min was more appropriate for reliable estimation of most N 2 O fluxes (85.6% of measured fluxes are above MDF±0.002 nmolm -2 s -1 ). Our study highlights the importance of adjusted closure time for each gas.
BibTeX:
@article{AliceCourtois2019,
  author = {Alice Courtois, Elodie and Stahl, Clément and Burban, Benoit and Van Den Berge, Joke and Berveiller, Daniel and Bréchet, Laëtitia and Larned Soong, Jennifer and Arriga, Nicola and Peñuelas, Josep and August Janssens, Ivan},
  title = {Automatic high-frequency measurements of full soil greenhouse gas fluxes in a tropical forest},
  journal = {Biogeosciences},
  publisher = {Copernicus GmbH},
  year = {2019},
  volume = {16},
  number = {3},
  pages = {785--796},
  doi = {10.5194/bg-16-785-2019}
}
Alves M, Music B, Nadeau DF and Anctil F (2019), "Comparing the Performance of the Maximum Entropy Production Model With a Land Surface Scheme in Simulating Surface Energy Fluxes", Journal of Geophysical Research: Atmospheres., mar, 2019. Vol. 124(6), pp. 3279-3300. Blackwell Publishing Ltd.
Abstract: Hydrological projections under future climate change have been shown to be sensitive to the formulation of evapotranspiration. Many hydrological models still rely on empirical formulations of this flux, and hence do not take into account the surface energy budget. On the other hand, land surface schemes, which are used within the climate models to describe land hydrology and associated surface heat fluxes (SHF), rely on the energy conservation. Due to land surface schemes complexity, they are not suitable for integration in traditional hydrological models. A newly developed and relatively simple Maximum Entropy Production model, which operates under the constraint of energy conservation and allows for an appropriate partitioning of available energy into SHF, appears to be a good alternative for integration in hydrological models. However, the MEP's performances still need to be evaluated under various environmental conditions. This study aims to evaluate the SHF simulated by MEP using observations over a multiyear period from several carefully chosen snow-free sites located in low-latitude regions. Moreover, simulated fluxes were compared to those derived from the Canadian Land Surface Scheme (CLASS), which was run at the same sites. The analysis of simulated and observed fluxes associated with different water stress conditions suggests that the abilities of MEP and CLASS in estimating sensible and latent heat fluxes are comparable. It was also found that the MEP and CLASS fluxes are in a good agreement with observations. However, the simulated nocturnal fluxes show that both models are in less agreement with the observations.
BibTeX:
@article{Alves2019,
  author = {Alves, M. and Music, B. and Nadeau, D. F. and Anctil, F.},
  title = {Comparing the Performance of the Maximum Entropy Production Model With a Land Surface Scheme in Simulating Surface Energy Fluxes},
  journal = {Journal of Geophysical Research: Atmospheres},
  publisher = {Blackwell Publishing Ltd},
  year = {2019},
  volume = {124},
  number = {6},
  pages = {3279--3300},
  doi = {10.1029/2018JD029282}
}
Araujo M, Noriega C, Medeiros C, Lefèvre N, Ibánhez JSP, Flores Montes M, da Silva AC and Santos MdL (2019), "On the variability in the CO2 system and water productivity in the western tropical Atlantic off North and Northeast Brazil", Journal of Marine Systems., jan, 2019. Vol. 189, pp. 62-77. Elsevier BV.
Abstract: A high-resolution nutrient biochemistry and carbonate system surface synoptic data set from the N-NE Brazilian continental shelf was reanalyzed to fill a gap in the time series of the carbonate system in the region and to allow us to perform a historical analysis of its evolution in recent years. We used data collected from 7 oceanographic cruises (n = 852) undertaken between March 1995 and September 2001 during the Brazilian Program “REVIZEE” in the North (N) and Northeast (NE) Economical Exclusive Zones of Brazil. Measured temperature and salinity data, which exhibited strong fluctuations (25.5 °C – 29.5 °C and 13.2–37.4 units, respectively), showed significant differences between the N and NE campaigns. The concentrations of dissolved inorganic nitrogen (DIN), PO4âˆ' and SiO2âˆ' were higher in the N region than in the NE region, mainly due to fluvial transport, and nitrogen: phosphorus (N:P) ratios of 16 and oxygen supersaturation were observed within the Amazon plume. The concentrations of riverine nutrients in the N region support primary production occurring in the offshore plume area. The calculated total alkalinity (1031–2437 μmol kgâˆ'1) values showed strong spatial variations that were mainly associated with the Amazon plume. The calculated pCO2 values reached 423 μatm offshore in the NE region during boreal winter. The calculated sea-air CO2 fluxes (average: +0.3 ± 1.7 mmol mâˆ'2 dâˆ'1; range: âˆ'1.2 to +2.0 mmol mâˆ'2 dâˆ'1) showed spatial and temporal variations, with negative values (sink) in the region of the Amazon River plume and positive values (source) offshore in the NE region (4°S to 12°S). The variability in the sea-air CO2 fluxes in the N and NE regions was explained by variations in biological activity and the thermodynamic effect of temperature, respectively. The analysis of available data, complemented with those presented here, indicated that the surface water pCO2 values showed a positive temporal trend (+1.10 ± 0.2 μatm yrâˆ'1) in the NE region during the period of 1987–2010. This rate of increase is lower than that verified to have occurred in the atmosphere (+1.72 ± 0.01 μatm yrâˆ'1) during the same period.
BibTeX:
@article{Araujo2019,
  author = {Araujo, Moacyr and Noriega, Carlos and Medeiros, Carmen and Lefèvre, Nathalie and Ibánhez, J Severino P and Flores Montes, Manuel and da Silva, Alex Costa and Santos, Maria de Lourdes},
  title = {On the variability in the CO2 system and water productivity in the western tropical Atlantic off North and Northeast Brazil},
  journal = {Journal of Marine Systems},
  publisher = {Elsevier BV},
  year = {2019},
  volume = {189},
  pages = {62--77},
  doi = {10.1016/j.jmarsys.2018.09.008}
}
Ariza-Carricondo C, Di Mauro F, De Beeck MO, Roland M, Gielen B, Vitale D, Ceulemans R and Papale D (2019), "A comparison of different methods for assessing leaf area index in four canopy types", Central European Forestry Journal., jun, 2019. Vol. 65(2), pp. 67-80. Walter de Gruyter GmbH.
Abstract: The agreement of Leaf Area Index (LAI) assessments from three indirect methods, i.e. the LAI-2200 Plant Canopy Analyzer, the SS1 SunScan Canopy Analysis System and Digital Hemispherical Photography (DHP) was evaluated for four canopy types, i.e. a short rotation coppice plantation (SRC) with poplar, a Scots pine stand, a Pedunculate oak stand and a maize field. In the SRC and in the maize field, the indirect measurements were compared with direct measurements (litter fall and harvesting). In the low LAI range (0 to 2) the discrepancies of the SS1 were partly explained by the inability to properly account for clumping and the uncertainty of the ellipsoidal leaf angle distribution parameter. The higher values for SS1 in the medium (2 to 6) to high (6 to 8) ranges might be explained by gap fraction saturation for LAI-2200 and DHP above certain values. Wood area index-understood as the woody light-blocking elements from the canopy with respect to diameter growth-accounted for overestimation by all indirect methods when compared to direct methods in the SRC. The inter-comparison of the three indirect methods in the four canopy types showed a general agreement for all methods in the medium LAI range (2 to 6). LAI-2200 and DHP revealed the best agreement among the indirect methods along the entire range of LAI (0 to 8) in all canopy types. SS1 showed some discrepancies with the LAI-2200 and DHP at low (0 to 2) and high ranges of LAI (6 to 8).
BibTeX:
@article{Ariza-Carricondo2019,
  author = {Ariza-Carricondo, Cristina and Di Mauro, Francesca and De Beeck, Maarten Op and Roland, Marilyn and Gielen, Bert and Vitale, Domenico and Ceulemans, Reinhart and Papale, Dario},
  title = {A comparison of different methods for assessing leaf area index in four canopy types},
  journal = {Central European Forestry Journal},
  publisher = {Walter de Gruyter GmbH},
  year = {2019},
  volume = {65},
  number = {2},
  pages = {67--80},
  doi = {10.2478/forj-2019-0011}
}
Baeten L, Bruelheide H, van der Plas F, Kambach S, Ratcliffe S, Jucker T, Allan E, Ampoorter E, Barbaro L, Bastias CC, Bauhus J, Benavides R, Bonal D, Bouriaud O, Bussotti F, Carnol M, Castagneyrol B, Charbonnier Y, Chećko E, Coomes DA, Dahlgren J, Dawud SM, De Wandeler H, Domisch T, Finér L, Fischer M, Fotelli M, Gessler A, Grossiord C, Guyot V, Hättenschwiler S, Jactel H, Jaroszewicz B, Joly FX, Koricheva J, Lehtonen A, Müller S, Muys B, Nguyen D, Pollastrini M, Radoglou K, Raulund-Rasmussen K, Ruiz-Benito P, Selvi F, Stenlid J, Valladares F, Vesterdal L, Verheyen K, Wirth C, Zavala MA and Scherer-Lorenzen M (2019), "Identifying the tree species compositions that maximize ecosystem functioning in European forests", Journal of Applied Ecology., dec, 2019. Vol. 56(3), pp. 733-744. Wiley.
Abstract: Forest ecosystem functioning generally benefits from higher tree species richness, but variation within richness levels is typically large. This is mostly due to the contrasting performances of communities with different compositions. Evidence-based understanding of composition effects on forest productivity, as well as on multiple other functions will enable forest managers to focus on the selection of species that maximize functioning, rather than on diversity per se. We used a dataset of 30 ecosystem functions measured in stands with different species richness and composition in six European forest types. First, we quantified whether the compositions that maximize annual above-ground wood production (productivity) generally also fulfil the multiple other ecosystem functions (multifunctionality). Then, we quantified the species identity effects and strength of interspecific interactions to identify the “best” and “worst” species composition for multifunctionality. Finally, we evaluated the real-world frequency of occurrence of best and worst mixtures, using harmonized data from multiple national forest inventories. The most productive tree species combinations also tended to express relatively high multifunctionality, although we found a relatively wide range of compositions with high- or low-average multifunctionality for the same level of productivity. Monocultures were distributed among the highest as well as the lowest performing compositions. The variation in functioning between compositions was generally driven by differences in the performance of the component species and, to a lesser extent, by particular interspecific interactions. Finally, we found that the most frequent species compositions in inventory data were monospecific stands and that the most common compositions showed below-average multifunctionality and productivity. Synthesis and applications. Species identity and composition effects are essential to the development of high-performing production systems, for instance in forestry and agriculture. They therefore deserve great attention in the analysis and design of functional biodiversity studies if the aim is to inform ecosystem management. A management focus on tree productivity does not necessarily trade-off against other ecosystem functions; high productivity and multifunctionality can be combined with an informed selection of tree species and species combinations.
BibTeX:
@article{Baeten2019,
  author = {Baeten, Lander and Bruelheide, Helge and van der Plas, Fons and Kambach, Stephan and Ratcliffe, Sophia and Jucker, Tommaso and Allan, Eric and Ampoorter, Evy and Barbaro, Luc and Bastias, Cristina C and Bauhus, Jürgen and Benavides, Raquel and Bonal, Damien and Bouriaud, Olivier and Bussotti, Filippo and Carnol, Monique and Castagneyrol, Bastien and Charbonnier, Yohan and Chećko, Ewa and Coomes, David A and Dahlgren, Jonas and Dawud, Seid Muhie and De Wandeler, Hans and Domisch, Timo and Finér, Leena and Fischer, Markus and Fotelli, Mariangela and Gessler, Arthur and Grossiord, Charlotte and Guyot, Virginie and Hättenschwiler, Stephan and Jactel, Hervé and Jaroszewicz, Bogdan and Joly, François Xavier and Koricheva, Julia and Lehtonen, Aleksi and Müller, Sandra and Muys, Bart and Nguyen, Diem and Pollastrini, Martina and Radoglou, Kalliopi and Raulund-Rasmussen, Karsten and Ruiz-Benito, Paloma and Selvi, Federico and Stenlid, Jan and Valladares, Fernando and Vesterdal, Lars and Verheyen, Kris and Wirth, Christian and Zavala, Miguel A and Scherer-Lorenzen, Michael},
  editor = {Mori, Akira},
  title = {Identifying the tree species compositions that maximize ecosystem functioning in European forests},
  journal = {Journal of Applied Ecology},
  publisher = {Wiley},
  year = {2019},
  volume = {56},
  number = {3},
  pages = {733--744},
  doi = {10.1111/1365-2664.13308}
}
Balzarolo M, Valdameri N, Fu YH, Schepers L, Janssens IA and Campioli M (2019), "Different determinants of radiation use efficiency in cold and temperate forests", Global Ecology and Biogeography., aug, 2019. Vol. 28(11), pp. 1649-1667. Wiley.
Abstract: Aim: To verify which vegetation and environmental factors are the most important in determining the spatial and temporal variability of average and maximum values of radiation use efficiency (RUEann and RUEmax, respectively) of cold and temperate forests. Location: Forty-eight cold and temperate forests distributed across the Northern Hemisphere. Major taxa studied: Evergreen and deciduous trees. Time period: 2000–2011. Methods: We analysed the impact of 17 factors as potential determinants of mean RUE (at 8 days interval, annual and interannual level) and RUEmax (at annual and interannual level) in cold and temperate forests by using linear regression and random forests models. Results: Mean annual RUE (RUEann, c. 1.1 gC/MJ) and RUEmax (c. 0.8 gC/MJ) did not differ between cold and temperate forests. However, for cold forests, RUEann was affected by temperature-related variables, while for temperate forests RUEann was affected by drought-related variables. Leaf area index (LAI) was important for both forest types, while N deposition only for cold forests and cloud cover only for temperate forest. RUEmax of cold forests was mainly driven by N deposition and LAI, whereas for temperate forests only a weak relationship between RUEmax and CO2 concentration was found. Short-term variability of RUE was strongly related to the meteorological variables and varied during the season and was stronger in summer than spring or autumn. Interannual variability of RUEann and RUEmax was only weakly related to the interannual variability of the environmental drivers. Main conclusions: Cold and temperate forests show different relationships with the environment and vegetation properties. Among the RUE drivers observed, the least anticipated was N deposition. RUE is strongly related to short-term and seasonal changes in meteorological variables among seasons and among sites. Our results should be considered in the formulation of climate zone-specific tools for remote sensing and global models.
BibTeX:
@article{Balzarolo2019,
  author = {Balzarolo, Manuela and Valdameri, Nadia and Fu, Yongshuo H and Schepers, Lennert and Janssens, Ivan A and Campioli, Matteo},
  editor = {Kerkhoff, Andrew},
  title = {Different determinants of radiation use efficiency in cold and temperate forests},
  journal = {Global Ecology and Biogeography},
  publisher = {Wiley},
  year = {2019},
  volume = {28},
  number = {11},
  pages = {1649--1667},
  doi = {10.1111/geb.12985}
}
Bange HW, Arévalo-Martínez DL, de la Paz M, Farías L, Kaiser J, Kock A, Law CS, Rees AP, Rehder G, Tortell PD, Upstill-Goddard RC and Wilson ST (2019), "A harmonized nitrous oxide (N 2 O) ocean observation network for the 21st century", Frontiers in Marine Science., apr, 2019. Vol. 6(APR) Frontiers Media SA.
Abstract: Nitrous oxide (N 2 O) is an important atmospheric trace gas involved in tropospheric warming and stratospheric ozone depletion. Estimates of the global ocean contribution to N 2 O emissions average 21% (range: 10 to 53%). Ongoing environmental changes such as warming, deoxygenation and acidification are affecting oceanic N 2 O cycling and emissions to the atmosphere. International activities over the last decades aimed at improving estimates of global N 2 O emissions, including (i) the MarinE MethanE and NiTrous Oxide database (MEMENTO) for archiving of quality-controlled data, and (ii) a recent large-scale inter-laboratory comparison by Working Group 143 of the Scientific Committee on Ocean Research (SCOR). To reduce uncertainties in oceanic N 2 O emission estimates and to characterize the spatial and temporal variability in N 2 O distributions in a changing ocean, we propose the establishment of a harmonized N 2 O Observation Network (N 2 O-ON) combining discrete and continuous data from various platforms. The network will integrate observations obtained by calibrated techniques, using time series measurements at fixed stations and repeated hydrographic sections on voluntary observing ships and research vessels. In addition to exploiting existing oceanographic infrastructure, we propose the establishment of central calibration facilities in selected international laboratories to improve accuracy, and ensure standardization and comparability of N 2 O measurements. Final data products will include a harmonized global N 2 O concentration and emission fields for use in model validation and projections of future oceanic N 2 O emissions, to inform the global research community and policy makers.
BibTeX:
@article{Bange2019,
  author = {Bange, Hermann W and Arévalo-Martínez, Damian L and de la Paz, Mercedes and Farías, Laura and Kaiser, Jan and Kock, Annette and Law, Cliff S and Rees, Andrew P and Rehder, Gregor and Tortell, Philippe D and Upstill-Goddard, Robert C and Wilson, Samuel T},
  title = {A harmonized nitrous oxide (N 2 O) ocean observation network for the 21st century},
  journal = {Frontiers in Marine Science},
  publisher = {Frontiers Media SA},
  year = {2019},
  volume = {6},
  number = {APR},
  doi = {10.3389/fmars.2019.00157}
}
Bastos A, Ciais P, Chevallier F, Rödenbeck C, Ballantyne AP, Maignan F, Yin Y, Fernández-Martínez M, Friedlingstein P, Peñuelas J, Piao SL, Sitch S, Smith WK, Wang X, Zhu Z, Haverd V, Kato E, Jain AK, Lienert S, Lombardozzi D, Nabel JEMS, Peylin P, Poulter B and Zhu D (2019), "Contrasting effects of CO2 fertilization, land-use change and warming on seasonal amplitude of Northern Hemisphere CO2 exchange", Atmospheric Chemistry and Physics., oct, 2019. Vol. 19(19), pp. 12361-12375. Copernicus GmbH.
Abstract: Continuous atmospheric CO2 monitoring data indicate an increase in the amplitude of seasonal CO2-cycle exchange (SCANBP) in northern high latitudes. The major drivers of enhanced SCANBP remain unclear and intensely debated, with land-use change, CO2 fertilization and warming being identified as likely contributors. We integrated CO2-flux data from two atmospheric inversions (consistent with atmospheric records) and from 11 state-of-the-art land-surface models (LSMs) to evaluate the relative importance of individual contributors to trends and drivers of the SCANBP of CO2 fluxes for 1980-2015. The LSMs generally reproduce the latitudinal increase in SCANBP trends within the inversions range. Inversions and LSMs attribute SCANBP increase to boreal Asia and Europe due to enhanced vegetation productivity (in LSMs) and point to contrasting effects of CO2 fertilization (positive) and warming (negative) on SCANBP. Our results do not support land-use change as a key contributor to the increase in SCANBP. The sensitivity of simulated microbial respiration to temperature in LSMs explained biases in SCANBP trends, which suggests that SCANBP could help to constrain model turnover times.
BibTeX:
@article{Bastos2019,
  author = {Bastos, Ana and Ciais, Philippe and Chevallier, Frédéric and Rödenbeck, Christian and Ballantyne, Ashley P and Maignan, Fabienne and Yin, Yi and Fernández-Martínez, Marcos and Friedlingstein, Pierre and Peñuelas, Josep and Piao, Shilong L and Sitch, Stephen and Smith, William K and Wang, Xuhui and Zhu, Zaichun and Haverd, Vanessa and Kato, Etsushi and Jain, Atul K and Lienert, Sebastian and Lombardozzi, Danica and Nabel, Julia E M S and Peylin, Philippe and Poulter, Benjamin and Zhu, Dan},
  title = {Contrasting effects of CO2 fertilization, land-use change and warming on seasonal amplitude of Northern Hemisphere CO2 exchange},
  journal = {Atmospheric Chemistry and Physics},
  publisher = {Copernicus GmbH},
  year = {2019},
  volume = {19},
  number = {19},
  pages = {12361--12375},
  doi = {10.5194/acp-19-12361-2019}
}
Bechtold M, De Lannoy GJM, Koster RD, Reichle RH, Mahanama SP, Bleuten W, Bourgault MA, Brümmer C, Burdun I, Desai AR, Devito K, Grünwald T, Grygoruk M, Humphreys ER, Klatt J, Kurbatova J, Lohila A, Munir TM, Nilsson MB, Price JS, Röhl M, Schneider A and Tiemeyer B (2019), "PEAT-CLSM: A Specific Treatment of Peatland Hydrology in the NASA Catchment Land Surface Model", Journal of Advances in Modeling Earth Systems., jul, 2019. Vol. 11(7), pp. 2130-2162.
Abstract: Peatlands are poorly represented in global Earth system modeling frameworks. Here we add a peatland-specific land surface hydrology module (PEAT-CLSM) to the Catchment Land Surface Model (CLSM) of the NASA Goddard Earth Observing System (GEOS) framework. The amended TOPMODEL approach of the original CLSM that uses topography characteristics to model catchment processes is discarded, and a peatland-specific model concept is realized in its place. To facilitate its utilization in operational GEOS efforts, PEAT-CLSM uses the basic structure of CLSM and the same global input data. Parameters used in PEAT-CLSM are based on literature data. A suite of CLSM and PEAT-CLSM simulations for peatland areas between 40°N and 75°N is presented and evaluated against a newly compiled data set of groundwater table depth and eddy covariance observations of latent and sensible heat fluxes in natural and seminatural peatlands. CLSM's simulated groundwater tables are too deep and variable, whereas PEAT-CLSM simulates a mean groundwater table depth of âˆ'0.20 m (snow-free unfrozen period) with moderate temporal fluctuations (standard deviation of 0.10 m), in significantly better agreement with in situ observations. Relative to an operational CLSM version that simply includes peat as a soil class, the temporal correlation coefficient is increased on average by 0.16 and reaches 0.64 for bogs and 0.66 for fens when driven with global atmospheric forcing data. In PEAT-CLSM, runoff is increased on average by 38% and evapotranspiration is reduced by 19%. The evapotranspiration reduction constitutes a significant improvement relative to eddy covariance measurements.
BibTeX:
@article{Bechtold2019,
  author = {Bechtold, M and De Lannoy, G J M and Koster, R D and Reichle, R H and Mahanama, S P and Bleuten, W and Bourgault, M A and Brümmer, C and Burdun, I and Desai, A R and Devito, K and Grünwald, T and Grygoruk, M and Humphreys, E R and Klatt, J and Kurbatova, J and Lohila, A and Munir, T M and Nilsson, M B and Price, J S and Röhl, M and Schneider, A and Tiemeyer, B},
  title = {PEAT-CLSM: A Specific Treatment of Peatland Hydrology in the NASA Catchment Land Surface Model},
  journal = {Journal of Advances in Modeling Earth Systems},
  year = {2019},
  volume = {11},
  number = {7},
  pages = {2130--2162},
  url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2018MS001574},
  doi = {10.1029/2018MS001574}
}
Berger C, Bieri M, Bradshaw K, Brümmer C, Clemen T, Hickler T, Kutsch WL, Lenfers UA, Martens C, Midgley GF, Mukwashi K, Odipo V, Scheiter S, Schmullius C, Baade J, du Toit JCO, Scholes RJ, Smit IPJ, Stevens N and Twine W (2019), "Linking scales and disciplines: an interdisciplinary cross-scale approach to supporting climate-relevant ecosystem management", Climatic Change. Vol. 156(1), pp. 139-150.
Abstract: Southern Africa is particularly sensitive to climate change, due to both ecological and socio-economic factors, with rural land users among the most vulnerable groups. The provision of information to support climate-relevant decision-making requires an understanding of the projected impacts of change and complex feedbacks within the local ecosystems, as well as local demands on ecosystem services. In this paper, we address the limitation of current approaches for developing management relevant socio-ecological information on the projected impacts of climate change and human activities. We emphasise the need for linking disciplines and approaches by expounding the methodology followed in our two consecutive projects. These projects combine disciplines and levels of measurements from the leaf level (ecophysiology) to the local landscape level (flux measurements) and from the local household level (socio-economic surveys) to the regional level (remote sensing), feeding into a variety of models at multiple scales. Interdisciplinary, multi-scaled, and integrated socio-ecological approaches, as proposed here, are needed to compliment reductionist and linear, scale-specific approaches. Decision support systems are used to integrate and communicate the data and models to the local decision-makers.
BibTeX:
@article{Berger2019,
  author = {Berger, Christian and Bieri, Mari and Bradshaw, Karen and Brümmer, Christian and Clemen, Thomas and Hickler, Thomas and Kutsch, Werner Leo and Lenfers, Ulfia A and Martens, Carola and Midgley, Guy F and Mukwashi, Kanisios and Odipo, Victor and Scheiter, Simon and Schmullius, Christiane and Baade, Jussi and du Toit, Justin C O and Scholes, Robert J and Smit, Izak P J and Stevens, Nicola and Twine, Wayne},
  title = {Linking scales and disciplines: an interdisciplinary cross-scale approach to supporting climate-relevant ecosystem management},
  journal = {Climatic Change},
  year = {2019},
  volume = {156},
  number = {1},
  pages = {139--150},
  url = {https://doi.org/10.1007/s10584-019-02544-0}
}
Berhanu TA, Hoffnagle J, Rella C, Kimhak D, Nyfeler P and Leuenberger M (2019), "High-precision atmospheric oxygen measurement comparisons between a newly built CRDS analyzer and existing measurement techniques", Atmospheric Measurement Techniques., dec, 2019. Vol. 12(12), pp. 6803-6826. Copernicus GmbH.
Abstract: Carbon dioxide and oxygen are tightly coupled in land biosphere CO2-O2 exchange processes, whereas they are not coupled in oceanic exchange. For this reason, atmospheric oxygen measurements can be used to constrain the global carbon cycle, especially oceanic uptake. However, accurately quantifying small (∼ 1-100 ppm) variations in O2 is analytically challenging due to the very large atmospheric background which constitutes about 20.9%(209500 ppm) of atmospheric air. Here we present a detailed description of a newly developed high-precision oxygen mixing ratio and isotopic composition analyzer (Picarro G2207) that is based on cavity ring-down spectroscopy (CRDS) as well as to its operating principles; we also demonstrate comprehensive laboratory and field studies using the abovementioned instrument. From the laboratory tests, we calculated a shortterm precision (standard error of 1 min O2 mixing ratio measurements) of 1 ppm for this analyzer based on measurements of eight standard gases analyzed for 2 h, respectively. In contrast to the currently existing techniques, the instrument has an excellent long-term stability; therefore, calibration every 12 h is sufficient to get an overall uncertainty of 5 ppm. Measurements of ambient air were also conducted at the Jungfraujoch high-altitude research station and the Beromünster tall tower in Switzerland. At both sites, we observed opposing and diurnally varying CO2 and O2 profiles due to different processes such as combustion, photosynthesis, and respiration. Based on the combined measurements at Beromünster tower, we determined height-dependent O2 V CO2 oxidation ratios varying between -0:98 and -1:60; these ratios increased with the height of the tower inlet, possibly due to different source contributions such as natural gas combustion, which has a high oxidation ratio, and biological processes, which have oxidation ratios that are relatively lower.
BibTeX:
@article{Berhanu2019,
  author = {Berhanu, Tesfaye A and Hoffnagle, John and Rella, Chris and Kimhak, David and Nyfeler, Peter and Leuenberger, Markus},
  title = {High-precision atmospheric oxygen measurement comparisons between a newly built CRDS analyzer and existing measurement techniques},
  journal = {Atmospheric Measurement Techniques},
  publisher = {Copernicus GmbH},
  year = {2019},
  volume = {12},
  number = {12},
  pages = {6803--6826},
  doi = {10.5194/amt-12-6803-2019}
}
Berhongaray G, Cotrufo FM, Janssens IA and Ceulemans R (2019), "Below-ground carbon inputs contribute more than above-ground inputs to soil carbon accrual in a bioenergy poplar plantation", Plant and Soil., oct, 2019. Vol. 434(1-2), pp. 363-378. Springer Science and Business Media LLC.
Abstract: Background and aims: Soil organic carbon (SOC) accrual is central to the discussion on active atmospheric CO 2 removal strategies, but it requires a clear understanding of the mechanisms driving new SOC formation. SOC is formed from the decomposition of above- and below-ground plant inputs, yet their accurate quantification remains a major challenge. In the current study the in-growth soil core and δ 13 C methods were combined to quantify the net C input from single or combined above- and below-ground parts of a poplar (Populus) bioenergy plantation. Methods: Three different mesh sizes were used for the in-growth cores in four different treatments designed to estimate the relative contributions of above-ground litter fall, fine roots and mycorrhizae (C3 input from the poplar) to the new C formation in cores filled with a C4 soil, by applying a mass balance equation. Results: Soil C formation was higher in the treatments with roots as compared to the treatments with above-ground C inputs only (29 vs 16 g C m âˆ'2 ), despite the disproportionally lower root inputs as compared to above-ground C inputs (34 vs 175 g C m âˆ'2 y âˆ'1 ). Soil C formation from different sources (above- and below-ground) was additive; i.e. the observed soil C formation in the combined treatment was the sum of those in the single soil C input treatments. As a result, below-ground C-inputs had a high conversion efficiency to SOC of 76%. Above-ground plant inputs had a very low SOC formation efficiency of 9%, and were presumably mainly mineralized by microorganisms. Conclusion: The higher soil C accumulation rates from below-ground C inputs are particularly important in bioenergy plantations where the above-ground biomass is frequently removed for biomass and energy production.
BibTeX:
@article{Berhongaray2019,
  author = {Berhongaray, Gonzalo and Cotrufo, Francesca M and Janssens, Ivan A and Ceulemans, Reinhart},
  title = {Below-ground carbon inputs contribute more than above-ground inputs to soil carbon accrual in a bioenergy poplar plantation},
  journal = {Plant and Soil},
  publisher = {Springer Science and Business Media LLC},
  year = {2019},
  volume = {434},
  number = {1-2},
  pages = {363--378},
  doi = {10.1007/s11104-018-3850-z}
}
Besnard S, Carvalhais N, Altaf Arain M, Black A, Brede B, Buchmann N, Chen J, Clevers JGPW, Dutrieux LP, Gans F, Herold M, Jung M, Kosugi Y, Knohl A, Law BE, Paul-Limoges E, Lohila A, Merbold L, Roupsard O, Valentini R, Wolf S, Zhang X and Reichstein M (2019), "Memory effects of climate and vegetation affecting net ecosystem CO2 fluxes in global forests", PLoS ONE., feb, 2019. Vol. 14(2), pp. e0211510. Public Library of Science (PLoS).
Abstract: Forests play a crucial role in the global carbon (C) cycle by storing and sequestering a substantial amount of C in the terrestrial biosphere. Due to temporal dynamics in climate and vegetation activity, there are significant regional variations in carbon dioxide (CO2) fluxes between the biosphere and atmosphere in forests that are affecting the global C cycle. Current forest CO2 flux dynamics are controlled by instantaneous climate, soil, and vegetation conditions, which carry legacy effects from disturbances and extreme climate events. Our level of understanding from the legacies of these processes on net CO2 fluxes is still limited due to their complexities and their long-term effects. Here, we combined remote sensing, climate, and eddy-covariance flux data to study net ecosystem CO2 exchange (NEE) at 185 forest sites globally. Instead of commonly used non-dynamic statistical methods, we employed a type of recurrent neural network (RNN), called Long Short-Term Memory network (LSTM) that captures information from the vegetation and climate's temporal dynamics. The resulting data-driven model integrates interannual and seasonal variations of climate and vegetation by using Landsat and climate data at each site. The presented LSTM algorithm was able to effectively describe the overall seasonal variability (Nash-Sutcliffe efficiency, NSE = 0.66) and across-site (NSE = 0.42) variations in NEE, while it had less success in predicting specific seasonal and interannual anomalies (NSE = 0.07). This analysis demonstrated that an LSTM approach with embedded climate and vegetation memory effects outperformed a non-dynamic statistical model (i.e. Random Forest) for estimating NEE. Additionally, it is shown that the vegetation mean seasonal cycle embeds most of the information content to realistically explain the spatial and seasonal variations in NEE. These findings show the relevance of capturing memory effects from both climate and vegetation in quantifying spatio-temporal variations in forest NEE.
BibTeX:
@article{Besnard2019,
  author = {Besnard, Simon and Carvalhais, Nuno and Altaf Arain, M and Black, Andrew and Brede, Benjamin and Buchmann, Nina and Chen, Jiquan and Clevers, Jan G P W and Dutrieux, Loïc P and Gans, Fabian and Herold, Martin and Jung, Martin and Kosugi, Yoshiko and Knohl, Alexander and Law, Beverly E and Paul-Limoges, Eugénie and Lohila, Annalea and Merbold, Lutz and Roupsard, Olivier and Valentini, Riccardo and Wolf, Sebastian and Zhang, Xudong and Reichstein, Markus},
  editor = {Hui, Dafeng},
  title = {Memory effects of climate and vegetation affecting net ecosystem CO2 fluxes in global forests},
  journal = {PLoS ONE},
  publisher = {Public Library of Science (PLoS)},
  year = {2019},
  volume = {14},
  number = {2},
  pages = {e0211510},
  doi = {10.1371/journal.pone.0211510}
}
Bigeard G, Coudert B, Chirouze J, Er-Raki S, Boulet G, Ceschia E and Jarlan L (2019), "Ability of a soil-vegetation-atmosphere transfer model and a two-source energy balance model to predict evapotranspiration for several crops and climate conditions", Hydrology and Earth System Sciences., dec, 2019. Vol. 23(12), pp. 5033-5058. Copernicus GmbH.
Abstract: The heterogeneity of Agroecosystems, in terms of hydric conditions, crop types and states, and meteorological forcing, is difficult to characterize precisely at the field scale over an agricultural landscape. This study aims to perform a sensitivity study with respect to the uncertain model inputs of two classical approaches used to map the evapotranspiration of agroecosystems: (1) a surface energy balance (SEB) model, the Two-Source Energy Balance (TSEB) model, forced with thermal infrared (TIR) data as a proxy for the crop hydric conditions, and (2) a soil-vegetation-atmosphere transfer (SVAT) model, the SEtHyS model, where hydric conditions are computed from a soil water budget. To this end, the models skill was compared using a large and unique in situ database covering different crops and climate conditions, which was acquired over three experimental sites in southern France and Morocco. On average, the models provide 30 min estimations of latent heat flux (LE) with a RMSE of around 55Wm-2 for TSEB and 47Wm-2 for SEtHyS, and estimations of sensible heat flux (H) with a RMSE of around 29Wm-2 for TSEB and 38Wm-2 for SEtHyS. A sensitivity analysis based on realistic errors aimed to estimate the potential decrease in performance induced by the spatialization process. For the SVAT model, the multi-objective calibration iterative procedure (MCIP) is used to determine and test different sets of parameters. TSEB is run with only one set of parameters and provides acceptable performance for all crop stages apart from the early growing season (LAI0.2m2 m-2) and when hydric stress occurs. An in-depth study on the Priestley- Taylor key parameter highlights its marked diurnal cycle and the need to adjust its value to improve flux partitioning between the sensible and latent heat fluxes (1.5 and 1.25 for France and Morocco, respectively). Optimal values of 1.8-2 were highlighted under cloudy conditions, which is of particular interest due to the emergence of low-altitude drone acquisition. Under developed vegetation (LAI0.8m2 m-2) and unstressed conditions, using sets of parameters that only differentiate crop types is a valuable trade-off for SEtHyS. This study provides some scientific elements regarding the joint use of both approaches and TIR imagery, via the development of new data assimilation and calibration strategies..
BibTeX:
@article{Bigeard2019,
  author = {Bigeard, Guillaume and Coudert, Benoit and Chirouze, Jonas and Er-Raki, Salah and Boulet, Gilles and Ceschia, Eric and Jarlan, Lionel},
  title = {Ability of a soil-vegetation-atmosphere transfer model and a two-source energy balance model to predict evapotranspiration for several crops and climate conditions},
  journal = {Hydrology and Earth System Sciences},
  publisher = {Copernicus GmbH},
  year = {2019},
  volume = {23},
  number = {12},
  pages = {5033--5058},
  doi = {10.5194/hess-23-5033-2019}
}
Billesbach DP, Chan SW, Cook DR, Papale D, Bracho-Garrillo R, Verfallie J, Vargas R and Biraud SC (2019), "Effects of the Gill-Solent WindMaster-Pro “w-boost” firmware bug on eddy covariance fluxes and some simple recovery strategies", Agricultural and Forest Meteorology., feb, 2019. Vol. 265, pp. 145-151. Elsevier BV.
Abstract: In late 2015 and early 2016, work done by the AmeriFlux Management Project Technical Team (amerilfux.lbl.gov) helped to uncover an issue with Gill WindMaster and WindMaster Pro sonic anemometers used by many researchers for eddy covariance flux measurements. Gill has addressed this issue and has since sent out a notice that the vertical wind speed component (a critical piece of all eddy covariance fluxes) was being erroneously computed and reported. The problem (known as the “w-boost” bug) resulted in positive (upward) wind speeds being under-reported by 16.6% and negative (downward) wind speeds being under-reported by 28.9%. This has the potential to cause similar under estimates in fluxes derived from measurements using these instruments. Additionally, the bug affects corrections for angle of attack as derived by Nakai and Shimoyama, rendering them invalid. While the manufacturer has offered a firmware upgrade for existing instruments that will fix this issue, many existing data sets have been affected by it and are currently in use by the scientific community. To address the issue of affected data, currently in use, we analyzed multi-year and short-term data sets from a variety of ecosystems to assess methods of correcting existing flux data. We found that simple multiplicative correction factors (∼1.18) may be used to remove most of the “w-boost” bias from fluxes in existing data sets that do not include angle of attack corrections.
BibTeX:
@article{Billesbach2019,
  author = {Billesbach, D P and Chan, S W and Cook, D R and Papale, D and Bracho-Garrillo, R and Verfallie, J and Vargas, R and Biraud, S C},
  title = {Effects of the Gill-Solent WindMaster-Pro “w-boost” firmware bug on eddy covariance fluxes and some simple recovery strategies},
  journal = {Agricultural and Forest Meteorology},
  publisher = {Elsevier BV},
  year = {2019},
  volume = {265},
  pages = {145--151},
  doi = {10.1016/j.agrformet.2018.11.010}
}
Bowring SPK, Lauerwald R, Guenet B, Zhu D, Guimberteau M, Tootchi A, Ducharne A and Ciais P (2019), "ORCHIDEE MICT-LEAK (r5459), a global model for the production, transport, and transformation of dissolved organic carbon from Arctic permafrost regions - Part 1: Rationale, model description, and simulation protocol", Geoscientific Model Development., aug, 2019. Vol. 12(8), pp. 3503-3521. Copernicus GmbH.
Abstract: Few Earth system models adequately represent the unique permafrost soil biogeochemistry and its respective processes; this significantly contributes to uncertainty in estimating their responses, and that of the planet at large, to warming. Likewise, the riverine component of what is known as the "boundless carbon cycle" is seldom recognised in Earth system modelling. The hydrological mobilisation of organic material from a ∼ 1330-1580 PgC carbon stock to the river network results in either sedimentary settling or atmospheric "evasion", processes widely expected to increase with amplified Arctic climate warming. Here, the production, transport, and atmospheric release of dissolved organic carbon (DOC) from high-latitude permafrost soils into inland waters and the ocean are explicitly represented for the first time in the land surface component (ORCHIDEE) of a CMIP6 global climate model (Institut Pierre Simon Laplace - IPSL). The model, ORCHIDEE MICT-LEAK, which represents the merger of previously described ORCHIDEE versions MICT and LEAK, mechanistically represents (a) vegetation and soil physical processes for high-latitude snow, ice, and soil phenomena and (b) the cycling of DOC and CO2, including atmospheric evasion, along the terrestrial-aquatic continuum from soils through the river network to the coast at 0.5 to 2° resolution. This paper, the first in a two-part study, presents the rationale for including these processes in a high-latitude-specific land surface model, then describes the model with a focus on novel process implementations, followed by a summary of the model configuration and simulation protocol. The results of these simulation runs, conducted for the Lena River basin, are evaluated against observational data in the second part of this study.
BibTeX:
@article{Bowring2019,
  author = {Bowring, Simon P K and Lauerwald, Ronny and Guenet, Bertrand and Zhu, Dan and Guimberteau, Matthieu and Tootchi, Ardalan and Ducharne, Agnès and Ciais, Philippe},
  title = {ORCHIDEE MICT-LEAK (r5459), a global model for the production, transport, and transformation of dissolved organic carbon from Arctic permafrost regions - Part 1: Rationale, model description, and simulation protocol},
  journal = {Geoscientific Model Development},
  publisher = {Copernicus GmbH},
  year = {2019},
  volume = {12},
  number = {8},
  pages = {3503--3521},
  doi = {10.5194/gmd-12-3503-2019}
}
Box JE, Colgan WT, Christensen TR, Schmidt NM, Lund M, Parmentier FJW, Brown R, Bhatt US, Euskirchen ES, Romanovsky VE, Walsh JE, Overland JE, Wang M, Corell RW, Meier WN, Wouters B, Mernild S, Mård J, Pawlak J and Olsen MS (2019), "Key indicators of Arctic climate change: 1971-2017", Environmental Research Letters., apr, 2019. Vol. 14(4), pp. 45010. IOP Publishing.
Abstract: Key observational indicators of climate change in the Arctic, most spanning a 47 year period (1971-2017) demonstrate fundamental changes among nine key elements of the Arctic system. We find that, coherent with increasing air temperature, there is an intensification of the hydrological cycle, evident from increases in humidity, precipitation, river discharge, glacier equilibrium line altitude and land ice wastage. Downward trends continue in sea ice thickness (and extent) and spring snow cover extent and duration, while near-surface permafrost continues to warm. Several of the climate indicators exhibit a significant statistical correlation with air temperature or precipitation, reinforcing the notion that increasing air temperatures and precipitation are drivers of major changes in various components of the Arctic system. To progress beyond a presentation of the Arctic physical climate changes, we find a correspondence between air temperature and biophysical indicators such as tundra biomass and identify numerous biophysical disruptions with cascading effects throughout the trophic levels. These include: increased delivery of organic matter and nutrients to Arctic near-coastal zones; condensed flowering and pollination plant species periods; timing mismatch between plant flowering and pollinators; increased plant vulnerability to insect disturbance; increased shrub biomass; increased ignition of wildfires; increased growing season CO2 uptake, with counterbalancing increases in shoulder season and winter CO2 emissions; increased carbon cycling, regulated by local hydrology and permafrost thaw; conversion between terrestrial and aquatic ecosystems; and shifting animal distribution and demographics. The Arctic biophysical system is now clearly trending away from its 20th Century state and into an unprecedented state, with implications not only within but beyond the Arctic. The indicator time series of this study are freely downloadable at AMAP.no.
BibTeX:
@article{Box2019,
  author = {Box, Jason E and Colgan, William T and Christensen, Torben Røjle and Schmidt, Niels Martin and Lund, Magnus and Parmentier, Frans Jan W and Brown, Ross and Bhatt, Uma S and Euskirchen, Eugénie S and Romanovsky, Vladimir E and Walsh, John E and Overland, James E and Wang, Muyin and Corell, Robert W and Meier, Walter N and Wouters, Bert and Mernild, Sebastian and Mård, Johanna and Pawlak, Janet and Olsen, Morten Skovgård},
  title = {Key indicators of Arctic climate change: 1971-2017},
  journal = {Environmental Research Letters},
  publisher = {IOP Publishing},
  year = {2019},
  volume = {14},
  number = {4},
  pages = {45010},
  doi = {10.1088/1748-9326/aafc1b}
}
Brændholt A, Ibrom A, Ambus P, Larsen KS and Pilegaard K (2019), "Combining a quantum cascade laser spectrometer with an automated closed-chamber system for δ13C measurements of forest soil, tree stem and tree root CO2 fluxess", Forests., may, 2019. Vol. 10(5), pp. 432. MDPI AG.
Abstract: Recent advances in laser spectroscopy have allowed for real-time measurements of the 13C/12C isotopic ratio in CO2, thereby providing new ways to investigate carbon cycling in natural ecosystems. In this study, we combined an Aerodyne quantum cascade laser spectrometer for CO2 isotopes with a LI-COR LI-8100A/8150 automated chamber system to measure the δ13C of CO2 during automated closed-chamber measurements. The isotopic composition of the CO2 flux was determined for each chamber measurement by applying the Keeling plot method. We found that the δ13C measured by the laser spectrometer was influenced by water vapour and CO2 concentration of the sample air and we developed a method to correct for these effects to yield accurate measurements of δ13C. Overall, correcting for the CO2 concentration increased the δ13C determined from the Keeling plots by 3.4%‰ compared to 2.1%‰ for the water vapour correction. We used the combined system to measure δ13C of the CO2 fluxes automatically every two hours from intact soil, trenched soil, tree stems and coarse roots during a two-month campaign in a Danish beech forest. The mean δ13C was -29.8 ± 0.32%‰ for the intact soil plots, which was similar to the mean δ13C of -29.8 ± 1.2%‰ for the trenched soil plots. The lowest δ13C was found for the root plots with a mean of -32.6 ± 0.78%‰. The mean δ13C of the stems was -30.2 ± 0.74%‰, similar to the mean δ13C of the soil plots. In conclusion, the study showed the potential of using a quantum cascade laser spectrometer to measure δ13C of CO2 during automated closed-chamber measurements, thereby allowing for measurements of isotopic ecosystem CO2 fluxes at a high temporal resolution. It also highlighted the importance of proper correction for cross-sensitivity with water vapour and CO2 concentration of the sample air to get accurate measurements of δ13C.
BibTeX:
@article{Brændholt2019,
  author = {Brændholt, Andreas and Ibrom, Andreas and Ambus, Per and Larsen, Klaus Steenberg and Pilegaard, Kim},
  title = {Combining a quantum cascade laser spectrometer with an automated closed-chamber system for δ13C measurements of forest soil, tree stem and tree root CO2 fluxess},
  journal = {Forests},
  publisher = {MDPI AG},
  year = {2019},
  volume = {10},
  number = {5},
  pages = {432},
  doi = {10.3390/f10050432}
}
Brown MS, Munro DR, Feehan CJ, Sweeney C, Ducklow HW and Schofield OM (2019), "Enhanced oceanic CO2 uptake along the rapidly changing West Antarctic Peninsula". sep, 2019.
Abstract: The global ocean is an important sink for anthropogenic CO2 (ref. 1). Nearly half of the oceanic CO2 uptake occurs in the Southern Ocean2. Although the role of the Southern Ocean CO2 sink in the global carbon cycle is recognized, there are uncertainties regarding its contemporary trend3,4, with a need for improved mechanistic understanding, especially in productive Antarctic coastal regions experiencing substantial changes in temperature and sea ice5. Here, we demonstrate strong coupling between summer upper ocean stability, phytoplankton dynamics and oceanic CO2 uptake along the rapidly changing West Antarctic Peninsula using a 25-year dataset (1993–2017). Greater upper ocean stability drives enhanced biological production and biological dissolved inorganic carbon drawdown, resulting in greater oceanic CO2 uptake. Diatoms achieve higher biomass, oceanic CO2 uptake and uptake efficiency than other phytoplankton. Over the past 25 years, changes in sea ice dynamics have driven an increase in upper ocean stability, phytoplankton biomass and biological dissolved inorganic carbon drawdown, resulting in a nearly fivefold increase in summer oceanic CO2 uptake. We hypothesize that continued warming and declines in sea ice will lead to a decrease in biological dissolved inorganic carbon drawdown, negatively impacting summer oceanic CO2 uptake. These results from the West Antarctic Peninsula provide a framework to understand how oceanic CO2 uptake in other Antarctic coastal regions may be altered due to climate change.
BibTeX:
@misc{Brown2019,
  author = {Brown, Michael S. and Munro, David R. and Feehan, Colette J. and Sweeney, Colm and Ducklow, Hugh W. and Schofield, Oscar M.},
  title = {Enhanced oceanic CO2 uptake along the rapidly changing West Antarctic Peninsula},
  booktitle = {Nature Climate Change},
  publisher = {Nature Publishing Group},
  year = {2019},
  volume = {9},
  number = {9},
  pages = {678--683},
  url = {https://doi.org/10.1038/s41558-019-0552-3},
  doi = {10.1038/s41558-019-0552-3}
}
Buchen C, Roobroeck D, Augustin J, Behrendt U, Boeckx P and Ulrich A (2019), "High N2O consumption potential of weakly disturbed fen mires with dissimilar denitrifier community structure", Soil Biology and Biochemistry., mar, 2019. Vol. 130, pp. 63-72.
BibTeX:
@article{Buchen2019,
  author = {Buchen, C and Roobroeck, D and Augustin, J and Behrendt, U and Boeckx, P and Ulrich, A},
  title = {High N2O consumption potential of weakly disturbed fen mires with dissimilar denitrifier community structure},
  journal = {Soil Biology and Biochemistry},
  year = {2019},
  volume = {130},
  pages = {63--72},
  url = {https://linkinghub.elsevier.com/retrieve/pii/S0038071718304115},
  doi = {10.1016/j.soilbio.2018.12.001}
}
Burri S, Haeler E, Eugster W, Haeni M, Etzold S, Walthert L, Braun S and Zweifel R (2019), "How did Swiss forest trees respond to the hot summer 2015?", Erde., dec, 2019. Vol. 150(4), pp. 214-229. Gesellschaft fur Erdkunde zu Berlin.
Abstract: Central Europe experienced an exceptionally hot summer in 2015. The area of investigation in the Central Alps in Switzerland faced the second warmest summer since the beginning of measurements in 1864. As a consequence, agriculture suffered from considerable production losses. But how were forests affected by the hot summer? We analyzed stem growth data, measured by automated point dendrometers,from 50 trees across nine sites covering the four main Swiss tree species spruce (Picea abies),fir (Abies alba), beech (Fagus sylvatica) and oak (Quercus spp.) in the years 2014 (relatively wet and cool) and 2015 (hot and dry). Annual growth and environmental conditions were determined by, and related to, the growing period based on daily resolved growth data. Our multi-species approach revealed a wide range of responses. Radial growth of spruce was largely reduced during the hot summer 2015 for sites located below 1500 m a.s.l. Growth of beech responded even positively at several sites on the Swiss Plateau. Fir and oak did not significantly deviate from their respective average growth rate. We conclude that one hot summer actually matters for stem growth, but its effect is not a priori negative. The timing of the heat wave is of highest importance. A relatively wet previous year, a wet spring and the relatively late occurrence of the heat wave in the wood growth period led to a less strong growth reduction than what could have been expected from agricultural plants. Endogenous effects like mast fruiting and legacy effects from past conditions are suggested to further play an important role for stem growth.
BibTeX:
@article{Burri2019,
  author = {Burri, Susanne and Haeler, Elena and Eugster, Werner and Haeni, Matthias and Etzold, Sophia and Walthert, Lorenz and Braun, Sabine and Zweifel, Roman},
  title = {How did Swiss forest trees respond to the hot summer 2015?},
  journal = {Erde},
  publisher = {Gesellschaft fur Erdkunde zu Berlin},
  year = {2019},
  volume = {150},
  number = {4},
  pages = {214--229},
  doi = {10.12854/erde-2019-420}
}
Bushinsky SM, Landschützer P, Rödenbeck C, Gray AR, Baker D, Mazloff MR, Resplandy L, Johnson KS and Sarmiento JL (2019), "Reassessing Southern Ocean Air‐Sea CO textlesssubtextgreater2textless/subtextgreater Flux Estimates With the Addition of Biogeochemical Float Observations", Global Biogeochemical Cycles., nov, 2019. Vol. 33(11), pp. 1370-1388. Blackwell Publishing Ltd.
Abstract: New estimates of pCO2 from profiling floats deployed by the Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) project have demonstrated the importance of wintertime outgassing south of the Polar Front, challenging the accepted magnitude of Southern Ocean carbon uptake (Gray et al., 2018, https://doi:10.1029/2018GL078013). Here, we put 3.5 years of SOCCOM observations into broader context with the global surface carbon dioxide database (Surface Ocean CO2 Atlas, SOCAT) by using the two interpolation methods currently used to assess the ocean models in the Global Carbon Budget (Le Quéré et al., 2018, https://doi:10.5194/essd-10-2141-2018) to create a ship-only, a float-weighted, and a combined estimate of Southern Ocean carbon fluxes (textless35°S). In our ship-only estimate, we calculate a mean uptake of −1.14 ± 0.19 Pg C/yr for 2015–2017, consistent with prior studies. The float-weighted estimate yields a significantly lower Southern Ocean uptake of −0.35 ± 0.19 Pg C/yr. Subsampling of high-resolution ocean biogeochemical process models indicates that some of the differences between float and ship-only estimates of the Southern Ocean carbon flux can be explained by spatial and temporal sampling differences. The combined ship and float estimate minimizes the root-mean-square pCO2 difference between the mapped product and both data sets, giving a new Southern Ocean uptake of −0.75 ± 0.22 Pg C/yr, though with uncertainties that overlap the ship-only estimate. An atmospheric inversion reveals that a shift of this magnitude in the contemporary Southern Ocean carbon flux must be compensated for by ocean or land sinks within the Southern Hemisphere.
BibTeX:
@article{Bushinsky2019,
  author = {Bushinsky, Seth M. and Landschützer, Peter and Rödenbeck, Christian and Gray, Alison R. and Baker, David and Mazloff, Matthew R. and Resplandy, Laure and Johnson, Kenneth S. and Sarmiento, Jorge L.},
  title = {Reassessing Southern Ocean Air‐Sea CO textlesssubtextgreater2textless/subtextgreater Flux Estimates With the Addition of Biogeochemical Float Observations},
  journal = {Global Biogeochemical Cycles},
  publisher = {Blackwell Publishing Ltd},
  year = {2019},
  volume = {33},
  number = {11},
  pages = {1370--1388},
  url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2019GB006176},
  doi = {10.1029/2019GB006176}
}
Bushinsky SM, Takeshita Y and Williams NL (2019), "Observing Changes in Ocean Carbonate Chemistry: Our Autonomous Future". sep, 2019.
Abstract: Purpose of Review: We summarize recent progress on autonomous observations of ocean carbonate chemistry and the development of a network of sensors capable of observing carbonate processes at multiple temporal and spatial scales. Recent Findings: The development of versatile pH sensors suitable for both deployment on autonomous vehicles and in compact, fixed ecosystem observatories has been a major development in the field. The initial large-scale deployment of profiling floats equipped with these new pH sensors in the Southern Ocean has demonstrated the feasibility of a global autonomous open-ocean carbonate observing system. Summary: Our developing network of autonomous carbonate observations is currently targeted at surface ocean CO2 fluxes and compact ecosystem observatories. New integration of developed sensors on gliders and surface vehicles will increase our coastal and regional observational capability. Most autonomous platforms observe a single carbonate parameter, which leaves us reliant on the use of empirical relationships to constrain the rest of the carbonate system. Sensors now in development promise the ability to observe multiple carbonate system parameters from a range of vehicles in the near future.
BibTeX:
@misc{Bushinsky2019a,
  author = {Bushinsky, Seth M. and Takeshita, Yuichiro and Williams, Nancy L.},
  title = {Observing Changes in Ocean Carbonate Chemistry: Our Autonomous Future},
  booktitle = {Current Climate Change Reports},
  publisher = {Springer},
  year = {2019},
  volume = {5},
  number = {3},
  pages = {207--220},
  url = {https://doi.org/10.1007/s40641-019-00129-8},
  doi = {10.1007/s40641-019-00129-8}
}
Byrne A, Jones B, Strong D, Journal A, Byrne B, Jones DBA, Strong K, Polavarapu SM, Harper AB, Baker DF and Maksyutov S (2019), "On what scales can GOSAT flux inversions constrain anomalies in terrestrial ecosystems? A NOTE ON VERSIONS On what scales can GOSAT flux inversions constrain anomalies in terrestrial ecosystems?", Atmos. Chem. Phys. Vol. 19, pp. 13017-13035.
Abstract: Interannual variations in temperature and precipitation impact the carbon balance of terrestrial ecosystems , leaving an imprint in atmospheric CO 2. Quantifying the impact of climate anomalies on the net ecosystem exchange (NEE) of terrestrial ecosystems can provide a constraint to evaluate terrestrial biosphere models against and may provide an emergent constraint on the response of terrestrial ecosystems to climate change. We investigate the spatial scales over which interannual variability in NEE can be constrained using atmospheric CO 2 observations from the Greenhouse Gases Observing Satellite (GOSAT). NEE anomalies are calculated by performing a series of inversion analyses using the GEOS-Chem adjoint model to assimilate GOSAT observations. Monthly NEE anomalies are compared to "proxies", variables that are associated with anomalies in the terrestrial carbon cycle, and to upscaled NEE estimates from FLUXCOM. Statistically significant correlations (P textless 0.05) are obtained between posterior NEE anomalies and anomalies in soil temperature and FLUXCOM NEE on continental and larger scales in the tropics, as well as in the northern extratropics on subcontinental scales during the summer (R 2 ≥ 0.49), suggesting that GOSAT measurements provide a constraint on NEE interannual variability (IAV) on these spatial scales. Furthermore, we show that GOSAT flux inversions are generally better correlated with the environmental proxies and FLUXCOM NEE than NEE anomalies produced by a set of terrestrial biosphere models (TBMs), suggesting that GOSAT flux inversions could be used to evaluate TBM NEE fluxes.
BibTeX:
@article{Byrne2019,
  author = {Byrne, Authors and Jones, B ; and Strong, Dba ; and Journal, Al and Byrne, Brendan and Jones, Dylan B A and Strong, Kimberly and Polavarapu, Saroja M and Harper, Anna B and Baker, David F and Maksyutov, Shamil},
  title = {On what scales can GOSAT flux inversions constrain anomalies in terrestrial ecosystems? A NOTE ON VERSIONS On what scales can GOSAT flux inversions constrain anomalies in terrestrial ecosystems?},
  journal = {Atmos. Chem. Phys},
  year = {2019},
  volume = {19},
  pages = {13017--13035},
  url = {http://hdl.handle.net/10871/39986},
  doi = {10.5194/acp-19-13017-2019}
}
Campbell JL and Laudon H (2019), "Carbon response to changing winter conditions in northern regions: Current understanding and emerging research needs", Environmental Reviews., dec, 2019. Vol. 27(4), pp. 545-566.
Abstract: Winter is an important period for ecological processes in northern regions; however, compared to other seasons, the impacts of winter climate on ecosystems are poorly understood. In this review we evaluate the influence of winter climate on carbon dynamics based on the current state of knowledge and highlight emerging topics and future research challenges. Studies that have addressed this topic include plot-scale snow cover manipulation experiments that alter soil temperatures, empirical investigations along natural climatic gradients, laboratory temperature incubation experiments aimed at isolating influential factors in controlled environments, and time series of climate and carbon data that evaluate long-term natural variation and trends. Combined, these studies have demonstrated how winter climate can influence carbon in complex ways that in some cases are consistent across studies and in other cases are difficult to predict. Despite advances in our understanding, there is a great need for studies that further explore: (i) carry-over effects from one season to another, (ii) ecosystem processes in the fall–winter and winter–spring shoulder seasons, (iii) the impacts of extreme events, (iv) novel experimental approaches, and (v) improvements to models to include ecological effects of winter climate. We also call for the establishment of an international winter climate change research network that enhances collaboration and coordination among studies, which could provide a more thorough understanding of how the snow-covered period influences carbon cycling, thereby improving our ability to predict future responses to climate change.
BibTeX:
@article{Campbell2019,
  author = {Campbell, John L and Laudon, Hjalmar},
  title = {Carbon response to changing winter conditions in northern regions: Current understanding and emerging research needs},
  journal = {Environmental Reviews},
  year = {2019},
  volume = {27},
  number = {4},
  pages = {545--566},
  url = {http://www.nrcresearchpress.com/doi/10.1139/er-2018-0097},
  doi = {10.1139/er-2018-0097}
}
Campeau A, Bishop K, Amvrosiadi N, Billett MF, Garnett MH, Laudon H, Öquist MG and Wallin MB (2019), "Current forest carbon fixation fuels stream CO 2 emissions", Nature Communications., dec, 2019. Vol. 10(1), pp. 1876.
Abstract: Stream CO 2 emissions contribute significantly to atmospheric climate forcing. While there are strong indications that groundwater inputs sustain these emissions, the specific biogeochemical pathways and timescales involved in this lateral CO 2 export are still obscure. Here, via an extensive radiocarbon ( 14 C) characterisation of CO 2 and DOC in stream water and its groundwater sources in an old-growth boreal forest, we demonstrate that the 14 C-CO 2 is consistently in tune with the current atmospheric 14 C-CO 2 level and shows little association with the 14 C-DOC in the same waters. Our findings thus indicate that stream CO 2 emissions act as a shortcut that returns CO 2 recently fixed by the forest vegetation to the atmosphere. Our results expose a positive feedback mechanism within the C budget of forested catchments, where stream CO 2 emissions will be highly sensitive to changes in forest C allocation patterns associated with climate and land-use changes.
BibTeX:
@article{Campeau2019,
  author = {Campeau, A and Bishop, K and Amvrosiadi, N and Billett, M F and Garnett, M H and Laudon, H and Öquist, M G and Wallin, M B},
  title = {Current forest carbon fixation fuels stream CO 2 emissions},
  journal = {Nature Communications},
  year = {2019},
  volume = {10},
  number = {1},
  pages = {1876},
  url = {http://www.nature.com/articles/s41467-019-09922-3},
  doi = {10.1038/s41467-019-09922-3}
}
Capotondi A, Jacox M, Bowler C, Kavanaugh M, Lehodey P, Barrie D, Brodie S, Chaffron S, Cheng W, Dias DF, Eveillard D, Guidi L, Iudicone D, Lovenduski NS, Nye JA, Ortiz I, Pirhalla D, Pozo Buil M, Saba V, Sheridan S, Siedlecki S, Subramanian A, de Vargas C, Di Lorenzo E, Doney SC, Hermann AJ, Joyce T, Merrifield M, Miller AJ, Not F and Pesant S (2019), "Observational Needs Supporting Marine Ecosystems Modeling and Forecasting: From the Global Ocean to Regional and Coastal Systems". oct, 2019.
Abstract: Many coastal areas host rich marine ecosystems and are also centers of economic activities, including fishing, shipping and recreation. Due to the socioeconomic and ecological importance of these areas, predicting relevant indicators of the ecosystem state on sub-seasonal to interannual timescales is gaining increasing attention. Depending on the application, forecasts may be sought for variables and indicators spanning physics (e.g., sea level, temperature, currents), chemistry (e.g., nutrients, oxygen, pH), and biology (from viruses to top predators). Many components of the marine ecosystem are known to be influenced by leading modes of climate variability, which provide a physical basis for predictability. However, prediction capabilities remain limited by the lack of a clear understanding of the physical and biological processes involved, as well as by insufficient observations for forecast initialization and verification. The situation is further complicated by the influence of climate change on ocean conditions along coastal areas, including sea level rise, increased stratification, and shoaling of oxygen minimum zones. Observations are thus vital to all aspects of marine forecasting: statistical and/or dynamical model development, forecast initialization, and forecast validation, each of which has different observational requirements, which may be also specific to the study region. Here, we use examples from United States (U.S.) coastal applications to identify and describe the key requirements for an observational network that is needed to facilitate improved process understanding, as well as for sustaining operational ecosystem forecasting. We also describe new holistic observational approaches, e.g., approaches based on acoustics, inspired by Tara Oceans or by landscape ecology, which have the potential to support and expand ecosystem modeling and forecasting activities by bridging global and local observations.
BibTeX:
@misc{Capotondi2019,
  author = {Capotondi, Antonietta and Jacox, Michael and Bowler, Chris and Kavanaugh, Maria and Lehodey, Patrick and Barrie, Daniel and Brodie, Stephanie and Chaffron, Samuel and Cheng, Wei and Dias, Daniela F. and Eveillard, Damien and Guidi, Lionel and Iudicone, Daniele and Lovenduski, Nicole S. and Nye, Janet A. and Ortiz, Ivonne and Pirhalla, Douglas and Pozo Buil, Mercedes and Saba, Vincent and Sheridan, Scott and Siedlecki, Samantha and Subramanian, Aneesh and de Vargas, Colomban and Di Lorenzo, Emanuele and Doney, Scott C. and Hermann, Albert J. and Joyce, Terrence and Merrifield, Mark and Miller, Arthur J. and Not, Fabrice and Pesant, Stephane},
  title = {Observational Needs Supporting Marine Ecosystems Modeling and Forecasting: From the Global Ocean to Regional and Coastal Systems},
  booktitle = {Frontiers in Marine Science},
  publisher = {Frontiers Media S.A.},
  year = {2019},
  volume = {6},
  pages = {623},
  url = {https://ec.europa.eu/maritimeaffairs/},
  doi = {10.3389/fmars.2019.00623}
}
Carter BR, Williams NL, Evans W, Fassbender AJ, Barbero L, Hauri C, Feely RA and Sutton AJ (2019), "Time of Detection as a Metric for Prioritizing Between Climate Observation Quality, Frequency, and Duration", Geophysical Research Letters., apr, 2019. Vol. 46(7), pp. 3853-3861. Blackwell Publishing Ltd.
Abstract: We advance a simple framework based on “time of detection” for estimating the observational needs of studies assessing climate changes amidst natural variability and apply it to several examples related to ocean acidification. This approach aims to connect the Global Ocean Acidification Observing Network “weather” and “climate” data quality thresholds with a single dynamic threshold appropriate for a range of potential ocean signals and environments. A key implication of the framework is that measurement frequency can be as important as measurement accuracy, particularly in highly variable environments. Pragmatic cost-benefit analyses based on this framework can be performed to quantitatively determine which observing strategy will accomplish a given detection goal soonest and resolve a signal with the greatest confidence and to assess how the trade-offs between measurement frequency and accuracy vary regionally.
BibTeX:
@article{Carter2019,
  author = {Carter, B. R. and Williams, N. L. and Evans, W. and Fassbender, A. J. and Barbero, L. and Hauri, C. and Feely, R. A. and Sutton, A. J.},
  title = {Time of Detection as a Metric for Prioritizing Between Climate Observation Quality, Frequency, and Duration},
  journal = {Geophysical Research Letters},
  publisher = {Blackwell Publishing Ltd},
  year = {2019},
  volume = {46},
  number = {7},
  pages = {3853--3861},
  url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2018GL080773},
  doi = {10.1029/2018GL080773}
}
Cernusak LA, Haverd V, Brendel O, Le Thiec D, Guehl JM and Cuntz M (2019), "Robust Response of Terrestrial Plants to Rising CO2", Trends in Plant Science., jul, 2019. Vol. 24(7), pp. 578-586. Elsevier BV.
Abstract: Human-caused CO2 emissions over the past century have caused the climate of the Earth to warm and have directly impacted on the functioning of terrestrial plants. We examine the global response of terrestrial gross primary production (GPP) to the historic change in atmospheric CO2. The GPP of the terrestrial biosphere has increased steadily, keeping pace remarkably in proportion to the rise in atmospheric CO2. Water-use efficiency, namely the ratio of CO2 uptake by photosynthesis to water loss by transpiration, has increased as a direct leaf-level effect of rising CO2. This has allowed an increase in global leaf area, which has conspired with stimulation of photosynthesis per unit leaf area to produce a maximal response of the terrestrial biosphere to rising atmospheric CO2 and contemporary climate change.
BibTeX:
@article{Cernusak2019,
  author = {Cernusak, Lucas A and Haverd, Vanessa and Brendel, Oliver and Le Thiec, Didier and Guehl, Jean Marc and Cuntz, Matthias},
  title = {Robust Response of Terrestrial Plants to Rising CO2},
  journal = {Trends in Plant Science},
  publisher = {Elsevier BV},
  year = {2019},
  volume = {24},
  number = {7},
  pages = {578--586},
  doi = {10.1016/j.tplants.2019.04.003}
}
Chen JM, Ju W, Ciais P, Viovy N, Liu R, Liu Y and Lu X (2019), "Vegetation structural change since 1981 significantly enhanced the terrestrial carbon sink", Nature Communications., sep, 2019. Vol. 10(1) Springer Science and Business Media LLC.
Abstract: Satellite observations show that leaf area index (LAI) has increased globally since 1981, but the impact of this vegetation structural change on the global terrestrial carbon cycle has not been systematically evaluated. Through process-based diagnostic ecosystem modeling, we find that the increase in LAI alone was responsible for 12.4% of the accumulated terrestrial carbon sink (95 ± 5 Pg C) from 1981 to 2016, whereas other drivers of CO2 fertilization, nitrogen deposition, and climate change (temperature, radiation, and precipitation) contributed to 47.0%, 1.1%, and âˆ'28.6% of the sink, respectively. The legacy effects of past changes in these drivers prior to 1981 are responsible for the remaining 65.5% of the accumulated sink from 1981 to 2016. These results refine the attribution of the land sink to the various drivers and would help constrain prognostic models that often have large uncertainties in simulating changes in vegetation and their impacts on the global carbon cycle.
BibTeX:
@article{Chen2019,
  author = {Chen, Jing M and Ju, Weimin and Ciais, Philippe and Viovy, Nicolas and Liu, Ronggao and Liu, Yang and Lu, Xuehe},
  title = {Vegetation structural change since 1981 significantly enhanced the terrestrial carbon sink},
  journal = {Nature Communications},
  publisher = {Springer Science and Business Media LLC},
  year = {2019},
  volume = {10},
  number = {1},
  doi = {10.1038/s41467-019-12257-8}
}
Chen Y, Shen W, Gao S, Zhang K, Wang J and Huang N (2019), "Estimating deciduous broadleaf forest gross primary productivity by remote sensing data using a random forest regression model", Journal of Applied Remote Sensing., aug, 2019. Vol. 13(3), pp. 1-17.
BibTeX:
@article{Chen2019a,
  author = {Chen, Yue and Shen, Wei and Gao, Shuai and Zhang, Kun and Wang, Jian and Huang, Ni},
  title = {Estimating deciduous broadleaf forest gross primary productivity by remote sensing data using a random forest regression model},
  journal = {Journal of Applied Remote Sensing},
  year = {2019},
  volume = {13},
  number = {3},
  pages = {1--17},
  url = {https://doi.org/10.1117/1.JRS.13.038502},
  doi = {10.1117/1.JRS.13.038502}
}
Chi J, Nilsson MB, Kljun N, Wallerman J, Fransson JES, Laudon H, Lundmark T and Peichl M (2019), "The carbon balance of a managed boreal landscape measured from a tall tower in northern Sweden", Agricultural and Forest Meteorology., aug, 2019. Vol. 274, pp. 29-41.
Abstract: Boreal forests exchange large amounts of carbon dioxide (CO2) with the atmosphere. A managed boreal landscape usually comprises various potential CO2 sinks and sources across forest stands of varying age classes, clear-cut areas, mires, and lakes. Due to this heterogeneity and complexity, large uncertainties exist regarding the net CO2 balance at the landscape scale. In this study, we present the first estimate of the net CO2 exchange over a managed boreal landscape (∼68 km2) in northern Sweden, based on tall tower eddy covariance measurements. Our results suggest that from March 1, 2016 to February 28, 2018, the heterogeneous landscape was a net CO2 sink with a 2-year mean uptake of âˆ'87 ± 6 g C mâˆ'2 yrâˆ'1. Due to an earlier and warmer spring and sunnier autumn, the landscape was a stronger CO2 sink during the first year (âˆ'122 ± 8 g C mâˆ'2) compared to the second year (âˆ'52 ± 9 g C mâˆ'2). Footprint analysis shows that 87% of the CO2 flux measurements originated from forests, whereas mires, clear-cuts, lakes, and grassland contributed 11%, 1%, 0.7%, and 0.2%, respectively. Altogether, the CO2 sink strength of the heterogeneous landscape was up to 38% lower compared to the sink strength of a mature stand surrounding the tower. Overall, this study suggests that the managed boreal landscape acted as a CO2 sink and advocates tall tower eddy covariance measurements to improve regional carbon budget estimates.
BibTeX:
@article{Chi2019,
  author = {Chi, Jinshu and Nilsson, Mats B and Kljun, Natascha and Wallerman, Jörgen and Fransson, Johan E S and Laudon, Hjalmar and Lundmark, Tomas and Peichl, Matthias},
  title = {The carbon balance of a managed boreal landscape measured from a tall tower in northern Sweden},
  journal = {Agricultural and Forest Meteorology},
  year = {2019},
  volume = {274},
  pages = {29--41},
  url = {https://linkinghub.elsevier.com/retrieve/pii/S0168192319301509},
  doi = {10.1016/j.agrformet.2019.04.010}
}
Chiesa M, Bignotti L, Finco A, Marzuoli R and Gerosa G (2019), "Size-resolved aerosol fluxes above a broadleaved deciduous forest", Agricultural and Forest Meteorology., dec, 2019. Vol. 279, pp. 107757. Elsevier BV.
Abstract: In order to understand the aerosol exchange dynamics between the atmosphere and a peri-urban forest ecosystem located in the Po Valley, a region characterized by high PM concentrations, eddy covariance (EC) aerosol fluxes were measured between September and December 2017. The aerosol sampling, performed with an Electrical Low Pressure Impactor (ELPI +, DEKATI), involved a wide range of particle sizes including both ultrafine and fine aerosol. The monitoring campaign comprised a period with leaves (PL) and a period without leaves (PNL) to assess their influence on the emission and deposition fluxes. The diurnal profiles of particle number (PN) fluxes associated to the geometric mean diameters (GMD) of 0.02 µm and 0.48 µm were chosen as representative of the behaviour of ultrafine and fine particles, respectively. Fluxes of ultrafine particles showed a net emission pattern both in PL and PNL assuming values up to 5.6 106 mâˆ'2 sâˆ'1 and 4.5textperiodcentered106 mâˆ'2 sâˆ'1, respectively. Instead, fine particles fluxes showed a net deposition pattern in PL, assuming values up to âˆ'1.1 textperiodcentered 106 mâˆ'2 sâˆ'1, while in PNL a slight emission up to 4.1 textperiodcentered105 mâˆ'2 sâˆ'1 occurred. The behaviour of the fluxes of the cumulative classes PM0.1 and PM1 was similar to the one of the PN fluxes of ultrafine and fine aerosol, respectively. Deposition velocities were calculated for PL and PNL depending on the atmospheric stability class. The values emerged from this study (from âˆ'0.25 cm sâˆ'1 up to 0.12 cm sâˆ'1) evidenced that under stable and very stable atmospheric conditions all size classes presented negative or slightly positive deposition velocities both in PL and PNL. Instead under unstable conditions fine particles showed deposition velocities whose direction changed in the two periods (PL and PNL).
BibTeX:
@article{Chiesa2019,
  author = {Chiesa, M and Bignotti, L and Finco, A and Marzuoli, R and Gerosa, G},
  title = {Size-resolved aerosol fluxes above a broadleaved deciduous forest},
  journal = {Agricultural and Forest Meteorology},
  publisher = {Elsevier BV},
  year = {2019},
  volume = {279},
  pages = {107757},
  doi = {10.1016/j.agrformet.2019.107757}
}
Ciais P, Tan J, Wang X, Roedenbeck C, Chevallier F, Piao SL, Moriarty R, Broquet G, Le Quéré C, Canadell JG, Peng S, Poulter B, Liu Z and Tans P (2019), "Five decades of northern land carbon uptake revealed by the interhemispheric CO2 gradient", Nature., apr, 2019. Vol. 568(7751), pp. 221-225. Nature Publishing Group.
Abstract: The global land and ocean carbon sinks have increased proportionally with increasing carbon dioxide emissions during the past decades1. It is thought that Northern Hemisphere lands make a dominant contribution to the global land carbon sink2–7; however, the long-term trend of the northern land sink remains uncertain. Here, using measurements of the interhemispheric gradient of atmospheric carbon dioxide from 1958 to 2016, we show that the northern land sink remained stable between the 1960s and the late 1980s, then increased by 0.5 ± 0.4 petagrams of carbon per year during the 1990s and by 0.6 ± 0.5 petagrams of carbon per year during the 2000s. The increase of the northern land sink in the 1990s accounts for 65% of the increase in the global land carbon flux during that period. The subsequent increase in the 2000s is larger than the increase in the global land carbon flux, suggesting a coincident decrease of carbon uptake in the Southern Hemisphere. Comparison of our findings with the simulations of an ensemble of terrestrial carbon models5,8 over the same period suggests that the decadal change in the northern land sink between the 1960s and the 1990s can be explained by a combination of increasing concentrations of atmospheric carbon dioxide, climate variability and changes in land cover. However, the increase during the 2000s is underestimated by all models, which suggests the need for improved consideration of changes in drivers such as nitrogen deposition, diffuse light and land-use change. Overall, our findings underscore the importance of Northern Hemispheric land as a carbon sink.
BibTeX:
@article{Ciais2019,
  author = {Ciais, P. and Tan, J. and Wang, X. and Roedenbeck, C. and Chevallier, F. and Piao, S. L. and Moriarty, R. and Broquet, G. and Le Quéré, C. and Canadell, J. G. and Peng, S. and Poulter, B. and Liu, Z. and Tans, P.},
  title = {Five decades of northern land carbon uptake revealed by the interhemispheric CO2 gradient},
  journal = {Nature},
  publisher = {Nature Publishing Group},
  year = {2019},
  volume = {568},
  number = {7751},
  pages = {221--225},
  url = {https://www.nature.com/articles/s41586-019-1078-6},
  doi = {10.1038/s41586-019-1078-6}
}
Collalti A, Thornton PE, Cescatti A, Rita A, Borghetti M, Nolè A, Trotta C, Ciais P and Matteucci G (2019), "The sensitivity of the forest carbon budget shifts across processes along with stand development and climate change", Ecological Applications., feb, 2019. Vol. 29(2) Wiley.
Abstract: The future trajectory of atmospheric CO2 concentration depends on the development of the terrestrial carbon sink, which in turn is influenced by forest dynamics under changing environmental conditions. An in-depth understanding of model sensitivities and uncertainties in non-steady-state conditions is necessary for reliable and robust projections of forest development and under scenarios of global warming and CO2 enrichment. Here, we systematically assessed if a biogeochemical process-based model (3D-CMCC-CNR), which embeds similarities with many other vegetation models, applied in simulating net primary productivity (NPP) and standing woody biomass (SWB), maintained a consistent sensitivity to its 55 input parameters through time, during forest ageing and structuring as well as under climate change scenarios. Overall, the model applied at three contrasting European forests showed low sensitivity to the majority of its parameters. Interestingly, model sensitivity to parameters varied through the course of 100 yr of simulations. In particular, the model showed a large responsiveness to the allometric parameters used for initialize forest carbon and nitrogen pools early in forest simulation (i.e., for NPP up to ˜37%, 256 g Ctextperiodcenteredmâˆ'2textperiodcenteredyrâˆ'1 and for SWB up to ˜90%, 65 Mg C/ha, when compared to standard simulation), with this sensitivity decreasing sharply during forest development. At medium to longer time scales, and under climate change scenarios, the model became increasingly more sensitive to additional and/or different parameters controlling biomass accumulation and autotrophic respiration (i.e., for NPP up to ˜30%, 167 g Ctextperiodcenteredmâˆ'2textperiodcenteredyrâˆ'1 and for SWB up to ˜24%, 64 Mg C/ha, when compared to standard simulation). Interestingly, model outputs were shown to be more sensitive to parameters and processes controlling stand development rather than to climate change (i.e., warming and changes in atmospheric CO2 concentration) itself although model sensitivities were generally higher under climate change scenarios. Our results suggest the need for sensitivity and uncertainty analyses that cover multiple temporal scales along forest developmental stages to better assess the potential of future forests to act as a global terrestrial carbon sink.
BibTeX:
@article{Collalti2019,
  author = {Collalti, Alessio and Thornton, Peter E and Cescatti, Alessandro and Rita, Angelo and Borghetti, Marco and Nolè, Angelo and Trotta, Carlo and Ciais, Philippe and Matteucci, Giorgio},
  title = {The sensitivity of the forest carbon budget shifts across processes along with stand development and climate change},
  journal = {Ecological Applications},
  publisher = {Wiley},
  year = {2019},
  volume = {29},
  number = {2},
  doi = {10.1002/eap.1837}
}
Conil S, Helle J, Langrene L, Laurent O, Delmotte M and Ramonet M (2019), "Continuous atmospheric CO2, CH4 and CO measurements at the Observatoire Pérenne de l'Environnement (OPE) station in France from 2011 to 2018", Atmospheric Measurement Techniques., dec, 2019. Vol. 12(12), pp. 6361-6383. Copernicus GmbH.
Abstract: Located in north-east France, the Observatoire Pérenne de l'Environnement (OPE) station was built during the Integrated Carbon Observation System (ICOS) Demonstration Experiment to monitor the greenhouse gases mole fraction. Its continental rural background setting fills the gaps between oceanic or mountain stations and urban stations within the ICOS network. Continuous measurements of several greenhouse gases using high-precision spectrometers started in 2011 on a tall tower with three sampling inlets at 10, 50 and 120 m above ground level (a.g.l.). Measurement quality is regularly assessed using several complementary approaches based on reference high-pressure cylinders, audits using travelling instruments and sets of travelling cylinders ("cucumber" intercomparison programme). Thanks to the quality assurance strategy recommended by ICOS, measurement uncertainties are within the World Meteorological Organisation compatibility goals for carbon dioxide (CO2), methane (CH4) and carbon monoxide (CO). The time series of mixing ratios from 2011 to the end of 2018 are used to analyse trends and diurnal and seasonal cycles. The CO2 and CH4 annual growth rates are 2.4 ppm yr-1 and 8.8 ppb yr-1 respectively for measurements at 120 m a.g.l. over the investigated period. However, no significant trend has been recorded for CO mixing ratios. The afternoon mean residuals (defined as the differences between midday observations and a smooth fitted curve) of these three compounds are significantly stronger during the cold period when inter-species correlations are high, compared to the warm period. The variabilities of residuals show a close link with air mass backtrajectories.
BibTeX:
@article{Conil2019,
  author = {Conil, Sébastien and Helle, Julie and Langrene, Laurent and Laurent, Olivier and Delmotte, Marc and Ramonet, Michel},
  title = {Continuous atmospheric CO2, CH4 and CO measurements at the Observatoire Pérenne de l'Environnement (OPE) station in France from 2011 to 2018},
  journal = {Atmospheric Measurement Techniques},
  publisher = {Copernicus GmbH},
  year = {2019},
  volume = {12},
  number = {12},
  pages = {6361--6383},
  doi = {10.5194/amt-12-6361-2019}
}
Conte A, Fares S, Salvati L, Savi F, Matteucci G, Mazzenga F, Spano D, Sirca C, Marras S, Galvagno M, Cremonese E and Montagnani L (2019), "Ecophysiological Responses to Rainfall Variability in Grassland and Forests Along a Latitudinal Gradient in Italy", Frontiers in Forests and Global Change., may, 2019. Vol. 2 Frontiers Media SA.
Abstract: In the Mediterranean region, ecosystems are severely affected by climate variability. The Italian Peninsula is a hot spot for biodiversity thanks to heterogeneous landscape and Mediterranean, Continental, and Alpine climates hosting a broad range of plant functional types along a limited latitudinal range from 40' to 46' N. In this study we applied a comparative approach integrating descriptive statistics, time series analysis, and multivariate techniques to answer the following questions: (i) do the climatic variables affect GPP, Reco, WUE and ET to a similar extent among different sites? (ii) Does a common response pattern exist among ecosystems along a latitudinal gradient in Italy? And, finally (iii) do these ecosystems respond synchronically to meteorological conditions or does a delayed response exists? Six sites along a latitudinal, altitudinal and vegetational gradient from semi-arid (southern Italy) to a mountainous Mediterranean site (central Italy) and sub-humid wet Alpine sites (northern Italy) were considered. For each site, carbon and water fluxes and meteorological data collected during two hydrologically-contrasting years (i.e. a dry and a wet year) were analysed. Principal Component Analysis was adopted to identify temporal and spatial variations in Gross Primary Productivity (GPP), Ecosystem Respiration (Reco), Water Use Efficiency (WUE) and Evapotranspiration (ET). The model outlined differences among Mediterranean semi-arid, Mediterranean mountainous, and Alpine sites in response to contrasting precipitation regimes. GPP, Reco, WUE and ET increased up to 16, 19, 25 and 28 %, respectively in semi-arid Mediterranean sites and up to 15, 32, 15 and 11%, respectively in Alpine sites in the wet year compared to the dry year. Air temperature was revealed to be one of the most important variables affecting GPP, Reco, WUE and ET in all the study sites. While relative air humidity was more important in southern Mediterranean sites, global radiation was more significant in northern Italy. Our work suggests that a realistic prediction of the main responses of Italian forests under climate change should also take in account delayed responses due to acclimation to abiotic stress or changing environmental conditions.
BibTeX:
@article{Conte2019,
  author = {Conte, Adriano and Fares, Silvano and Salvati, Luca and Savi, Flavia and Matteucci, Giorgio and Mazzenga, Francesco and Spano, Donatella and Sirca, Costantino and Marras, Serena and Galvagno, Marta and Cremonese, Edoardo and Montagnani, Leonardo},
  title = {Ecophysiological Responses to Rainfall Variability in Grassland and Forests Along a Latitudinal Gradient in Italy},
  journal = {Frontiers in Forests and Global Change},
  publisher = {Frontiers Media SA},
  year = {2019},
  volume = {2},
  doi = {10.3389/ffgc.2019.00016}
}
Couldrey MP, Oliver KIC, Yool A, Halloran PR and Achterberg EP (2019), "Drivers of 21textlesssuptextgreatersttextless/suptextgreater Century carbon cycle variability in the North Atlantic Ocean", Biogeosciences Discussions., jan, 2019. , pp. 1-33. Copernicus GmbH.
Abstract: textlessptextgreatertextlessstrongtextgreaterAbstract.textless/strongtextgreater The North Atlantic carbon sink is a prominent component of global climate, storing large amounts of atmospheric carbon dioxide (COtextlesssubtextgreater2textless/subtextgreater), but this basin's COtextlesssubtextgreater2textless/subtextgreater uptake variability presents challenges for future climate prediction. A comprehensive mechanistic understanding of the processes that give rise to year-to-year (interannual) and decade-to-decade (decadal) variability in the North Atlantic's dissolved inorganic carbon (DIC) inventory is lacking. Here, we numerically simulate the oceanic response to human-induced (anthropogenic) climate change from the industrial era to the year 2100. The model distinguishes how different physical, chemical, and biological processes modify the basin's DIC inventory; the saturation, soft tissue, and carbonate pumps, anthropogenic emissions, and other processes causing air-sea disequilibria. There are four ‘natural' pools (saturation, soft tissue, carbonate, and disequilibrium), and an ‘anthropogenic' pool. Interannual variability of the North Atlantic DIC inventory arises primarily due to temperature- and alkalinity-induced changes in carbon solubility (saturation concentrations). A mixture of saturation and anthropogenic drivers cause decadal variability. Multidecadal variability results from the opposing effects of saturation versus soft tissue carbon, and anthropogenic carbon uptake. By the year 2100, the North Atlantic gains 66 Pg (1 Pg = 10textlesssuptextgreater15textless/suptextgreater grams) of anthropogenic carbon, and the natural carbon pools collectively decline by 4.8 Pg. The first order controls on interannual variability of the North Atlantic carbon sink size are therefore largely physical, and the biological pump emerges as an important driver of change on multidecadal timescales. Further work should identify specifically which physical processes underlie the interannual saturation-dominated DIC variability documented here.textless/ptextgreater
BibTeX:
@article{Couldrey2019,
  author = {Couldrey, Matthew P. and Oliver, Kevin I. C. and Yool, Andrew and Halloran, Paul R. and Achterberg, Eric P.},
  title = {Drivers of 21textlesssuptextgreatersttextless/suptextgreater Century carbon cycle variability in the North Atlantic Ocean},
  journal = {Biogeosciences Discussions},
  publisher = {Copernicus GmbH},
  year = {2019},
  pages = {1--33},
  doi = {10.5194/bg-2019-16}
}
Crabbe RA, Janouš D, DaÅ™enová E and Pavelka M (2019), "Exploring the potential of LANDSAT-8 for estimation of forest soil CO 2 efflux", International Journal of Applied Earth Observation and Geoinformation., may, 2019. Vol. 77, pp. 42-52. Elsevier BV.
Abstract: Monitoring forest soil carbon dioxide efflux (FCO 2 ) is important as it contributes significantly to terrestrial ecosystem respiration and is hence a major factor in global carbon cycle. FCO 2 monitoring is usually conducted by the use of soil chambers to sample various point positions, but this method is difficult to replicate at spatially large research sites. Satellite remote sensing is accustomed to monitoring environmental phenomenon at large spatial scale, however its utilisation in FCO 2 monitoring is under-explored. To this end, this study explored the potential of LANDSAT-8 to estimate FCO 2 with the specific aims of deriving land surface temperature (LST) from LANDSAT-8 and then develop FCO 2 model on the basis of LANDSAT-8 LST to account for seasonal and inter-annual variations of FCO 2 . The study was conducted over an old European beech forest (Fagus sylvatica) in Czech Republic. In the end, two kinds of linear mixed effect models were built; Model-1 (inter-annual variations of FCO 2 ) and Model-2 (seasonal variations of FCO 2 ). The difference between Model-1 and Model-2 lies in their random factors; while Model-1 has ‘year' of FCO 2 measurement as a random factor, Model-2 has ‘season' of FCO 2 measurement as a random factor. When modelling without random factors, LANDSAT-8 LST as the fixed predictor in both models was able to account for 26% (marginal R 2 = 0.26) of FCO 2 variability in Model-1 whereas it accounted for 29% in Model-2. However, the parameterisation of random effects improved the performance of both models. Model-1 was the best in that it explained 65% (conditional R 2 = 0.65) of variability in FCO 2 and produced the least deviation from observed FCO 2 (RMSE = 0.38 μmol/m 2 /s). This study adds to the limited number of previous similar studies with the aim of encouraging satellite remote sensing integration in FCO 2 observation.
BibTeX:
@article{Crabbe2019,
  author = {Crabbe, Richard A and Janouš, Dalibor and DaÅ™enová, Eva and Pavelka, Marian},
  title = {Exploring the potential of LANDSAT-8 for estimation of forest soil CO 2 efflux},
  journal = {International Journal of Applied Earth Observation and Geoinformation},
  publisher = {Elsevier BV},
  year = {2019},
  volume = {77},
  pages = {42--52},
  doi = {10.1016/j.jag.2018.12.007}
}
Creamean JM, Mignani C, Bukowiecki N and Conen F (2019), "Using freezing spectra characteristics to identify ice-nucleating particle populations during the winter in the Alps", Atmospheric Chemistry and Physics., jun, 2019. Vol. 19(12), pp. 8123-8140.
BibTeX:
@article{Creamean2019,
  author = {Creamean, Jessie M. and Mignani, Claudia and Bukowiecki, Nicolas and Conen, Franz},
  title = {Using freezing spectra characteristics to identify ice-nucleating particle populations during the winter in the Alps},
  journal = {Atmospheric Chemistry and Physics},
  year = {2019},
  volume = {19},
  number = {12},
  pages = {8123--8140},
  url = {https://acp.copernicus.org/articles/19/8123/2019/},
  doi = {10.5194/acp-19-8123-2019}
}
Crowell S, Baker D, Schuh A, Basu S, Jacobson AR, Chevallier F, Liu J, Deng F, Feng L, Mckain K, Chatterjee A, Miller JB, Stephens BB, Eldering A, Crisp D, Schimel D, Nassar R, O'dell CW, Oda T, Sweeney C, Palmer PI and Jones DBA (2019), "The 2015-2016 carbon cycle as seen from OCO-2 and the global in situ network", Atmos. Chem. Phys. Vol. 19, pp. 9797-9831.
Abstract: The Orbiting Carbon Observatory-2 has been on orbit since 2014, and its global coverage holds the potential to reveal new information about the carbon cycle through the use of top-down atmospheric inversion methods combined with column average CO 2 retrievals. We employ a large ensemble of atmospheric inversions utilizing different transport models, data assimilation techniques, and prior flux distributions in order to quantify the satellite-informed fluxes from OCO-2 Version 7r land observations and their uncertainties at continental scales. Additionally, we use in situ measurements to provide a baseline against which to compare the satellite-constrained results. We find that within the ensemble spread, in situ observations, and satellite retrievals constrain a similar global total carbon sink of 3.7 ± 0.5 PgC yr −1 , and 1.5±0.6 PgC yr −1 for global land, for the 2015-2016 annual mean. This agreement breaks down in smaller regions, and we discuss the differences between the experiments. Of particular interest is the difference between the different assimilation constraints in the tropics, with the largest differences occurring in tropical Africa, which could be an indication of the global perturbation from the 2015-2016 El Niño. Evaluation of posterior concentrations using TCCON and aircraft observations gives some limited insight into the quality of the different assimilation constraints, but the lack of such data in the tropics inhibits our ability to make strong conclusions there. Copyright statement. The works published in this journal are distributed under the Creative Commons Attribution 4.0 License. This license does not affect the Crown copyright work, which is re-usable under the Open Government Licence (OGL). The Creative Commons Attribution 4.0 License and the OGL are interoperable and do not conflict with, reduce or limit each other. Published by Copernicus Publications on behalf of the European Geosciences Union. 9798 S. Crowell et al.: The 2015-2016 carbon cycle as seen from OCO-2 and the global in situ network
BibTeX:
@article{Crowell2019,
  author = {Crowell, Sean and Baker, David and Schuh, Andrew and Basu, Sourish and Jacobson, Andrew R and Chevallier, Frederic and Liu, Junjie and Deng, Feng and Feng, Liang and Mckain, Kathryn and Chatterjee, Abhishek and Miller, John B and Stephens, Britton B and Eldering, Annmarie and Crisp, David and Schimel, David and Nassar, Ray and O'dell, Christopher W and Oda, Tomohiro and Sweeney, Colm and Palmer, Paul I and Jones, Dylan B A},
  title = {The 2015-2016 carbon cycle as seen from OCO-2 and the global in situ network},
  journal = {Atmos. Chem. Phys},
  year = {2019},
  volume = {19},
  pages = {9797--9831},
  url = {https://doi.org/10.5194/acp-19-9797-2019},
  doi = {10.5194/acp-19-9797-2019}
}
Cui W and Chui TFM (2019), "Temporal and spatial variations of energy balance closure across FLUXNET research sites", Agricultural and Forest Meteorology., jun, 2019. Vol. 271, pp. 12-21. Elsevier B.V..
Abstract: There is always a discrepancy between available energy and output energy in the surface energy budget of FLUXNET research sites. Using the daily data retrieved from the FLUXNET database, the energy balance closure (EBC) of around 150 sites covering nine land covers and five Köppen climate zones [i.e. tropical area (A), dry area (B), mild temperate area (C), snow area (D) and polar area (E)] was analyzed. The temporal and spatial variations of EBC in different land covers and climate zones were summarized, and the relationships between EBC and environmental variables were explored. The possible differences in the EBCs of sites with open path (OP) and closed path (CP) gas analyzers were also examined at different precipitation levels in various climate zones. The results showed that EBC was positively related to air temperature (Ta) and vapor pressure deficit (VPD) below certain thresholds. Better EBCs were observed in land covers with stable evaporative fraction (i.e. the ratio of latent heat flux to the sum of latent and sensible heat fluxes). For land covers with seasonal varying evaporative fraction, the larger evaporative fraction in summer corresponded with better EBCs. OP systems resulted in better EBCs at various precipitation levels, and EBCs decreased with increasing precipitation for both OP and CP systems. In addition, the relationship between EBC and CO 2 fluxes was different among the different land covers. There was a positive relationship for most land covers but not for savannah, shrub land, and evergreen broadleaf forest. The relationships between EBC and CO 2 as well as EBC and other environmental variables are cross-influenced, which could be related to the stomata aperture and metabolism of the vegetation. Overall, this study summarized patterns of EBCs that could be used to correct eddy covariance data and energy balance closure related models. It further enhanced our understanding of the potential link between EBC and vegetation physiology that could facilitate the modeling and prediction of biophysical processes related to water, energy, and carbon fluxes from the leaf to ecosystem levels.
BibTeX:
@article{Cui2019,
  author = {Cui, Wenhui and Chui, Ting Fong May},
  title = {Temporal and spatial variations of energy balance closure across FLUXNET research sites},
  journal = {Agricultural and Forest Meteorology},
  publisher = {Elsevier B.V.},
  year = {2019},
  volume = {271},
  pages = {12--21},
  doi = {10.1016/j.agrformet.2019.02.026}
}
Dangal SRS, Tian H, Xu R, Chang J, Canadell JG, Ciais P, Pan S, Yang J and Zhang B (2019), "Global Nitrous Oxide Emissions From Pasturelands and Rangelands: Magnitude, Spatiotemporal Patterns, and Attribution", Global Biogeochemical Cycles., feb, 2019. Vol. 33(2), pp. 200-222. American Geophysical Union (AGU).
Abstract: The application of manure and mineral nitrogen (N) fertilizer, and livestock excreta deposition are the main drivers of nitrous oxide (N 2 O) emissions in agricultural systems. However, the magnitude and spatiotemporal variations of N 2 O emissions due to different management practices (excreta deposition and manure/fertilizer application) from grassland ecosystems remain unclear. In this study, we used the Dynamic Land Ecosystem Model to simulate the spatiotemporal variation in global N 2 O emissions and their attribution to different sources from both intensively managed (pasturelands) and extensively managed (rangelands) grasslands during 1961–2014. Over the study period, pasturelands and rangelands experienced a significant increase in N 2 O emissions from 1.74 Tg N 2 O-N in 1961 to 3.11 Tg N 2 O-N in 2014 (p  0.05). Globally, pasturelands and rangelands were responsible for 54% (2.2 Tg N 2 O-N) of the total agricultural N 2 O emissions (4.1 Tg N 2 O-N) in 2006. Natural and anthropogenic sources contributed 26% (0.64 Tg N 2 O-N/year) and 74% (1.78 Tg N 2 O-N/year) of the net emissions, respectively. Across different biomes, pasturelands (i.e., C3 and C4) were the single largest contributor to N 2 O fluxes, accounting for 86% of the net global emissions from grasslands. Among different sources, livestock excreta deposition contributed 54% of the net emissions, followed by manure N (13%) and mineral N (7%) application. Regionally, southern Asia contributed 38% of the total emissions, followed by Europe (29%) and North America (16%). Our modeling study demonstrates that livestock excreta deposition and manure/fertilizer application have dramatically altered the N cycle in pasturelands, with a substantial impact on the climate system.
BibTeX:
@article{Dangal2019,
  author = {Dangal, Shree R S and Tian, Hanqin and Xu, Rongting and Chang, Jinfeng and Canadell, Josep G and Ciais, Philippe and Pan, Shufen and Yang, Jia and Zhang, Bowen},
  title = {Global Nitrous Oxide Emissions From Pasturelands and Rangelands: Magnitude, Spatiotemporal Patterns, and Attribution},
  journal = {Global Biogeochemical Cycles},
  publisher = {American Geophysical Union (AGU)},
  year = {2019},
  volume = {33},
  number = {2},
  pages = {200--222},
  doi = {10.1029/2018GB006091}
}
Darenova E, Dušek J and Mžourková-Macalková L (2019), "Are the hydrophobic membrane tubes suitable for instantaneous soil CO 2 concentration measurements?", In Indian Journal of Geo Marine Sciences. Vol. 48(02), pp. 223-227.
BibTeX:
@techreport{Darenova2019,
  author = {Darenova, Eva and Dušek, Jiří and Mžourková-Macalková, Lenka},
  title = {Are the hydrophobic membrane tubes suitable for instantaneous soil CO 2 concentration measurements?},
  booktitle = {Indian Journal of Geo Marine Sciences},
  year = {2019},
  volume = {48},
  number = {02},
  pages = {223--227}
}
Darenova E, Szatniewska J, Acosta M and Pavelka M (2019), "Variability of stem CO2 efflux response to temperature over the diel period", Tree Physiology., dec, 2019. Vol. 39(5), pp. 877-887. Oxford University Press (OUP).
Abstract: This study presents results from continuous measurements of stem CO2 efflux carried out for seven growing seasons in a young Norway spruce forest. The objective of the study was to determine differences in temperature sensitivity of stem CO2 efflux (Q10) during night (when sap flow is zero or nearly zero), during early afternoon (when the maximum rate of sap flow occurs) and during two transition periods between the aforementioned periods. The highest Q10 was recorded during the period of zero sap flow, while the lowest Q10 was observed in period of the highest sap flow. Calculating Q10 using only data from the period of zero sap flow resulted in a Q10 that was higher by as much as 19% compared with Q10 calculated using 24 h data. On the other hand, basing the calculation on data from the period of the highest sap flow yielded 5.6% lower Q10 than if 24 h data were used. Considering that change in CO2 efflux lagged in time behind changing stem temperature, there was only a small effect on calculated Q10 for periods with zero and the highest sap flow. A larger effect of the time lag (by as much as 15%) was observed for the two transition periods. Stem CO2 efflux was modelled based on the night CO2 efflux response to temperature. This model had a tendency to overestimate CO2 efflux during daytime, thus indicating potential daytime depression of stem CO2 efflux compared with the values predicated on the basis of temperature caused by CO2 transport upward in the sap flow. This view was supported by our results inasmuch as the overestimation grew with sap flow that was modelled on the basis of photosynthetically active radiation and vapour pressure deficit.
BibTeX:
@article{Darenova2019a,
  author = {Darenova, Eva and Szatniewska, Justyna and Acosta, Manuel and Pavelka, Marian},
  editor = {Ryan, Michael},
  title = {Variability of stem CO2 efflux response to temperature over the diel period},
  journal = {Tree Physiology},
  publisher = {Oxford University Press (OUP)},
  year = {2019},
  volume = {39},
  number = {5},
  pages = {877--887},
  doi = {10.1093/treephys/tpy134}
}
Davis RE, Talley LD, Roemmich D, Owens WB, Rudnick DL, Toole J, Weller R, McPhaden MJ and Barth JA (2019), "100 Years of Progress in Ocean Observing Systems", Meteorological Monographs., jan, 2019. Vol. 59, pp. 3.1-3.46. American Meteorological Society.
Abstract: The history of over 100 years of observing the ocean is reviewed. The evolution of particular classes of ocean measurements (e.g., shipboard hydrography, moorings, and drifting floats) are summarized along with some of the discoveries and dynamical understanding they made possible. By the 1970s, isolated and “expedition” observational approaches were evolving into experimental campaigns that covered large ocean areas and addressed multiscale phenomena using diverse instrumental suites and associated modeling and analysis teams. The Mid-Ocean Dynamics Experiment (MODE) addressed mesoscale “eddies” and their interaction with larger-scale currents using new ocean modeling and experiment design techniques and a suite of developing observational methods. Following MODE, new instrument networks were established to study processes that dominated ocean behavior in different regions. The Tropical Ocean Global Atmosphere program gathered multiyear time series in the tropical Pacific to understand, and eventually predict, evolution of coupled ocean–atmosphere phenomena like El Niño–Southern Oscillation (ENSO). The World Ocean Circulation Experiment (WOCE) sought to quantify ocean transport throughout the global ocean using temperature, salinity, and other tracer measurements along with fewer direct velocity measurements with floats and moorings. Western and eastern boundary currents attracted comprehensive measurements, and various coastal regions, each with its unique scientific and societally important phenomena, became home to regional observing systems. Today, the trend toward networked observing arrays of many instrument types continues to be a productive way to understand and predict large-scale ocean phenomena.
BibTeX:
@article{Davis2019,
  author = {Davis, Russ E. and Talley, Lynne D. and Roemmich, Dean and Owens, W. Brechner and Rudnick, Daniel L. and Toole, John and Weller, Robert and McPhaden, Michael J. and Barth, John A.},
  title = {100 Years of Progress in Ocean Observing Systems},
  journal = {Meteorological Monographs},
  publisher = {American Meteorological Society},
  year = {2019},
  volume = {59},
  pages = {3.1--3.46},
  url = {http://journals.ametsoc.org/mono/article-pdf/doi/10.1175/AMSMONOGRAPHS-D-18-0014.1/4941360/amsmonographs-d-18-0014_1.pdf},
  doi = {10.1175/amsmonographs-d-18-0014.1}
}
De Marco A, Proietti C, Anav A, Ciancarella L, D'Elia I, Fares S, Fornasier MF, Fusaro L, Gualtieri M, Manes F, Marchetto A, Mircea M, Paoletti E, Piersanti A, Rogora M, Salvati L, Salvatori E, Screpanti A, Vialetto G, Vitale M and Leonardi C (2019), "Impacts of air pollution on human and ecosystem health, and implications for the National Emission Ceilings Directive: Insights from Italy", Environment International., apr, 2019. Vol. 125, pp. 320-333. Elsevier BV.
Abstract: Across the 28 EU member states there were nearly half a million premature deaths in 2015 as a result of exposure to PM2.5, O3 and NO2. To set the target for air quality levels and avoid negative impacts for human and ecosystems health, the National Emission Ceilings Directive (NECD, 2016/2284/EU) sets objectives for emission reduction for SO2, NOx, NMVOCs, NH3 and PM2.5 for each Member State as percentages of reduction to be reached in 2020 and 2030 compared to the emission levels into 2005. One of the innovations of NECD is Article 9, that mentions the issue of “monitoring air pollution impacts” on ecosystems. We provide a clear picture of what is available in term of monitoring network for air pollution impacts on Italian ecosystems, summarizing what has been done to control air pollution and its effects on different ecosystems in Italy. We provide an overview of the impacts of air pollution on health of the Italian population and evaluate opportunities and implementation of Article 9 in the Italian context, as a case study beneficial for all Member States. The results showed that SO42âˆ' deposition strongly decreased in all monitoring sites in Italy over the period 1999–2017, while NO3âˆ' and NH4+ decreased more slightly. As a consequence, most of the acid-sensitive sites which underwent acidification in the 1980s partially recovered. The O3 concentration at forest sites showed a decreasing trend. Consequently, AOT40 (the metric identified to protect vegetation from ozone pollution) showed a decrease, even if values were still above the limit for forest protection (5000 ppb hâˆ'1), while PODy (flux-based metric under discussion as new European legislative standard for forest protection) showed an increase. National scale studies pointed out that PM10 and NO2 induced about 58,000 premature deaths (year 2005), due to cardiovascular and respiratory diseases. The network identified for Italy contains a good number of monitoring sites (6 for terrestrial ecosystem monitoring, 4 for water bodies monitoring and 11 for ozone impact monitoring) distributed over the territory and will produce a high number of monitored parameters for the implementation of the NECD.
BibTeX:
@article{DeMarco2019,
  author = {De Marco, Alessandra and Proietti, Chiara and Anav, Alessandro and Ciancarella, Luisella and D'Elia, Ilaria and Fares, Silvano and Fornasier, Maria Francesca and Fusaro, Lina and Gualtieri, Maurizio and Manes, Fausto and Marchetto, Aldo and Mircea, Mihaela and Paoletti, Elena and Piersanti, Antonio and Rogora, Michela and Salvati, Luca and Salvatori, Elisabetta and Screpanti, Augusto and Vialetto, Giovanni and Vitale, Marcello and Leonardi, Cristina},
  title = {Impacts of air pollution on human and ecosystem health, and implications for the National Emission Ceilings Directive: Insights from Italy},
  journal = {Environment International},
  publisher = {Elsevier BV},
  year = {2019},
  volume = {125},
  pages = {320--333},
  doi = {10.1016/j.envint.2019.01.064}
}
DeCola P, Tarasova O, Brunner D, Maksyutov S, Manning A, Vogel F, Gurney K, Turnbull J, Zavala-Araiza D, Kort E, Robinson R, Canadell P, Ciais P, Vladu F, Houweling S, Lauvaux T, Mueller K, Vermeulen A(LU and Al. E (2019), "An Integrated Global Greenhouse Gas Information System (IG3IS) Science Implementation Plane - GAW Report No. 245". Thesis at: WMO. Geneva , pp. 62.
Abstract: The implementation of the Paris Agreement will require countries and sub-national entities to take actions to reduce emissions of greenhouse gases in an optimal way. To assist the countries in meeting their commitments the World Meteorological Organization (WMO) and its partners have initiated the development of an Integrated Global Greenhouse Gas Information System (IG3IS). IG3IS looks to serve users (decision-makers) who are able and willing to take actions to reduce emissions of greenhouse gases and pollutants that reduce air quality. This service is based on existing and successful methods and use-cases for which the scientific and technical skill is proven or emerging. The Science Implementation Plan presents the suite of the technical solutions that are available to address articulated user needs on different scales (from national to facility). It also paves the way for the development of future solutions where additional research is required. This document presents the main principles of the IG3IS Science Implementation Plan. The choice of the objective to be implemented has to be made by the countries or sub-national implementation bodies/practitioners. For each individual objective, the plan presents the available and proven tools based on measurements and model analyses. It summarizes key elements required to implement individual solutions. The plan describes the approach to the modelling coordination activities to ensure harmonized and quality assured global implementation and compatibility of the products delivered on different scales. The measure of success of the IG3IS implementation is the use of the provided information for valuable and additional emission reduction actions, building user confidence and practitioner skills in the value of atmospheric composition measurements as an essential part of the climate change mitigation and pollution remediation tool kits. The IG3IS team defined four implementation objectives: 1) improve knowledge of national emissions (including reduction of uncertainties of inventory reporting to the United Nations Framework Convention on Climate Change (UNFCCC)); 2) locate and quantify previously unknown emission reduction opportunities such as fugitive methane emissions from industrial sources; 3) provide sub-national entities such as large urban source regions (for example, megacities) with timely and quantified information on the amounts, trends and attribution by sector of their greenhouse gas (GHG) emissions to evaluate and guide progress towards emission reduction goals; and 4) support for the Paris Agreement's global stocktake through the integration of these objectives. This Science Implementation Plan documents the “good-practice” methodological guidelines for how atmospheric measurements and analysis methods can deliver valuable information under each objective area. This plan and the team that prepared it, will serve to guide WMO Members and their partners in the definition and implementation of new IG3IS projects that apply and advance these “good-practice” capabilities. The plan will evolve overtime to respond to new policy challenges and to capture emerging capabilities. Successful application of IG3IS methods depends on intimate dialogue between scientists and users in order to ensure that user requirements are met, and so that users are introduced to previously unknown capabilities that may drive them to address challenges in new ways. IG3IS takes a highly collaborative “Translation Atmospheric Sciences” approach to deliver science-based services to potential stakeholders/users and is well in line with the implementation plan of the Global Atmosphere Watch (GAW) Programme. The plan directly supports implementation of the WMO Strategic Plan for 2020-2023, Objective 3.2 “Advance policy-relevant science”.
BibTeX:
@techreport{DeCola2019,
  author = {DeCola, Phil and Tarasova, Oksana and Brunner, Dominik and Maksyutov, Shamil and Manning, Alistair and Vogel, Felix and Gurney, Kevin and Turnbull, Jocelyn and Zavala-Araiza, Daniel and Kort, Eric and Robinson, Rod and Canadell, Pep and Ciais, Philippe and Vladu, Florin and Houweling, Sander and Lauvaux, Thomas and Mueller, Kim and Vermeulen, Alex (Lund University) and Al., Et},
  title = {An Integrated Global Greenhouse Gas Information System (IG3IS) Science Implementation Plane - GAW Report No. 245},
  school = {WMO},
  year = {2019},
  pages = {62},
  url = {https://library.wmo.int/index.php?lvl=etagere_see&id=144#.WK2TTBiZNB}
}
Deirmendjian L, Anschutz P, Morel C, Mollier A, Augusto L, Loustau D, Cotovicz LC, Buquet D, Lajaunie K, Chaillou G, Voltz B, Charbonnier C, Poirier D and Abril G (2019), "Importance of the vegetation-groundwater-stream continuum to understand transformation of biogenic carbon in aquatic systems – A case study based on a pine-maize comparison in a lowland sandy watershed (Landes de Gascogne, SW France)", Science of the Total Environment., apr, 2019. Vol. 661, pp. 613-629. Elsevier BV.
Abstract: During land-aquatic transfer, carbon (C) and inorganic nutrients (IN) are transformed in soils, groundwater, and at the groundwater-surface water interface as well as in stream channels and stream sediments. However, processes and factors controlling these transfers and transformations are not well constrained, particularly with respect to land use effect. We compared C and IN concentrations in shallow groundwater and first-order streams of a sandy lowland catchment dominated by two types of land use: pine forest and maize cropland. Contrary to forest groundwater, crop groundwater exhibited oxic conditions all-year round as a result of higher evapotranspiration and better lateral drainage that decreased the water table below the organic-rich soil horizon, prevented the leaching of soil-generated dissolved organic carbon (DOC) in groundwater, and thus limited consumption of dissolved oxygen (O 2 ). In crop groundwater, oxic conditions inhibited denitrification and methanogenesis resulting in high nitrate (NO 3âˆ' ; on average 1140 ± 485 μmol L âˆ'1 ) and low methane (CH 4 ; 40 ± 25 nmol L âˆ'1 ) concentrations. Conversely, anoxic conditions in forest groundwater led to lower NO 3âˆ' (25 ± 40 μmol L âˆ' 1) and higher CH 4 (1770 ± 1830 nmol L âˆ'1 ) concentrations. The partial pressure of carbon dioxide (pCO 2 ; 30,650 ± 11,590 ppmv) in crop groundwater was significantly lower than in forest groundwater (50,630 ± 26,070 ppmv), and was apparently caused by the deeper water table delaying downward diffusion of soil CO 2 to the water table. In contrast, pCO 2 was not significantly different in crop (4480 ± 2680 ppmv) and forest (4900 ± 4500 ppmv) streams, suggesting faster degassing in forest streams resulting from greater water turbulence. Although NO 3âˆ' concentrations indicated that denitrification occurred in riparian-forest groundwater, crop streams nevertheless exhibited important signs of spring and summer eutrophication such as the development of macrophytes. Stream eutrophication favored development of anaerobic conditions in crop stream sediments, as evidenced by increased ammonia (NH 4+ ) and CH 4 in stream waters and concomitant decreased in NO 3âˆ' concentrations as a result of sediment denitrification. In crop streams, dredging and erosion of streambed sediments during winter sustained high concentration of particulate organic C, NH 4+ and CH 4 . In forest streams, dissolved iron (Fe 2+ ), NH 4+ and CH 4 were negatively correlated with O 2 reflecting the gradual oxygenation of stream water and associated oxidations of Fe 2+ , NH 4+ and CH 4 . The results overall showed that forest groundwater behaved as source of CO 2 and CH 4 to streams, the intensity depending on the hydrological connectivity among soils, groundwater, and streams. CH 4 production was prevented in cropland in soils and groundwater, however crop groundwater acted as a source of CO 2 to streams (but less so than forest groundwater). Conversely, in streams, pCO 2 was not significantly affected by land use while CH 4 production was enhanced by cropland. At the catchment scale, this study found substantial biogeochemical heterogeneity in C and IN concentrations between forest and crop waters, demonstrating the importance of including the full vegetation-groundwater-stream continuum when estimating land-water fluxes of C (and nitrogen) and attempting to understand their spatial and temporal dynamics.
BibTeX:
@article{Deirmendjian2019,
  author = {Deirmendjian, Loris and Anschutz, Pierre and Morel, Christian and Mollier, Alain and Augusto, Laurent and Loustau, Denis and Cotovicz, Luiz Carlos and Buquet, Damien and Lajaunie, Katixa and Chaillou, Gwenaëlle and Voltz, Baptiste and Charbonnier, Céline and Poirier, Dominique and Abril, Gwenaël},
  title = {Importance of the vegetation-groundwater-stream continuum to understand transformation of biogenic carbon in aquatic systems – A case study based on a pine-maize comparison in a lowland sandy watershed (Landes de Gascogne, SW France)},
  journal = {Science of the Total Environment},
  publisher = {Elsevier BV},
  year = {2019},
  volume = {661},
  pages = {613--629},
  doi = {10.1016/j.scitotenv.2019.01.152}
}
Delon C, Galy-Lacaux C, Serça D, Personne E, Mougin E, Adon M, Le Dantec V, Loubet B, Fensholt R and Tagesson T (2019), "Modelling land-atmosphere daily exchanges of NO, NH3, and CO2 in a semi-arid grazed ecosystem in Senegal", Biogeosciences., may, 2019. Vol. 16(9), pp. 2049-2077. Copernicus GmbH.
Abstract: Three different models (STEP-GENDEC-NOflux, Zhang2010, and Surfatm) are used to simulate NO, CO2, and NH3 fluxes at the daily scale for 2 years (2012-2013) in a semi-arid grazed ecosystem at Dahra (15°24′10′ ′ N, 15°25′56′ ′W, Senegal, Sahel). Model results are evaluated against experimental results acquired during three field campaigns. At the end of the dry season, when the first rains re-wet the dry soils, the model STEP-GENDEC-NOflux simulates the sudden mineralization of buried litter, leading to pulses in soil respiration and NO fluxes. The contribution of wet season fluxes of NO and CO2 to the annual mean is respectively 51% and 57 %. NH3 fluxes are simulated by two models: Surfatm and Zhang2010. During the wet season, air humidity and soil moisture increase, leading to a transition between low soil NH3 emissions (which dominate during the dry months) and large NH3 deposition on vegetation during wet months. Results show a great impact of the soil emission potential, a difference in the deposition processes on the soil and the vegetation between the two models with however a close agreement of the total fluxes. The order of magnitude of NO, NH3, and CO2 fluxes is correctly represented by the models, as well as the sharp transitions between seasons, specific to the Sahel region. The role of soil moisture in flux magnitude is highlighted, whereas the role of soil temperature is less obvious. The simultaneous increase in NO and CO2 emissions and NH3 deposition at the beginning of the wet season is attributed to the availability of mineral nitrogen in the soil and also to microbial processes, which distribute the roles between respiration (CO2 emissions), nitrification (NO emissions), volatilization, and deposition (NH3 emission/deposition). The objectives of this study are to understand the origin of carbon and nitrogen compounds exchanges between the soil and the atmosphere and to quantify these exchanges on a longer timescale when only a few measurements have been performed.
BibTeX:
@article{Delon2019,
  author = {Delon, Claire and Galy-Lacaux, Corinne and Serça, Dominique and Personne, Erwan and Mougin, Eric and Adon, Marcellin and Le Dantec, Valérie and Loubet, Benjamin and Fensholt, Rasmus and Tagesson, Torbern},
  title = {Modelling land-atmosphere daily exchanges of NO, NH3, and CO2 in a semi-arid grazed ecosystem in Senegal},
  journal = {Biogeosciences},
  publisher = {Copernicus GmbH},
  year = {2019},
  volume = {16},
  number = {9},
  pages = {2049--2077},
  doi = {10.5194/bg-16-2049-2019}
}
Denvil-Sommer A, Gehlen M, Vrac M and Mejia C (2019), "LSCE-FFNN-v1: a two-step neural network model for the reconstruction of surface ocean <i>p</i>CO<sub>2</sub> over the global ocean", Geoscientific Model Development., may, 2019. Vol. 12(5), pp. 2091-2105. Copernicus GmbH.
Abstract: textlessptextgreatertextless![CDATA[Abstract. A new feed-forward neural network (FFNN) model is presented to reconstruct surface ocean partial pressure of carbon dioxide (pCO2) over the global ocean. The model consists of two steps: (1) the reconstruction of pCO2 climatology, and (2) the reconstruction of pCO2 anomalies with respect to the climatology. For the first step, a gridded climatology was used as the target, along with sea surface salinity (SSS), sea surface temperature (SST), sea surface height (SSH), chlorophyll a (Chl a), mixed layer depth (MLD), as well as latitude and longitude as predictors. For the second step, data from the Surface Ocean CO2 Atlas (SOCAT) provided the target. The same set of predictors was used during step (2) augmented by their anomalies. During each step, the FFNN model reconstructs the nonlinear relationships between pCO2 and the ocean predictors. It provides monthly surface ocean pCO2 distributions on a 1∘×1∘ grid for the period from 2001 to 2016. Global ocean pCO2 was reconstructed with satisfying accuracy compared with independent observational data from SOCAT. However, errors were larger in regions with poor data coverage (e.g., the Indian Ocean, the Southern Ocean and the subpolar Pacific). The model captured the strong interannual variability of surface ocean pCO2 with reasonable skill over the equatorial Pacific associated with ENSO (the El Niño–Southern Oscillation). Our model was compared to three pCO2 mapping methods that participated in the Surface Ocean pCO2 Mapping intercomparison (SOCOM) initiative. We found a good agreement in seasonal and interannual variability between the models over the global ocean. However, important differences still exist at the regional scale, especially in the Southern Hemisphere and, in particular, in the southern Pacific and the Indian Ocean, as these regions suffer from poor data coverage. Large regional uncertainties in reconstructed surface ocean pCO2 and sea–air CO2 fluxes have a strong influence on global estimates of CO2 fluxes and trends.]]textgreatertextless/ptextgreater
BibTeX:
@article{Denvil-Sommer2019,
  author = {Denvil-Sommer, Anna and Gehlen, Marion and Vrac, Mathieu and Mejia, Carlos},
  title = {LSCE-FFNN-v1: a two-step neural network model for the reconstruction of surface ocean <i>p</i>CO<sub>2</sub> over the global ocean},
  journal = {Geoscientific Model Development},
  publisher = {Copernicus GmbH},
  year = {2019},
  volume = {12},
  number = {5},
  pages = {2091--2105},
  url = {https://gmd.copernicus.org/articles/12/2091/2019/},
  doi = {10.5194/gmd-12-2091-2019}
}
DeVries T, Le Quéré C, Andrews O, Berthet S, Hauck J, Ilyina T, Landschützer P, Lenton A, Lima ID, Nowicki M, Schwinger J and Séférian R (2019), "Decadal trends in the ocean carbon sink", Proceedings of the National Academy of Sciences of the United States of America., jun, 2019. Vol. 116(24), pp. 11646-11651. National Academy of Sciences.
Abstract: Measurements show large decadal variability in the rate of CO2 accumulation in the atmosphere that is not driven by CO2 emissions. The decade of the 1990s experienced enhanced carbon accumulation in the atmosphere relative to emissions, while in the 2000s, the atmospheric growth rate slowed, even though emissions grew rapidly. These variations are driven by natural sources and sinks of CO2 due to the ocean and the terrestrial biosphere. In this study, we compare three independent methods for estimating oceanic CO2 uptake and find that the ocean carbon sink could be responsible for up to 40% of the observed decadal variability in atmospheric CO2 accumulation. Data-based estimates of the ocean carbon sink from pCO2 mapping methods and decadal ocean inverse models generally agree on the magnitude and sign of decadal variability in the ocean CO2 sink at both global and regional scales. Simulations with ocean biogeochemical models confirm that climate variability drove the observed decadal trends in ocean CO2 uptake, but also demonstrate that the sensitivity of ocean CO2 uptake to climate variability may be too weak in models. Furthermore, all estimates point toward coherent decadal variability in the oceanic and terrestrial CO2 sinks, and this variability is not well-matched by current global vegetation models. Reconciling these differences will help to constrain the sensitivity of oceanic and terrestrial CO2 uptake to climate variability and lead to improved climate projections and decadal climate predictions.
BibTeX:
@article{DeVries2019,
  author = {DeVries, Tim and Le Quéré, Corinne and Andrews, Oliver and Berthet, Sarah and Hauck, Judith and Ilyina, Tatiana and Landschützer, Peter and Lenton, Andrew and Lima, Ivan D. and Nowicki, Michael and Schwinger, Jörg and Séférian, Roland},
  title = {Decadal trends in the ocean carbon sink},
  journal = {Proceedings of the National Academy of Sciences of the United States of America},
  publisher = {National Academy of Sciences},
  year = {2019},
  volume = {116},
  number = {24},
  pages = {11646--11651},
  url = {https://www.pnas.org/content/116/24/11646 https://www.pnas.org/content/116/24/11646.abstract},
  doi = {10.1073/pnas.1900371116}
}
Djomo SN, De Groote T, Gobin A, Ceulemans R and Janssens IA (2019), "Combining a land surface model with life cycle assessment for identifying the optimal management of short rotation coppice in Belgium", Biomass and Bioenergy., feb, 2019. Vol. 121, pp. 78-88. Elsevier BV.
Abstract: Poplar (Populus spp.) and willow (Salix spp.) short rotation coppice (SRC) are attractive feedstock for conversion to renewable electricity. Site managers typically optimize biomass production at their sites. However, maximum biomass production does not necessarily equate an optimal CO2 balance, water use and energy production. This is because many operational actions consume water and energy and emit CO2, either on-site or off-site. Coupling a land surface model (ORCHIDEE-SRC) with life cycle assessment enabled us to determine the optimal management for SRC in Belgium. We simulated 120 different management scenarios for each of two well-studied Belgian SRC sites (i.e. Boom and Lochristi). Simulated soil carbon changes suggested substantial carbon losses of 20–30 Mg haâˆ'1 over a time period of 20 years, which were within observation-based uncertainty bounds. Results showed that in Belgium, which has a temperate maritime climate, optimal management of SRC has a rotation cycle of two years without irrigation. Energy inputs for this optimal management were 5.2 GJ haâˆ'1 yrâˆ'1 for the Boom site and 5.3 GJ haâˆ'1 yrâˆ'1 for the Lochristi site, while the biomass yields at Boom and Lochristi were 9.0 Mg haâˆ'1 yrâˆ'1 and 9.4 Mg haâˆ'1 yrâˆ'1, respectively. The energy ratio (i.e., ratio of bioelectricity output to cumulative energy input) for this optimal management was 12, on average. Planting density turned out to be unimportant, while rotation length turned out to be most important to obtain the highest energy ratio and still maintain high biomass yield. Scenarios with high energy-input generated more bioenergy outputs, but the energy gains did not compensate for the increased energy inputs. Reductions in energy consumption per unit of bioenergy output should target the agricultural stage since it accounted for the largest energy share in the production chain.
BibTeX:
@article{Djomo2019,
  author = {Djomo, S Njakou and De Groote, T and Gobin, A and Ceulemans, R and Janssens, I A},
  title = {Combining a land surface model with life cycle assessment for identifying the optimal management of short rotation coppice in Belgium},
  journal = {Biomass and Bioenergy},
  publisher = {Elsevier BV},
  year = {2019},
  volume = {121},
  pages = {78--88},
  doi = {10.1016/j.biombioe.2018.12.010}
}
Draper C and Reichle RH (2019), "Assimilation of satellite soil moisture for improved atmospheric reanalyses", Monthly Weather Review., jun, 2019. Vol. 147(6), pp. 2163-2188. American Meteorological Society.
Abstract: A newly developed, weakly coupled land and atmosphere data assimilation system for NASA's Global Earth Observing System model is presented, and used to demonstrate the benefit of assimilating satellite soil moisture into an atmospheric reanalysis. Specifically, Advanced Scatterometer and Soil Moisture Ocean Salinity soil moisture retrievals are assimilated into a system that uses the same model, atmospheric assimilation system, and atmospheric observations as the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2). The atmosphere is sensitive to soil moisture only under certain conditions. Hence, while the globally averaged model improvements were small, regionally, the soil moisture assimilation induced some substantial improvements. For example, in a large region spanning from western Europe across southern Russia, the soil moisture assimilation decreased the RMSE against independent station observations of daily maximum 2-m temperature (Tmax2m ) by up to 0.4 K, and of 2-m specific humidity (q2m) by up to 0.5 g kg-1. Over all available stations, the mean Tmax2m RMSE was reduced from 2.82 to 2.79 K, while the mean q2m RMSE was reduced from 1.25 to 1.20 g kg-1. The soil moisture assimilation also reduced the mean RMSE across 29 flux tower sites from 34.2 to 32.6Wm-2 for latent heating, and from 37.7 to 36.5Wm-2 for sensible heating. For all variables evaluated, the soil moisture assimilation improved the model at monthly to seasonal, rather than daily, time scales. Based on the above experiments, it is recommended that satellite soil moisture be assimilated into future reanalyses, including the follow-on to MERRA-2.
BibTeX:
@article{Draper2019,
  author = {Draper, Clara and Reichle, Rolf H.},
  title = {Assimilation of satellite soil moisture for improved atmospheric reanalyses},
  journal = {Monthly Weather Review},
  publisher = {American Meteorological Society},
  year = {2019},
  volume = {147},
  number = {6},
  pages = {2163--2188},
  doi = {10.1175/MWR-D-18-0393.1}
}
Druel A, Ciais P, Krinner G and Peylin P (2019), "Modeling the Vegetation Dynamics of Northern Shrubs and Mosses in the ORCHIDEE Land Surface Model", Journal of Advances in Modeling Earth Systems., jul, 2019. Vol. 11(7), pp. 2020-2035. American Geophysical Union (AGU).
Abstract: Parameterizations of plant competition processes involving shrubs, mosses, grasses, and trees were introduced with the recently implemented shrubs and mosses plant functional types in the ORCHIDEE dynamic global vegetation model in order to improve the representation of high latitude vegetation dynamics. Competition is based on light capture for growth, net primary productivity, and survival to cold-induced mortality during winter. Trees are assumed to outcompete shrubs and grasses for light, and shrubs outcompete grasses. Shrubs are modeled to have a higher survival than trees to extremely cold winters because of thermic protection by snow. The fractional coverage of each plant type is based on their respective net primary productivity and winter mortality of trees and shrubs. Gridded simulations were carried out for the historical period and the 21st century following the RCP4.5 and 8.5 scenarios. We evaluate the simulated present-day vegetation with an observation-based distribution map and literature data of boreal shrubs. The simulation produces a realistic present-day boreal vegetation distribution, with shrubs, mosses north of trees and grasses. Nevertheless, the model underestimated local shrub expansion compared to observations from selected sites in the Arctic during the last 30 years suggesting missing processes (nutrients and microscale effects). The RCP4.5 and RCP8.5 projections show a substantial decrease of bare soil, an increase in tree and moss cover and an increase of shrub net primary productivity. Finally, the impact of new vegetation types and associated processes is discussed in the context of climate feedbacks.
BibTeX:
@article{Druel2019,
  author = {Druel, Arsène and Ciais, Philippe and Krinner, Gerhard and Peylin, Philippe},
  title = {Modeling the Vegetation Dynamics of Northern Shrubs and Mosses in the ORCHIDEE Land Surface Model},
  journal = {Journal of Advances in Modeling Earth Systems},
  publisher = {American Geophysical Union (AGU)},
  year = {2019},
  volume = {11},
  number = {7},
  pages = {2020--2035},
  doi = {10.1029/2018MS001531}
}
Drushka K, Asher WE, Sprintall J, Gille ST and Hoang C (2019), "Global patterns of submesoscale surface salinity variability", Journal of Physical Oceanography., jul, 2019. Vol. 49(7), pp. 1669-1685. American Meteorological Society.
Abstract: Surface salinity variability on O(1–10) km lateral scales (the submesoscale) generates density variability and thus has implications for submesoscale dynamics. Satellite salinity measurements represent a spatial average over horizontal scales of approximately 40–100 km but are compared to point measurements for validation, so submesoscale salinity variability also complicates validation of satellite salinities. Here, we combine several databases of historical thermosalinograph (TSG) measurements made from ships to globally characterize surface submesoscale salinity, temperature, and density variability. In river plumes; regions affected by ice melt or upwelling; and the Gulf Stream, South Atlantic, and Agulhas Currents, submesoscale surface salinity variability is large. In these regions, horizontal salinity variability appears to explain some of the differences between surface salinities from the Aquarius and SMOS satellites and salinities measured with Argo floats. In other words, apparent satellite errors in highly variable regions in fact arise because Argo point measurements do not represent spatially averaged satellite data. Salinity dominates over temperature in generating submesoscale surface density variability throughout the tropical rainbands, in river plumes, and in polar regions. Horizontal density fronts on 10-km scales tend to be compensated (salinity and temperature have opposing effects on density) throughout most of the global oceans, with the exception of the south Indian and southwest Pacific Oceans between 20° and 30°S, where fronts tend to be anticompensated.
BibTeX:
@article{Drushka2019,
  author = {Drushka, Kyla and Asher, William E. and Sprintall, Janet and Gille, Sarah T. and Hoang, Clifford},
  title = {Global patterns of submesoscale surface salinity variability},
  journal = {Journal of Physical Oceanography},
  publisher = {American Meteorological Society},
  year = {2019},
  volume = {49},
  number = {7},
  pages = {1669--1685},
  url = {http://www.legos.obs-mip.fr},
  doi = {10.1175/JPO-D-19-0018.1}
}
Dumortier P, Aubinet M, Lebeau F, Naiken A and Heinesch B (2019), "Point source emission estimation using eddy covariance: Validation using an artificial source experiment", Agricultural and Forest Meteorology. Vol. 266-267, pp. 148-156. Elsevier BV.
Abstract: Eddy covariance is increasingly used to monitor cattle emissions. However, the turbulent flux calculation method and the footprint models upon which calculations are based are insufficiently validated. In addition, available footprint models presume the source to be placed at soil height, which is obviously not the case for cattle. The present study uses a single known artificial point source placed at cow's muzzle height in order to assess the impact of the flux calculation method (averaging method, averaging period, quality filters) and of the footprint model on the emission estimates. The optimal calculation method and footprint model combination (running mean, 15 min averaging periods, no application of the Foken and Wichura (1996) stationarity filter, and the use of the Kormann and Meixner (2001) footprint function) led to estimated emissions between 90 and 113% of the true emission, leading to the conclusion that the use of eddy-covariance for point-source emission estimation is feasible provided an adequate calculation method is selected.
BibTeX:
@article{Dumortier2019,
  author = {Dumortier, Pierre and Aubinet, Marc and Lebeau, Frédéric and Naiken, Alwin and Heinesch, Bernard},
  title = {Point source emission estimation using eddy covariance: Validation using an artificial source experiment},
  journal = {Agricultural and Forest Meteorology},
  publisher = {Elsevier BV},
  year = {2019},
  volume = {266-267},
  pages = {148--156},
  url = {https://doi.org/10.1016%2Fj.agrformet.2018.12.012},
  doi = {10.1016/j.agrformet.2018.12.012}
}
Efren LB, Exbrayat JF, Lund M, Christensen TR, Tamstorf MP, Slevin D, Hugelius G, Bloom AA and Williams M (2019), "Evaluation of terrestrial pan-Arctic carbon cycling using a data-assimilation system", Earth System Dynamics., apr, 2019. Vol. 10(2), pp. 233-255. Copernicus GmbH.
Abstract: There is a significant knowledge gap in the current state of the terrestrial carbon (C) budget. Recent studies have highlighted a poor understanding particularly of C pool transit times and of whether productivity or biomass dominate these biases. The Arctic, accounting for approximately 50% of the global soil organic C stocks, has an important role in the global C cycle. Here, we use the CARbon DAta MOdel (CARDAMOM) data-assimilation system to produce pan-Arctic terrestrial C cycle analyses for 2000-2015. This approach avoids using traditional plant functional type or steady-state assumptions. We integrate a range of data (soil organic C, leaf area index, biomass, and climate) to determine the most likely state of the high-latitude C cycle at a 11 resolution and also to provide general guidance about the controlling biases in transit times. On average, CARDAMOM estimates regional mean rates of photosynthesis of 565 gCm2 yr1 (90% confidence interval between the 5th and 95th percentiles: 428, 741), autotrophic respiration of 270 g Cm2 yr1 (182, 397) and heterotrophic respiration of 219 g Cm2 yr1 (31, 1458), suggesting a pan-Arctic sink of 67 (287, 1160) gCm2 yr1, weaker in tundra and stronger in taiga. However, our confidence intervals remain large (and so the region could be a source of C), reflecting uncertainty assigned to the regional data products. We show a clear spatial and temporal agreement between CARDAMOM analyses and different sources of assimilated and independent data at both pan-Arctic and local scales but also identify consistent biases between CARDAMOM and validation data. The assimilation process requires clearer error quantification for leaf area index (LAI) and biomass products to resolve these biases. Mapping of vegetation C stocks and change over time and soil C ages linked to soil C stocks is required for better analytical constraint. Comparing CARDAMOM analyses to global vegetation models (GVMs) for the same period, we conclude that transit times of vegetation C are inconsistently simulated in GVMs due to a combination of uncertainties from productivity and biomass calculations. Our findings highlight that GVMs need to focus on constraining both current vegetation C stocks and net primary production to improve a process-based understanding of C cycledynamics in the Arctic.
BibTeX:
@article{Efren2019,
  author = {Efren, Lopez Blanco and Exbrayat, Jean Francois and Lund, Magnus and Christensen, Torben R and Tamstorf, Mikkel P and Slevin, Darren and Hugelius, Gustaf and Bloom, Anthony A and Williams, Mathew},
  title = {Evaluation of terrestrial pan-Arctic carbon cycling using a data-assimilation system},
  journal = {Earth System Dynamics},
  publisher = {Copernicus GmbH},
  year = {2019},
  volume = {10},
  number = {2},
  pages = {233--255},
  doi = {10.5194/esd-10-233-2019}
}
Esquivel-Muelbert A, Baker TR, Dexter KG, Lewis SL, Brienen RJW, Feldpausch TR, Lloyd J, Monteagudo-Mendoza A, Arroyo L, Álvarez-Dávila E, Higuchi N, Marimon BS, Marimon-Junior BH, Silveira M, Vilanova E, Gloor E, Malhi Y, Chave J, Barlow J, Bonal D, Davila Cardozo N, Erwin T, Fauset S, Hérault B, Laurance S, Poorter L, Qie L, Stahl C, Sullivan MJP, ter Steege H, Vos VA, Zuidema PA, Almeida E, Almeida de Oliveira E, Andrade A, Vieira SA, Aragão L, Araujo-Murakami A, Arets E, Aymard C GA, Baraloto C, Camargo PB, Barroso JG, Bongers F, Boot R, Camargo JL, Castro W, Chama Moscoso V, Comiskey J, Cornejo Valverde F, Lola da Costa AC, del Aguila Pasquel J, Di Fiore A, Fernanda Duque L, Elias F, Engel J, Flores Llampazo G, Galbraith D, Herrera Fernández R, Honorio Coronado E, Hubau W, Jimenez-Rojas E, Lima AJN, Umetsu RK, Laurance W, Lopez-Gonzalez G, Lovejoy T, Aurelio Melo Cruz O, Morandi PS, Neill D, Núñez Vargas P, Pallqui Camacho NC, Parada Gutierrez A, Pardo G, Peacock J, Peña-Claros M, Peñuela-Mora MC, Petronelli P, Pickavance GC, Pitman N, Prieto A, Quesada C, Ramírez-Angulo H, Réjou-Méchain M, Restrepo Correa Z, Roopsind A, Rudas A, Salomão R, Silva N, Silva Espejo J, Singh J, Stropp J, Terborgh J, Thomas R, Toledo M, Torres-Lezama A, Valenzuela Gamarra L, van de Meer PJ, van der Heijden G, van der Hout P, Vasquez Martinez R, Vela C, Vieira ICG and Phillips OL (2019), "Compositional response of Amazon forests to climate change", Global Change Biology., nov, 2019. Vol. 25(1), pp. 39-56. Wiley.
Abstract: Most of the planet's diversity is concentrated in the tropics, which includes many regions undergoing rapid climate change. Yet, while climate-induced biodiversity changes are widely documented elsewhere, few studies have addressed this issue for lowland tropical ecosystems. Here we investigate whether the floristic and functional composition of intact lowland Amazonian forests have been changing by evaluating records from 106 long-term inventory plots spanning 30Â years. We analyse three traits that have been hypothesized to respond to different environmental drivers (increase in moisture stress and atmospheric CO 2 concentrations): maximum tree size, biogeographic water-deficit affiliation and wood density. Tree communities have become increasingly dominated by large-statured taxa, but to date there has been no detectable change in mean wood density or water deficit affiliation at the community level, despite most forest plots having experienced an intensification of the dry season. However, among newly recruited trees, dry-affiliated genera have become more abundant, while the mortality of wet-affiliated genera has increased in those plots where the dry season has intensified most. Thus, a slow shift to a more dry-affiliated Amazonia is underway, with changes in compositional dynamics (recruits and mortality) consistent with climate-change drivers, but yet to significantly impact whole-community composition. The Amazon observational record suggests that the increase in atmospheric CO 2 is driving a shift within tree communities to large-statured species and that climate changes to date will impact forest composition, but long generation times of tropical trees mean that biodiversity change is lagging behind climate change.
BibTeX:
@article{Esquivel-Muelbert2019,
  author = {Esquivel-Muelbert, Adriane and Baker, Timothy R and Dexter, Kyle G and Lewis, Simon L and Brienen, Roel J W and Feldpausch, Ted R and Lloyd, Jon and Monteagudo-Mendoza, Abel and Arroyo, Luzmila and Álvarez-Dávila, Esteban and Higuchi, Niro and Marimon, Beatriz S and Marimon-Junior, Ben Hur and Silveira, Marcos and Vilanova, Emilio and Gloor, Emanuel and Malhi, Yadvinder and Chave, Jerôme and Barlow, Jos and Bonal, Damien and Davila Cardozo, Nallaret and Erwin, Terry and Fauset, Sophie and Hérault, Bruno and Laurance, Susan and Poorter, Lourens and Qie, Lan and Stahl, Clement and Sullivan, Martin J P and ter Steege, Hans and Vos, Vincent Antoine and Zuidema, Pieter A and Almeida, Everton and Almeida de Oliveira, Edmar and Andrade, Ana and Vieira, Simone Aparecida and Aragão, Luiz and Araujo-Murakami, Alejandro and Arets, Eric and Aymard C, Gerardo A and Baraloto, Christopher and Camargo, Plínio Barbosa and Barroso, Jorcely G and Bongers, Frans and Boot, Rene and Camargo, José Luís and Castro, Wendeson and Chama Moscoso, Victor and Comiskey, James and Cornejo Valverde, Fernando and Lola da Costa, Antonio Carlos and del Aguila Pasquel, Jhon and Di Fiore, Anthony and Fernanda Duque, Luisa and Elias, Fernando and Engel, Julien and Flores Llampazo, Gerardo and Galbraith, David and Herrera Fernández, Rafael and Honorio Coronado, Eurídice and Hubau, Wannes and Jimenez-Rojas, Eliana and Lima, Adriano José Nogueira and Umetsu, Ricardo Keichi and Laurance, William and Lopez-Gonzalez, Gabriela and Lovejoy, Thomas and Aurelio Melo Cruz, Omar and Morandi, Paulo S and Neill, David and Núñez Vargas, Percy and Pallqui Camacho, Nadir C and Parada Gutierrez, Alexander and Pardo, Guido and Peacock, Julie and Peña-Claros, Marielos and Peñuela-Mora, Maria Cristina and Petronelli, Pascal and Pickavance, Georgia C and Pitman, Nigel and Prieto, Adriana and Quesada, Carlos and Ramírez-Angulo, Hirma and Réjou-Méchain, Maxime and Restrepo Correa, Zorayda and Roopsind, Anand and Rudas, Agustín and Salomão, Rafael and Silva, Natalino and Silva Espejo, Javier and Singh, James and Stropp, Juliana and Terborgh, John and Thomas, Raquel and Toledo, Marisol and Torres-Lezama, Armando and Valenzuela Gamarra, Luis and van de Meer, Peter J and van der Heijden, Geertje and van der Hout, Peter and Vasquez Martinez, Rodolfo and Vela, Cesar and Vieira, Ima Célia Guimarães and Phillips, Oliver L},
  title = {Compositional response of Amazon forests to climate change},
  journal = {Global Change Biology},
  publisher = {Wiley},
  year = {2019},
  volume = {25},
  number = {1},
  pages = {39--56},
  doi = {10.1111/gcb.14413}
}
Fan L, Wigneron JP, Ciais P, Chave J, Brandt M, Fensholt R, Saatchi SS, Bastos A, Al-Yaari A, Hufkens K, Qin Y, Xiao X, Chen C, Myneni RB, Fernandez-Moran R, Mialon A, Rodriguez-Fernandez NJ, Kerr Y, Tian F and Peñuelas J (2019), "Satellite-observed pantropical carbon dynamics", Nature Plants., jul, 2019. Vol. 5(9), pp. 944-951. Springer Science and Business Media LLC.
Abstract: Changes in terrestrial tropical carbon stocks have an important role in the global carbon budget. However, current observational tools do not allow accurate and large-scale monitoring of the spatial distribution and dynamics of carbon stocks1. Here, we used low-frequency L-band passive microwave observations to compute a direct and spatially explicit quantification of annual aboveground carbon (AGC) fluxes and show that the tropical net AGC budget was approximately in balance during 2010 to 2017, the net budget being composed of gross losses of âˆ'2.86 PgC yrâˆ'1 offset by gross gains of âˆ'2.97 PgC yrâˆ'1 between continents. Large interannual and spatial fluctuations of tropical AGC were quantified during the wet 2011 La Niña year and throughout the extreme dry and warm 2015–2016 El Niño episode. These interannual fluctuations, controlled predominantly by semiarid biomes, were shown to be closely related to independent global atmospheric CO2 growth-rate anomalies (Pearson's r = 0.86), highlighting the pivotal role of tropical AGC in the global carbon budget.
BibTeX:
@article{Fan2019,
  author = {Fan, Lei and Wigneron, Jean Pierre and Ciais, Philippe and Chave, Jérôme and Brandt, Martin and Fensholt, Rasmus and Saatchi, Sassan S and Bastos, Ana and Al-Yaari, Amen and Hufkens, Koen and Qin, Yuanwei and Xiao, Xiangming and Chen, Chi and Myneni, Ranga B and Fernandez-Moran, Roberto and Mialon, Arnaud and Rodriguez-Fernandez, N J and Kerr, Yann and Tian, Feng and Peñuelas, Josep},
  title = {Satellite-observed pantropical carbon dynamics},
  journal = {Nature Plants},
  publisher = {Springer Science and Business Media LLC},
  year = {2019},
  volume = {5},
  number = {9},
  pages = {944--951},
  doi = {10.1038/s41477-019-0478-9}
}
Fares S, Alivernini A, Conte A and Maggi F (2019), "Ozone and particle fluxes in a Mediterranean forest predicted by the AIRTREE model", Science of the Total Environment., sep, 2019. Vol. 682, pp. 494-504. Elsevier BV.
Abstract: Mediterranean forests are among the most threatened ecosystems by the concurrent effects of climate change and atmospheric pollution. In this work we parameterized the AIRTREE multi-layer model to predict CO2, water, ozone, and fine particles exchanges between leaves and the atmosphere. AIRTREE consists of four different modules: (1) a canopy environmental module determines the leaf temperature and radiative fluxes at different levels from above to the bottom of the canopy; (2) a hydrological module predicts soil water flow and water availability to the plant's photosynthetic apparatus; (3) a photosynthesis module estimates the net photosynthesis and stomatal conductance, and (4) a deposition module estimates ozone and PM deposition sinks as a function of the resistances to gas diffusion in the atmosphere, and within the canopy and leaf boundary layer. We describe the AIRTREE model framework, accuracy and sensitivity by comparing modeling results against long-term continuous Eddy Covariance measurements of ozone, water, and CO2 fluxes in a Mediterranean Holm oak forest, and we discuss potential application of AIRTREE for ozone-risk assessment in view of availability of a large observational database from ecosystems distributed worldwide.
BibTeX:
@article{Fares2019,
  author = {Fares, Silvano and Alivernini, Alessandro and Conte, Adriano and Maggi, Federico},
  title = {Ozone and particle fluxes in a Mediterranean forest predicted by the AIRTREE model},
  journal = {Science of the Total Environment},
  publisher = {Elsevier BV},
  year = {2019},
  volume = {682},
  pages = {494--504},
  doi = {10.1016/j.scitotenv.2019.05.109}
}
Fennel K, Alin S, Barbero L, Evans W, Bourgeois T, Cooley S, Dunne J, Feely RA, Hernandez-Ayon JM, Hu X, Lohrenz S, Muller-Karger F, Najjar R, Robbins L, Shadwick E, Siedlecki S, Steiner N, Sutton A, Turk D, Vlahos P and Wang ZA (2019), "Carbon cycling in the North American coastal ocean: a synthesis", Biogeosciences., mar, 2019. Vol. 16(6), pp. 1281-1304. Copernicus GmbH.
Abstract: textlessptextgreatertextless![CDATA[Abstract. A quantification of carbon fluxes in the coastal ocean and across its boundaries with the atmosphere, land, and the open ocean is important for assessing the current state and projecting future trends in ocean carbon uptake and coastal ocean acidification, but this is currently a missing component of global carbon budgeting. This synthesis reviews recent progress in characterizing these carbon fluxes for the North American coastal ocean. Several observing networks and high-resolution regional models are now available. Recent efforts have focused primarily on quantifying the net air–sea exchange of carbon dioxide (CO2). Some studies have estimated other key fluxes, such as the exchange of organic and inorganic carbon between shelves and the open ocean. Available estimates of air–sea CO2 flux, informed by more than a decade of observations, indicate that the North American Exclusive Economic Zone (EEZ) acts as a sink of 160±80 Tg C yr−1, although this flux is not well constrained. The Arctic and sub-Arctic, mid-latitude Atlantic, and mid-latitude Pacific portions of the EEZ account for 104, 62, and −3.7 Tg C yr−1, respectively, while making up 51 %, 25 %, and 24 % of the total area, respectively. Combining the net uptake of 160±80 Tg C yr−1 with an estimated carbon input from land of 106±30 Tg C yr−1 minus an estimated burial of 65±55 Tg C yr−1 and an estimated accumulation of dissolved carbon in EEZ waters of 50±25 Tg C yr−1 implies a carbon export of 151±105 Tg C yr−1 to the open ocean. The increasing concentration of inorganic carbon in coastal and open-ocean waters leads to ocean acidification. As a result, conditions favoring the dissolution of calcium carbonate occur regularly in subsurface coastal waters in the Arctic, which are naturally prone to low pH, and the North Pacific, where upwelling of deep, carbon-rich waters has intensified. Expanded monitoring and extension of existing model capabilities are required to provide more reliable coastal carbon budgets, projections of future states of the coastal ocean, and quantification of anthropogenic carbon contributions.]]textgreatertextless/ptextgreater
BibTeX:
@article{Fennel2019,
  author = {Fennel, Katja and Alin, Simone and Barbero, Leticia and Evans, Wiley and Bourgeois, Timothée and Cooley, Sarah and Dunne, John and Feely, Richard A. and Hernandez-Ayon, Jose Martin and Hu, Xinping and Lohrenz, Steven and Muller-Karger, Frank and Najjar, Raymond and Robbins, Lisa and Shadwick, Elizabeth and Siedlecki, Samantha and Steiner, Nadja and Sutton, Adrienne and Turk, Daniela and Vlahos, Penny and Wang, Zhaohui Aleck},
  title = {Carbon cycling in the North American coastal ocean: a synthesis},
  journal = {Biogeosciences},
  publisher = {Copernicus GmbH},
  year = {2019},
  volume = {16},
  number = {6},
  pages = {1281--1304},
  url = {https://bg.copernicus.org/articles/16/1281/2019/},
  doi = {10.5194/bg-16-1281-2019}
}
Fernández-Martínez M, Sardans J, Chevallier F, Ciais P, Obersteiner M, Vicca S, Canadell JG, Bastos A, Friedlingstein P, Sitch S, Piao SL, Janssens IA and Peñuelas J (2019), "Global trends in carbon sinks and their relationships with CO2 and temperature", Nature Climate Change., dec, 2019. Vol. 9(1), pp. 73-79. Springer Science and Business Media LLC.
Abstract: Elevated CO2 concentrations increase photosynthesis and, potentially, net ecosystem production (NEP), meaning a greater CO2 uptake. Climate, nutrients and ecosystem structure, however, influence the effect of increasing CO2. Here we analysed global NEP from MACC-II and Jena CarboScope atmospheric inversions and ten dynamic global vegetation models (TRENDY), using statistical models to attribute the trends in NEP to its potential drivers: CO2, climatic variables and land-use change. We found that an increased CO2 was consistently associated with an increased NEP (1995–2014). Conversely, increased temperatures were negatively associated with NEP. Using the two atmospheric inversions and TRENDY, the estimated global sensitivities for CO2 were 6.0 ± 0.1, 8.1 ± 0.3 and 3.1 ± 0.1 PgC per 100 ppm (˜1 °C increase), and âˆ'0.5 ± 0.2, âˆ'0.9 ± 0.4 and âˆ'1.1 ± 0.1 PgC °Câˆ'1 for temperature. These results indicate a positive CO2 effect on terrestrial C sinks that is constrained by climate warming.
BibTeX:
@article{Fernandez-Martinez2019,
  author = {Fernández-Martínez, M and Sardans, J and Chevallier, F and Ciais, P and Obersteiner, M and Vicca, S and Canadell, J G and Bastos, A and Friedlingstein, P and Sitch, S and Piao, S L and Janssens, I A and Peñuelas, J},
  title = {Global trends in carbon sinks and their relationships with CO2 and temperature},
  journal = {Nature Climate Change},
  publisher = {Springer Science and Business Media LLC},
  year = {2019},
  volume = {9},
  number = {1},
  pages = {73--79},
  doi = {10.1038/s41558-018-0367-7}
}
Fischer FJ, Maréchaux I and Chave J (2019), "Improving plant allometry by fusing forest models and remote sensing", New Phytologist., apr, 2019. Vol. 223(3), pp. 1159-1165. Wiley.
Abstract: Allometry determines how tree shape and function scale with each other, related through size. Allometric relationships help scale processes from the individual to the global scale and constitute a core component of vegetation models. Allometric relationships have been expected to emerge from optimisation theory, yet this does not suitably predict empirical data. Here we argue that the fusion of high-resolution data, such as those derived from airborne laser scanning, with individual-based forest modelling offers insight into how plant size contributes to large-scale biogeochemical processes. We review the challenges in allometric scaling, how they can be tackled by advances in data-model fusion, and how individual-based models can serve as data integrators for dynamic global vegetation models.
BibTeX:
@article{Fischer2019,
  author = {Fischer, Fabian Jörg and Maréchaux, Isabelle and Chave, Jérôme},
  title = {Improving plant allometry by fusing forest models and remote sensing},
  journal = {New Phytologist},
  publisher = {Wiley},
  year = {2019},
  volume = {223},
  number = {3},
  pages = {1159--1165},
  doi = {10.1111/nph.15810}
}
Fitzky AC, Sandén H, Karl T, Fares S, Calfapietra C, Grote R, Saunier A and Rewald B (2019), "The Interplay Between Ozone and Urban Vegetation—BVOC Emissions, Ozone Deposition, and Tree Ecophysiology", Frontiers in Forests and Global Change., sep, 2019. Vol. 2 Frontiers Media SA.
Abstract: Tropospheric ozone (Osub3/sub) is one of the most prominent air pollution problems in Europe and other countries worldwide. Human health is affected by Osub3/sub via the respiratory as well the cardiovascular systems. Even though trees are present in relatively low numbers in urban areas, they can be a dominant factor in the regulation of urban Osub3/sub concentrations. Trees affect the Osub3/sub concentration via emission of biogenic volatile organic compounds (BVOC), which can act as a precursor of Osub3/sub, and by Osub3/sub deposition on leaves. The role of urban trees with regard to Osub3/sub will gain further importance as NOsubx/sub concentrations continue declining and climate warming is progressing—rendering especially the urban ozone chemistry more sensitive to BVOC emissions. However, the role of urban vegetation on the local regulation of tropospheric Osub3/sub concentrations is complex and largely influenced by species-specific emission rates of BVOCs and Osub3/sub deposition rates, both highly modified by tree physiological status. In this review, we shed light on processes related to trees that affect tropospheric ozone concentrations in metropolitan areas from rural settings to urban centers, and discuss their importance under present and future conditions. After a brief overview on the mechanisms regulating Osub3/sub concentrations in urban settings, we focus on effects of tree identity and tree physiological status, as affected by multiple stressors, influencing both BVOC emission and Osub3/sub deposition rates. In addition, we highlight differences along the rural-urban gradient affecting tropospheric Osub3/sub concentrations and current knowledge gaps with the potential to improve future models on tropospheric Osub3/sub formation in metropolitan areas.
BibTeX:
@article{Fitzky2019,
  author = {Fitzky, Anne Charlott and Sandén, Hans and Karl, Thomas and Fares, Silvano and Calfapietra, Carlo and Grote, Rüdiger and Saunier, Amélie and Rewald, Boris},
  title = {The Interplay Between Ozone and Urban Vegetation—BVOC Emissions, Ozone Deposition, and Tree Ecophysiology},
  journal = {Frontiers in Forests and Global Change},
  publisher = {Frontiers Media SA},
  year = {2019},
  volume = {2},
  doi = {10.3389/ffgc.2019.00050}
}
Freeman NM, Munro DR, Sprintall J, Mazloff MR, Purkey S, Rosso I, DeRanek CA and Sweeney C (2019), "The Observed Seasonal Cycle of Macronutrients in Drake Passage: Relationship to Fronts and Utility as a Model Metric", Journal of Geophysical Research: Oceans., jul, 2019. Vol. 124(7), pp. 4763-4783. Blackwell Publishing Ltd.
Abstract: The Drake Passage Time-series (DPT) is used to quantify the spatial and seasonal variability of historically undersampled, biogeochemically relevant properties across the Drake Passage. From 2004–2017, discrete ship-based observations of surface macronutrients (silicate, nitrate, and phosphate), temperature, and salinity have been collected 5–8 times per year as part of the DPT program. Using the DPT and Antarctic Circumpolar Current (ACC) front locations derived from concurrent expendable bathythermograph data, the distinct physical and biogeochemical characteristics of ACC frontal zones are characterized. Biogeochemical-Argo floats in the region confirm that the near-surface sampling scheme of the DPT robustly captures mixed-layer biogeochemistry. While macronutrient concentrations consistently increase toward the Antarctic continent, their meridional distribution, variability, and biogeochemical gradients are unique across physical ACC fronts, suggesting a combination of physical and biological processes controlling nutrient availability and nutrient front location. The Polar Front is associated with the northern expression of the Silicate Front, marking the biogeographically relevant location between silicate-poor and silicate-rich waters. South of the northern Silicate Front, the silicate-to-nitrate ratio increases, with the sharpest gradient in silicate associated with the Southern ACC Front (i.e., the southern expression of the Silicate Front). Nutrient cycling is an important control on variability in the surface ocean partial pressure of carbon dioxide (pCO2). The robust characterization of the spatiotemporal variability of nutrients presented here highlights the utility of biogeochemical time series for diagnosing and potentially reducing biases in modeling Southern Ocean pCO2 variability, and by inference, air-sea CO2 flux.
BibTeX:
@article{Freeman2019,
  author = {Freeman, Natalie M. and Munro, David R. and Sprintall, Janet and Mazloff, Matthew R. and Purkey, Sarah and Rosso, Isabella and DeRanek, Carissa A. and Sweeney, Colm},
  title = {The Observed Seasonal Cycle of Macronutrients in Drake Passage: Relationship to Fronts and Utility as a Model Metric},
  journal = {Journal of Geophysical Research: Oceans},
  publisher = {Blackwell Publishing Ltd},
  year = {2019},
  volume = {124},
  number = {7},
  pages = {4763--4783},
  url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2019JC015052},
  doi = {10.1029/2019JC015052}
}
Frey M, Sha MK, Hase F, Kiel M, Blumenstock T, Harig R, Surawicz G, Deutscher NM, Shiomi K, Franklin JE, Bösch H, Chen J, Grutter M, Ohyama H, Sun Y, Butz A, Mengistu Tsidu G, Ene D, Wunch D, Cao Z, Garcia O, Ramonet M, Vogel F and Orphal J (2019), "Building the COllaborative Carbon Column Observing Network (COCCON): Long-term stability and ensemble performance of the EM27/SUN Fourier transform spectrometer", Atmospheric Measurement Techniques., mar, 2019. Vol. 12(3), pp. 1513-1530. Copernicus GmbH.
Abstract: In a 3.5-year long study, the long-term performance of a mobile, solar absorption Bruker EM27/SUN spectrometer, used for greenhouse gas observations, is checked with respect to a co-located reference Bruker IFS 125HR spectrometer, which is part of the Total Carbon Column Observing Network (TCCON). We find that the EM27/SUN is stable on timescales of several years; the drift per year between the EM27/SUN and the official TCCON product is 0.02 ppmv for XCO2 and 0.9 ppbv for XCH4, which is within the 1σ precision of the comparison, 0.6 ppmv for XCO2 and 4.3 ppbv for XCH4. The bias between the two data sets is 3.9 ppmv for XCO2 and 13.0 ppbv for XCH4. In order to avoid sensitivity-dependent artifacts, the EM27/SUN is also compared to a truncated IFS 125HR data set derived from full-resolution TCCON interferograms. The drift is 0.02 ppmv for XCO2 and 0.2 ppbv for XCH4 per year, with 1σ precisions of 0.4 ppmv for XCO2 and 1.4 ppbv for XCH4, respectively. The bias between the two data sets is 0.6 ppmv for XCO2 and 0.5 ppbv for XCH4. With the presented long-term stability, the EM27/SUN qualifies as an useful supplement to the existing TCCON network in remote areas. To achieve consistent performance, such an extension requires careful testing of any spectrometers involved by application of common quality assurance measures. One major aim of the COllaborative Carbon Column Observing Network (COCCON) infrastructure is to provide these services to all EM27/SUN operators. In the framework of COCCON development, the performance of an ensemble of 30 EM27/SUN spectrometers was tested and found to be very uniform, enhanced by the centralized inspection performed at the Karlsruhe Institute of Technology prior to deployment. Taking into account measured instrumental line shape parameters for each spectrometer, the resulting average bias across the ensemble with respect to the reference EM27/SUN used in the long-term study in XCO2 is 0.20 ppmv, while it is 0.8 ppbv for XCH4. The average standard deviation of the ensemble is 0.13 ppmv for XCO2 and 0.6 ppbv for XCH4. In addition to the robust metric based on absolute differences, we calculate the standard deviation among the empirical calibration factors. The resulting 2σ uncertainty is 0.6 ppmv for XCO2 and 2.2 ppbv for XCH4. As indicated by the executed long-term study on one device presented here, the remaining empirical calibration factor deduced for each individual instrument can be assumed constant over time. Therefore the application of these empirical factors is expected to further improve the EM27/SUN network conformity beyond the scatter among the empirical calibration factors reported above.
BibTeX:
@article{Frey2019,
  author = {Frey, Matthias and Sha, Mahesh K and Hase, Frank and Kiel, Matthäus and Blumenstock, Thomas and Harig, Roland and Surawicz, Gregor and Deutscher, Nicholas M and Shiomi, Kei and Franklin, Jonathan E and Bösch, Hartmut and Chen, Jia and Grutter, Michel and Ohyama, Hirofumi and Sun, Youwen and Butz, André and Mengistu Tsidu, Gizaw and Ene, Dragos and Wunch, Debra and Cao, Zhensong and Garcia, Omaira and Ramonet, Michel and Vogel, Felix and Orphal, Johannes},
  title = {Building the COllaborative Carbon Column Observing Network (COCCON): Long-term stability and ensemble performance of the EM27/SUN Fourier transform spectrometer},
  journal = {Atmospheric Measurement Techniques},
  publisher = {Copernicus GmbH},
  year = {2019},
  volume = {12},
  number = {3},
  pages = {1513--1530},
  doi = {10.5194/amt-12-1513-2019}
}
Friedlingstein P, Jones MW, O'Sullivan M, Andrew RM, Hauck J, Peters GP, Peters W, Pongratz J, Sitch S, Le Quéré C, DBakker OCE, Canadell1 JG, Ciais1 P, Jackson RB, Anthoni1 P, Barbero L, Bastos A, Bastrikov V, Becker M, Bopp L, Buitenhuis E, Chandra N, Chevallier F, Chini LP, Currie KI, Feely RA, Gehlen M, Gilfillan D, Gkritzalis T, Goll DS, Gruber N, Gutekunst S, Harris I, Haverd V, Houghton RA, Hurtt G, Ilyina T, Jain AK, Joetzjer E, Kaplan JO, Kato E, Goldewijk KK, Korsbakken JI, Landschützer P, Lauvset SK, Lefèvre N, Lenton A, Lienert S, Lombardozzi D, Marland G, McGuire PC, Melton JR, Metzl N, Munro DR, Nabel JEMS, Nakaoka SI, Neill C, Omar AM, Ono T, Peregon A, Pierrot D, Poulter B, Rehder G, Resplandy L, Robertson E, Rödenbeck C, Séférian R, Schwinger J, Smith N, Tans PP, Tian H, Tilbrook B, Tubiello FN, Van Der Werf GR, Wiltshire AJ and Zaehle S (2019), "Global carbon budget 2019", Earth System Science Data., dec, 2019. Vol. 11(4), pp. 1783-1838.
Abstract: Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere-the "global carbon budget"-is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe data sets and methodology to quantify the five major components of the global carbon budget and their uncertainties. Fossil CO2 emissions (EFF) are based on energy statistics and cement production data, while emissions from land use change (ELUC), mainly deforestation, are based on land use and land use change data and bookkeeping models. Atmospheric CO2 concentration is measured directly and its growth rate (GATM) is computed from the annual changes in concentration. The ocean CO2 sink (SOCEAN) and terrestrial CO2 sink (SLAND) are estimated with global process models constrained by observations. The resulting carbon budget imbalance (BIM), the difference between the estimated total emissions and the estimated changes in the atmosphere, ocean, and terrestrial biosphere, is a measure of imperfect data and understanding of the contemporary carbon cycle. All uncertainties are reported as ±1σ. For the last decade available (2009-2018), EFF was 9:5±0:5 GtC yr-1, ELUC 1:5±0:7 GtC yr-1, GATM 4:9±0:02 GtC yr-1 (2:3±0:01 ppm yr-1), SOCEAN 2:5±0:6 GtC yr-1, and SLAND 3:2±0:6 GtC yr-1, with a budget imbalance BIM of 0.4 GtC yr-1 indicating overestimated emissions and/or underestimated sinks. For the year 2018 alone, the growth in EFF was about 2.1% and fossil emissions increased to 10:0±0:5 GtC yr-1, reaching 10 GtC yr-1 for the first time in history, ELUC was 1:5±0:7 GtC yr-1, for total anthropogenic CO2 emissions of 11:5±0:9 GtC yr-1 (42:5±3:3 GtCO2). Also for 2018, GATM was 5:1±0:2 GtC yr-1 (2:4±0:1 ppm yr-1), SOCEAN was 2:6±0:6 GtC yr-1, and SLAND was 3:5±0:7 GtC yr-1, with a BIM of 0.3 GtC. The global atmospheric CO2 concentration reached 407:38±0:1 ppm averaged over 2018. For 2019, preliminary data for the first 6-10 months indicate a reduced growth in EFF of C0:6% (range of.0:2% to 1.5 %) based on national emissions projections for China, the USA, the EU, and India and projections of gross domestic product corrected for recent changes in the carbon intensity of the economy for the rest of the world. Overall, the mean and trend in the five components of the global carbon budget are consistently estimated over the period 1959-2018, but discrepancies of up to 1 GtC yr-1 persist for the representation of semi-decadal variability in CO2 fluxes. A detailed comparison among individual estimates and the introduction of a broad range of observations shows (1) no consensus in the mean and trend in land use change emissions over the last decade, (2) a persistent low agreement between the different methods on the magnitude of the land CO2 flux in the northern extra-tropics, and (3) an apparent underestimation of the CO2 variability by ocean models outside the tropics. This living data update documents changes in the methods and data sets used in this new global carbon budget and the progress in understanding of the global carbon cycle compared with previous publications of this data set (Le Quéré et al., 2018a, b, 2016, 2015a, b, 2014, 2013). The data generated by this work are available at https://doi.org/10.18160/gcp-2019 (Friedlingstein et al., 2019).
BibTeX:
@article{Friedlingstein2019,
  author = {Friedlingstein, Pierre and Jones, Matthew W and O'Sullivan, Michael and Andrew, Robbie M and Hauck, Judith and Peters, Glen P and Peters, Wouter and Pongratz, Julia and Sitch, Stephen and Le Quéré, Corinne and DBakker, Orothee C E and Canadell1, Josep G and Ciais1, Philippe and Jackson, Robert B and Anthoni1, Peter and Barbero, Leticia and Bastos, Ana and Bastrikov, Vladislav and Becker, Meike and Bopp, Laurent and Buitenhuis, Erik and Chandra, Naveen and Chevallier, Frédéric and Chini, Louise P and Currie, Kim I and Feely, Richard A and Gehlen, Marion and Gilfillan, Dennis and Gkritzalis, Thanos and Goll, Daniel S and Gruber, Nicolas and Gutekunst, Sören and Harris, Ian and Haverd, Vanessa and Houghton, Richard A and Hurtt, George and Ilyina, Tatiana and Jain, Atul K and Joetzjer, Emilie and Kaplan, Jed O and Kato, Etsushi and Goldewijk, Kees Klein and Korsbakken, Jan Ivar and Landschützer, Peter and Lauvset, Siv K and Lefèvre, Nathalie and Lenton, Andrew and Lienert, Sebastian and Lombardozzi, Danica and Marland, Gregg and McGuire, Patrick C and Melton, Joe R and Metzl, Nicolas and Munro, David R and Nabel, Julia E M S and Nakaoka, Shin Ichiro and Neill, Craig and Omar, Abdirahman M and Ono, Tsuneo and Peregon, Anna and Pierrot, Denis and Poulter, Benjamin and Rehder, Gregor and Resplandy, Laure and Robertson, Eddy and Rödenbeck, Christian and Séférian, Roland and Schwinger, Jörg and Smith, Naomi and Tans, Pieter P and Tian, Hanqin and Tilbrook, Bronte and Tubiello, Francesco N and Van Der Werf, Guido R and Wiltshire, Andrew J and Zaehle, Sönke},
  title = {Global carbon budget 2019},
  journal = {Earth System Science Data},
  year = {2019},
  volume = {11},
  number = {4},
  pages = {1783--1838},
  url = {https://www.earth-syst-sci-data.net/11/1783/2019/},
  doi = {10.5194/essd-11-1783-2019}
}
Fröb F, Olsen A, Becker M, Chafik L, Johannessen T, Reverdin G and Omar A (2019), "Wintertime fCO 2 Variability in the Subpolar North Atlantic Since 2004", Geophysical Research Letters., feb, 2019. Vol. 46(3), pp. 1580-1590.
Abstract: Winter data of surface ocean temperature (SST), salinity (SSS) and CO 2 fugacity (fCO 2 ) collected on the VOS M/V Nuka Arctica in the subpolar North Atlantic between 2004 and 2017 are used to establish trends, drivers, and interannual variability. Over the period, waters cooled and freshened, and the fCO 2 increased at a rate similar to the atmospheric CO 2 growth rate. When accounting for the freshening, the inferred increase in dissolved inorganic carbon (DIC) was found to be approximately twice that expected from atmospheric CO 2 alone. This is attributed to the cooling. In the Irminger Sea, fCO 2 exhibited additional interannual variations driven by atmospheric forcing through winter mixing. As winter fCO 2 in the region is close to the atmospheric, the subpolar North Atlantic has varied between being slightly supersaturated and slightly undersaturated over the investigated period.
BibTeX:
@article{Frob2019,
  author = {Fröb, F and Olsen, A and Becker, M and Chafik, L and Johannessen, T and Reverdin, G and Omar, A},
  title = {Wintertime fCO 2 Variability in the Subpolar North Atlantic Since 2004},
  journal = {Geophysical Research Letters},
  year = {2019},
  volume = {46},
  number = {3},
  pages = {1580--1590},
  url = {http://doi.wiley.com/10.1029/2018GL080554},
  doi = {10.1029/2018GL080554}
}
Geng MS, Christensen JH and Christensen TR (2019), "Potential future methane emission hot spots in Greenland", Environmental Research Letters., mar, 2019. Vol. 14(3), pp. 35001. IOP Publishing.
Abstract: Climate models have been making significant progress encompassing an increasing number of complex feedback mechanisms from natural ecosystems. Permafrost thaw and subsequent induced greenhouse gas emissions, however, remain a challenge for climate models at large. Deducing permafrost conditions and associated greenhouse gas emissions from parameters that are simulated in climate models would be a helpful step towards estimating emission budgets from permafrost regions. Here we use a regional climate model with a 5 km horizontal resolution to assess future potential methane (CH4) emissions over presently unglaciated areas in Greenland under an RCP8.5 scenario. A simple frost index is applied to estimate permafrost conditions from the model output. CH4 flux measurements from two stations in Greenland; Nuuk representing sub-Arctic and Zackenberg high-Arctic climate, are used to establish a relationship between emissions and near surface air temperature. Permafrost conditions in Greenland change drastically by the end of the 21st century in an RCP8.5 climate. Continuous permafrost remains stable only in North Greenland, the north-west coast, the northern tip of Disko Island, and Nuussuaq. Southern Greenland conditions only sustain sporadic permafrost conditions and largely at high elevations, whereas former permafrost in other regions thaws. The increasing thawed soil leads to increasing CH4 emissions. Especially the area surrounding Kangerlussuaq, Scoresby Land, and the southern coast of Greenland exhibit potentially high emissions during the longer growing season. The constructed maps and budgets combining modelled permafrost conditions with observed CH4 fluxes from CH4 promoting sites represent a useful tool to identify areas in need of additional monitoring as they highlight potential CH4 hot spots.
BibTeX:
@article{Geng2019,
  author = {Geng, Marilena Sophie and Christensen, Jens Hesselbjerg and Christensen, Torben Røjle},
  title = {Potential future methane emission hot spots in Greenland},
  journal = {Environmental Research Letters},
  publisher = {IOP Publishing},
  year = {2019},
  volume = {14},
  number = {3},
  pages = {35001},
  doi = {10.1088/1748-9326/aaf34b}
}
Giemsa E, Jacobeit J, Ries L and Hachinger S (2019), "Investigating regional source and sink patterns of Alpine CO2 and CH4 concentrations based on a back trajectory receptor model", Environmental Sciences Europe., dec, 2019. Vol. 31(1), pp. 49.
BibTeX:
@article{Giemsa2019,
  author = {Giemsa, Esther and Jacobeit, Jucundus and Ries, Ludwig and Hachinger, Stephan},
  title = {Investigating regional source and sink patterns of Alpine CO2 and CH4 concentrations based on a back trajectory receptor model},
  journal = {Environmental Sciences Europe},
  year = {2019},
  volume = {31},
  number = {1},
  pages = {49},
  url = {https://enveurope.springeropen.com/articles/10.1186/s12302-019-0233-x},
  doi = {10.1186/s12302-019-0233-x}
}
Gonzaga Gomez L, Loubet B, Lafouge F, Ciuraru R, Buysse P, Durand B, Gueudet JC, Fanucci O, Fortineau A, Zurfluh O, Decuq C, Kammer J, Duprix P, Bsaibes S, Truong F, Gros V and Boissard C (2019), "Comparative study of biogenic volatile organic compounds fluxes by wheat, maize and rapeseed with dynamic chambers over a short period in northern France", Atmospheric Environment., oct, 2019. Vol. 214, pp. 116855. Elsevier BV.
Abstract: Biogenic volatile organic compounds (BVOC) are mainly emitted from vegetation. However there is still little information on BVOC exchanges with crops. In this study we measured fluxes of BVOC from wheat, maize and rapeseed crops near Paris at the plant level during a full-week period for each species. We used dynamic automated chambers coupled to a Proton Transfer Reaction, Quadrupole ion guide, Time of Flight mass spectrometer (PTR-Qi-Tof-MS) instrument for online measurements of BVOC. Our results confirm the hypothesis that many unexplored compounds contribute to BVOC exchanges between crops and the atmosphere, although for all plant species methanol was dominating the emissions (55–85% of the sum of the BVOC exchanges fluxes on a mass basis) followed by acetone and acetaldehyde. The 10 most exchanged compounds, excluding methanol, contributed more than 50% of the summed fluxes and the 100 most exchanged contributed to more than 90%. The summed BVOC emission and deposition presented large interspecies variations, but limited intra-species variability, with a summed net flux of 0.11 ± 0.02 μgBVOC gDWâˆ'1 hâˆ'1 for maize, 1.5 ± 0.7 μgBVOC gDWâˆ'1 hâˆ'1 for wheat, and 9.1 ± 2.4 μgBVOC gDWâˆ'1 hâˆ'1 for rapeseed. The 10 most emitted compounds were mostly emitted during the day and were correlated with both photosynthetically active radiation and temperature and anti-correlated with relative humidity. This study provides the first evaluation so far of the biosphere-atmosphere fluxes for several BVOC. In particular we provide a first evaluation of standard emission factor for isoprene and monoterpene for wheat and rapeseed at their respective growth stages. This study is however limited to a week period at a given stage for each species and at the plant level.
BibTeX:
@article{GonzagaGomez2019,
  author = {Gonzaga Gomez, Lais and Loubet, Benjamin and Lafouge, Florence and Ciuraru, Raluca and Buysse, Pauline and Durand, Brigitte and Gueudet, Jean Christophe and Fanucci, Olivier and Fortineau, A and Zurfluh, Olivier and Decuq, Céline and Kammer, Julien and Duprix, Pascal and Bsaibes, S and Truong, François and Gros, Valérie and Boissard, Christophe},
  title = {Comparative study of biogenic volatile organic compounds fluxes by wheat, maize and rapeseed with dynamic chambers over a short period in northern France},
  journal = {Atmospheric Environment},
  publisher = {Elsevier BV},
  year = {2019},
  volume = {214},
  pages = {116855},
  doi = {10.1016/j.atmosenv.2019.116855}
}
Gourlez de la Motte L, Dumortier P, Beckers Y, Bodson B, Heinesch B and Aubinet M (2019), "Herd position habits can bias net CO 2 ecosystem exchange estimates in free range grazed pastures", Agricultural and Forest Meteorology., apr, 2019. Vol. 268, pp. 156-168. Elsevier BV.
Abstract: The eddy covariance (EC) technique has been widely used to quantify the net CO 2 ecosystem exchange (NEE) of grasslands, which is an important component of grassland carbon and greenhouse gas budgets. In free range grazed pastures, NEE estimations are supposed to also include cattle respiration. However, cattle respiration measurement by an EC system is challenging as animals act as moving points emitting CO 2 that are more or less captured by the EC tower depending on their presence in the footprint. Often it is supposed that, over the long term, cattle distribution in the pasture is homogeneous so that fluctuations due to moving sources are averaged and NEE estimates are reasonably representative of cattle respiration. In this study, we test this hypothesis by comparing daily cow respiration rate per livestock unit (LU) estimated by postulating a homogeneous cow repartition over the whole pasture with three other estimates based on animal localization data, animal scale carbon budget and confinement experiments. We applied these methods to an intensively managed free range grassland and showed that the NEE estimate based on a homogeneous cow repartition was systematically lower than the three other estimates. The bias was about 60 g C m –2 yr –1 , which corresponded to around 40% of the annual NEE. The sign and the importance of this bias is site specific, as it depends on cow location habits in relation to the footprint of the EC measurements which highlight the importance of testing the hypothesis of homogeneity of cattle distribution on each site. Consequently, in order to allow estimating the validity of this hypothesis but also to improve inter site comparisons, we advocate to compute separately pasture NEE and grazer's respiration. For the former we propose a method based on cattle presence detection using CH 4 fluxes, elimination of data with cattle and gap filling on the basis of data without cattle. For the second we present and discuss three independent methods (animal localization with GPS, animal scale carbon budget, confinement experiments) to estimate the cattle respiration rate.
BibTeX:
@article{GourlezdelaMotte2019,
  author = {Gourlez de la Motte, Louis and Dumortier, Pierre and Beckers, Yves and Bodson, Bernard and Heinesch, Bernard and Aubinet, Marc},
  title = {Herd position habits can bias net CO 2 ecosystem exchange estimates in free range grazed pastures},
  journal = {Agricultural and Forest Meteorology},
  publisher = {Elsevier BV},
  year = {2019},
  volume = {268},
  pages = {156--168},
  doi = {10.1016/j.agrformet.2019.01.015}
}
Gregor L, Lebehot AD, Kok S and Scheel Monteiro PM (2019), "A comparative assessment of the uncertainties of global surface ocean CO<sub>2</sub> estimates using a machine-learning ensemble (CSIR-ML6 version 2019a) – have we hit the wall?", Geoscientific Model Development., dec, 2019. Vol. 12(12), pp. 5113-5136. Copernicus GmbH.
Abstract: textlessptextgreatertextless![CDATA[Abstract. Over the last decade, advanced statistical inference and machine learning have been used to fill the gaps in sparse surface ocean CO2 measurements (Rödenbeck et al., 2015). The estimates from these methods have been used to constrain seasonal, interannual and decadal variability in sea–air CO2 fluxes and the drivers of these changes (Landschützer et al., 2015, 2016; Gregor et al., 2018). However, it is also becoming clear that these methods are converging towards a common bias and root mean square error (RMSE) boundary: “the wall”, which suggests that pCO2 estimates are now limited by both data gaps and scale-sensitive observations. Here, we analyse this problem by introducing a new gap-filling method, an ensemble average of six machine-learning models (CSIR-ML6 version 2019a, Council for Scientific and Industrial Research – Machine Learning ensemble with Six members), where each model is constructed with a two-step clustering-regression approach. The ensemble average is then statistically compared to well-established methods. The ensemble average, CSIR-ML6, has an RMSE of 17.16 µatm and bias of 0.89 µatm when compared to a test dataset kept separate from training procedures. However, when validating our estimates with independent datasets, we find that our method improves only incrementally on other gap-filling methods. We investigate the differences between the methods to understand the extent of the limitations of gap-filling estimates of pCO2. We show that disagreement between methods in the South Atlantic, southeastern Pacific and parts of the Southern Ocean is too large to interpret the interannual variability with confidence. We conclude that improvements in surface ocean pCO2 estimates will likely be incremental with the optimisation of gap-filling methods by (1) the inclusion of additional clustering and regression variables (e.g. eddy kinetic energy), (2) increasing the sampling resolution and (3) successfully incorporating pCO2 estimates from alternate platforms (e.g. floats, gliders) into existing machine-learning approaches.]]textgreatertextless/ptextgreater
BibTeX:
@article{Gregor2019,
  author = {Gregor, Luke and Lebehot, Alice D. and Kok, Schalk and Scheel Monteiro, Pedro M.},
  title = {A comparative assessment of the uncertainties of global surface ocean CO<sub>2</sub> estimates using a machine-learning ensemble (CSIR-ML6 version 2019a) – have we hit the wall?},
  journal = {Geoscientific Model Development},
  publisher = {Copernicus GmbH},
  year = {2019},
  volume = {12},
  number = {12},
  pages = {5113--5136},
  url = {https://gmd.copernicus.org/articles/12/5113/2019/},
  doi = {10.5194/gmd-12-5113-2019}
}
Grossiord C, Christoffersen B, Alonso-Rodríguez AM, Anderson-Teixeira K, Asbjornsen H, Aparecido LMT, Carter Berry Z, Baraloto C, Bonal D, Borrego I, Burban B, Chambers JQ, Christianson DS, Detto M, Faybishenko B, Fontes CG, Fortunel C, Gimenez BO, Jardine KJ, Kueppers L, Miller GR, Moore GW, Negron-Juarez R, Stahl C, Swenson NG, Trotsiuk V, Varadharajan C, Warren JM, Wolfe BT, Wei L, Wood TE, Xu C and McDowell NG (2019), "Precipitation mediates sap flux sensitivity to evaporative demand in the neotropics", Oecologia., sep, 2019. Vol. 191(3), pp. 519-530. Springer Science and Business Media LLC.
Abstract: Transpiration in humid tropical forests modulates the global water cycle and is a key driver of climate regulation. Yet, our understanding of how tropical trees regulate sap flux in response to climate variability remains elusive. With a progressively warming climate, atmospheric evaporative demand [i.e., vapor pressure deficit (VPD)] will be increasingly important for plant functioning, becoming the major control of plant water use in the twenty-first century. Using measurements in 34 tree species at seven sites across a precipitation gradient in the neotropics, we determined how the maximum sap flux velocity (vmax) and the VPD threshold at which vmax is reached (VPDmax) vary with precipitation regime [mean annual precipitation (MAP); seasonal drought intensity (PDRY)] and two functional traits related to foliar and wood economics spectra [leaf mass per area (LMA); wood specific gravity (WSG)]. We show that, even though vmax is highly variable within sites, it follows a negative trend in response to increasing MAP and PDRY across sites. LMA and WSG exerted little effect on vmax and VPDmax, suggesting that these widely used functional traits provide limited explanatory power of dynamic plant responses to environmental variation within hyper-diverse forests. This study demonstrates that long-term precipitation plays an important role in the sap flux response of humid tropical forests to VPD. Our findings suggest that under higher evaporative demand, trees growing in wetter environments in humid tropical regions may be subjected to reduced water exchange with the atmosphere relative to trees growing in drier climates.
BibTeX:
@article{Grossiord2019,
  author = {Grossiord, Charlotte and Christoffersen, Bradley and Alonso-Rodríguez, Aura M and Anderson-Teixeira, Kristina and Asbjornsen, Heidi and Aparecido, Luiza Maria T and Carter Berry, Z and Baraloto, Christopher and Bonal, Damien and Borrego, Isaac and Burban, Benoit and Chambers, Jeffrey Q and Christianson, Danielle S and Detto, Matteo and Faybishenko, Boris and Fontes, Clarissa G and Fortunel, Claire and Gimenez, Bruno O and Jardine, Kolby J and Kueppers, Lara and Miller, Gretchen R and Moore, Georgianne W and Negron-Juarez, Robinson and Stahl, Clément and Swenson, Nathan G and Trotsiuk, Volodymyr and Varadharajan, Charu and Warren, Jeffrey M and Wolfe, Brett T and Wei, Liang and Wood, Tana E and Xu, Chonggang and McDowell, Nate G},
  title = {Precipitation mediates sap flux sensitivity to evaporative demand in the neotropics},
  journal = {Oecologia},
  publisher = {Springer Science and Business Media LLC},
  year = {2019},
  volume = {191},
  number = {3},
  pages = {519--530},
  doi = {10.1007/s00442-019-04513-x}
}
Gruber N, Landschützer P and Lovenduski NS (2019), "The Variable Southern Ocean Carbon Sink", Annual Review of Marine Science., jan, 2019. Vol. 11(1), pp. 159-186. Annual Reviews Inc..
Abstract: textlessptextgreater The CO textlesssubtextgreater2textless/subtextgreater uptake by the Southern Ocean (textless35°S) varies substantially on all timescales and is a major determinant of the variations of the global ocean carbon sink. Particularly strong are the decadal changes characterized by a weakening period of the Southern Ocean carbon sink in the 1990s and a rebound after 2000. The weakening in the 1990s resulted primarily from a southward shift of the westerlies that enhanced the upwelling and outgassing of respired (i.e., natural) CO textlesssubtextgreater2textless/subtextgreater . The concurrent reduction in the storage rate of anthropogenic CO textlesssubtextgreater2textless/subtextgreater in the mode and intermediate waters south of 35°S suggests that this shift also decreased the uptake of anthropogenic CO textlesssubtextgreater2textless/subtextgreater . The rebound and the subsequent strong, decade-long reinvigoration of the carbon sink appear to have been driven by cooling in the Pacific Ocean, enhanced stratification in the Atlantic and Indian Ocean sectors, and a reduced overturning. Current-generation ocean models generally do not reproduce these variations and are poorly skilled at making decadal predictions in this region. textless/ptextgreater
BibTeX:
@article{Gruber2019,
  author = {Gruber, Nicolas and Landschützer, Peter and Lovenduski, Nicole S.},
  title = {The Variable Southern Ocean Carbon Sink},
  journal = {Annual Review of Marine Science},
  publisher = {Annual Reviews Inc.},
  year = {2019},
  volume = {11},
  number = {1},
  pages = {159--186},
  url = {https://www.annualreviews.org/doi/10.1146/annurev-marine-121916-063407},
  doi = {10.1146/annurev-marine-121916-063407}
}
Haro K, Ouarma I, Nana B, Bere A, Tubreoumya GC, Kam SZ, Laville P, Loubet B and Koulidiati J (2019), "Assessment of CH4 and CO2 surface emissions from Polesgo's landfill (Ouagadougou, Burkina Faso) based on static chamber method", Advances in Climate Change Research., sep, 2019. Vol. 10(3), pp. 181-191. Elsevier BV.
Abstract: Methane (CH4) and carbon dioxide (CO2) surface emissions from Polesgo's landfill (Ouagadougou, Burkina Faso) were measured using the static chamber technique in 2017 and 2018. The Polesgo's landfill was composed of four zones: Phase I, II, Phase III, and SP. The surface of Phase I was fully covered and its conditions are better for surface emission measurements. As results concerning the Phase I zone, the geospatial means flux rates of CH4 (657 mg mâˆ'2 hâˆ'1 in 2017 and 1210 mg mâˆ'2 hâˆ'1 in 2018, respectively) are measured higher than the tolerable value reported in literature. The emitted CH4 or CO2 have permitted to locate higher surface emissions which are related to the cover state. The calculated gas collection efficiency (27.4% in 2017 and 23.0% in 2018) is low compared to those reported for landfills integrating landfill gas (LFG) extraction system. The carbon footprint calculations (24,966 tCO2-eq 2017 and 40,025 tCO2-eq in 2018, respectively) shown that Polesgo's landfill is a significant source of greenhouse gases (GHG) and its important potential for organic recovery can contribute to reduce the carbon footprint.
BibTeX:
@article{Haro2019,
  author = {Haro, Kayaba and Ouarma, Issoufou and Nana, Bernard and Bere, Antoine and Tubreoumya, Guy Christian and Kam, Sié Zacharie and Laville, Patricia and Loubet, Benjamin and Koulidiati, Jean},
  title = {Assessment of CH4 and CO2 surface emissions from Polesgo's landfill (Ouagadougou, Burkina Faso) based on static chamber method},
  journal = {Advances in Climate Change Research},
  publisher = {Elsevier BV},
  year = {2019},
  volume = {10},
  number = {3},
  pages = {181--191},
  doi = {10.1016/j.accre.2019.09.002}
}
Hartman SE, Humphreys MP, Kivimäe C, Woodward EMS, Kitidis V, McGrath T, Hydes DJ, Greenwood N, Hull T, Ostle C, Pearce DJ, Sivyer D, Stewart BM, Walsham P, Painter SC, McGovern E, Harris C, Griffiths A, Smilenova A, Clarke J, Davis C, Sanders R and Nightingale P (2019), "Seasonality and spatial heterogeneity of the surface ocean carbonate system in the northwest European continental shelf", Progress in Oceanography., oct, 2019. Vol. 177, pp. 101909. Elsevier BV.
Abstract: In 2014–5 the UK NERC sponsored an 18 month long Shelf Sea Biogeochemistry research programme which collected over 1500 nutrient and carbonate system samples across the NW European Continental shelf, one of the largest continental shelves on the planet. This involved the cooperation of 10 different Institutes and Universities, using 6 different vessels. Additional carbon dioxide (CO2) data were obtained from the underway systems on three of the research vessels. Here, we present and discuss these data across 9 ecohydrodynamic regions, adapted from those used by the EU Marine Strategy Framework Directive (MSFD). We observed strong seasonal and regional variability in carbonate chemistry around the shelf in relation to nutrient biogeochemistry. Whilst salinity increased (and alkalinity decreased) out from the near-shore coastal waters offshore throughout the year nutrient concentrations varied with season. Spatial and seasonal variations in the ratio of DIC to nitrate concentration were seen that could impact carbon cycling. A decrease in nutrient concentrations and a pronounced under-saturation of surface pCO2 was evident in the spring in most regions, especially in the Celtic Sea. This decrease was less pronounced in Liverpool Bay and to the North of Scotland, where nutrient concentrations remained measurable throughout the year. The near-shore and relatively shallow ecosystems such as the eastern English Channel and southern North Sea were associated with a thermally driven increase in pCO2 to above atmospheric levels in summer and an associated decrease in pH. Non-thermal processes (such as mixing and the remineralisation of organic material) dominated in winter in most regions but especially in the northwest of Scotland and in Liverpool Bay. The large database collected will improve understanding of carbonate chemistry over the North-Western European Shelf in relation to nutrient biogeochemistry, particularly in the context of climate change and ocean acidification.
BibTeX:
@article{Hartman2019,
  author = {Hartman, S E and Humphreys, M P and Kivimäe, C and Woodward, E M S and Kitidis, V and McGrath, T and Hydes, D J and Greenwood, N and Hull, T and Ostle, C and Pearce, D J and Sivyer, D and Stewart, B M and Walsham, P and Painter, S C and McGovern, E and Harris, C and Griffiths, A and Smilenova, A and Clarke, J and Davis, C and Sanders, R and Nightingale, P},
  title = {Seasonality and spatial heterogeneity of the surface ocean carbonate system in the northwest European continental shelf},
  journal = {Progress in Oceanography},
  publisher = {Elsevier BV},
  year = {2019},
  volume = {177},
  pages = {101909},
  doi = {10.1016/j.pocean.2018.02.005}
}
Hastie A, Lauerwald R, Ciais P and Regnier P (2019), "Aquatic carbon fluxes dampen the overall variation of net ecosystem productivity in the Amazon basin: An analysis of the interannual variability in the boundless carbon cycle", Global Change Biology., apr, 2019. Vol. 25(6), pp. 2094-2111. Wiley.
Abstract: The river–floodplain network plays an important role in the carbon (C) cycle of the Amazon basin, as it transports and processes a significant fraction of the C fixed by terrestrial vegetation, most of which evades as CO 2 from rivers and floodplains back to the atmosphere. There is empirical evidence that exceptionally dry or wet years have an impact on the net C balance in the Amazon. While seasonal and interannual variations in hydrology have a direct impact on the amounts of C transferred through the river–floodplain system, it is not known how far the variation of these fluxes affects the overall Amazon C balance. Here, we introduce a new wetland forcing file for the ORCHILEAK model, which improves the representation of floodplain dynamics and allows us to closely reproduce data-driven estimates of net C exports through the river–floodplain network. Based on this new wetland forcing and two climate forcing datasets, we show that across the Amazon, the percentage of net primary productivity lost to the river–floodplain system is highly variable at the interannual timescale, and wet years fuel aquatic CO 2 evasion. However, at the same time overall net ecosystem productivity (NEP) and C sequestration are highest during wet years, partly due to reduced decomposition rates in water-logged floodplain soils. It is years with the lowest discharge and floodplain inundation, often associated with El Nino events, that have the lowest NEP and the highest total (terrestrial plus aquatic) CO 2 emissions back to atmosphere. Furthermore, we find that aquatic C fluxes display greater variation than terrestrial C fluxes, and that this variation significantly dampens the interannual variability in NEP of the Amazon basin. These results call for a more integrative view of the C fluxes through the vegetation-soil-river-floodplain continuum, which directly places aquatic C fluxes into the overall C budget of the Amazon basin.
BibTeX:
@article{Hastie2019,
  author = {Hastie, Adam and Lauerwald, Ronny and Ciais, Philippe and Regnier, Pierre},
  title = {Aquatic carbon fluxes dampen the overall variation of net ecosystem productivity in the Amazon basin: An analysis of the interannual variability in the boundless carbon cycle},
  journal = {Global Change Biology},
  publisher = {Wiley},
  year = {2019},
  volume = {25},
  number = {6},
  pages = {2094--2111},
  doi = {10.1111/gcb.14620}
}
Hayes F, Mills G, Alonso R, González-Fernández I, Coyle M, Grünhage L, Gerosa G, Karlsson PE and Marzuoli R (2019), "A Site-Specific Analysis of the Implications of a Changing Ozone Profile and Climate for Stomatal Ozone Fluxes in Europe", Water, Air, and Soil Pollution., dec, 2019. Vol. 230(1) Springer Science and Business Media LLC.
Abstract: In this study, we used eight sites from across Europe to investigate the implications of a future climate (2 °C warmer and 20% drier) and a changing ozone profile (increased background concentrations and reduced peaks) on stomatal ozone fluxes of three widely occurring plant species. A changing ozone profile with small increases in background ozone concentrations over the course of a growing season could have significant impacts on the annual accumulated stomatal ozone uptake, even if peak concentrations of ozone are reduced. Predicted increases in stomatal ozone uptake showed a strong relationship with latitude and were larger at sites from northern and mid-Europe than those from southern Europe. At the sites from central and northern regions of Europe, including the UK and Sweden, climatic conditions were highly conducive to stomatal ozone uptake by vegetation during the summer months and therefore an increase in daily mean ozone concentration of 3–16% during this time of year (from increased background concentrations, reduced peaks) would have a large impact on stomatal ozone uptake. In contrast, during spring and autumn, the climatic conditions can limit ozone uptake for many species. Although small increases in ozone concentration during these seasons could cause a modest increase in ozone uptake, for those species that are active at low temperatures, a 2 °C increase in temperature would increase stomatal ozone uptake even in the absence of further increases in ozone concentration. Predicted changes in climate could alter ozone uptake even with no change in ozone profile. For some southern regions of Europe, where temperatures are close to or above optimum for stomatal opening, an increase in temperature of 2 °C could limit stomatal ozone uptake by enhancing stomatal closure during the summer months, whereas during the spring, when many plants are actively growing, a small increase in temperature would increase stomatal ozone uptake.
BibTeX:
@article{Hayes2019,
  author = {Hayes, Felicity and Mills, Gina and Alonso, Rocio and González-Fernández, Ignacio and Coyle, Mhairi and Grünhage, Ludger and Gerosa, Giacomo and Karlsson, Per Erik and Marzuoli, Riccardo},
  title = {A Site-Specific Analysis of the Implications of a Changing Ozone Profile and Climate for Stomatal Ozone Fluxes in Europe},
  journal = {Water, Air, and Soil Pollution},
  publisher = {Springer Science and Business Media LLC},
  year = {2019},
  volume = {230},
  number = {1},
  doi = {10.1007/s11270-018-4057-x}
}
Haynes KD, Baker IT, Denning AS, Wolf S, Wohlfahrt G, Kiely G, Minaya RC and Haynes JM (2019), "Representing Grasslands Using Dynamic Prognostic Phenology Based on Biological Growth Stages: Part 2. Carbon Cycling", Journal of Advances in Modeling Earth Systems., dec, 2019. Vol. 11(12), pp. 4440-4465. Blackwell Publishing Ltd.
Abstract: Grasslands are one of the most widely distributed and abundant vegetation types globally, and land surface models struggle to accurately simulate grassland carbon dioxide, energy, and water fluxes. Here we hypothesize that this is due to land surface models having difficulties in reproducing grassland phenology, in particular in response to the seasonal and interannual variability of precipitation. Using leaf area index (LAI), net primary productivity, and flux data at 55 sites spanning climate zones, the aim of this study is to evaluate a novel prognostic phenology model (Simple Biosphere Model, SiB4) while simultaneously illustrating grassland relationships across precipitation gradients. Evaluating from 2000 to 2014, SiB4 predicts daily LAI, carbon, and energy fluxes with root-mean-square errors textless 15% and individual biases textless10%; however, not including management likely reduces its performance. Grassland mean annual LAI increases linearly with mean annual precipitation, with both SiB4 and the Moderate Resolution Imaging Spectroradiometer (MODIS) showing a 0.13 increase in LAI per 100-mm increase in precipitation. Both gross primary production and ecosystem respiration increase with growing season length by ∼8.5 g C m−2 per day, with SiB4 and Fluxnet estimates within 18%. Despite differences in mean annual precipitation and growing season length, all grassland sites shift to seasonal carbon sinks one month prior to peak uptake. During a U.S. drought, MODIS and SiB4 had nearly identical LAI responses, and the LAI change due to drought was less than the LAI change across the precipitation gradient, indicating that grassland drought response is not as strong as the overlying climate response.
BibTeX:
@article{Haynes2019,
  author = {Haynes, Katherine D. and Baker, Ian T. and Denning, A. Scott and Wolf, Sebastian and Wohlfahrt, Georg and Kiely, Gerard and Minaya, Renee C. and Haynes, John M.},
  title = {Representing Grasslands Using Dynamic Prognostic Phenology Based on Biological Growth Stages: Part 2. Carbon Cycling},
  journal = {Journal of Advances in Modeling Earth Systems},
  publisher = {Blackwell Publishing Ltd},
  year = {2019},
  volume = {11},
  number = {12},
  pages = {4440--4465},
  doi = {10.1029/2018MS001541}
}
He Y, Peng S, Liu Y, Li X, Wang K, Ciais P, Arain MA, Fang Y, Fisher JB, Goll D, Hayes D, Huntzinger DN, Ito A, Jain AK, Janssens IA, Mao J, Matteo C, Michalak AM, Peng C, Peñuelas J, Poulter B, Qin D, Ricciuto DM, Schaefer K, Schwalm CR, Shi X, Tian H, Vicca S, Wei Y, Zeng N and Zhu Q (2019), "Global vegetation biomass production efficiency constrained by models and observations", Global Change Biology., sep, 2019. Vol. 26(3), pp. 1474-1484. Wiley.
Abstract: Plants use only a fraction of their photosynthetically derived carbon for biomass production (BP). The biomass production efficiency (BPE), defined as the ratio of BP to photosynthesis, and its variation across and within vegetation types is poorly understood, which hinders our capacity to accurately estimate carbon turnover times and carbon sinks. Here, we present a new global estimation of BPE obtained by combining field measurements from 113 sites with 14 carbon cycle models. Our best estimate of global BPE is 0.41 ± 0.05, excluding cropland. The largest BPE is found in boreal forests (0.48 ± 0.06) and the lowest in tropical forests (0.40 ± 0.04). Carbon cycle models overestimate BPE, although models with carbon–nitrogen interactions tend to be more realistic. Using observation-based estimates of global photosynthesis, we quantify the global BP of non-cropland ecosystems of 41 ± 6 Pg C/year. This flux is less than net primary production as it does not contain carbon allocated to symbionts, used for exudates or volatile carbon compound emissions to the atmosphere. Our study reveals a positive bias of 24 ± 11% in the model-estimated BP (10 of 14 models). When correcting models for this bias while leaving modeled carbon turnover times unchanged, we found that the global ecosystem carbon storage change during the last century is decreased by 67% (or 58 Pg C).
BibTeX:
@article{He2019,
  author = {He, Yue and Peng, Shushi and Liu, Yongwen and Li, Xiangyi and Wang, Kai and Ciais, Philippe and Arain, M Altaf and Fang, Yuanyuan and Fisher, Joshua B and Goll, Daniel and Hayes, Daniel and Huntzinger, Deborah N and Ito, Akihiko and Jain, Atul K and Janssens, Ivan A and Mao, Jiafu and Matteo, Campioli and Michalak, Anna M and Peng, Changhui and Peñuelas, Josep and Poulter, Benjamin and Qin, Dahe and Ricciuto, Daniel M and Schaefer, Kevin and Schwalm, Christopher R and Shi, Xiaoying and Tian, Hanqin and Vicca, Sara and Wei, Yaxing and Zeng, Ning and Zhu, Qiuan},
  title = {Global vegetation biomass production efficiency constrained by models and observations},
  journal = {Global Change Biology},
  publisher = {Wiley},
  year = {2019},
  volume = {26},
  number = {3},
  pages = {1474--1484},
  doi = {10.1111/gcb.14816}
}
Helfter C, Mullinger N, Vieno M, O'Doherty S, Ramonet M, Palmer PI and Nemitz E (2019), "Country-scale greenhouse gas budgets using shipborne measurements: A case study for the UK and Ireland", Atmospheric Chemistry and Physics., mar, 2019. Vol. 19(5), pp. 3043-3063. Copernicus GmbH.
Abstract: We present a mass balance approach to estimate the seasonal and annual budgets of carbon dioxide (CO2) and methane (CH4) of the United Kingdom (excluding Scotland) and the Republic of Ireland from concentration measurements taken on a ferry along the east coast of the United Kingdom over a 3-year period (2015-2017). We estimate the annual emissions of CH4 to be 2.55±0.48 Tg, which is consistent with the combined 2.29 Tg reported to the United Nations Framework Convention on Climate Change by the individual countries. The net CO2 budget (i.e. including all anthropogenic and biogenic sources and sinks of CO2) is estimated at 881.0±125.8 Tg, with a net biogenic contribution of 458.7 Tg (taken as the difference between the estimated net emissions and the inventory value, which accounts for anthropogenic emissions only). The largest emissions for both gases were observed in a broad latitudinal band (52.5-54°N), which coincides with densely populated areas. The emissions of both gases were seasonal (maxima in winter and minima in summer), strongly correlated with natural gas usage and, to a lesser extent, also anti-correlated with mean air temperature. Methane emissions exhibited a statistically significant anti-correlation with air temperature at the seasonal timescale in the central region spanning 52.8-54.2°N, which hosts a relatively high density of waste treatment facilities. Methane emissions from landfills have been shown to sometimes increase with decreasing air temperature due to changes in the CH4-oxidising potential of the topsoil, and we speculate that the waste sector contributes significantly to the CH4 budget of this central region. This study brings independent verification of the emission budgets estimated using alternative products (e.g. mass balance budgets by aircraft measurements, inverse modelling, inventorying) and offers an opportunity to investigate the seasonality of these emissions, which is usually not possible.
BibTeX:
@article{Helfter2019,
  author = {Helfter, Carole and Mullinger, Neil and Vieno, Massimo and O'Doherty, Simon and Ramonet, Michel and Palmer, Paul I and Nemitz, Eiko},
  title = {Country-scale greenhouse gas budgets using shipborne measurements: A case study for the UK and Ireland},
  journal = {Atmospheric Chemistry and Physics},
  publisher = {Copernicus GmbH},
  year = {2019},
  volume = {19},
  number = {5},
  pages = {3043--3063},
  doi = {10.5194/acp-19-3043-2019}
}
Hemes KS, Chamberlain SD, Eichelmann E, Anthony T, Valach A, Kasak K, Szutu D, Verfaillie J, Silver WL and Baldocchi DD (2019), "Assessing the carbon and climate benefit of restoring degraded agricultural peat soils to managed wetlands", Agricultural and Forest Meteorology., apr, 2019. Vol. 268, pp. 202-214. Elsevier B.V..
Abstract: Restoring degraded peat soils presents an attractive, but largely untested, climate change mitigation approach. Drained peat soils used for agriculture can be large greenhouse gas sources. By restoring subsided peat soils to managed, impounded wetlands, significant agricultural emissions are avoided, and soil carbon can be sequestered and protected. Here, we synthesize 36 site-years of continuous carbon dioxide and methane flux data from a mesonetwork of eddy covariance towers in the Sacramento-San Joaquin Delta in California, USA to compute carbon and greenhouse gas budgets for drained agricultural land uses and compare these to restored deltaic wetlands. We found that restored wetlands effectively sequestered carbon and halted soil carbon loss associated with drained agricultural land uses. Depending on the age and disturbance regime of the restored wetland, many land use conversions from agriculture to restored wetland resulted in emission reductions over a 100-year timescale. With a simple model of radiative forcing and atmospheric lifetimes, we showed that restored wetlands do not begin to accrue greenhouse gas benefits until nearly a half century, and become net sinks from the atmosphere after a century. Due to substantial interannual variability and uncertainty about the multi-decadal successional trajectory of managed, restored wetlands, ongoing ecosystem flux measurements are critical for understanding the long-term impacts of wetland restoration for climate change mitigation.
BibTeX:
@article{Hemes2019,
  author = {Hemes, Kyle S. and Chamberlain, Samuel D. and Eichelmann, Elke and Anthony, Tyler and Valach, Amy and Kasak, Kuno and Szutu, Daphne and Verfaillie, Joe and Silver, Whendee L. and Baldocchi, Dennis D.},
  title = {Assessing the carbon and climate benefit of restoring degraded agricultural peat soils to managed wetlands},
  journal = {Agricultural and Forest Meteorology},
  publisher = {Elsevier B.V.},
  year = {2019},
  volume = {268},
  pages = {202--214},
  doi = {10.1016/j.agrformet.2019.01.017}
}
Holding T, Ashton IG, Shutler JD, Land PE, Nightingale PD, Rees AP, Brown I, Piolle JF, Kock A, Bange HW, Woolf DK, Goddijn-Murphy L, Pereira R, Paul F, Girard-Ardhuin F, Chapron B, Rehder G, Ardhuin F and Donlon CJ (2019), "The fluxengine air-sea gas flux toolbox: Simplified interface and extensions for in situ analyses and multiple sparingly soluble gases", Ocean Science., dec, 2019. Vol. 15(6), pp. 1707-1728. Copernicus GmbH.
Abstract: The flow (flux) of climate-critical gases, such as carbon dioxide (span classCombining double low line"inline-formula"CO2/span), between the ocean and the atmosphere is a fundamental component of our climate and an important driver of the biogeochemical systems within the oceans. Therefore, the accurate calculation of these air-sea gas fluxes is critical if we are to monitor the oceans and assess the impact that these gases are having on Earth's climate and ecosystems. FluxEngine is an open-source software toolbox that allows users to easily perform calculations of air-sea gas fluxes from model, in situ, and Earth observation data. The original development and verification of the toolbox was described in a previous publication. The toolbox has now been considerably updated to allow for its use as a Python library, to enable simplified installation, to ensure verification of its installation, to enable the handling of multiple sparingly soluble gases, and to enable the greatly expanded functionality for supporting in situ dataset analyses. This new functionality for supporting in situ analyses includes user-defined grids, time periods and projections, the ability to reanalyse in situ span classCombining double low line"inline-formula"CO2/span data to a common temperature dataset, and the ability to easily calculate gas fluxes using in situ data from drifting buoys, fixed moorings, and research cruises. Here we describe these new capabilities and demonstrate their application through illustrative case studies. The first case study demonstrates the workflow for accurately calculating span classCombining double low line"inline-formula"CO2/span fluxes using in situ data from four research cruises from the Surface Ocean span classCombining double low line"inline-formula"CO2/span ATlas (SOCAT) database. The second case study calculates air-sea span classCombining double low line"inline-formula"CO2/span fluxes using in situ data from a fixed monitoring station in the Baltic Sea. The third case study focuses on nitrous oxide (span classCombining double low line"inline-formula"N2O/span) and, through a user-defined gas transfer parameterisation, identifies that biological surfactants in the North Atlantic could suppress individual span classCombining double low line"inline-formula"N2O/span sea-air gas fluxes by up to 13 %. The fourth and final case study illustrates how a dissipation-based gas transfer parameterisation can be implemented and used. The updated version of the toolbox (version 3) and all documentation is now freely available.
BibTeX:
@article{Holding2019,
  author = {Holding, Thomas and Ashton, Ian G and Shutler, Jamie D and Land, Peter E and Nightingale, Philip D and Rees, Andrew P and Brown, Ian and Piolle, Jean Francois and Kock, Annette and Bange, Hermann W and Woolf, David K and Goddijn-Murphy, Lonneke and Pereira, Ryan and Paul, Frederic and Girard-Ardhuin, Fanny and Chapron, Bertrand and Rehder, Gregor and Ardhuin, Fabrice and Donlon, Craig J},
  title = {The fluxengine air-sea gas flux toolbox: Simplified interface and extensions for in situ analyses and multiple sparingly soluble gases},
  journal = {Ocean Science},
  publisher = {Copernicus GmbH},
  year = {2019},
  volume = {15},
  number = {6},
  pages = {1707--1728},
  doi = {10.5194/os-15-1707-2019}
}
Horemans JA, Arriga N and Ceulemans R (2019), "Greenhouse gas budget of a poplar bioenergy plantation in Belgium: CO2 uptake outweighs CH4 and N2O emissions", GCB Bioenergy., oct, 2019. Vol. 11(12), pp. 1435-1443. Wiley.
Abstract: Biomass from short-rotation coppice (SRC) of woody perennials is being increasingly used as a bioenergy source to replace fossil fuels, but accurate assessments of the long-term greenhouse gas (GHG) balance of SRC are lacking. To evaluate its mitigation potential, we monitored the GHG balance of a poplar (Populus) SRC in Flanders, Belgium, over 7 years comprising three rotations (i.e., two 2 year rotations and one 3 year rotation). In the beginning—that is, during the establishment year and during each year immediately following coppicing—the SRC plantation was a net source of GHGs. Later on—that is, during each second or third year after coppicing—the site shifted to a net sink. From the sixth year onward, there was a net cumulative GHG uptake reaching âˆ'35.8 Mg CO2 eq/ha during the seventh year. Over the three rotations, the total CO2 uptake was âˆ'51.2 Mg CO2/ha, while the emissions of CH4 and N2O amounted to 8.9 and 6.5 Mg CO2 eq/ha, respectively. As the site was non-fertilized, non-irrigated, and only occasionally flooded, CO2 fluxes dominated the GHG budget. Soil disturbance after land conversion and after coppicing were the main drivers for CO2 losses. One single N2O pulse shortly after SRC establishment contributed significantly to the N2O release. The results prove the potential of SRC biomass plantations to reduce GHG emissions and demonstrate that, for the poplar plantation under study, the high CO2 uptake outweighs the emissions of non-CO2 greenhouse gases.
BibTeX:
@article{Horemans2019,
  author = {Horemans, Joanna A and Arriga, Nicola and Ceulemans, Reinhart},
  title = {Greenhouse gas budget of a poplar bioenergy plantation in Belgium: CO2 uptake outweighs CH4 and N2O emissions},
  journal = {GCB Bioenergy},
  publisher = {Wiley},
  year = {2019},
  volume = {11},
  number = {12},
  pages = {1435--1443},
  doi = {10.1111/gcbb.12648}
}
van der Horst SVJ, Pitman AJ, De Kauwe MG, Ukkola A, Abramowitz G and Isaac P (2019), "How representative are FLUXNET measurements of surface fluxes during temperature extremes?", Biogeosciences., apr, 2019. Vol. 16(8), pp. 1829-1844.
BibTeX:
@article{VanderHorst2019,
  author = {van der Horst, Sophie V J and Pitman, Andrew J and De Kauwe, Martin G and Ukkola, Anna and Abramowitz, Gab and Isaac, Peter},
  title = {How representative are FLUXNET measurements of surface fluxes during temperature extremes?},
  journal = {Biogeosciences},
  year = {2019},
  volume = {16},
  number = {8},
  pages = {1829--1844},
  url = {https://www.biogeosciences.net/16/1829/2019/},
  doi = {10.5194/bg-16-1829-2019}
}
Huang M, Piao S, Ciais P, Peñuelas J, Wang X, Keenan TF, Peng S, Berry JA, Wang K, Mao J, Alkama R, Cescatti A, Cuntz M, De Deurwaerder H, Gao M, He Y, Liu Y, Luo Y, Myneni RB, Niu S, Shi X, Yuan W, Verbeeck H, Wang T, Wu J and Janssens IA (2019), "Air temperature optima of vegetation productivity across global biomes", Nature Ecology and Evolution., mar, 2019. Vol. 3(5), pp. 772-779. Springer Science and Business Media LLC.
Abstract: The global distribution of the optimum air temperature for ecosystem-level gross primary productivity (Topteco) is poorly understood, despite its importance for ecosystem carbon uptake under future warming. We provide empirical evidence for the existence of such an optimum, using measurements of in situ eddy covariance and satellite-derived proxies, and report its global distribution. Topteco is consistently lower than the physiological optimum temperature of leaf-level photosynthetic capacity, which typically exceeds 30 °C. The global average Topteco is estimated to be 23 ± 6 °C, with warmer regions having higher Topteco values than colder regions. In tropical forests in particular, Topteco is close to growing-season air temperature and is projected to fall below it under all scenarios of future climate, suggesting a limited safe operating space for these ecosystems under future warming.
BibTeX:
@article{Huang2019a,
  author = {Huang, Mengtian and Piao, Shilong and Ciais, Philippe and Peñuelas, Josep and Wang, Xuhui and Keenan, Trevor F and Peng, Shushi and Berry, Joseph A and Wang, Kai and Mao, Jiafu and Alkama, Ramdane and Cescatti, Alessandro and Cuntz, Matthias and De Deurwaerder, Hannes and Gao, Mengdi and He, Yue and Liu, Yongwen and Luo, Yiqi and Myneni, Ranga B and Niu, Shuli and Shi, Xiaoying and Yuan, Wenping and Verbeeck, Hans and Wang, Tao and Wu, Jin and Janssens, Ivan A},
  title = {Air temperature optima of vegetation productivity across global biomes},
  journal = {Nature Ecology and Evolution},
  publisher = {Springer Science and Business Media LLC},
  year = {2019},
  volume = {3},
  number = {5},
  pages = {772--779},
  doi = {10.1038/s41559-019-0838-x}
}
Huang W, Raza SA, Mirzov O and Harrie L (2019), "Assessment and Benchmarking of Spatially Enabled RDF Stores for the Next Generation of Spatial Data Infrastructure", ISPRS International Journal of Geo-Information., jul, 2019. Vol. 8(7), pp. 310. MDPI AG.
Abstract: textlessptextgreaterGeospatial information is indispensable for various real-world applications and is thus a prominent part of today's data science landscape. Geospatial data is primarily maintained and disseminated through spatial data infrastructures (SDIs). However, current SDIs are facing challenges in terms of data integration and semantic heterogeneity because of their partially siloed data organization. In this context, linked data provides a promising means to unravel these challenges, and it is seen as one of the key factors moving SDIs toward the next generation. In this study, we investigate the technical environment of the support for geospatial linked data by assessing and benchmarking some popular and well-known spatially enabled RDF stores (RDF4J, GeoSPARQL-Jena, Virtuoso, Stardog, and GraphDB), with a focus on GeoSPARQL compliance and query performance. The tests were performed in two different scenarios. In the first scenario, geospatial data forms a part of a large-scale data infrastructure and is integrated with other types of data. In this scenario, we used ICOS Carbon Portal's metadata—a real-world Earth Science linked data infrastructure. In the second scenario, we benchmarked the RDF stores in a dedicated SDI environment that contains purely geospatial data, and we used geospatial datasets with both crowd-sourced and authoritative data (the same test data used in a previous benchmark study, the Geographica benchmark). The assessment and benchmarking results demonstrate that the GeoSPARQL compliance of the RDF stores has encouragingly advanced in the last several years. The query performances are generally acceptable, and spatial indexing is imperative when handling a large number of geospatial objects. Nevertheless, query correctness remains a challenge for cross-database interoperability. In conclusion, the results indicate that the spatial capacity of the RDF stores has become increasingly mature, which could benefit the development of future SDIs.textless/ptextgreater
BibTeX:
@article{Huang2019b,
  author = {Huang, Weiming and Raza, Syed Amir and Mirzov, Oleg and Harrie, Lars},
  title = {Assessment and Benchmarking of Spatially Enabled RDF Stores for the Next Generation of Spatial Data Infrastructure},
  journal = {ISPRS International Journal of Geo-Information},
  publisher = {MDPI AG},
  year = {2019},
  volume = {8},
  number = {7},
  pages = {310},
  url = {https://www.mdpi.com/2220-9964/8/7/310},
  doi = {10.3390/ijgi8070310}
}
Huang X, Xiao J and Ma M (2019), "Evaluating the Performance of Satellite-Derived Vegetation Indices for Estimating Gross Primary Productivity Using FLUXNET Observations across the Globe", Remote Sensing., aug, 2019. Vol. 11(15), pp. 1823.
Abstract: Satellite-derived vegetation indices (VIs) have been widely used to approximate or estimate gross primary productivity (GPP). However, it remains unclear how the VI-GPP relationship varies with indices, biomes, timescales, and the bidirectional reflectance distribution function (BRDF) effect. We examined the relationship between VIs and GPP for 121 FLUXNET sites across the globe and assessed how the VI-GPP relationship varied among a variety of biomes at both monthly and annual timescales. We used three widely-used VIs: normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), and 2-band EVI (EVI2) as well as a new VI - NIRV and used surface reflectance both with and without BRDF correction from the moderate resolution imaging spectroradiometer (MODIS) to calculate these indices. The resulting traditional (NDVI, EVI, EVI2, and NIRV) and BRDF-corrected (NDVIBRDF, EVIBRDF, EVI2BRDF, and NIRV, BRDF) VIs were used to examine the VI-GPP relationship. At the monthly scale, all VIs were moderate or strong predictors of GPP, and the BRDF correction improved their performance. EVI2BRDF and NIRV, BRDF had similar performance in capturing the variations in tower GPP as did the MODIS GPP product. The VIs explained lower variance in tower GPP at the annual scale than at the monthly scale. The BRDF-correction of surface reflectance did not improve the VI-GPP relationship at the annual scale. The VIs had similar capability in capturing the interannual variability in tower GPP as MODIS GPP. VIs were influenced by temperature and water stresses and were more sensitive to temperature stress than to water stress. VIs in combination with environmental factors could improve the prediction of GPP than VIs alone. Our findings can help us better understand how the VI-GPP relationship varies among indices, biomes, and timescales and how the BRDF effect influences the VI-GPP relationship.
BibTeX:
@article{Huang2019,
  author = {Huang, Xiaojuan and Xiao, Jingfeng and Ma, Mingguo},
  title = {Evaluating the Performance of Satellite-Derived Vegetation Indices for Estimating Gross Primary Productivity Using FLUXNET Observations across the Globe},
  journal = {Remote Sensing},
  year = {2019},
  volume = {11},
  number = {15},
  pages = {1823},
  url = {https://www.mdpi.com/2072-4292/11/15/1823},
  doi = {10.3390/rs11151823}
}
Hurdebise Q, Aubinet M, Heinesch B and Vincke C (2019), "Increasing temperatures over an 18-year period shortens growing season length in a beech (Fagus sylvatica L.)-dominated forest", Annals of Forest Science., jul, 2019. Vol. 76(3) Springer Science and Business Media LLC.
Abstract: Key message: Using long-term measurements in a mature beech (Fagus sylvatica L.)-dominated forest located in east Belgium, this paper showed that spring and autumn temperature increases during the last two decades led to an earlier end and a shortening of the growing season. These phenological shifts impact negatively but not significantly the forest annual net ecosystem productivity. Context: The mechanisms controlling temperate forest phenology are not fully understood nor are the impacts of climate change and the consequences for forest productivity. Aims: The aim of this paper is to contribute to the understanding of how temperate forest phenology and net ecosystem productivity (NEP) interplay and respond to temperature and its evolution. Methods: Indicators of leaf phenology and productivity dynamics at the start and the end of the growing season, as well as combinations of these indicators (length of the growing season), were derived from a long-term (1997–2014) dataset of eddy covariance and light transmission measurements taken over a mature beech-dominated temperate forest. Results: The start and the end of the growing season were correlated to spring (and autumn, for the end) temperatures. Despite no trends in annual average temperatures being detected during the observation period, April and November temperatures significantly increased. As a result, an earlier but slower start and an earlier end, inducing a shorter length of the growing season, were observed over the studied period. The first shift positively impacts the mixed forest NEP but is mainly related to the presence of conifers in the subplot. The earlier end of the growing season, more related to beech phenology, negatively impacts the forest NEP. Overall, these two effects partially compensate each other, leading to a non-significant impact on NEP. Conclusion: Increasing temperatures over the 18-year studied period shortened the growing season length, without affecting significantly the mixed forest NEP. However, as beeches are only affected by the earlier end of the growing season, this suggests a phenologically driven beech productivity reduction in the forest.
BibTeX:
@article{Hurdebise2019,
  author = {Hurdebise, Quentin and Aubinet, Marc and Heinesch, Bernard and Vincke, Caroline},
  title = {Increasing temperatures over an 18-year period shortens growing season length in a beech (Fagus sylvatica L.)-dominated forest},
  journal = {Annals of Forest Science},
  publisher = {Springer Science and Business Media LLC},
  year = {2019},
  volume = {76},
  number = {3},
  doi = {10.1007/s13595-019-0861-8}
}
Ivakhov VM, Paramonova NN, Privalov VI, Zinchenko AV, Loskutova MA, Makshtas AP, Kustov VY, Laurila T, Aurela M and Asmi E (2019), "Atmospheric Concentration of Carbon Dioxide at Tiksi and Cape Baranov Stations in 2010–2017", Russian Meteorology and Hydrology., apr, 2019. Vol. 44(4), pp. 291-299. Allerton Press.
Abstract: The study presents the results of continuous measurements of carbon dioxide concentration in the atmospheric surface layer at Tiksi and Cape Baranov Arctic stations over the period of August 2010–May 2017 and over the whole 2016, respectively. The amplitude of diurnal variations in the CO2 concentration in Tiksi from June to September is 1.1 ± 1.3, 2.4 ± 2.0, 4.1 ± 2.3, and 2.0 ± 2.4 ppm. Diurnal variations in CO2 at Cape Baranov station are absent. The observed seasonal variations in the CO2 concentration are compared with the data of the MBL empirical model for the marine atmospheric boundary layer of the Arctic region. In 2016, the difference between the observed and model concentrations at Tiksi and Cape Baranov stations amounted to 1.7 and 0.5 ppm, respectively, in winter and âˆ'3.0 and âˆ'1.9 ppm, respectively, in summer. It is shown that wildfires in Siberia caused a long synchronous increase in the CO2 concentration by 20 ppm in Tiksi and by 15 ppm at Cape Baranov station.
BibTeX:
@article{Ivakhov2019,
  author = {Ivakhov, V M and Paramonova, N N and Privalov, V I and Zinchenko, A V and Loskutova, M A and Makshtas, A P and Kustov, V Y and Laurila, T and Aurela, M and Asmi, E},
  title = {Atmospheric Concentration of Carbon Dioxide at Tiksi and Cape Baranov Stations in 2010–2017},
  journal = {Russian Meteorology and Hydrology},
  publisher = {Allerton Press},
  year = {2019},
  volume = {44},
  number = {4},
  pages = {291--299},
  doi = {10.3103/S1068373919040095}
}
Jakovljević T, Marchetto A, Lovreškov L, Potočić N, Seletković I, Indir K, Jelić G, Butorac L, Zgrablić Ž, De Marco A, Simioni G, Ognjenović M and Jurinjak Tušek A (2019), "Assessment of Atmospheric Deposition and Vitality Indicators in Mediterranean Forest Ecosystems", Sustainability., nov, 2019. Vol. 11(23), pp. 6805. MDPI AG.
Abstract: Considering the fragility of the Mediterranean environment, there is an increasing need to improve the knowledge of this forest environment. The aim of this study was to examine the effects of air pollution on the forest ecosystem's condition by analyzing tree vitality. The study area was chosen to represent the most important and the most common species in Mediterranean forest ecosystems of the Eastern Adriatic coast. Quercus pubescens, Quercus ilex, Pinus halepensis, and Pinus nigra plots were equipped with rain collectors and dendrometer bands. Sampling, measurements, and analyses of atmospheric deposition, foliar nutrient, defoliation, and growth were all carried out. Results showed that actual N deposition loads were the lowest in Aleppo pine forest and the highest in holm oak forests. This, however, did not have an effect on the concentrations of N in foliage. Most elements' concentrations were in the plausible range. No relevant differences in mean defoliation between the plots were observed. The plots with a lower percentage of basal area increment (BAI%) were found to have lower defoliation. The research was conducted to bridge the gap in the knowledge of air pollutants and vitality indicators in different forest types. These findings are a valuable contribution to the sustainable forest management of Mediterranean forest.
BibTeX:
@article{Jakovljevic2019,
  author = {Jakovljević, Tamara and Marchetto, Aldo and Lovreškov, Lucija and Potočić, Nenad and Seletković, Ivan and Indir, Krunoslav and Jelić, Goran and Butorac, Lukrecija and Zgrablić, Željko and De Marco, Alessandra and Simioni, Guillaume and Ognjenović, Mladen and Jurinjak Tušek, Ana},
  title = {Assessment of Atmospheric Deposition and Vitality Indicators in Mediterranean Forest Ecosystems},
  journal = {Sustainability},
  publisher = {MDPI AG},
  year = {2019},
  volume = {11},
  number = {23},
  pages = {6805},
  doi = {10.3390/su11236805}
}
Järvi L, Havu M, Ward HC, Bellucco V, McFadden JP, Toivonen T, Heikinheimo V, Kolari P, Riikonen A and Grimmond CSB (2019), "Spatial Modeling of Local-Scale Biogenic and Anthropogenic Carbon Dioxide Emissions in Helsinki", Journal of Geophysical Research: Atmospheres., aug, 2019. Vol. 124(15), pp. 8363-8384. American Geophysical Union (AGU).
Abstract: There is a growing need to simulate the effect of urban planning on both local climate and greenhouse gas emissions. Here, a new urban surface carbon dioxide (CO2) flux module for the Surface Urban Energy and Water Balance Scheme is described and evaluated using eddy covariance observations at two sites in Helsinki in 2012. The spatial variability and magnitude of local-scale anthropogenic and biogenic CO2 flux components at high spatial (250 m × 250 m) and temporal (hourly) resolution are examined by combining high-resolution (down to 2 m) airborne lidar-derived land use data and mobility data to account for people's movement. Urban effects are included in the biogenic components parameterized using urban eddy covariance and chamber observations. Surface Urban Energy and Water Balance Scheme reproduces the seasonal and diurnal variability of the CO2 flux well. Annual totals deviate 3% from observations in the city center and 2% in a suburban location. In the latter, traffic is the dominant CO2 source but summertime vegetation partly offsets traffic-related emissions. In the city center, emissions from traffic and human metabolism dominate and the vegetation effect is minor due to the low proportion of vegetation surface cover (22%). Within central Helsinki, human metabolism accounts for 39% of the net local-scale emissions and together with road traffic is to a large extent responsible for the spatial variability of the emissions. Annually, the biogenic emissions and sinks are in near balance and thus the effect of vegetation on the carbon balance is small in this high-latitude city.
BibTeX:
@article{Jarvi2019,
  author = {Järvi, Leena and Havu, Minttu and Ward, Helen C and Bellucco, Veronica and McFadden, Joseph P and Toivonen, Tuuli and Heikinheimo, Vuokko and Kolari, Pasi and Riikonen, Anu and Grimmond, C Sue B},
  title = {Spatial Modeling of Local-Scale Biogenic and Anthropogenic Carbon Dioxide Emissions in Helsinki},
  journal = {Journal of Geophysical Research: Atmospheres},
  publisher = {American Geophysical Union (AGU)},
  year = {2019},
  volume = {124},
  number = {15},
  pages = {8363--8384},
  doi = {10.1029/2018JD029576}
}
Jauhiainen J, Alm J, Bjarnadottir B, Callesen I, Christiansen JR, Clarke N, Dalsgaard L, He H, Jordan S, Kazanavičiute V, Klemedtsson L, Lauren A, Lazdins A, Lehtonen A, Lohila A, Lupikis A, Mander Ü, Minkkinen K, Kasimir Å, Olsson M, Ojanen P, Óskarsson H, Sigurdsson BD, Søgaard G, Soosaar K, Vesterdal L and Laiho R (2019), "Reviews and syntheses: Greenhouse gas exchange data from drained organic forest soils-A review of current approaches and recommendations for future research", Biogeosciences., dec, 2019. Vol. 16(23), pp. 4687-4703. Copernicus GmbH.
Abstract: Drained organic forest soils in boreal and temperate climate zones are believed to be significant sources of the greenhouse gases (GHGs) carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), but the annual fluxes are still highly uncertain. Drained organic soils exemplify systems where many studies are still carried out with relatively small resources, several methodologies and manually operated systems, which further involve different options for the detailed design of the measurement and data analysis protocols for deriving the annual flux. It would be beneficial to set certain guidelines for how to measure and report the data, so that data from individual studies could also be used in synthesis work based on data collation and modelling. Such synthesis work is necessary for deciphering general patterns and trends related to, e.g., site types, climate, and management, and the development of corresponding emission factors, i.e. estimates of the net annual soil GHG emission and removal, which can be used in GHG inventories. Development of specific emission factors also sets prerequisites for the background or environmental data to be reported in individual studies. We argue that wide applicability greatly increases the value of individual studies. An overall objective of this paper is to support future monitoring campaigns in obtaining high-value data.We analysed peer-reviewed public cations presenting CO2, CH4 and N2O flux data for drained organic forest soils in boreal and temperate climate zones, focusing on data that have been used, or have the potential to be used, for estimating net annual soil GHG emissions and removals. We evaluated the methods used in data collection and identified major gaps in background or environmental data. Based on these, we formulated recommendations for future research.
BibTeX:
@article{Jauhiainen2019,
  author = {Jauhiainen, Jyrki and Alm, Jukka and Bjarnadottir, Brynhildur and Callesen, Ingeborg and Christiansen, Jesper R and Clarke, Nicholas and Dalsgaard, Lise and He, Hongxing and Jordan, Sabine and Kazanavičiute, Vaiva and Klemedtsson, Leif and Lauren, Ari and Lazdins, Andis and Lehtonen, Aleksi and Lohila, Annalea and Lupikis, Ainars and Mander, Ülo and Minkkinen, Kari and Kasimir, Åsa and Olsson, Mats and Ojanen, Paavo and Óskarsson, Hlynur and Sigurdsson, Bjarni D and Søgaard, Gunnhild and Soosaar, Kaido and Vesterdal, Lars and Laiho, Raija},
  title = {Reviews and syntheses: Greenhouse gas exchange data from drained organic forest soils-A review of current approaches and recommendations for future research},
  journal = {Biogeosciences},
  publisher = {Copernicus GmbH},
  year = {2019},
  volume = {16},
  number = {23},
  pages = {4687--4703},
  doi = {10.5194/bg-16-4687-2019}
}
Jiang LQ, Carter BR, Feely RA, Lauvset SK and Olsen A (2019), "Surface ocean pH and buffer capacity: past, present and future", Scientific Reports., dec, 2019. Vol. 9(1) Springer Science and Business Media LLC.
Abstract: The ocean's chemistry is changing due to the uptake of anthropogenic carbon dioxide (CO2). This phenomenon, commonly referred to as “Ocean Acidification”, is endangering coral reefs and the broader marine ecosystems. In this study, we combine a recent observational seawater CO2 data product, i.e., the 6th version of the Surface Ocean CO2 Atlas (1991–2018, ˜23 million observations), with temporal trends at individual locations of the global ocean from a robust Earth System Model to provide a high-resolution regionally varying view of global surface ocean pH and the Revelle Factor. The climatology extends from the pre-Industrial era (1750 C.E.) to the end of this century under historical atmospheric CO2 concentrations (pre-2005) and the Representative Concentrations Pathways (post-2005) of the Intergovernmental Panel on Climate Change (IPCC)'s 5th Assessment Report. By linking the modeled pH trends to the observed modern pH distribution, the climatology benefits from recent improvements in both model design and observational data coverage, and is likely to provide improved regional OA trajectories than the model output could alone, therefore, will help guide the regional OA adaptation strategies. We show that air-sea CO2 disequilibrium is the dominant mode of spatial variability for surface pH, and discuss why pH and calcium carbonate mineral saturation states, two important metrics for OA, show contrasting spatial variability.
BibTeX:
@article{Jiang2019b,
  author = {Jiang, Li Qing and Carter, Brendan R and Feely, Richard A and Lauvset, Siv K and Olsen, Are},
  title = {Surface ocean pH and buffer capacity: past, present and future},
  journal = {Scientific Reports},
  publisher = {Springer Science and Business Media LLC},
  year = {2019},
  volume = {9},
  number = {1},
  doi = {10.1038/s41598-019-55039-4}
}
Jiang P, Liu H, Piao S, Ciais P, Wu X, Yin Y and Wang H (2019), "Enhanced growth after extreme wetness compensates for post-drought carbon loss in dry forests", Nature Communications., jan, 2019. Vol. 10(1) Springer Science and Business Media LLC.
Abstract: While many studies have reported that drought events have substantial negative legacy effects on forest growth, it remains unclear whether wetness events conversely have positive growth legacy effects. Here, we report pervasive and substantial growth enhancement after extreme wetness by examining tree radial growth at 1929 forest sites, satellite-derived vegetation greenness, and land surface model simulations. Enhanced growth after extreme wetness lasts for 1 to 5 years and compensates for 93 ± 8% of the growth deficit after extreme drought across global water-limited regions. Remarkable wetness-enhanced growths are observed in dry forests and gymnosperms, whereas the enhanced growths after extreme wetness are much smaller in wet forests and angiosperms. Limited or no enhanced growths are simulated by the land surface models after extreme wetness. These findings provide new evidence for improving climate-vegetation models to include the legacy effects of both drought and wet climate extremes.
BibTeX:
@article{Jiang2019a,
  author = {Jiang, Peng and Liu, Hongyan and Piao, Shilong and Ciais, Philippe and Wu, Xiuchen and Yin, Yi and Wang, Hongya},
  title = {Enhanced growth after extreme wetness compensates for post-drought carbon loss in dry forests},
  journal = {Nature Communications},
  publisher = {Springer Science and Business Media LLC},
  year = {2019},
  volume = {10},
  number = {1},
  doi = {10.1038/s41467-018-08229-z}
}
Jiang ZP, Yuan J, Hartman SE and Fan W (2019), "Enhancing the observing capacity for the surface ocean by the use of Volunteer Observing Ship", Acta Oceanologica Sinica., jul, 2019. Vol. 38(7), pp. 114-120. Springer Verlag.
Abstract: Knowledge of the surface ocean dynamics and the underlying controlling mechanisms is critical to understand the natural variability of the ocean and to predict its future response to climate change. In this paper, we highlight the potential use of Volunteer Observing Ship (VOS), as carrier for automatic underway measuring system and as platform for sample collection, to enhance the observing capacity for the surface ocean. We review the concept, history, present status and future development of the VOS-based in situ surface ocean observation. The successes of various VOS projects demonstrate that, along with the rapid advancing sensor techniques, VOS is able to improve the temporal resolution and spatial coverage of the surface ocean observation in a highly cost-effective manner. A sustained and efficient marine monitoring system in the future should integrate the advantages of various observing platforms including VOS.
BibTeX:
@article{Jiang2019,
  author = {Jiang, Zong Pei and Yuan, Jiajun and Hartman, Susan E. and Fan, Wei},
  title = {Enhancing the observing capacity for the surface ocean by the use of Volunteer Observing Ship},
  journal = {Acta Oceanologica Sinica},
  publisher = {Springer Verlag},
  year = {2019},
  volume = {38},
  number = {7},
  pages = {114--120},
  url = {https://link.springer.com/article/10.1007/s13131-019-1463-3},
  doi = {10.1007/s13131-019-1463-3}
}
Jung M, Koirala S, Weber U, Ichii K, Gans F, Camps-Valls G, Papale D, Schwalm C, Tramontana G and Reichstein M (2019), "The FLUXCOM ensemble of global land-atmosphere energy fluxes", Scientific Data., dec, 2019. Vol. 6(1), pp. 74.
BibTeX:
@article{Jung2019,
  author = {Jung, Martin and Koirala, Sujan and Weber, Ulrich and Ichii, Kazuhito and Gans, Fabian and Camps-Valls, Gustau and Papale, Dario and Schwalm, Christopher and Tramontana, Gianluca and Reichstein, Markus},
  title = {The FLUXCOM ensemble of global land-atmosphere energy fluxes},
  journal = {Scientific Data},
  year = {2019},
  volume = {6},
  number = {1},
  pages = {74},
  url = {http://www.nature.com/articles/s41597-019-0076-8},
  doi = {10.1038/s41597-019-0076-8}
}
Juráň S, Šigut L, Holub P, Fares S, Klem K, Grace J and Urban O (2019), "Ozone flux and ozone deposition in a mountain spruce forest are modulated by sky conditions", Science of the Total Environment., jul, 2019. Vol. 672, pp. 296-304. Elsevier BV.
Abstract: In order to understand the main driving factors of ozone (O 3 ) deposition we tested the hypothesis that sky conditions (cloudy, partly cloudy, and clear sky) modulate O 3 flux in forest ecosystems via stomatal regulation. The hypothesis is based on the fact that complex microclimate conditions under cloudy sky usually stimulate stomatal conductance. O 3 fluxes were inferred from a concentration gradient in a mountainous Norway spruce forest in the Czech Republic (Central Europe) for years 2012–2016 and measured directly by eddy-covariance during the summer of 2017. Daily and seasonal O 3 depositions were calculated separately for days with cloudy, partly cloudy, and clear sky conditions. The data show unequivocally that more O 3 is taken up under cloudy and partially cloudy skies. Moreover, we found significant interactive effects of sky conditions and season on O 3 flux. Though there are other mechanisms and pathways involved in the transport of O 3 to the plant-soil system, the highest O 3 deposition was associated to the highest stomatal conductance during partly cloudy and cloudy sky conditions in all seasons, while lower O 3 ecosystem fluxes were observed under clear sky conditions despite the highest O 3 concentrations at this time. These findings suggest that forests growing at sites where conditions are predominantly cloudy are expected to deposit higher extent of O 3 than less-cloudy forests being thus more threatened by phytotoxic O 3 .
BibTeX:
@article{JuraA2019,
  author = {Juráň, Stanislav and Šigut, Ladislav and Holub, Petr and Fares, Silvano and Klem, Karel and Grace, John and Urban, Otmar},
  title = {Ozone flux and ozone deposition in a mountain spruce forest are modulated by sky conditions},
  journal = {Science of the Total Environment},
  publisher = {Elsevier BV},
  year = {2019},
  volume = {672},
  pages = {296--304},
  doi = {10.1016/j.scitotenv.2019.03.491}
}
Kadavý J, Adamec Z, Uherková B, Kneifl M, Knott R, Kučera A, Friedl M, DaÅ™enová E, Skládanka J and Drápela K (2019), "Growth response of sessile oak and European hornbeam to traditional coppice-with-standards management", Forests., jun, 2019. Vol. 10(6), pp. 515. MDPI AG.
Abstract: Research Highlights: The influence of litter raking and livestock grazing on the development of juvenile sessile oak and European hornbeam sprouts as well as on sessile oak standards were studied. Such experiments are very rare, especially in central Europe where these activities have been prohibited for several decades. Little is known on how these ancient management activities affect tree growth. Background and Objectives: Traditional management practices in coppice forests such as grazing and litter raking have been abandoned, but have recently been studied as to whether these practices can substantially contribute to an increase in the species diversity of coppices. The important question is, however, how these practices influence the growth of coppice-with-standards. Therefore, this study focused on the effect of grazing, litter raking, and their combination on both sprouts and adult trees in a coppice-with-standards system one year after harvest. Materials and Methods: The experiment was carried out in the area of the Training Forest Enterprise Masaryk Forest Křtiny, Czech Republic, in a forest stand dominated by sessile oak and European hornbeam. We analyzed 132 oak polycormons, 132 hornbeam polycormons, and 163 oak standards. Results: The number of sprouts per stump was affected by the stump size and management practice: (A) coppice-with-standards, litter raking, and sheep grazing; (B) coppice-with-standards and sheep grazing; (C) coppice-with-standards and litter raking; and (D) coppice-with-standards), but not by tree species. The number of the sprouts as well as their height increased with the stump size. In contrast, grazing resulted in a smaller height of the sprouts while thinner sprouts were found under a combination of grazing and raking. When comparing the species, the oak sprouts were higher and thicker when compared to the hornbeam sprouts. The increment of standards increased after stand harvest. This, however, was not the result of grazing or raking, but the response to the reduction of tree number and thus of competition between neighboring trees. Conclusions: The results showed that there were rather negative impacts from the implemented traditional management practices on the growth of sprouts. This may lead to the question of whether ecological diversity resulting from the traditional practices may prevail their negative effect on the growth of the coppices.
BibTeX:
@article{Kadavy2019,
  author = {Kadavý, Jan and Adamec, Zdeněk and Uherková, Barbora and Kneifl, Michal and Knott, Robert and Kučera, Aleš and Friedl, Michal and DaÅ™enová, Eva and Skládanka, JiÅ™í and Drápela, Karel},
  title = {Growth response of sessile oak and European hornbeam to traditional coppice-with-standards management},
  journal = {Forests},
  publisher = {MDPI AG},
  year = {2019},
  volume = {10},
  number = {6},
  pages = {515},
  doi = {10.3390/f10060515}
}
Keenan TF, Migliavacca M, Papale D, Baldocchi D, Reichstein M, Torn M and Wutzler T (2019), "Widespread inhibition of daytime ecosystem respiration", Nature Ecology and Evolution., feb, 2019. Vol. 3(3), pp. 407-415.
Abstract: The global land surface absorbs about a third of anthropogenic emissions each year, due to the difference between two key processes: ecosystem photosynthesis and respiration. Despite the importance of these two processes, it is not possible to measure either at the ecosystem scale during the daytime. Eddy-covariance measurements are widely used as the closest ‘quasi-direct' ecosystem-scale observation from which to estimate ecosystem photosynthesis and respiration. Recent research, however, suggests that current estimates may be biased by up to 25%, due to a previously unaccounted for process: the inhibition of leaf respiration in the light. Yet the extent of inhibition remains debated, and implications for estimates of ecosystem-scale respiration and photosynthesis remain unquantified. Here, we quantify an apparent inhibition of daytime ecosystem respiration across the global FLUXNET eddy-covariance network and identify a pervasive influence that varies by season and ecosystem type. We develop partitioning methods that can detect an apparent ecosystem-scale inhibition of daytime respiration and find that diurnal patterns of ecosystem respiration might be markedly different than previously thought. The results call for the re-evaluation of global terrestrial carbon cycle models and also suggest that current global estimates of photosynthesis and respiration may be biased, some on the order of magnitude of anthropogenic fossil fuel emissions.
BibTeX:
@article{Keenan2019,
  author = {Keenan, Trevor F and Migliavacca, Mirco and Papale, Dario and Baldocchi, Dennis and Reichstein, Markus and Torn, Margaret and Wutzler, Thomas},
  title = {Widespread inhibition of daytime ecosystem respiration},
  journal = {Nature Ecology and Evolution},
  year = {2019},
  volume = {3},
  number = {3},
  pages = {407--415},
  url = {http://www.nature.com/articles/s41559-019-0809-2},
  doi = {10.1038/s41559-019-0809-2}
}
Keppler L and Landschützer P (2019), "Regional Wind Variability Modulates the Southern Ocean Carbon Sink", Scientific Reports., dec, 2019. Vol. 9(1), pp. 1-10. Nature Publishing Group.
Abstract: The Southern Ocean south of 35°S accounts for approximately half of the annual oceanic carbon uptake, thereby substantially mitigating the effects of anthropogenic carbon dioxide (CO 2 ) emissions. The intensity of this important carbon sink varies considerably on inter-annual to decadal timescales. However, the drivers of this variability are still debated, challenging our ability to accurately predict the future role of the Southern Ocean in absorbing atmospheric carbon. Analysing mapped sea-air CO 2 fluxes, estimated from upscaled surface ocean CO 2 measurements, we find that the overall Southern Ocean carbon sink has weakened since ˜2011, reversing the trend of the reinvigoration period of the 2000s. Although we find significant regional positive and negative responses of the Southern Ocean carbon uptake to changes in the Southern Annular Mode (SAM) over the past 35 years, the net effect of the SAM on the Southern Ocean carbon sink variability is approximately zero, due to the opposing effects of enhanced outgassing in upwelling regions and enhanced carbon uptake elsewhere. Instead, regional shifts in sea level pressure, linked to zonal wavenumber 3 (ZW3) and related changes in surface winds substantially contribute to the inter-annual to decadal variability of the Southern Ocean carbon sink.
BibTeX:
@article{Keppler2019,
  author = {Keppler, Lydia and Landschützer, Peter},
  title = {Regional Wind Variability Modulates the Southern Ocean Carbon Sink},
  journal = {Scientific Reports},
  publisher = {Nature Publishing Group},
  year = {2019},
  volume = {9},
  number = {1},
  pages = {1--10},
  url = {www.nature.com/scientificreports},
  doi = {10.1038/s41598-019-43826-y}
}
Khatiwala S, Schmittner A and Muglia J (2019), "Air-sea disequilibrium enhances ocean carbon storage during glacial periods", Science Advances., jun, 2019. Vol. 5(6), pp. eaaw4981. American Association for the Advancement of Science.
Abstract: The prevailing hypothesis for lower atmospheric carbon dioxide (CO2) concentrations during glacial periods is an increased efficiency of the ocean's biological pump. However, tests of this and other hypotheses have been hampered by the difficulty to accurately quantify ocean carbon components. Here, we use an observationally constrained earth system model to precisely quantify these components and the role that different processes play in simulated glacial-interglacial CO2 variations. We find that air-sea disequilibrium greatly amplifies the effects of cooler temperatures and iron fertilization on glacial ocean carbon storage even as the efficiency of the soft-tissue biological pump decreases. These two processes, which have previously been regarded as minor, explain most of our simulated glacial CO2 drawdown, while ocean circulation and sea ice extent, hitherto considered dominant, emerge as relatively small contributors.
BibTeX:
@article{Khatiwala2019,
  author = {Khatiwala, S. and Schmittner, A. and Muglia, J.},
  title = {Air-sea disequilibrium enhances ocean carbon storage during glacial periods},
  journal = {Science Advances},
  publisher = {American Association for the Advancement of Science},
  year = {2019},
  volume = {5},
  number = {6},
  pages = {eaaw4981},
  url = {http://advances.sciencemag.org/},
  doi = {10.1126/sciadv.aaw4981}
}
Kitidis V, Shutler JD, Ashton I, Warren M, Brown I, Findlay H, Hartman SE, Sanders R, Humphreys M, Kivimäe C, Greenwood N, Hull T, Pearce D, McGrath T, Stewart BM, Walsham P, McGovern E, Bozec Y, Gac JP, van Heuven SMAC, Hoppema M, Schuster U, Johannessen T, Omar A, Lauvset SK, Skjelvan I, Olsen A, Steinhoff T, Körtzinger A, Becker M, Lefevre N, Diverrès D, Gkritzalis T, Cattrijsse A, Petersen W, Voynova YG, Chapron B, Grouazel A, Land PE, Sharples J and Nightingale PD (2019), "Winter weather controls net influx of atmospheric CO2 on the north-west European shelf", Scientific Reports., dec, 2019. Vol. 9(1) Springer Science and Business Media LLC.
Abstract: Shelf seas play an important role in the global carbon cycle, absorbing atmospheric carbon dioxide (CO2) and exporting carbon (C) to the open ocean and sediments. The magnitude of these processes is poorly constrained, because observations are typically interpolated over multiple years. Here, we used 298500 observations of CO2 fugacity (fCO2) from a single year (2015), to estimate the net influx of atmospheric CO2 as 26.2 ± 4.7 Tg C yrâˆ'1 over the open NW European shelf. CO2 influx from the atmosphere was dominated by influx during winter as a consequence of high winds, despite a smaller, thermally-driven, air-sea fCO2 gradient compared to the larger, biologically-driven summer gradient. In order to understand this climate regulation service, we constructed a carbon-budget supplemented by data from the literature, where the NW European shelf is treated as a box with carbon entering and leaving the box. This budget showed that net C-burial was a small sink of 1.3 ± 3.1 Tg C yrâˆ'1, while CO2 efflux from estuaries to the atmosphere, removed the majority of river C-inputs. In contrast, the input from the Baltic Sea likely contributes to net export via the continental shelf pump and advection (34.4 ± 6.0 Tg C yrâˆ'1).
BibTeX:
@article{Kitidis2019,
  author = {Kitidis, Vassilis and Shutler, Jamie D and Ashton, Ian and Warren, Mark and Brown, Ian and Findlay, Helen and Hartman, Sue E and Sanders, Richard and Humphreys, Matthew and Kivimäe, Caroline and Greenwood, Naomi and Hull, Tom and Pearce, David and McGrath, Triona and Stewart, Brian M and Walsham, Pamela and McGovern, Evin and Bozec, Yann and Gac, Jean Philippe and van Heuven, Steven M A C and Hoppema, Mario and Schuster, Ute and Johannessen, Truls and Omar, Abdirahman and Lauvset, Siv K and Skjelvan, Ingunn and Olsen, Are and Steinhoff, Tobias and Körtzinger, Arne and Becker, Meike and Lefevre, Nathalie and Diverrès, Denis and Gkritzalis, Thanos and Cattrijsse, André and Petersen, Wilhelm and Voynova, Yoana G and Chapron, Bertrand and Grouazel, Antoine and Land, Peter E and Sharples, Jonathan and Nightingale, Philip D},
  title = {Winter weather controls net influx of atmospheric CO2 on the north-west European shelf},
  journal = {Scientific Reports},
  publisher = {Springer Science and Business Media LLC},
  year = {2019},
  volume = {9},
  number = {1},
  doi = {10.1038/s41598-019-56363-5}
}
Kiuru P, Ojala A, Mammarella I, Heiskanen J, Erkkilä KM, Miettinen H, Vesala T and Huttula T (2019), "Applicability and consequences of the integration of alternative models for CO2 transfer velocity into a process-based lake model", Biogeosciences., sep, 2019. Vol. 16(17), pp. 3297-3317. Copernicus GmbH.
Abstract: Freshwater lakes are important in carbon cycling, especially in the boreal zone where many lakes are supersaturated with the greenhouse gas carbon dioxide (CO2) and emit it to the atmosphere, thus ventilating carbon originally fixed by the terrestrial system. The exchange of CO2 between water and the atmosphere is commonly estimated using simple wind-based parameterizations or models of gas transfer velocity (k). More complex surface renewal models, however, have been shown to yield more correct estimates of k in comparison with direct CO2 flux measurements. We incorporated four gas exchange models with different complexity into a vertical process-based physico-biochemical lake model, MyLake C, and assessed the performance and applicability of the alternative lake model versions to simulate air-water CO2 fluxes over a small boreal lake. None of the incorporated gas exchange models significantly outperformed the other models in the simulations in comparison to the measured near-surface CO2 concentrations or respective air-water CO2 fluxes calculated directly with the gas exchange models using measurement data as input. The use of more complex gas exchange models in the simulation, on the contrary, led to difficulties in obtaining a sufficient gain of CO2 in the water column and thus resulted in lower CO2 fluxes and water column CO2 concentrations compared to the respective measurement-based values. The inclusion of sophisticated and more correct models for air-water CO2 exchange in process-based lake models is crucial in efforts to properly assess lacustrine carbon budgets through model simulations in both single lakes and on a larger scale. However, finding higher estimates for both the internal and external sources of inorganic carbon in boreal lakes is important if improved knowledge of the magnitude of CO2 evasion from lakes is included in future studies on lake carbon budgets.
BibTeX:
@article{Kiuru2019,
  author = {Kiuru, Petri and Ojala, Anne and Mammarella, Ivan and Heiskanen, Jouni and Erkkilä, Kukka Maaria and Miettinen, Heli and Vesala, Timo and Huttula, Timo},
  title = {Applicability and consequences of the integration of alternative models for CO2 transfer velocity into a process-based lake model},
  journal = {Biogeosciences},
  publisher = {Copernicus GmbH},
  year = {2019},
  volume = {16},
  number = {17},
  pages = {3297--3317},
  doi = {10.5194/bg-16-3297-2019}
}
Kivimäki E, Lindqvist H, Hakkarainen J, Laine M, Sussmann R, Tsuruta A, Detmers R, Deutscher NM, Dlugokencky EJ, Hase F, Hasekamp O, Kivi R, Morino I, Notholt J, Pollard DF, Roehl C, Schneider M, Sha MK, Velazco VA, Warneke T, Wunch D, Yoshida Y and Tamminen J (2019), "Evaluation and analysis of the seasonal cycle and variability of the trend from GOSAT methane retrievals", Remote Sensing., apr, 2019. Vol. 11(7) MDPI AG.
Abstract: Methane (CH4) is a potent greenhouse gas with a large temporal variability. To increase the spatial coverage, methane observations are increasingly made from satellites that retrieve the column-averaged dry air mole fraction of methane (XCH4). To understand and quantify the spatial differences of the seasonal cycle and trend of XCH4 in more detail, and to ultimately help reduce uncertainties in methane emissions and sinks, we evaluated and analyzed the average XCH4 seasonal cycle and trend from three Greenhouse Gases Observing Satellite (GOSAT) retrieval algorithms: National Institute for Environmental Studies algorithm version 02.75, RemoTeC CH4 Proxy algorithm version 2.3.8 and RemoTeC CH4 Full Physics algorithm version 2.3.8. Evaluations were made against the Total Carbon Column Observing Network (TCCON) retrievals at 15 TCCON sites for 2009-2015, and the analysis was performed, in addition to the TCCON sites, at 31 latitude bands between latitudes 44.43°S and 53.13°N. At latitude bands, we also compared the trend of GOSAT XCH4retrievals to the NOAA's Marine Boundary Layer reference data. The average seasonal cycle and the non-linear trend were, for the first time for methane, modeled with a dynamic regression method called Dynamic Linear Model that quantifies the trend and the seasonal cycle, and provides reliable uncertainties for the parameters. Our results show that, if the number of co-located soundings is sufficiently large throughout the year, the seasonal cycle and trend of the three GOSAT retrievals agree well, mostly within the uncertainty ranges, with the TCCON retrievals. Especially estimates of the maximum day of XCH4 agree well, both between the GOSAT and TCCON retrievals, and between the three GOSAT retrievals at the latitude bands. In our analysis, we showed that there are large spatial differences in the trend and seasonal cycle of XCH4. These differences are linked to the regional CH4 sources and sinks, and call for further research.
BibTeX:
@article{Kivimaki2019,
  author = {Kivimäki, Ella and Lindqvist, Hannakaisa and Hakkarainen, Janne and Laine, Marko and Sussmann, Ralf and Tsuruta, Aki and Detmers, Rob and Deutscher, Nicholas M. and Dlugokencky, Edward J. and Hase, Frank and Hasekamp, Otto and Kivi, Rigel and Morino, Isamu and Notholt, Justus and Pollard, David F. and Roehl, Coleen and Schneider, Matthias and Sha, Mahesh Kumar and Velazco, Voltaire A. and Warneke, Thorsten and Wunch, Debra and Yoshida, Yukio and Tamminen, Johanna},
  title = {Evaluation and analysis of the seasonal cycle and variability of the trend from GOSAT methane retrievals},
  journal = {Remote Sensing},
  publisher = {MDPI AG},
  year = {2019},
  volume = {11},
  number = {7},
  doi = {10.3390/RS11070882}
}
Klosterhalfen A, Graf A, Brüggemann N, Drüe C, Esser O, González-Dugo MP, Heinemann G, Jacobs CMJ, Mauder M, Moene AF, Ney P, Pütz T, Rebmann C, Rodríguez MR, Scanlon TM, Schmidt M, Steinbrecher R, Thomas CK, Valler V, Zeeman MJ and Vereecken H (2019), "Source partitioning of H2O and CO2 fluxes based on high-frequency eddy covariance data: A comparison between study sites", Biogeosciences., mar, 2019. Vol. 16(6), pp. 1111-1132. Copernicus GmbH.
Abstract: For an assessment of the roles of soil and vegetation in the climate system, a further understanding of the flux components of H2O and CO2 (e.g., transpiration, soil respiration) and their interaction with physical conditions and physiological functioning of plants and ecosystems is necessary. To obtain magnitudes of these flux components, we applied source partitioning approaches after Scanlon and Kustas (2010; SK10) and after Thomas et al. (2008; TH08) to high-frequency eddy covariance measurements of 12 study sites covering different ecosystems (croplands, grasslands, and forests) in different climatic regions. Both partitioning methods are based on higher-order statistics of the H2O and CO2 fluctuations, but proceed differently to estimate transpiration, evaporation, net primary production, and soil respiration. We compared and evaluated the partitioning results obtained with SK10 and TH08, including slight modifications of both approaches. Further, we analyzed the interrelations among the performance of the partitioning methods, turbulence characteristics, and site characteristics (such as plant cover type, canopy height, canopy density, and measurement height). We were able to identify characteristics of a data set that are prerequisites for adequate performance of the partitioning methods. SK10 had the tendency to overestimate and TH08 to underestimate soil flux components. For both methods, the partitioning of CO2 fluxes was less robust than for H2O fluxes. Results derived with SK10 showed relatively large dependencies on estimated water use efficiency (WUE) at the leaf level, which is a required input. Measurements of outgoing longwave radiation used for the estimation of foliage temperature (used in WUE) could slightly increase the quality of the partitioning results. A modification of the TH08 approach, by applying a cluster analysis for the conditional sampling of respiration-evaporation events, performed satisfactorily, but did not result in significant advantages compared to the original method versions developed by Thomas et al. (2008). The performance of each partitioning approach was dependent on meteorological conditions, plant development, canopy height, canopy density, and measurement height. Foremost, the performance of SK10 correlated page1112 negatively with the ratio between measurement height and canopy height. The performance of TH08 was more dependent on canopy height and leaf area index. In general, all site characteristics that increase dissimilarities between scalars appeared to enhance partitioning performance for SK10 and TH08.
BibTeX:
@article{Klosterhalfen2019,
  author = {Klosterhalfen, Anne and Graf, Alexander and Brüggemann, Nicolas and Drüe, Clemens and Esser, Odilia and González-Dugo, María P and Heinemann, Günther and Jacobs, Cor M J and Mauder, Matthias and Moene, Arnold F and Ney, Patrizia and Pütz, Thomas and Rebmann, Corinna and Rodríguez, Mario Ramos and Scanlon, Todd M and Schmidt, Marius and Steinbrecher, Rainer and Thomas, Christoph K and Valler, Veronika and Zeeman, Matthias J and Vereecken, Harry},
  title = {Source partitioning of H2O and CO2 fluxes based on high-frequency eddy covariance data: A comparison between study sites},
  journal = {Biogeosciences},
  publisher = {Copernicus GmbH},
  year = {2019},
  volume = {16},
  number = {6},
  pages = {1111--1132},
  doi = {10.5194/bg-16-1111-2019}
}
Klosterhalfen A, Moene AF, Schmidt M, Scanlon TM, Vereecken H and Graf A (2019), "Sensitivity analysis of a source partitioning method for H2O and CO2 fluxes based on high frequency eddy covariance data: Findings from field data and large eddy simulations", Agricultural and Forest Meteorology., feb, 2019. Vol. 265, pp. 152-170. Elsevier BV.
Abstract: Scanlon and Sahu (2008) and Scanlon and Kustas (2010) proposed a source partitioning method (SK10 in the following) to estimate contributions of transpiration, evaporation, photosynthesis, and respiration to H2O and CO2 fluxes obtained by the eddy covariance method. High frequency eddy covariance raw data time series are needed, and the source partitioning is estimated based on separate application of the flux-variance similarity theory to stomatal and non-stomatal components of the regarded fluxes, as well as on additional assumptions on leaf-level water use efficiency (WUE). We applied SK10 to data from two test sites (forest and cropland) and analyzed partitioning results depending on various ways to estimate WUE from available data. Also, we conducted large eddy simulations (LES), simulating the turbulent transport of H2O and CO2 for contrasting vertical distributions of the canopy sinks/sources, as well as for varying relative magnitudes of soil sources and canopy sinks/sources. SK10 was applied to the synthetic high frequency data generated by LES and the effects of canopy type, measurement height, given sink-source-distributions, and input of varying WUEs were tested regarding the partitioning performance. SK10 requires that the correlation coefficient between stomatal and non-stomatal scalar fluctuations is determined by the ratio of the transfer efficiencies of these scalar components, an assumption (transfer assumption in the following) that could be tested with the generated LES data. The partitioning results of the field sites yielded satisfactory flux fractions, when fair-weather conditions (no precipitation) and a high productive state of the vegetation were present. Further, partitioning performance with regard to soil fluxes increased with crop maturity. Results also showed relatively large dependencies on WUE, where the partitioning factors (median) changed by around -57% and +36%. Measurements of outgoing longwave radiation used for the estimation of foliage temperature and WUE could slightly increase the plausibility of the partitioning results in comparison to soil respiration measurements by decreasing the partitioning factor by up to 42%. The LES-based analysis revealed that for a satisfying performance of SK10, a certain degree of decorrelation of the H2O and CO2 fluctuations (here, |ρq'c'| 0.975) was needed. This decorrelation is enhanced by a clear separation between soil sources and canopy sinks/sources, and for observations within the roughness sublayer. The expected dependence of the partitioning results on the WUE input could be observed. However, due to violation of the abovementioned transfer assumption, the known true input WUE did not yield the known true input partitioning. This could only be achieved after introducing correction factors for the transfer assumption, which were known however only in the special case of the LES experiments.
BibTeX:
@article{Klosterhalfen2019a,
  author = {Klosterhalfen, A and Moene, A F and Schmidt, M and Scanlon, T M and Vereecken, H and Graf, A},
  title = {Sensitivity analysis of a source partitioning method for H2O and CO2 fluxes based on high frequency eddy covariance data: Findings from field data and large eddy simulations},
  journal = {Agricultural and Forest Meteorology},
  publisher = {Elsevier BV},
  year = {2019},
  volume = {265},
  pages = {152--170},
  doi = {10.1016/j.agrformet.2018.11.003}
}
Knox SH, Jackson RB, Poulter B, McNicol G, Fluet-Chouinard E, Zhang Z, Hugelius G, Bousquet P, Canadell JG, Saunois M, Papale D, Chu H, Keenan TF, Baldocchi D, Torn MS, Mammarella I, Trotta C, Aurela M, Bohrer G, Campbell DI, Cescatti A, Chamberlain S, Chen J, Chen W, Dengel S, Desai AR, Euskirchen E, Friborg T, Gasbarra D, Goded I, Goeckede M, Heimann M, Helbig M, Hirano T, Hollinger DY, Iwata H, Kang M, Klatt J, Krauss KW, Kutzbach L, Lohila A, Mitra B, Morin TH, Nilsson MB, Niu S, Noormets A, Oechel WC, Peichl M, Peltola O, Reba ML, Richardson AD, Runkle BRK, Ryu Y, Sachs T, Schäfer KVR, Schmid HP, Shurpali N, Sonnentag O, Tang ACI, Ueyama M, Vargas R, Vesala T, Ward EJ, Windham-Myers L, Wohlfahrt G and Zona D (2019), "FluXNET-CH4 synthesis activity objectives, observations, and future directions", Bulletin of the American Meteorological Society., dec, 2019. Vol. 100(12), pp. 2607-2632.
Abstract: We describe a new coordination activity and initial results for a global synthesis of eddy covariance CH4 flux measurements.
BibTeX:
@article{Knox2019,
  author = {Knox, Sara H and Jackson, Robert B and Poulter, Benjamin and McNicol, Gavin and Fluet-Chouinard, Etienne and Zhang, Zhen and Hugelius, Gustaf and Bousquet, Philippe and Canadell, Josep G and Saunois, Marielle and Papale, Dario and Chu, Housen and Keenan, Trevor F and Baldocchi, Dennis and Torn, Margaret S and Mammarella, Ivan and Trotta, Carlo and Aurela, Mika and Bohrer, Gil and Campbell, David I and Cescatti, Alessandro and Chamberlain, Samuel and Chen, Jiquan and Chen, Weinan and Dengel, Sigrid and Desai, Ankur R and Euskirchen, Eugenie and Friborg, Thomas and Gasbarra, Daniele and Goded, Ignacio and Goeckede, Mathias and Heimann, Martin and Helbig, Manuel and Hirano, Takashi and Hollinger, David Y and Iwata, Hiroki and Kang, Minseok and Klatt, Janina and Krauss, Ken W and Kutzbach, Lars and Lohila, Annalea and Mitra, Bhaskar and Morin, Timothy H and Nilsson, Mats B and Niu, Shuli and Noormets, Asko and Oechel, Walter C and Peichl, Matthias and Peltola, Olli and Reba, Michele L and Richardson, Andrew D and Runkle, Benjamin R K and Ryu, Youngryel and Sachs, Torsten and Schäfer, Karina V R and Schmid, Hans Peter and Shurpali, Narasinha and Sonnentag, Oliver and Tang, Angela C I and Ueyama, Masahito and Vargas, Rodrigo and Vesala, Timo and Ward, Eric J and Windham-Myers, Lisamarie and Wohlfahrt, Georg and Zona, Donatella},
  title = {FluXNET-CH4 synthesis activity objectives, observations, and future directions},
  journal = {Bulletin of the American Meteorological Society},
  year = {2019},
  volume = {100},
  number = {12},
  pages = {2607--2632},
  url = {http://journals.ametsoc.org/doi/10.1175/BAMS-D-18-0268.1},
  doi = {10.1175/BAMS-D-18-0268.1}
}
Kohonen K-M, Kolari P, Kooijmans LM, Chen H, Seibt U, Sun W and Mammarella I (2019), "Towards standardized processing of eddy covariance flux measurements of carbonyl sulfide", Atmospheric Measurement Techniques Discussions., oct, 2019. , pp. 1-30. Copernicus GmbH.
Abstract: Carbonyl sulfide (COS) flux measurements with the eddy covariance (EC) technique are growing in popularity with the recent development in using COS to estimate gross photosynthesis at the ecosystem scale. Flux data intercomparison would benefit from standardized protocols for COS flux data processing. In this study, we analyze how various data processing steps affect the final flux and provide a method for gap-filling COS fluxes. Different methods for determining the lag time between COS mixing ratio and the vertical wind velocity (w) resulted in a maximum of 12 % difference in the cumulative COS flux. Due to limited COS measurement precision, small COS fluxes (below approximately 3 pmol mâˆ'2 sâˆ'1) could not be detected when the lag time was determined from maximizing the covariance between COS and w. We recommend using a combination of COS and carbon dioxide (CO2) lag times in determining the COS flux, depending on the flux magnitude compared to the detection limit of each averaging period. Different high frequency spectral corrections had a maximum effect of 10 % on COS flux calculations and different detrending methods only 1.2 %. Relative total uncertainty was more than five times higher for low COS fluxes (absolute flux lower than 3 pmol mâˆ'2 sâˆ'1) than for low CO2 fluxes (lower than 1.5 μmol mâˆ'2 sâˆ'1), indicating a low signal-to-noise ratio of COS fluxes. Due to similarities in ecosystem COS and CO2 exchange, and the low signal-to-noise ratio of COS fluxes that is similar to methane, we recommend a combination of CO2 and methane flux processing protocols for COS EC fluxes. [ABSTRACT FROM AUTHOR]
BibTeX:
@article{Kohonen2019,
  author = {Kohonen, Kukka-Maaria and Kolari, Pasi and Kooijmans, Linda M and Chen, Huilin and Seibt, Ulli and Sun, Wu and Mammarella, Ivan},
  title = {Towards standardized processing of eddy covariance flux measurements of carbonyl sulfide},
  journal = {Atmospheric Measurement Techniques Discussions},
  publisher = {Copernicus GmbH},
  year = {2019},
  pages = {1--30},
  doi = {10.5194/amt-2019-313}
}
Kondo M, Patra PK, Sitch S, Friedlingstein P, Poulter B, Chevallier F, Ciais P, Canadell JG, Bastos A, Lauerwald R, Calle L, Ichii K, Anthoni P, Arneth A, Haverd V, Jain AK, Kato E, Kautz M, Law RM, Lienert S, Lombardozzi D, Maki T, Nakamura T, Peylin P, Rödenbeck C, Zhuravlev R, Saeki T, Tian H, Zhu D and Ziehn T (2019), "State of the science in reconciling top-down and bottom-up approaches for terrestrial CO2 budget", Global Change Biology., mar, 2019. Vol. 26(3), pp. 1068-1084. Wiley.
Abstract: Robust estimates of CO2 budget, CO2 exchanged between the atmosphere and terrestrial biosphere, are necessary to better understand the role of the terrestrial biosphere in mitigating anthropogenic CO2 emissions. Over the past decade, this field of research has advanced through understanding of the differences and similarities of two fundamentally different approaches: “top-down” atmospheric inversions and “bottom-up” biosphere models. Since the first studies were undertaken, these approaches have shown an increasing level of agreement, but disagreements in some regions still persist, in part because they do not estimate the same quantity of atmosphere–biosphere CO2 exchange. Here, we conducted a thorough comparison of CO2 budgets at multiple scales and from multiple methods to assess the current state of the science in estimating CO2 budgets. Our set of atmospheric inversions and biosphere models, which were adjusted for a consistent flux definition, showed a high level of agreement for global and hemispheric CO2 budgets in the 2000s. Regionally, improved agreement in CO2 budgets was notable for North America and Southeast Asia. However, large gaps between the two methods remained in East Asia and South America. In other regions, Europe, boreal Asia, Africa, South Asia, and Oceania, it was difficult to determine whether those regions act as a net sink or source because of the large spread in estimates from atmospheric inversions. These results highlight two research directions to improve the robustness of CO2 budgets: (a) to increase representation of processes in biosphere models that could contribute to fill the budget gaps, such as forest regrowth and forest degradation; and (b) to reduce sink–source compensation between regions (dipoles) in atmospheric inversion so that their estimates become more comparable. Advancements on both research areas will increase the level of agreement between the top-down and bottom-up approaches and yield more robust knowledge of regional CO2 budgets.
BibTeX:
@article{Kondo2019,
  author = {Kondo, Masayuki and Patra, Prabir K and Sitch, Stephen and Friedlingstein, Pierre and Poulter, Benjamin and Chevallier, Frederic and Ciais, Philippe and Canadell, Josep G and Bastos, Ana and Lauerwald, Ronny and Calle, Leonardo and Ichii, Kazuhito and Anthoni, Peter and Arneth, Almut and Haverd, Vanessa and Jain, Atul K and Kato, Etsushi and Kautz, Markus and Law, Rachel M and Lienert, Sebastian and Lombardozzi, Danica and Maki, Takashi and Nakamura, Takashi and Peylin, Philippe and Rödenbeck, Christian and Zhuravlev, Ruslan and Saeki, Tazu and Tian, Hanqin and Zhu, Dan and Ziehn, Tilo},
  title = {State of the science in reconciling top-down and bottom-up approaches for terrestrial CO2 budget},
  journal = {Global Change Biology},
  publisher = {Wiley},
  year = {2019},
  volume = {26},
  number = {3},
  pages = {1068--1084},
  doi = {10.1111/gcb.14917}
}
Kondrik D, Kazakov E and Pozdnyakov D (2019), "A synthetic satellite dataset of the spatio-temporal distributions of <i>Emiliania huxleyi</i> blooms and their impacts on Arctic and sub-Arctic marine environments (1998–2016)", Earth System Science Data., jan, 2019. Vol. 11(1), pp. 119-128. Copernicus GmbH.
Abstract: textlessptextgreatertextless![CDATA[Abstract. A 19-year (1998–2016) continuous dataset is presented of coccolithophore Emiliania huxleyi distributions and activity, i.e. the release of CaCO3 in water and the decrease of uptake of dissolved CO2 by Emiliania huxleyi cells (e.g. Kondrik et al., 2018a), in Arctic and sub-Arctic seas. The dataset is based on optical remote-sensing data (mostly OC CCI data) with assimilation of different relevant in situ observations, preprocessed with authorial algorithms. Alongside bloom locations, we provide both detailed information on E. huxleyi impacts on carbon balance and the sub-datasets of quantified coccolith concentrations, particulate inorganic carbon content and CO2 partial pressure in water driven by coccolithophores. All data are presented on a regular 4×4 km grid at a temporal resolution of 8 days. The paper describes the theoretical and methodological basis for all processing and modelling steps. The data are available on Zenodo: https://doi.org/10.5281/zenodo.1402033.]]textgreatertextless/ptextgreater
BibTeX:
@article{Kondrik2019,
  author = {Kondrik, Dmitry and Kazakov, Eduard and Pozdnyakov, Dmitry},
  title = {A synthetic satellite dataset of the spatio-temporal distributions of <i>Emiliania huxleyi</i> blooms and their impacts on Arctic and sub-Arctic marine environments (1998–2016)},
  journal = {Earth System Science Data},
  publisher = {Copernicus GmbH},
  year = {2019},
  volume = {11},
  number = {1},
  pages = {119--128},
  url = {https://essd.copernicus.org/articles/11/119/2019/},
  doi = {10.5194/essd-11-119-2019}
}
Kooijmans LMJ, Sun W, Aalto J, Erkkilä KM, Maseyk K, Seibt U, Vesala T, Mammarella I and Chen H (2019), "Influences of light and humidity on carbonyl sulfide-based estimates of photosynthesis", Proceedings of the National Academy of Sciences of the United States of America., jan, 2019. Vol. 116(7), pp. 2470-2475. Proceedings of the National Academy of Sciences.
Abstract: Understanding climate controls on gross primary productivity (GPP) is crucial for accurate projections of the future land carbon cycle. Major uncertainties exist due to the challenge in separating GPP and respiration from observations of the carbon dioxide (CO 2 ) flux. Carbonyl sulfide (COS) has a dominant vegetative sink, and plant COS uptake is used to infer GPP through the leaf relative uptake (LRU) ratio of COS to CO 2 fluxes. However, little is known about variations of LRU under changing environmental conditions and in different phenological stages. We present COS and CO 2 fluxes and LRU of Scots pine branches measured in a boreal forest in Finland during the spring recovery and summer. We find that the diurnal dynamics of COS uptake is mainly controlled by stomatal conductance, but the leaf internal conductance could significantly limit the COS uptake during the daytime and early in the season. LRU varies with light due to the differential light responses of COS and CO 2 uptake, and with vapor pressure deficit (VPD) in the peak growing season, indicating a humidity-induced stomatal control. Our COS-based GPP estimates show that it is essential to incorporate the variability of LRU with environmental variables for accurate estimation of GPP on ecosystem, regional, and global scales.
BibTeX:
@article{Kooijmans2019,
  author = {Kooijmans, Linda M J and Sun, Wu and Aalto, Juho and Erkkilä, Kukka Maaria and Maseyk, Kadmiel and Seibt, Ulrike and Vesala, Timo and Mammarella, Ivan and Chen, Huilin},
  title = {Influences of light and humidity on carbonyl sulfide-based estimates of photosynthesis},
  journal = {Proceedings of the National Academy of Sciences of the United States of America},
  publisher = {Proceedings of the National Academy of Sciences},
  year = {2019},
  volume = {116},
  number = {7},
  pages = {2470--2475},
  doi = {10.1073/pnas.1807600116}
}
Koren G, Schneider L, van der Velde IR, van Schaik E, Gromov SS, Adnew GA, Mrozek Martino DJ, Hofmann MEG, Liang M-C, Mahata S, Bergamaschi P, van der Laan-Luijkx IT, Krol MC, Röckmann T and Peters W (2019), "Global 3-D Simulations of the Triple Oxygen Isotope Signature Δ textlesssuptextgreater17textless/suptextgreater O in Atmospheric CO textlesssubtextgreater2textless/subtextgreater", Journal of Geophysical Research: Atmospheres., aug, 2019. Vol. 124(15), pp. 8808-8836. Blackwell Publishing Ltd.
Abstract: The triple oxygen isotope signature Δ17O in atmospheric CO2, also known as its “17O excess,” has been proposed as a tracer for gross primary production (the gross uptake of CO2 by vegetation through photosynthesis). We present the first global 3-D model simulations for Δ17O in atmospheric CO2 together with a detailed model description and sensitivity analyses. In our 3-D model framework we include the stratospheric source of Δ17O in CO2 and the surface sinks from vegetation, soils, ocean, biomass burning, and fossil fuel combustion. The effect of oxidation of atmospheric CO on Δ17O in CO2 is also included in our model. We estimate that the global mean Δ17O (defined as Δ17O = ln(δ17O+1)−𝜆λRL textperiodcentered ln(δ18O+1) with λRL = 0.5229) of CO2 in the lowest 500 m of the atmosphere is 39.6 per meg, which is ∼20 per meg lower than estimates from existing box models. We compare our model results with a measured stratospheric Δ17O in CO2 profile from Sodankylä (Finland), which shows good agreement. In addition, we compare our model results with tropospheric measurements of Δ17O in CO2 from Göttingen (Germany) and Taipei (Taiwan), which shows some agreement but we also find substantial discrepancies that are subsequently discussed. Finally, we show model results for Zotino (Russia), Mauna Loa (United States), Manaus (Brazil), and South Pole, which we propose as possible locations for future measurements of Δ17O in tropospheric CO2 that can help to further increase our understanding of the global budget of Δ17O in atmospheric CO2.
BibTeX:
@article{Koren2019,
  author = {Koren, Gerbrand and Schneider, Linda and van der Velde, Ivar R. and van Schaik, Erik and Gromov, Sergey S. and Adnew, Getachew A. and Mrozek Martino, Dorota J. and Hofmann, Magdalena E. G. and Liang, Mao-Chang and Mahata, Sasadhar and Bergamaschi, Peter and van der Laan-Luijkx, Ingrid T. and Krol, Maarten C. and Röckmann, Thomas and Peters, Wouter},
  title = {Global 3-D Simulations of the Triple Oxygen Isotope Signature Δ textlesssuptextgreater17textless/suptextgreater O in Atmospheric CO textlesssubtextgreater2textless/subtextgreater},
  journal = {Journal of Geophysical Research: Atmospheres},
  publisher = {Blackwell Publishing Ltd},
  year = {2019},
  volume = {124},
  number = {15},
  pages = {8808--8836},
  url = {http://doi.wiley.com/10.1029/2019JD030387},
  doi = {10.1029/2019JD030387}
}
Korkiakoski M, Tuovinen JP, Penttilä T, Sarkkola S, Ojanen P, Minkkinen K, Rainne J, Laurila T and Lohila A (2019), "Greenhouse gas and energy fluxes in a boreal peatland forest after clear-cutting", Biogeosciences., sep, 2019. Vol. 16(19), pp. 3703-3723. Copernicus GmbH.
Abstract: The most common forest management method in Fennoscandia is rotation forestry, including clear-cutting and forest regeneration. In clear-cutting, stem wood is removed and the logging residues are either removed or left on site. Clear-cutting changes the microclimate and vegetation structure at the site, both of which affect the site's carbon balance. Peat soils with poor aeration and high carbon densities are especially prone to such changes, and significant changes in greenhouse gas exchange can be expected. We measured carbon dioxide (CO2) and energy fluxes with the eddy covariance method for 2 years (April 2016-March 2018) after clear-cutting a drained peatland forest. We observed a significant rise (23 cm) in the water table level and a large CO2 source (first year: 3086 ± 148 g CO2 m-2 yr-1; second year: 2072 ± 124 g CO2 m-2 yr-1). These large CO2 emissions resulted from the very low gross primary production (GPP) following the removal of photosynthesizing trees and the decline of ground vegetation, unable to compensate for the decomposition of logging residues and peat. During the second summer (June-August) after the clear-cutting, GPP had already increased by 96 % and total ecosystem respiration decreased by 14 % from the previous summer. The mean daytime ratio of sensible to latent heat flux decreased after harvesting from 2.6 in May 2016 to 1.0 in August 2016, and in 2017 it varied mostly within 0.6-1.0. In April-September, the mean daytime sensible heat flux was 33 % lower and latent heat flux 40 % higher in 2017, probably due to the recovery of ground vegetation that increased evapotranspiration and albedo of the site. In addition to CO2 and energy fluxes, we measured methane (CH4) and nitrous oxide (N2O) fluxes with manual chambers. After the clear-cutting, the site turned from a small CH4 sink into a small source and from N2O neutral to a significant N2O source. Compared to the large CO2 emissions, the 100-year global warming potential (GWP100) of the CH4 emissions was negligible. Also, the GWP100 due to increased N2O emissions was less than 10 % of that of the CO2 emission change.
BibTeX:
@article{Korkiakoski2019,
  author = {Korkiakoski, Mika and Tuovinen, Juha Pekka and Penttilä, Timo and Sarkkola, Sakari and Ojanen, Paavo and Minkkinen, Kari and Rainne, Juuso and Laurila, Tuomas and Lohila, Annalea},
  title = {Greenhouse gas and energy fluxes in a boreal peatland forest after clear-cutting},
  journal = {Biogeosciences},
  publisher = {Copernicus GmbH},
  year = {2019},
  volume = {16},
  number = {19},
  pages = {3703--3723},
  doi = {10.5194/bg-16-3703-2019}
}
Kosonen Z, Schnyder E, Hiltbrunner E, Thimonier A, Schmitt M, Seitler E and Thöni L (2019), "Current atmospheric nitrogen deposition still exceeds critical loads for sensitive, semi-natural ecosystems in Switzerland", Atmospheric Environment., aug, 2019. Vol. 211, pp. 214-225. Elsevier BV.
Abstract: Increased atmospheric nitrogen (N) deposition is driving nutrient imbalances, soil acidification, biodiversity losses and the long-term reduction in stability of sensitive ecosystems which previously had limited N. In this study, we analysed the concentrations of seven different N compounds in precipitation and in the air at 34 sites across Switzerland. We calculated the N deposition by precipitation (bulk deposition) and applied the inferential method to derive dry deposition (gases, aerosols) from air concentrations. We then quantified the total inorganic N deposition by adding together the bulk and dry deposition. Finally, the total inorganic N input into the sensitive ecosystems of the 34 sites was compared to the critical loads of these ecosystems. N deposition by precipitation was the main contributor to the total N load in 16 out of 34 sites, especially into open ecosystems such as alpine/subalpine grassland, mountain hay meadows, and raised bogs. Dry deposition of ammonia (NH3) was the second most important pathway, in particular for forests close to agricultural activities, due to high NH3 concentrations and the higher deposition velocity. The N deposition exceeded the lower limit of the Critical Load of Nitrogen (CLN) range at most sites, and at many sites even surpassed the upper limit of the CLN range. No, or minor, exceedances of the critical loads for N were found only at remote sites at higher elevation in the Central Alps. Annual inorganic N deposition between 2000 and 2017 revealed a significant decline in oxidised N compounds at four of five sites (âˆ'1.6–1.8% per year), but reduced compounds only decreased at two sites (âˆ'1% and âˆ'1.4% per year) and even increased at one site (+1.2% per year), despite adopted abatement strategies for agricultural practices. This emphasises that most sensitive ecosystems in Switzerland continue to be exposed to excessive N loads through atmospheric deposition, with detrimental consequences for the biodiversity and stability of these ecosystems.
BibTeX:
@article{Kosonen2019,
  author = {Kosonen, Zaida and Schnyder, Elvira and Hiltbrunner, Erika and Thimonier, Anne and Schmitt, Maria and Seitler, Eva and Thöni, Lotti},
  title = {Current atmospheric nitrogen deposition still exceeds critical loads for sensitive, semi-natural ecosystems in Switzerland},
  journal = {Atmospheric Environment},
  publisher = {Elsevier BV},
  year = {2019},
  volume = {211},
  pages = {214--225},
  doi = {10.1016/j.atmosenv.2019.05.005}
}
Kozii N, Haahti K, Tor-ngern P, Chi J, Hasselquist EM, Laudon H, Launiainen S, Oren R, Peichl M, Wallerman J and Hasselquist N (2019), "Partitioning the forest water balance within a boreal catchment using sapflux, eddy covariance and process-based model", Hydrology and Earth System Sciences Discussions., oct, 2019. , pp. 1-50. Copernicus GmbH.
Abstract: Predicting the binding mode of flexible polypeptides to proteins is an important task that falls outside the domain of applicability of most small molecule and proteinâˆ'protein docking tools. Here, we test the small molecule flexible ligand docking program Glide on a set of 19 non-α-helical peptides and systematically improve pose prediction accuracy by enhancing Glide sampling for flexible polypeptides. In addition, scoring of the poses was improved by post-processing with physics-based implicit solvent MM- GBSA calculations. Using the best RMSD among the top 10 scoring poses as a metric, the success rate (RMSD ≤ 2.0 Å for the interface backbone atoms) increased from 21% with default Glide SP settings to 58% with the enhanced peptide sampling and scoring protocol in the case of redocking to the native protein structure. This approaches the accuracy of the recently developed Rosetta FlexPepDock method (63% success for these 19 peptides) while being over 100 times faster. Cross-docking was performed for a subset of cases where an unbound receptor structure was available, and in that case, 40% of peptides were docked successfully. We analyze the results and find that the optimized polypeptide protocol is most accurate for extended peptides of limited size and number of formal charges, defining a domain of applicability for this approach.
BibTeX:
@article{Kozii2019,
  author = {Kozii, Natalia and Haahti, Kersti and Tor-ngern, Pantana and Chi, Jinshu and Hasselquist, Eliza Maher and Laudon, Hjalmar and Launiainen, Samuli and Oren, Ram and Peichl, Matthias and Wallerman, Jörgen and Hasselquist, Niles},
  title = {Partitioning the forest water balance within a boreal catchment using sapflux, eddy covariance and process-based model},
  journal = {Hydrology and Earth System Sciences Discussions},
  publisher = {Copernicus GmbH},
  year = {2019},
  pages = {1--50},
  doi = {10.5194/hess-2019-541}
}
Krupková L, Havránková K, Krejza J, Sedlák P and Marek MV (2019), "Impact of water scarcity on spruce and beech forests", Journal of Forestry Research. Vol. 30(3), pp. 899-909.
Abstract: One of the greatest threats posed by ongoing climate change may be regarded the drought caused by changes in precipitation distribution. The aim of presented study was to characterize reactions to dry conditions and conditions without drought stress on gross primary production (GPP) and net ecosystem production (NEP) of spruce and beech forests, as these two species dominate within the European continent. Daily courses of GPP and NEP of these two species were evaluated in relation to an expected decrease in CO2 uptake during dry days. The occurrence of CO2 uptake hysteresis in daily production was also investigated. Our study was performed at Bílý KÅ™íž (spruce) and Štítná (beech) mountain forest sites during 2010–2012 period. We applied eddy covariance technique for the estimation of carbon fluxes, vapor pressure deficit and precipitation characteristics together with the SoilClim model for the determination of drought conditions, and the inverse of the Penman–Monteith equation to compute canopy conductance. Significant differences were found in response to reduced water supply for both species. Spruce reacts by closing its stomata before noon and maintaining a reduced photosynthetic activity for the rest of the day, while beech keeps its stomata open as long as possible and slightly reduces photosynthetic activity evenly throughout the entire day. In the spruce forest, we found substantial hysteresis in the light response curve of GPP. In the beech forest, the shape of this curve was different: evening values exceeded morning values.
BibTeX:
@article{Krupkova2019,
  author = {Krupková, Lenka and Havránková, KateÅ™ina and Krejza, Jan and Sedlák, Pavel and Marek, Michal V},
  title = {Impact of water scarcity on spruce and beech forests},
  journal = {Journal of Forestry Research},
  year = {2019},
  volume = {30},
  number = {3},
  pages = {899--909},
  doi = {10.1007/s11676-018-0642-5}
}
Kulmala L, Pumpanen J, Kolari P, Dengel S, Berninger F, Köster K, Matkala L, Vanhatalo A, Vesala T and Bäck J (2019), "Inter- and intra-annual dynamics of photosynthesis differ between forest floor vegetation and tree canopy in a subarctic Scots pine stand", Agricultural and Forest Meteorology., jun, 2019. Vol. 271, pp. 1-11. Elsevier BV.
Abstract: We studied the inter- and intra-annual dynamics of the photosynthesis of forest floor vegetation and tree canopy in a subarctic Scots pine stand at the northern timberline in Finland. We tackled the issue using three different approaches: 1) measuring carbon dioxide exchange above and below canopy with the eddy covariance technique, 2) modelling the photosynthesis of the tree canopy based on shoot chamber measurements, and 3) upscaling the forest floor photosynthesis using biomass estimates and available information on the annual cycle of photosynthetic capacity of those species. The studied ecosystem was generally a weak sink of carbon but the sink strength showed notable year-to-year variation. Total ecosystem respiration and photosynthesis indicated a clear temperature limitation for the carbon exchange. However, the increase in photosynthetic production was steeper than the increase in respiration with temperature, indicating that warm temperatures increase the sink strength and do not stimulate the total ecosystem respiration as much in the 4-year window studied. The interannual variation in the photosynthetic production of the forest stand mainly resulted from the forest floor vegetation, whereas the photosynthesis of the tree canopy seemed to be more stable from year to year. Tree canopy photosynthesis increased earlier in the spring, whereas that of the forest floor increased after snowmelt, highlighting that models for photosynthesis in the northern area should also include snow cover in order to accurately estimate the seasonal dynamics of photosynthesis in these forests.
BibTeX:
@article{Kulmala2019,
  author = {Kulmala, Liisa and Pumpanen, Jukka and Kolari, Pasi and Dengel, Sigrid and Berninger, Frank and Köster, Kajar and Matkala, Laura and Vanhatalo, Anni and Vesala, Timo and Bäck, Jaana},
  title = {Inter- and intra-annual dynamics of photosynthesis differ between forest floor vegetation and tree canopy in a subarctic Scots pine stand},
  journal = {Agricultural and Forest Meteorology},
  publisher = {Elsevier BV},
  year = {2019},
  volume = {271},
  pages = {1--11},
  doi = {10.1016/j.agrformet.2019.02.029}
}
Lagergren F, Jönsson AM, Linderson H and Lindroth A (2019), "Time shift between net and gross CO2 uptake and growth derived from tree rings in pine and spruce", Trees - Structure and Function., jun, 2019. Vol. 33(3), pp. 765-776.
Abstract: Key message: A 6–9 month backward time shift of the carbon uptake gave the highest correlation between annual biomass increment and carbon uptake in this old even aged forest. Abstract: Plants' carbon uptake and allocation to different biomass compartments is an important process for both wood production and climate mitigation. Measurements of the net ecosystem carbon dioxide exchange between ecosystems and the atmosphere provide insights into the processes of photosynthesis, respiration and accumulation of carbon over time, and the increase in woody biomass can be assessed by allometric functions based on stem diameter measurements. The fraction of carbon allocated to radial stem growth varies over time, and a lag between carbon uptake and growth can be expected. The dynamics of non-structural carbohydrates and autotrophic and heterotrophic respiration are key mechanisms for understanding this lag effect. In this study, a 9-year record of carbon flux and tree-ring data from Norunda, Sweden was used to investigate the relationship between net and gross carbon uptake and carbon allocated to growth. The flux data were aggregated to monthly sums. When full 12-month periods of accumulated carbon exchange were successively shifted backwards in time, the highest correlation was found with a 6–9 month shift, showing that a large part of the previous growing season was important for explaining the biomass increment of the following year.
BibTeX:
@article{Lagergren2019,
  author = {Lagergren, Fredrik and Jönsson, Anna Maria and Linderson, Hans and Lindroth, Anders},
  title = {Time shift between net and gross CO2 uptake and growth derived from tree rings in pine and spruce},
  journal = {Trees - Structure and Function},
  year = {2019},
  volume = {33},
  number = {3},
  pages = {765--776},
  url = {http://link.springer.com/10.1007/s00468-019-01814-9},
  doi = {10.1007/s00468-019-01814-9}
}
Landschützer P, Ilyina T and Lovenduski NS (2019), "Detecting Regional Modes of Variability in Observation‐Based Surface Ocean textlessitextgreaterptextless/itextgreater CO textlesssubtextgreater2textless/subtextgreater", Geophysical Research Letters., mar, 2019. Vol. 46(5), pp. 2670-2679. Blackwell Publishing Ltd.
Abstract: We use a neural network-based estimate of the sea surface partial pressure of CO2 (pCO2) derived from measurements assembled within the Surface Ocean CO2 Atlas to investigate the dominant modes of pCO2 variability from 1982 through 2015. Our analysis shows that detrended and deseasonalized sea surface pCO2 varies substantially by region and the respective frequencies match those from the major modes of climate variability (Atlantic Multidecadal Oscillation, Pacific Decadal Oscillation, multivariate ENSO index, Southern Annular Mode), suggesting a climate modulated air-sea exchange of CO2. We find that most of the regional pCO2 variability is driven by changes in the ocean circulation and/or changes in biology, whereas the North Atlantic variability is tightly linked to temperature variations in the surface ocean and the resulting changes in solubility. Despite the 34-year time series, our analysis reveals that we can currently only detect one to two periods of slow frequency oscillations, challenging our ability to robustly link pCO2 variations to climate variability.
BibTeX:
@article{Landschutzer2019,
  author = {Landschützer, Peter and Ilyina, Tatiana and Lovenduski, Nicole S.},
  title = {Detecting Regional Modes of Variability in Observation‐Based Surface Ocean textlessitextgreaterptextless/itextgreater CO textlesssubtextgreater2textless/subtextgreater},
  journal = {Geophysical Research Letters},
  publisher = {Blackwell Publishing Ltd},
  year = {2019},
  volume = {46},
  number = {5},
  pages = {2670--2679},
  url = {https://onlinelibrary.wiley.com/doi/abs/10.1029/2018GL081756},
  doi = {10.1029/2018GL081756}
}
Langvall O and Ottosson Löfvenius M (2019), "Long-term standardized forest phenology in Sweden: a climate change indicator", International Journal of Biometeorology., oct, 2019.
Abstract: Because climate change alters patterns of vegetative growth, long-term phenological measurements and observations can provide important data for analyzing its impact. Phenological assessments are usually made as records of calendar dates when specific phase changes occur. Such assessments have benefits and are used in Citizen Science monitoring. However, these kinds of data often have low statistical precision when describing gradual changes. Frequent monitoring of the phenological traits of forest trees and berries as they undergo gradual change is needed to acquire good temporal resolution of transitions relative to other factors, such as susceptibility to frosts, insects, and fungi, and the use of berries as a food resource. Intensive weekly monitoring of the growth of apical and branch buds and the elongation of shoots and leaves on four tree species, and the abundance of flowers and berries of bilberry and lingonberry, has been performed in Sweden since 2006. Here, we present quantitative methods for interpolating such data, which detail the gradual changes between assessments in order to describe average rates of development and amount of interannual variation. Our analysis has shown the active growth period of trees to differ with latitude. We also observed a change in the timing of the maximum numbers of ripening berries and their successive decline. Data from tree phenology assessments can be used to recommend best forestry practice and to model tree growth, while berry data can be used to estimate when food resources for animals are most available.
BibTeX:
@article{Langvall2019,
  author = {Langvall, Ola and Ottosson Löfvenius, Mikaell},
  title = {Long-term standardized forest phenology in Sweden: a climate change indicator},
  journal = {International Journal of Biometeorology},
  year = {2019},
  url = {http://link.springer.com/10.1007/s00484-019-01817-8},
  doi = {10.1007/s00484-019-01817-8}
}
Le Traon PY, Reppucci A, Alvarez Fanjul E, Aouf L, Behrens A, Belmonte M, Bentamy A, Bertino L, Brando VE, Kreiner MB, Benkiran M, Carval T, Ciliberti SA, Claustre H, Clementi E, Coppini G, Cossarini G, De Alfonso Alonso-Muñoyerro M, Delamarche A, Dibarboure G, Dinessen F, Drevillon M, Drillet Y, Faugere Y, Fernández V, Fleming A, Garcia-Hermosa MI, Sotillo MG, Garric G, Gasparin F, Giordan C, Gehlen M, Gregoire ML, Guinehut S, Hamon M, Harris C, Hernandez F, Hinkler JB, Hoyer J, Karvonen J, Kay S, King R, Lavergne T, Lemieux-Dudon B, Lima L, Mao C, Martin MJ, Masina S, Melet A, Buongiorno Nardelli B, Nolan G, Pascual A, Pistoia J, Palazov A, Piolle JF, Pujol MI, Pequignet AC, Peneva E, Pérez Gómez B, Petit de la Villeon L, Pinardi N, Pisano A, Pouliquen S, Reid R, Remy E, Santoleri R, Siddorn J, She J, Staneva J, Stoffelen A, Tonani M, Vandenbulcke L, von Schuckmann K, Volpe G, Wettre C and Zacharioudaki A (2019), "From Observation to Information and Users: The Copernicus Marine Service Perspective", Frontiers in Marine Science., may, 2019. Vol. 6, pp. 234. Frontiers Media SA.
Abstract: The Copernicus Marine Environment Monitoring Service (CMEMS) provides regular and systematic reference information on the physical and biogeochemical ocean and sea-ice state for the global ocean and the European regional seas. CMEMS serves a wide range of users (more than 15,000 users are now registered to the service) and applications. Observations are a fundamental pillar of the CMEMS value-added chain that goes from observation to information and users. Observations are used by CMEMS Thematic Assembly Centres (TACs) to derive high-level data products and by CMEMS Monitoring and Forecasting Centres (MFCs) to validate and constrain their global and regional ocean analysis and forecasting systems. This paper presents an overview of CMEMS, its evolution, and how the value of in situ and satellite observations is increased through the generation of high-level products ready to be used by downstream applications and services. The complementary nature of satellite and in situ observations is highlighted. Long-term perspectives for the development of CMEMS are described and implications for the evolution of the in situ and satellite observing systems are outlined. Results from Observing System Evaluations (OSEs) and Observing System Simulation Experiments (OSSEs) illustrate the high dependencies of CMEMS systems on observations. Finally future CMEMS requirements for both satellite and in situ observations are detailed.
BibTeX:
@article{LeTraon2019,
  author = {Le Traon, Pierre Yves and Reppucci, Antonio and Alvarez Fanjul, Enrique and Aouf, Lotfi and Behrens, Arno and Belmonte, Maria and Bentamy, Abderrahim and Bertino, Laurent and Brando, Vittorio Ernesto and Kreiner, Matilde Brandt and Benkiran, Mounir and Carval, Thierry and Ciliberti, Stefania A. and Claustre, Hervé and Clementi, Emanuela and Coppini, Giovanni and Cossarini, Gianpiero and De Alfonso Alonso-Muñoyerro, Marta and Delamarche, Anne and Dibarboure, Gerald and Dinessen, Frode and Drevillon, Marie and Drillet, Yann and Faugere, Yannice and Fernández, Vicente and Fleming, Andrew and Garcia-Hermosa, M. Isabel and Sotillo, Marcos García and Garric, Gilles and Gasparin, Florent and Giordan, Cedric and Gehlen, Marion and Gregoire, Marilaure L. and Guinehut, Stephanie and Hamon, Mathieu and Harris, Chris and Hernandez, Fabrice and Hinkler, Jørgen B. and Hoyer, Jacob and Karvonen, Juha and Kay, Susan and King, Robert and Lavergne, Thomas and Lemieux-Dudon, Benedicte and Lima, Leonardo and Mao, Chongyuan and Martin, Matthew J. and Masina, Simona and Melet, Angelique and Buongiorno Nardelli, Bruno and Nolan, Glenn and Pascual, Ananda and Pistoia, Jenny and Palazov, Atanas and Piolle, Jean Francois and Pujol, Marie Isabelle and Pequignet, Anne Christine and Peneva, Elisaveta and Pérez Gómez, Begoña and Petit de la Villeon, Loic and Pinardi, Nadia and Pisano, Andrea and Pouliquen, Sylvie and Reid, Rebecca and Remy, Elisabeth and Santoleri, Rosalia and Siddorn, John and She, Jun and Staneva, Joanna and Stoffelen, Ad and Tonani, Marina and Vandenbulcke, Luc and von Schuckmann, Karina and Volpe, Gianluca and Wettre, Cecilie and Zacharioudaki, Anna},
  title = {From Observation to Information and Users: The Copernicus Marine Service Perspective},
  journal = {Frontiers in Marine Science},
  publisher = {Frontiers Media SA},
  year = {2019},
  volume = {6},
  pages = {234},
  url = {https://www.frontiersin.org/article/10.3389/fmars.2019.00234/full},
  doi = {10.3389/fmars.2019.00234}
}
Lebehot AD, Halloran PR, Watson AJ, McNeall D, Ford DA, Landschützer P, Lauvset SK and Schuster U (2019), "Reconciling Observation and Model Trends in North Atlantic Surface CO2", Global Biogeochemical Cycles., oct, 2019. Vol. 33(10), pp. 1204-1222. American Geophysical Union (AGU).
Abstract: The North Atlantic Ocean is a region of intense uptake of atmospheric CO2. To assess how this CO2 sink has evolved over recent decades, various approaches have been used to estimate basin-wide uptake from the irregularly sampled in situ CO2 observations. Until now, the lack of robust uncertainties associated with observation-based gap-filling methods required to produce these estimates has limited the capacity to validate climate model simulated surface ocean CO2 concentrations. After robustly quantifying basin-wide and annually varying interpolation uncertainties using both observational and model data, we show that the North Atlantic surface ocean fugacity of CO2 (fCO2âˆ'ocean) increased at a significantly slower rate than that simulated by the latest generation of Earth System Models during the period 1992–2014. We further show, with initialized model simulations, that the inability of these models to capture the observed trend in surface fCO2âˆ'ocean is primarily due to biases in the models' ocean biogeochemistry. Our results imply that current projections may underestimate the contribution of the North Atlantic to mitigating increasing future atmospheric CO2 concentrations.
BibTeX:
@article{Lebehot2019,
  author = {Lebehot, Alice D and Halloran, Paul R and Watson, Andrew J and McNeall, Doug and Ford, David A and Landschützer, Peter and Lauvset, Siv K and Schuster, Ute},
  title = {Reconciling Observation and Model Trends in North Atlantic Surface CO2},
  journal = {Global Biogeochemical Cycles},
  publisher = {American Geophysical Union (AGU)},
  year = {2019},
  volume = {33},
  number = {10},
  pages = {1204--1222},
  doi = {10.1029/2019GB006186}
}
Lefèvre N, Veleda D, Tyaquiçã P, Perruche C, Diverrès D and Ibánhez JSP (2019), "Basin-Scale Estimate of the Sea-Air CO2 Flux During the 2010 Warm Event in the Tropical North Atlantic", Journal of Geophysical Research: Biogeosciences., apr, 2019. Vol. 124(4), pp. 973-986. American Geophysical Union (AGU).
Abstract: Following the anomalous warming event occurring in the tropical North Atlantic in 2010, higher than usual surface fugacity of CO2 (fCO2) was observed. To evaluate the spatial extent of these anomalies and their drivers, and to quantify the sea-air CO2 flux at basin scale, the Mercator-Ocean model is used from 2006 to 2014 within the region 0–30°N, 70–15°W. Model outputs are generally in accordance with underway sea surface temperature, sea surface salinity, and surface fCO2 recorded by two merchant ships. The anomalous warming of 2010 is well reproduced by the model and is the main driver of fCO2 anomalies. The first coupled Empirical Orthogonal Function mode, between sea surface temperature and fCO2, captures more than 70% of the total variance and is characterized by a basin-scale warming associated to positive fCO2 anomalies. The corresponding principal components are correlated to the Tropical North Atlantic Index and identify 2010 as the year with the highest positive anomaly over 2006–2014. Exceptions to this general pattern are located near the African coast, where the weakening of the coastal upwelling causes negative inorganic carbon anomalies, and close to the Amazon River plume, where fCO2 anomalies are primarily associated with sea surface salinity anomalies. Although the fCO2 anomalies of 2010 appear mostly in spring, they affect the annual CO2 budget and lead to an increased CO2 outgassing twice as large (46.2 Tg C per year) as the mean annual flux over the 2006–2014 period (23.3 Tg C per year).
BibTeX:
@article{Lefevre2019,
  author = {Lefèvre, Nathalie and Veleda, Doris and Tyaquiçã, Pedro and Perruche, Coralie and Diverrès, Denis and Ibánhez, J Severino P},
  title = {Basin-Scale Estimate of the Sea-Air CO2 Flux During the 2010 Warm Event in the Tropical North Atlantic},
  journal = {Journal of Geophysical Research: Biogeosciences},
  publisher = {American Geophysical Union (AGU)},
  year = {2019},
  volume = {124},
  number = {4},
  pages = {973--986},
  doi = {10.1029/2018JG004840}
}
Leufen LH and Schädler G (2019), "Calculating the turbulent fluxes in the atmospheric surface layer with neural networks", Geoscientific Model Development., may, 2019. Vol. 12(5), pp. 2033-2047.
Abstract: The turbulent fluxes of momentum, heat and water vapour link the Earth's surface with the atmosphere. Therefore, the correct modelling of the flux interactions between these two systems with very different timescales is vital for climate and weather forecast models. Conventionally, these fluxes are modelled using Monin-Obukhov similarity theory (MOST) with stability functions derived from a small number of field experiments. This results in a range of formulations of these functions and thus also in differences in the flux calculations; furthermore, the underlying equations are non-linear and have to be solved iteratively at each time step of the model. In this study, we tried a different and more flexible approach, namely using an artificial neural network (ANN) to calculate the scaling quantities uand(used to parameterise the fluxes), thereby avoiding function fitting and iteration. The network was trained and validated with multi-year data sets from seven grassland, forest and wetland sites worldwide using the Broyden-Fletcher-Goldfarb-Shanno (BFGS) quasi-Newton backpropagation algorithm and six-fold cross validation. Extensive sensitivity tests showed that an ANN with six input variables and one hidden layer gave results comparable to (and in some cases even slightly better than) the standard method; moreover, this ANN performed considerably better than a multivariate linear regression model. Similar satisfying results were obtained when the ANN routine was implemented in a one-dimensional stand-alone land surface model (LSM), paving the way for implementation in three-dimensional climate models. In the case of the one-dimensional LSM, no CPU time was saved when using the ANN version, as the small time step o