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: 22 March 2022.

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Demol M, Wilkes P, Raumonen P, Moorthy SM, Calders K, Gielen B and Verbeeck H (2022), "Volumetric overestimation of small branches in 3D reconstructions of Fraxinus excelsior", Silva Fennica. Vol. 56(1), pp. 1-26.
Abstract: Terrestrial laser scanning (TLS) has been applied to estimate forest wood volume based on detailed 3D tree reconstructions from point cloud data. However, sources of uncertainties in the point cloud data (alignment and scattering errors, occlusion, foliage…) and the reconstruction algorithm type and parameterisation are known to affect the reconstruction, especially around finer branches. To better understand the impacts of these uncertainties on the accuracy of TLS-derived woody volume, high-quality TLS scans were collected in leaf-off conditions prior to destructive harvesting of two forest-grown common ash trees (Fraxinus excelsior L.; diameter at breast height ∼28 cm, woody volume of 732 and 868 L). We manually measured branch diameters at 265 locations in these trees. Estimates of branch diameters and tree volume from Quantitative Structure Models (QSM) were compared with these manual measurements. The accuracy of QSM branch diameter estimates decreased with smaller branch diameters. Tree woody volume was overes-timated (+336 L and +392 L) in both trees. Branches measuring < 5 cm in diameter accounted for 80% and 83% of this overestimation respectively. Filtering for scattering errors or improved coregistration approximately halved the overestimation. Range filtering and modified scanning layouts had mixed effects. The small branch overestimations originated primarily in limitations in scanner characteristics and coregistration errors rather than suboptimal QSM parameterisation. For TLS-derived estimates of tree volume, a higher quality point cloud allows smaller branches to be accurately reconstructed. Additional experiments need to elucidate if these results can be generalised beyond the setup of this study.
BibTeX:
@article{Demol2022,
  author = {Demol, Miro and Wilkes, Phil and Raumonen, Pasi and Moorthy, Sruthi M.Krishna and Calders, Kim and Gielen, Bert and Verbeeck, Hans},
  title = {Volumetric overestimation of small branches in 3D reconstructions of Fraxinus excelsior},
  journal = {Silva Fennica},
  year = {2022},
  volume = {56},
  number = {1},
  pages = {1--26},
  doi = {10.14214/sf.10550}
}
Etzold S, Sterck F, Bose AK, Braun S, Buchmann N, Eugster W, Gessler A, Kahmen A, Peters RL, Vitasse Y, Walthert L, Ziemiʼnska K and Zweifel R (2022), "Number of growth days and not length of the growth period determines radial stem growth of temperate trees", Ecology Letters., feb, 2022. Vol. 25(2), pp. 427-439. John Wiley & Sons, Ltd.
Abstract: Abstract Radial stem growth dynamics at seasonal resolution are essential to understand how forests respond to climate change. We studied daily radial growth of 160 individuals of seven temperate tree species at 47 sites across Switzerland over 8 years. Growth of all species peaked in the early part of the growth season and commenced shortly before the summer solstice, but with species-specific seasonal patterns. Day length set a window of opportunity for radial growth. Within this window, the probability of daily growth was constrained particularly by air and soil moisture, resulting in intermittent growth to occur only on 29 to 77 days (30% to 80%) within the growth period. The number of days with growth largely determined annual growth, whereas the growth period length contributed less. We call for accounting for these non-linear intra-annual and species-specific growth dynamics in tree and forest models to reduce uncertainties in predictions under climate change.
BibTeX:
@article{Etzold2022,
  author = {Etzold, Sophia and Sterck, Frank and Bose, Arun K and Braun, Sabine and Buchmann, Nina and Eugster, Werner and Gessler, Arthur and Kahmen, Ansgar and Peters, Richard L and Vitasse, Yann and Walthert, Lorenz and Ziemiʼnska, Kasia and Zweifel, Roman},
  title = {Number of growth days and not length of the growth period determines radial stem growth of temperate trees},
  journal = {Ecology Letters},
  publisher = {John Wiley & Sons, Ltd},
  year = {2022},
  volume = {25},
  number = {2},
  pages = {427--439},
  url = {https://doi.org/10.1111/ele.13933},
  doi = {10.1111/ele.13933}
}
Fu Z, Ciais P, Makowski D, Bastos A, Stoy PC, Ibrom A, Knohl A, Migliavacca M, Cuntz M, Šigut L, Peichl M, Loustau D, El-Madany TS, Buchmann N, Gharun M, Janssens I, Markwitz C, Grünwald T, Rebmann C, Mölder M, Varlagin A, Mammarella I, Kolari P, Bernhofer C, Heliasz M, Vincke C, Pitacco A, Cremonese E, Foltýnová L and Wigneron J-P (2022), "Uncovering the critical soil moisture thresholds of plant water stress for European ecosystems", Global Change Biology., mar, 2022. Vol. 28(6), pp. 2111-2123. John Wiley & Sons, Ltd.
Abstract: Abstract Understanding the critical soil moisture (SM) threshold (?crit) of plant water stress and land surface energy partitioning is a basis to evaluate drought impacts and improve models for predicting future ecosystem condition and climate. Quantifying the ?crit across biomes and climates is challenging because observations of surface energy fluxes and SM remain sparse. Here, we used the latest database of eddy covariance measurements to estimate ?crit across Europe by evaluating evaporative fraction (EF)-SM relationships and investigating the covariance between vapor pressure deficit (VPD) and gross primary production (GPP) during SM dry-down periods. We found that the ?crit and soil matric potential threshold in Europe are 16.5% and ?0.7 MPa, respectively. Surface energy partitioning characteristics varied among different vegetation types; EF in savannas had the highest sensitivities to SM in water-limited stage, and the lowest in forests. The sign of the covariance between daily VPD and GPP consistently changed from positive to negative during dry-down across all sites when EF shifted from relatively high to low values. This sign of the covariance changed after longer period of SM decline in forests than in grasslands and savannas. Estimated ?crit from the VPD?GPP covariance method match well with the EF?SM method, showing this covariance method can be used to detect the ?crit. We further found that soil texture dominates the spatial variability of ?crit while shortwave radiation and VPD are the major drivers in determining the spatial pattern of EF sensitivities. Our results highlight for the first time that the sign change of the covariance between daily VPD and GPP can be used as an indicator of how ecosystems transition from energy to SM limitation. We also characterized the corresponding ?crit and its drivers across diverse ecosystems in Europe, an essential variable to improve the representation of water stress in land surface models.
BibTeX:
@article{Fu2022,
  author = {Fu, Zheng and Ciais, Philippe and Makowski, David and Bastos, Ana and Stoy, Paul C and Ibrom, Andreas and Knohl, Alexander and Migliavacca, Mirco and Cuntz, Matthias and Šigut, Ladislav and Peichl, Matthias and Loustau, Denis and El-Madany, Tarek S and Buchmann, Nina and Gharun, Mana and Janssens, Ivan and Markwitz, Christian and Grünwald, Thomas and Rebmann, Corinna and Mölder, Meelis and Varlagin, Andrej and Mammarella, Ivan and Kolari, Pasi and Bernhofer, Christian and Heliasz, Michal and Vincke, Caroline and Pitacco, Andrea and Cremonese, Edoardo and Foltýnová, Lenka and Wigneron, Jean-Pierre},
  title = {Uncovering the critical soil moisture thresholds of plant water stress for European ecosystems},
  journal = {Global Change Biology},
  publisher = {John Wiley & Sons, Ltd},
  year = {2022},
  volume = {28},
  number = {6},
  pages = {2111--2123},
  url = {https://doi.org/10.1111/gcb.16050},
  doi = {10.1111/gcb.16050}
}
Fu Z, Ciais P, Prentice IC, Gentine P, Makowski D, Bastos A, Luo X, Green JK, Stoy PC, Yang H and Hajima T (2022), "Atmospheric dryness reduces photosynthesis along a large range of soil water deficits", Nature Communications. Vol. 13(1), pp. 989.
Abstract: Both low soil water content (SWC) and high atmospheric dryness (vapor pressure deficit, VPD) can negatively affect terrestrial gross primary production (GPP). The sensitivity of GPP to soil versus atmospheric dryness is difficult to disentangle, however, because of their covariation. Using global eddy-covariance observations, here we show that a decrease in SWC is not universally associated with GPP reduction. GPP increases in response to decreasing SWC when SWC is high and decreases only when SWC is below a threshold. By contrast, the sensitivity of GPP to an increase of VPD is always negative across the full SWC range. We further find canopy conductance decreases with increasing VPD (irrespective of SWC), and with decreasing SWC on drier soils. Maximum photosynthetic assimilation rate has negative sensitivity to VPD, and a positive sensitivity to decreasing SWC when SWC is high. Earth System Models underestimate the negative effect of VPD and the positive effect of SWC on GPP such that they should underestimate the GPP reduction due to increasing VPD in future climates.
BibTeX:
@article{Fu2022a,
  author = {Fu, Zheng and Ciais, Philippe and Prentice, I Colin and Gentine, Pierre and Makowski, David and Bastos, Ana and Luo, Xiangzhong and Green, Julia K and Stoy, Paul C and Yang, Hui and Hajima, Tomohiro},
  title = {Atmospheric dryness reduces photosynthesis along a large range of soil water deficits},
  journal = {Nature Communications},
  year = {2022},
  volume = {13},
  number = {1},
  pages = {989},
  url = {https://doi.org/10.1038/s41467-022-28652-7},
  doi = {10.1038/s41467-022-28652-7}
}
Hase N, Doktor D, Rebmann C, Dechant B, Mollenhauer H and Cuntz M (2022), "Identifying the main drivers of the seasonal decline of near-infrared reflectance of a temperate deciduous forest", Agricultural and Forest Meteorology. Vol. 313, pp. 108746.
Abstract: The physical mechanisms behind correlations of earth observations and remote sensing products are of vital importance. The so-called 'near-infrared reflectance of vegetation' (NIRV) and gross primary production (GPP) show high correlations among different ecosystems and temporal scales but the underlying relationship is still poorly understood. NIRV is defined as the product of normalized difference vegetation index (NDVI) and near-infrared (NIR) canopy reflectance (RNIR). We examined this relationship in the case of a temperate deciduous forest in Germany. GPP, RNIR and NIRV all exhibited a strong rise during leaf development in spring and a continual decline after the maximum in early summer. The decline of NIRV in late summer was mainly driven by the decline of RNIR, since NDVI remained saturated. Here we tested the RNIR decline attributions to changes in leaf area index, leaf optical properties, canopy structure, sun-sensor geometry, or understory vegetation by measuring seasonal variations of those factors of the temperate deciduous forest. Leaf area was nearly constant between May and mid September, leaf albedo decreased slightly, leaf angles increased over time towards more vertical leaves, and understory reflectance decreased considerably. We simulated the seasonal RNIR decline of the forest using the radiative transfer model FRT and quantified the sensitivity of the decline to variations in the measured parameters. FRT captured well the observed seasonal RNIR decline by Sentinel 2 using the measured optical and structural properties. Decreasing understory reflectance alone explained 43% of the simulated RNIR decrease, while leaf angle variations explained 31%, the solar zenith angle (SZA) 21%, leaf albedo 7%, and LAI 0%. The effect size of the SZA depended on the viewing angle and would hence be different for different satellites and for local instruments. The results may help to better understand and help to track seasonal changes in forest structure and leaf optical properties using remote sensing techniques. They also suggest that the proposed link between the seasonal evolution of GPP and NIRV may be weaker than expected.
BibTeX:
@article{Hase2022,
  author = {Hase, Niklas and Doktor, Daniel and Rebmann, Corinna and Dechant, Benjamin and Mollenhauer, Hannes and Cuntz, Matthias},
  title = {Identifying the main drivers of the seasonal decline of near-infrared reflectance of a temperate deciduous forest},
  journal = {Agricultural and Forest Meteorology},
  year = {2022},
  volume = {313},
  pages = {108746},
  url = {https://www.sciencedirect.com/science/article/pii/S0168192321004329},
  doi = {10.1016/j.agrformet.2021.108746}
}
Hough M, McCabe S, Vining SR, Pickering Pedersen E, Wilson RM, Lawrence R, Chang K-Y, Bohrer G, Coordinators TI, Riley WJ, Crill PM, Varner RK, Blazewicz SJ, Dorrepaal E, Tfaily MM, Saleska SR and Rich VI (2022), "Coupling plant litter quantity to a novel metric for litter quality explains C storage changes in a thawing permafrost peatland", Global Change Biology., feb, 2022. Vol. 28(3), pp. 950-968. John Wiley & Sons, Ltd.
Abstract: Abstract Permafrost thaw is a major potential feedback source to climate change as it can drive the increased release of greenhouse gases carbon dioxide (CO2) and methane (CH4). This carbon release from the decomposition of thawing soil organic material can be mitigated by increased net primary productivity (NPP) caused by warming, increasing atmospheric CO2, and plant community transition. However, the net effect on C storage also depends on how these plant community changes alter plant litter quantity, quality, and decomposition rates. Predicting decomposition rates based on litter quality remains challenging, but a promising new way forward is to incorporate measures of the energetic favorability to soil microbes of plant biomass decomposition. We asked how the variation in one such measure, the nominal oxidation state of carbon (NOSC), interacts with changing quantities of plant material inputs to influence the net C balance of a thawing permafrost peatland. We found: (1) Plant productivity (NPP) increased post-thaw, but instead of contributing to increased standing biomass, it increased plant biomass turnover via increased litter inputs to soil; (2) Plant litter thermodynamic favorability (NOSC) and decomposition rate both increased post-thaw, despite limited changes in bulk C:N ratios; (3) these increases caused the higher NPP to cycle more rapidly through both plants and soil, contributing to higher CO2 and CH4 fluxes from decomposition. Thus, the increased C-storage expected from higher productivity was limited and the high global warming potential of CH4 contributed a net positive warming effect. Although post-thaw peatlands are currently C sinks due to high NPP offsetting high CO2 release, this status is very sensitive to the plant community's litter input rate and quality. Integration of novel bioavailability metrics based on litter chemistry, including NOSC, into studies of ecosystem dynamics, is needed to improve the understanding of controls on arctic C stocks under continued ecosystem transition.
BibTeX:
@article{Hough2022,
  author = {Hough, Moira and McCabe, Samantha and Vining, S Rose and Pickering Pedersen, Emily and Wilson, Rachel M and Lawrence, Ryan and Chang, Kuang-Yu and Bohrer, Gil and Coordinators, The IsoGenie and Riley, William J and Crill, Patrick M and Varner, Ruth K and Blazewicz, Steven J and Dorrepaal, Ellen and Tfaily, Malak M and Saleska, Scott R and Rich, Virginia I},
  title = {Coupling plant litter quantity to a novel metric for litter quality explains C storage changes in a thawing permafrost peatland},
  journal = {Global Change Biology},
  publisher = {John Wiley & Sons, Ltd},
  year = {2022},
  volume = {28},
  number = {3},
  pages = {950--968},
  url = {https://doi.org/10.1111/gcb.15970},
  doi = {10.1111/gcb.15970}
}
Jordan A, Schumacher M and ICOS CAL - FCL (2022), "ICOS CAL - Quality Control Report 2021" ICOS CAL - FCL.
BibTeX:
@article{Jordan2022,
  author = {Jordan, Armin and Schumacher, Marcus and ICOS CAL - FCL},
  title = {ICOS CAL - Quality Control Report 2021},
  publisher = {ICOS CAL - FCL},
  year = {2022},
  url = {https://meta.icos-cp.eu/objects/8_58EsZZCIwHto3WYAFtw4w-},
  doi = {10.18160/RS2Q-RA1Q}
}
Korrensalo A, Mammarella I, Alekseychik P, Vesala T and Tuittila E-S (2022), "Plant mediated methane efflux from a boreal peatland complex", Plant and Soil. Vol. 471(1), pp. 375-392.
Abstract: Aerenchymous plants are an important control for methane efflux from peatlands to the atmosphere, providing a bypass from the anoxic peat and avoiding oxidation in the oxic peat. We aimed to quantify the drivers of aerenchymous peatland species methane transport and the importance of this process for ecosystem-scale methane efflux.
BibTeX:
@article{Korrensalo2022,
  author = {Korrensalo, A and Mammarella, I and Alekseychik, P and Vesala, T and Tuittila, E-S.},
  title = {Plant mediated methane efflux from a boreal peatland complex},
  journal = {Plant and Soil},
  year = {2022},
  volume = {471},
  number = {1},
  pages = {375--392},
  url = {https://doi.org/10.1007/s11104-021-05180-9},
  doi = {10.1007/s11104-021-05180-9}
}
Launiainen S, Katul GG, Leppä K, Kolari P, Aslan T, Grönholm T, Korhonen L, Mammarella I and Vesala T (2022), "Does growing atmospheric CO2 explain increasing carbon sink in a boreal coniferous forest?", Global Change Biology., feb, 2022. Vol. n/a(n/a) John Wiley & Sons, Ltd.
Abstract: Abstract The terrestrial net ecosystem productivity (NEP) has increased during the past three decades, but the mechanisms responsible are still unclear. We analyzed 17 years (2001?2017) of eddy-covariance measurements of NEP, evapotranspiration (ET) and light and water use efficiency from a boreal coniferous forest in Southern Finland for trends and inter-annual variability (IAV). The forest was a mean annual carbon sink (252 [±42] gC m-2a-1), and NEP increased at rate +6.4?7.0 gC m-2a-1 (or ca. +2.5% a-1) during the period. This was attributed to the increasing gross-primary productivity GPP and occurred without detectable change in ET. The start of annual carbon uptake period was advanced by 0.7 d a-1, and increase in GPP and NEP outside the main growing season contributed ca. one-third and one-fourth of the annual trend, respectively. Meteorological factors were responsible for the IAV of fluxes but did not explain the long-term trends. The growing season GPP trend was strongest in ample light during the peak growing season. Using a multi-layer ecosystem model, we showed that direct CO2 fertilization effect diminishes when moving from leaf to ecosystem, and only 30?40% of the observed ecosystem GPP increase could be attributed to CO2. The increasing trend in leaf-area index (LAI), stimulated by forest thinning in 2002, was the main driver of the enhanced GPP and NEP of the mid-rotation managed forest. It also compensated for the decrease of mean leaf stomatal conductance with increasing CO2 and LAI, explaining the apparent proportionality between observed GPP and CO2 trends. The results emphasize that attributing trends to their physical and physiological drivers is challenged by strong IAV, and uncertainty of LAI and species composition changes due to the dynamic flux footprint. The results enlighten the underlying mechanisms responsible for the increasing terrestrial carbon uptake in the boreal zone.
BibTeX:
@article{Launiainen2022,
  author = {Launiainen, Samuli and Katul, Gabriel G and Leppä, Kersti and Kolari, Pasi and Aslan, Toprak and Grönholm, Tiia and Korhonen, Lauri and Mammarella, Ivan and Vesala, Timo},
  title = {Does growing atmospheric CO2 explain increasing carbon sink in a boreal coniferous forest?},
  journal = {Global Change Biology},
  publisher = {John Wiley & Sons, Ltd},
  year = {2022},
  volume = {n/a},
  number = {n/a},
  url = {https://doi.org/10.1111/gcb.16117},
  doi = {10.1111/gcb.16117}
}
Lento J, Culp JM, Levenstein B, Aroviita J, Baturina MA, Bogan D, Brittain JE, Chin K, Christoffersen KS, Docherty C, Friberg N, Ingimarsson F, Jacobsen D, Lau DCP, Loskutova OA, Milner A, Mykrä H, Novichkova AA, Ólafsson JS, Schartau AK, Shaftel R and Goedkoop W (2022), "Temperature and spatial connectivity drive patterns in freshwater macroinvertebrate diversity across the Arctic", Freshwater Biology., jan, 2022. Vol. 67(1), pp. 159-175. John Wiley & Sons, Ltd.
Abstract: Abstract Warming in the Arctic is predicted to change freshwater biodiversity through loss of unique taxa and northward range expansion of lower latitude taxa. Detecting such changes requires establishing circumpolar baselines for diversity, and understanding the primary drivers of diversity. We examined benthic macroinvertebrate diversity using a circumpolar dataset of >1,500 Arctic lake and river sites. Rarefied α diversity within catchments was assessed along latitude and temperature gradients. Community composition was assessed through region-scale analysis of ? diversity and its components (nestedness and turnover), and analysis of biotic?abiotic relationships. Rarefied α diversity of lakes and rivers declined with increasing latitude, although more strongly across mainland regions than islands. Diversity was strongly related to air temperature, with the lowest diversity in the coldest catchments. Regional dissimilarity was highest when mainland regions were compared with islands, suggesting that connectivity limitations led to the strongest dissimilarity. High contributions of nestedness indicated that island regions contained a subset of the taxa found in mainland regions. High Arctic rivers and lakes were predominately occupied by Chironomidae and Oligochaeta, whereas Ephemeroptera, Plecoptera, and Trichoptera taxa were more abundant at lower latitudes. Community composition was strongly associated with temperature, although geology and precipitation were also important correlates. The strong association with temperature supports the prediction that warming will increase Arctic macroinvertebrate diversity, although low diversity on islands suggests that this increase will be limited by biogeographical constraints. Long-term harmonised monitoring across the circumpolar region is necessary to detect such changes to diversity and inform science-based management.
BibTeX:
@article{Lento2022,
  author = {Lento, Jennifer and Culp, Joseph M and Levenstein, Brianna and Aroviita, Jukka and Baturina, Maria A and Bogan, Daniel and Brittain, John E and Chin, Krista and Christoffersen, Kirsten S and Docherty, Catherine and Friberg, Nikolai and Ingimarsson, Finnur and Jacobsen, Dean and Lau, Danny Chun Pong and Loskutova, Olga A and Milner, Alexander and Mykrä, Heikki and Novichkova, Anna A and Ólafsson, Jón S and Schartau, Ann Kristin and Shaftel, Rebecca and Goedkoop, Willem},
  title = {Temperature and spatial connectivity drive patterns in freshwater macroinvertebrate diversity across the Arctic},
  journal = {Freshwater Biology},
  publisher = {John Wiley & Sons, Ltd},
  year = {2022},
  volume = {67},
  number = {1},
  pages = {159--175},
  url = {https://doi.org/10.1111/fwb.13805},
  doi = {10.1111/fwb.13805}
}
Petäjä T, Tabakova K, Manninen A, Ezhova E, O'Connor E, Moisseev D, Sinclair VA, Backman J, Levula J, Luoma K, Virkkula A, Paramonov M, Räty M, Äijälä M, Heikkinen L, Ehn M, Sipilä M, Yli-Juuti T, Virtanen A, Ritsche M, Hickmon N, Pulik G, Rosenfeld D, Worsnop DR, Bäck J, Kulmala M and Kerminen V-M (2022), "Influence of biogenic emissions from boreal forests on aerosol–cloud interactions", Nature Geoscience. Vol. 15(1), pp. 42-47.
Abstract: Boreal forest acts as a carbon sink and contributes to the formation of secondary organic aerosols via emission of aerosol precursor compounds. However, these influences on the climate system are poorly quantified. Here we show direct observational evidence that aerosol emissions from the boreal forest biosphere influence warm cloud microphysics and cloud–aerosol interactions in a scale-dependent and highly dynamic manner. Analyses of in situ and ground-based remote-sensing observations from the SMEAR II station in Finland, conducted over eight months in 2014, reveal substantial increases in aerosol load over the forest one to three days after aerosol-poor marine air enters the forest environment. We find that these changes are consistent with secondary organic aerosol formation and, together with water-vapour emissions from evapotranspiration, are associated with changes in the radiative properties of warm, low-level clouds. The feedbacks between boreal forest emissions and aerosol–cloud interactions and the highly dynamic nature of these interactions in air transported over the forest over timescales of several days suggest boreal forests have the potential to mitigate climate change on a continental scale. Our findings suggest that even small changes in aerosol precursor emissions, whether due to changing climatic or anthropogenic factors, may substantially modify the radiative properties of clouds in moderately polluted environments.
BibTeX:
@article{Petaejae2022,
  author = {Petäjä, T and Tabakova, K and Manninen, A and Ezhova, E and O'Connor, E and Moisseev, D and Sinclair, V A and Backman, J and Levula, J and Luoma, K and Virkkula, A and Paramonov, M and Räty, M and Äijälä, M and Heikkinen, L and Ehn, M and Sipilä, M and Yli-Juuti, T and Virtanen, A and Ritsche, M and Hickmon, N and Pulik, G and Rosenfeld, D and Worsnop, D R and Bäck, J and Kulmala, M and Kerminen, V.-M.},
  title = {Influence of biogenic emissions from boreal forests on aerosol–cloud interactions},
  journal = {Nature Geoscience},
  year = {2022},
  volume = {15},
  number = {1},
  pages = {42--47},
  url = {https://doi.org/10.1038/s41561-021-00876-0},
  doi = {10.1038/s41561-021-00876-0}
}
Poorter H, Knopf O, Wright IJ, Temme AA, Hogewoning SW, Graf A, Cernusak LA and Pons TL (2022), "A meta-analysis of responses of C3 plants to atmospheric CO2: dose–response curves for 85 traits ranging from the molecular to the whole-plant level", New Phytologist., feb, 2022. Vol. 233(4), pp. 1560-1596. John Wiley & Sons, Ltd.
Abstract: Summary Generalised dose?response curves are essential to understand how plants acclimate to atmospheric CO2. We carried out a meta-analysis of 630 experiments in which C3 plants were experimentally grown at different [CO2] under relatively benign conditions, and derived dose?response curves for 85 phenotypic traits. These curves were characterised by form, plasticity, consistency and reliability. Considered over a range of 200?1200 µmol mol?1 CO2, some traits more than doubled (e.g. area-based photosynthesis; intrinsic water-use efficiency), whereas others more than halved (area-based transpiration). At current atmospheric [CO2], 64% of the total stimulation in biomass over the 200?1200 µmol mol?1 range has already been realised. We also mapped the trait responses of plants to [CO2] against those we have quantified before for light intensity. For most traits, CO2 and light responses were of similar direction. However, some traits (such as reproductive effort) only responded to light, others (such as plant height) only to [CO2], and some traits (such as area-based transpiration) responded in opposite directions. This synthesis provides a comprehensive picture of plant responses to [CO2] at different integration levels and offers the quantitative dose?response curves that can be used to improve global change simulation models.
BibTeX:
@article{Poorter2022,
  author = {Poorter, Hendrik and Knopf, Oliver and Wright, Ian J and Temme, Andries A and Hogewoning, Sander W and Graf, Alexander and Cernusak, Lucas A and Pons, Thijs L},
  title = {A meta-analysis of responses of C3 plants to atmospheric CO2: dose–response curves for 85 traits ranging from the molecular to the whole-plant level},
  journal = {New Phytologist},
  publisher = {John Wiley & Sons, Ltd},
  year = {2022},
  volume = {233},
  number = {4},
  pages = {1560--1596},
  url = {https://doi.org/10.1111/nph.17802},
  doi = {10.1111/nph.17802}
}
Röttger S, Röttger A, Grossi C, Vargas A, Karstens U, Cinelli G, Chung E, Kikaj D, Rennick C, Mertes F and Radulescu I (2022), "Radon metrology for use in climate change observation and radiation protection at the environmental level", Advances in Geosciences. Vol. 57, pp. 37-47.
BibTeX:
@article{Roettger2022,
  author = {Röttger, S and Röttger, A and Grossi, C and Vargas, A and Karstens, U and Cinelli, G and Chung, E and Kikaj, D and Rennick, C and Mertes, F and Radulescu, I},
  title = {Radon metrology for use in climate change observation and radiation protection at the environmental level},
  journal = {Advances in Geosciences},
  year = {2022},
  volume = {57},
  pages = {37--47},
  url = {https://adgeo.copernicus.org/articles/57/37/2022/},
  doi = {10.5194/adgeo-57-37-2022}
}
Rust D, Katharopoulos I, Vollmer MK, Henne S, O'Doherty S, Say D, Emmenegger L, Zenobi R and Reimann S (2022), "Swiss halocarbon emissions for 2019 to 2020 assessed from regional atmospheric observations", Atmospheric Chemistry and Physics. Vol. 22(4), pp. 2447-2466.
BibTeX:
@article{Rust2022,
  author = {Rust, D and Katharopoulos, I and Vollmer, M K and Henne, S and O'Doherty, S and Say, D and Emmenegger, L and Zenobi, R and Reimann, S},
  title = {Swiss halocarbon emissions for 2019 to 2020 assessed from regional atmospheric observations},
  journal = {Atmospheric Chemistry and Physics},
  year = {2022},
  volume = {22},
  number = {4},
  pages = {2447--2466},
  url = {https://acp.copernicus.org/articles/22/2447/2022/},
  doi = {10.5194/acp-22-2447-2022}
}
Sytiuk A, Céréghino R, Hamard S, Delarue F, Guittet A, Barel JM, Dorrepaal E, Küttim M, Lamentowicz M, Pourrut B, Robroek BJM, Tuittila E-S and Jassey VEJ (2022), "Predicting the structure and functions of peatland microbial communities from Sphagnum phylogeny, anatomical and morphological traits and metabolites", Journal of Ecology., jan, 2022. Vol. 110(1), pp. 80-96. John Wiley & Sons, Ltd.
Abstract: Abstract Sphagnum mosses are keystone species in northern peatlands. Notably, they play an important role in peatland carbon (C) cycling by regulating the composition and activity of microbial communities. However, it remains unclear whether information on Sphagnum phylogeny and/or traits-based composition (i.e. anatomical and morphological traits and metabolites) can be used to predict the structure of microbial communities and their functioning. Here we evaluated whether Sphagnum phylogeny and traits predict additional variation in peatland microbial community composition and functioning beyond what would be predicted from environmental characteristics (i.e. climatic and edaphic conditions). We collected Sphagnum and microbial data from five European peatlands distributed along a latitudinal gradient from northern Sweden to southern France. These data allowed us to assess Sphagnum anatomical and morphological traits and metabolites at different sites along changing environmental conditions. Using structural equation modelling (SEM) and phylogenetic distance analyses, we investigated the role of Sphagnum traits in shaping microbial community composition and functioning along with environmental conditions. We show that microbial community composition and traits varied independently from both Sphagnum phylogeny and the latitudinal gradient. Specifically, the addition of Sphagnum traits to climatic and edaphic variables to the SEM allowed it to explain a larger proportion of the explained variance (R2). This observation was most apparent for the biomass of decomposers (+42%) and phototrophs (+19%), as well as for growth yield microbial traits (+10%). As such, that Sphagnum metabolites were important drivers for microbial community structure and traits, while Sphagnum anatomical and morphological traits were poor predictors. Synthesis. Our results highlight that Sphagnum metabolites are more likely to influence peatland microbial food web structure and functioning than Sphagnum anatomical and morphological traits. We provide further evidence that measurements of the plant metabolome, when combined with classical functional traits, improve our understanding of how the plants interact with their associated microbiomes.
BibTeX:
@article{Sytiuk2022,
  author = {Sytiuk, Anna and Céréghino, Régis and Hamard, Samuel and Delarue, Frédéric and Guittet, Amélie and Barel, Janna M and Dorrepaal, Ellen and Küttim, Martin and Lamentowicz, Mariusz and Pourrut, Bertrand and Robroek, Bjorn J M and Tuittila, Eeva-Stiina and Jassey, Vincent E J},
  title = {Predicting the structure and functions of peatland microbial communities from Sphagnum phylogeny, anatomical and morphological traits and metabolites},
  journal = {Journal of Ecology},
  publisher = {John Wiley & Sons, Ltd},
  year = {2022},
  volume = {110},
  number = {1},
  pages = {80--96},
  url = {https://doi.org/10.1111/1365-2745.13728},
  doi = {10.1111/1365-2745.13728}
}
Varner RK, Crill PM, Frolking S, McCalley CK, Burke SA, Chanton JP, Holmes ME, null Null, Saleska S and Palace MW (2022), "Permafrost thaw driven changes in hydrology and vegetation cover increase trace gas emissions and climate forcing in Stordalen Mire from 1970 to 2014", Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences., jan, 2022. Vol. 380(2215), pp. 20210022. Royal Society.
BibTeX:
@article{Varner2022,
  author = {Varner, Ruth K and Crill, Patrick M and Frolking, Steve and McCalley, Carmody K and Burke, Sophia A and Chanton, Jeffrey P and Holmes, M Elizabeth and null Null and Saleska, Scott and Palace, Michael W},
  title = {Permafrost thaw driven changes in hydrology and vegetation cover increase trace gas emissions and climate forcing in Stordalen Mire from 1970 to 2014},
  journal = {Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences},
  publisher = {Royal Society},
  year = {2022},
  volume = {380},
  number = {2215},
  pages = {20210022},
  url = {https://doi.org/10.1098/rsta.2021.0022},
  doi = {10.1098/rsta.2021.0022}
}
Vesala T, Kohonen K-M, Kooijmans LMJ, Praplan AP, Foltýnová L, Kolari P, Kulmala M, Bäck J, Nelson D, Yakir D, Zahniser M and Mammarella I (2022), "Long-term fluxes of carbonyl sulfide and their seasonality and interannual variability in a boreal forest", Atmospheric Chemistry and Physics. Vol. 22(4), pp. 2569-2584.
BibTeX:
@article{Vesala2022,
  author = {Vesala, T and Kohonen, K.-M. and Kooijmans, L M J and Praplan, A P and Foltýnová, L and Kolari, P and Kulmala, M and Bäck, J and Nelson, D and Yakir, D and Zahniser, M and Mammarella, I},
  title = {Long-term fluxes of carbonyl sulfide and their seasonality and interannual variability in a boreal forest},
  journal = {Atmospheric Chemistry and Physics},
  year = {2022},
  volume = {22},
  number = {4},
  pages = {2569--2584},
  url = {https://acp.copernicus.org/articles/22/2569/2022/},
  doi = {10.5194/acp-22-2569-2022}
}
Virkkala​​​​​​​ A-M, Natali SM, Rogers BM, Watts JD, Savage K, Connon SJ, Mauritz M, Schuur EAG, Peter D, Minions C, Nojeim J, Commane R, Emmerton CA, Goeckede M, Helbig M, Holl D, Iwata H, Kobayashi H, Kolari P, López-Blanco E, Marushchak ME, Mastepanov M, Merbold L, Parmentier F-JW, Peichl M, Sachs T, Sonnentag O, Ueyama M, Voigt C, Aurela M, Boike J, Celis G, Chae N, Christensen TR, Bret-Harte MS, Dengel S, Dolman H, Edgar CW, Elberling B, Euskirchen E, Grelle A, Hatakka J, Humphreys E, Järveoja J, Kotani A, Kutzbach L, Laurila T, Lohila A, Mammarella I, Matsuura Y, Meyer G, Nilsson MB, Oberbauer SF, Park S-J, Petrov R, Prokushkin AS, Schulze C, St. Louis VL, Tuittila E-S, Tuovinen J-P, Quinton W, Varlagin A, Zona D and Zyryanov VI (2022), "The ABCflux database: Arctic--boreal CO_2 flux observations and ancillary information aggregated to monthly time steps across terrestrial ecosystems", Earth System Science Data. Vol. 14(1), pp. 179-208.
BibTeX:
@article{Virkkala​​​​​​​2022,
  author = {Virkkala​​​​​​​, A.-M. and Natali, S M and Rogers, B M and Watts, J D and Savage, K and Connon, S J and Mauritz, M and Schuur, E A G and Peter, D and Minions, C and Nojeim, J and Commane, R and Emmerton, C A and Goeckede, M and Helbig, M and Holl, D and Iwata, H and Kobayashi, H and Kolari, P and López-Blanco, E and Marushchak, M E and Mastepanov, M and Merbold, L and Parmentier, F.-J. W and Peichl, M and Sachs, T and Sonnentag, O and Ueyama, M and Voigt, C and Aurela, M and Boike, J and Celis, G and Chae, N and Christensen, T R and Bret-Harte, M S and Dengel, S and Dolman, H and Edgar, C W and Elberling, B and Euskirchen, E and Grelle, A and Hatakka, J and Humphreys, E and Järveoja, J and Kotani, A and Kutzbach, L and Laurila, T and Lohila, A and Mammarella, I and Matsuura, Y and Meyer, G and Nilsson, M B and Oberbauer, S F and Park, S.-J. and Petrov, R and Prokushkin, A S and Schulze, C and St. Louis, V L and Tuittila, E.-S. and Tuovinen, J.-P. and Quinton, W and Varlagin, A and Zona, D and Zyryanov, V I},
  title = {The ABCflux database: Arctic--boreal CO_2 flux observations and ancillary information aggregated to monthly time steps across terrestrial ecosystems},
  journal = {Earth System Science Data},
  year = {2022},
  volume = {14},
  number = {1},
  pages = {179--208},
  url = {https://essd.copernicus.org/articles/14/179/2022/},
  doi = {10.5194/essd-14-179-2022}
}
Affolter S, Schibig M, Berhanu T, Bukowiecki N, Steinbacher M, Nyfeler P, Hervo M, Lauper J and Leuenberger M (2021), "Assessing local CO2 contamination revealed by two near-by high altitude records at Jungfraujoch, Switzerland", Environmental Research Letters. Vol. 16(4), pp. 44037. IOP Publishing.
Abstract: Remote research stations are guarantor of high-quality atmospheric measurements as they are essentially exposed to pristine air masses. However, in a context of increasing touristic pressure for certain sites, attention should be paid to the local anthropogenic emission related to the infrastructure itself. Among emissions, carbon dioxide (CO2) is the most important anthropogenic greenhouse gas and a major contributor to the current global warming. Here, we compared two years of CO2 dry air mole fraction records from Jungfraujoch (Swiss Alps) measured at the Sphinx Laboratory (3580 m a.s.l.; JFJ) and the East Ridge facility (3705 m a.s.l.; JER; horizontal distance of ∼1 km), respectively. Both stations show an overall increase of the annual mean CO2 mole fraction in line with current global trends. On a daily basis, values during the night (00h00–06h00) show robust coherence with variability ranging within the measurement uncertainties matching the WMO compatibility goal of 0.1 ppm, which we considered to be background air CO2 mole fraction for Central and Western Europe. However, JFJ record shows superimposed short-term variability with diurnal CO2 spikes centered around noon. Whereas the variability occurring during time intervals ranging from days to weeks seem to be driven by inputs of air masses from the planetary boundary layer, we suppose that the super-imposed diurnal CO2 spikes occurring essentially in summer are explained by local emission sources related to the infrastructure (visitors, tourism, etc). Nevertheless, we cannot point to a single triggering cause for those spikes as it probably results from a combination of factors. In order to minimize these local emissions, smooth collaboration between all the involved stakeholders is required.
BibTeX:
@article{Affolter2021,
  author = {Affolter, Stéphane and Schibig, Michael and Berhanu, Tesfaye and Bukowiecki, Nicolas and Steinbacher, Martin and Nyfeler, Peter and Hervo, Maxime and Lauper, Jürg and Leuenberger, Markus},
  title = {Assessing local CO2 contamination revealed by two near-by high altitude records at Jungfraujoch, Switzerland},
  journal = {Environmental Research Letters},
  publisher = {IOP Publishing},
  year = {2021},
  volume = {16},
  number = {4},
  pages = {44037},
  url = {http://dx.doi.org/10.1088/1748-9326/abe74a},
  doi = {10.1088/1748-9326/abe74a}
}
Alekseychik P, Korrensalo A, Mammarella I, Launiainen S, Tuittila E-S, Korpela I and Vesala T (2021), "Carbon balance of a Finnish bog: temporal variability and limiting factors based on 6 years of eddy-covariance data", Biogeosciences. Vol. 18(16), pp. 4681-4704.
BibTeX:
@article{Alekseychik2021,
  author = {Alekseychik, P and Korrensalo, A and Mammarella, I and Launiainen, S and Tuittila, E.-S. and Korpela, I and Vesala, T},
  title = {Carbon balance of a Finnish bog: temporal variability and limiting factors based on 6 years of eddy-covariance data},
  journal = {Biogeosciences},
  year = {2021},
  volume = {18},
  number = {16},
  pages = {4681--4704},
  url = {https://bg.copernicus.org/articles/18/4681/2021/},
  doi = {10.5194/bg-18-4681-2021}
}
Aslan T, Peltola O, Ibrom A, Nemitz E, Rannik Ü and Mammarella I (2021), "The high-frequency response correction of eddy covariance fluxes -- Part 2: An experimental approach for analysing noisy measurements of small fluxes", Atmospheric Measurement Techniques. Vol. 14(7), pp. 5089-5106.
BibTeX:
@article{Aslan2021,
  author = {Aslan, T and Peltola, O and Ibrom, A and Nemitz, E and Rannik, Ü and Mammarella, I},
  title = {The high-frequency response correction of eddy covariance fluxes -- Part 2: An experimental approach for analysing noisy measurements of small fluxes},
  journal = {Atmospheric Measurement Techniques},
  year = {2021},
  volume = {14},
  number = {7},
  pages = {5089--5106},
  url = {https://amt.copernicus.org/articles/14/5089/2021/},
  doi = {10.5194/amt-14-5089-2021}
}
Badraghi A, Ventura M, Polo A, Borruso L, Giammarchi F and Montagnani L (2021), "Soil respiration variation along an altitudinal gradient in the Italian Alps: Disentangling forest structure and temperature effects", PLOS ONE., aug, 2021. Vol. 16(8), pp. e0247893. Public Library of Science.
Abstract: On the mountains, along an elevation gradient, we generally observe an ample variation in temperature, with the associated difference in vegetation structure and composition and soil properties. With the aim of quantifying the relative importance of temperature, vegetation and edaphic properties on soil respiration (SR), we investigated changes in SR along an elevation gradient (404 to 2101 m a.s.l) in the southern slopes of the Alps in Northern Italy. We also analysed soil physicochemical properties, including soil organic carbon (SOC) and nitrogen (N) stocks, fine root C and N, litter C and N, soil bulk densities and soil pH at five forest sites, and also stand structural properties, including vegetation height, age and basal area. Our results indicated that SR rates increased with temperature in all sites, and 55–76% of SR variability was explained by temperature. Annual cumulative SR, ranging between 0.65–1.40 kg C m-2 yr-1, decreased along the elevation gradient, while temperature sensitivity (Q10) of SR increased with elevation. However, a high SR rate (1.27 kg C m-2 yr-1) and low Q10 were recorded in the mature conifer forest stand at 1731 m a.s.l., characterized by an uneven-aged structure and high dominant tree height, resulting in a nonlinear relationship between elevation and temperature. Reference SR at 10°C (SRref) was unrelated to elevation, but was related to tree height. A significant negative linear relationship was found between bulk density and elevation. Conversely, SOC, root C and N stock, pH, and litter mass were best fitted by nonlinear relationships with elevation. However, these parameters were not significantly correlated with SR when the effect of temperature was removed (SRref). These results demonstrate that the main factor affecting SR in forest ecosystems along this Alpine elevation gradient is temperature, but its regulating role can be strongly influenced by site biological characteristics, particularly vegetation type and structure, affecting litter quality and microclimate. This study also confirms that high elevation sites are rich in SOC and more sensitive to climate change, being prone to high C losses as CO2. Furthermore, our data indicate a positive relationship between Q10 and dominant tree height, suggesting that mature forest ecosystems characterized by an uneven-age structure, high SRref and moderate Q10, may be more resilient.
BibTeX:
@article{Badraghi2021,
  author = {Badraghi, Aysan and Ventura, Maurizio and Polo, Andrea and Borruso, Luigimaria and Giammarchi, Francesco and Montagnani, Leonardo},
  title = {Soil respiration variation along an altitudinal gradient in the Italian Alps: Disentangling forest structure and temperature effects},
  journal = {PLOS ONE},
  publisher = {Public Library of Science},
  year = {2021},
  volume = {16},
  number = {8},
  pages = {e0247893},
  url = {https://doi.org/10.1371/journal.pone.0247893}
}
Bai Y, Zhang S, Zhang J, Wang J, Yang S, Magliulo V, Vitale L and Zhao Y (2021), "Using remote sensing information to enhance the understanding of the coupling of terrestrial ecosystem evapotranspiration and photosynthesis on a global scale", International Journal of Applied Earth Observation and Geoinformation. Vol. 100, pp. 102329.
Abstract: Understanding the coupling of terrestrial ecosystem evapotranspiration (ET) and photosynthesis (gross primary productivity, GPP) is limited by inherent difficulties to provide accurate approximations of transpiration (T) and leaf-to-air vapor pressure difference (D) that is a key variable needed to define the stomata behaviors in generic methods. To address the issues and better characterize the ET-GPP relationship, we developed a novel remote sensing (RS)-driven approach (RCEEP) based on the underlying water use efficiency (uWUE) method (termed uWUE-Model). RCEEP partitions T from ET using the RS-derived fraction (rsFt) of T in ET and then links T and GPP via RS-derived canopy conductance (rsGc) instead of D. RCEEP, the original uWUE-Model, and two other uWUE-based versions (RT or RG) that only incorporate rsFt or rsGc were adjusted using the calibration data, and then inter-compared in terms of their performances (Nash-Sutcliffe efficiency, NSE) in estimating GPP from ET on a daily and monthly scale for both calibration and validation datasets — two subsets of data from 177 flux sites covering 11 biome types over the globe. Results revealed better performances of RT and RG as compared to uWUE-Model over most biomes, implying remarkable contributions of rsFt and rsGc to a more meaningful relationship between ET and GPP. RCEEP yielded the best performances over all biome types except for evergreen forest with reasonable mean NSE values of 0.67 – 0.68 (0.75) on a daily (monthly) scale. Further comparisons between RCEEP and two existing approaches concerning estimating GPP from ET revealed consistently better performances of RCEEP and thus, positive implications of introducing rsFt and rsGc in bridging ecosystem ET and GPP. Besides, rsFt should be used combined with rsGc to avoid degraded effectiveness for specific biome types (Savannah and Woody Savannah). These results are promising in view of improving or developing algorithms on coupled estimates of ecosystem ET and GPP and understanding the GPP dynamics concerning ET on a global scale.
BibTeX:
@article{Bai2021,
  author = {Bai, Yun and Zhang, Sha and Zhang, Jiahua and Wang, Jingwen and Yang, Shanshan and Magliulo, Vincenzo and Vitale, Luca and Zhao, Yanchuang},
  title = {Using remote sensing information to enhance the understanding of the coupling of terrestrial ecosystem evapotranspiration and photosynthesis on a global scale},
  journal = {International Journal of Applied Earth Observation and Geoinformation},
  year = {2021},
  volume = {100},
  pages = {102329},
  url = {https://www.sciencedirect.com/science/article/pii/S0303243421000362},
  doi = {10.1016/j.jag.2021.102329}
}
Bassiouni M and Vico G (2021), "Parsimony vs predictive and functional performance of three stomatal optimization principles in a big-leaf framework", New Phytologist., jul, 2021. Vol. 231(2), pp. 586-600. John Wiley & Sons, Ltd.
Abstract: Summary Stomatal optimization models can improve estimates of water and carbon fluxes with relatively low complexity, yet there is no consensus on which formulations are most appropriate for ecosystem-scale applications. We implemented three existing analytical equations for stomatal conductance, based on different water penalty functions, in a big-leaf comparison framework, and determined which optimization principles were most consistent with flux tower observations from different biomes. We used information theory to dissect controls of soil water supply and atmospheric demand on evapotranspiration in wet to dry conditions and to quantify missing or inadequate information in model variants. We ranked stomatal optimization principles based on parameter uncertainty, parsimony, predictive accuracy, and functional accuracy of the interactions between soil moisture, vapor pressure deficit, and evapotranspiration. Performance was high for all model variants. Water penalty functions with explicit representation of plant hydraulics did not substantially improve predictive or functional accuracy of ecosystem-scale evapotranspiration estimates, and parameterizations were more uncertain, despite having physiological underpinnings at the plant level. Stomatal optimization based on water use efficiency thus provided more information about ecosystem-scale evapotranspiration compared to those based on xylem vulnerability and proved more useful in improving ecosystem-scale models with less complexity.
BibTeX:
@article{Bassiouni2021,
  author = {Bassiouni, Maoya and Vico, Giulia},
  title = {Parsimony vs predictive and functional performance of three stomatal optimization principles in a big-leaf framework},
  journal = {New Phytologist},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {231},
  number = {2},
  pages = {586--600},
  url = {https://doi.org/10.1111/nph.17392},
  doi = {10.1111/nph.17392}
}
Bates JS, Montzka C, Schmidt M and Jonard F (2021), "Estimating Canopy Density Parameters Time-Series for Winter Wheat Using UAS Mounted LiDAR", Remote Sensing. Vol. 13(4)
Abstract: Monitoring of canopy density with related metrics such as leaf area index (LAI) makes a significant contribution to understanding and predicting processes in the soil–plant–atmosphere system and to indicating crop health and potential yield for farm management. Remote sensing methods using optical sensors that rely on spectral reflectance to calculate LAI have become more mainstream due to easy entry and availability. Methods with vegetation indices (VI) based on multispectral reflectance data essentially measure the green area index (GAI) or response to chlorophyll content of the canopy surface and not the entire aboveground biomass that may be present from non-green elements that are key to fully assessing the carbon budget. Methods with light detection and ranging (LiDAR) have started to emerge using gap fraction (GF) to estimate the plant area index (PAI) based on canopy density. These LiDAR methods have the main advantage of being sensitive to both green and non-green plant elements. They have primarily been applied to forest cover with manned airborne LiDAR systems (ALS) and have yet to be used extensively with crops such as winter wheat using LiDAR on unmanned aircraft systems (UAS). This study contributes to a better understanding of the potential of LiDAR as a tool to estimate canopy structure in precision farming. The LiDAR method proved to have a high to moderate correlation in spatial variation to the multispectral method. The LiDAR-derived PAI values closely resemble the SunScan Ceptometer GAI ground measurements taken early in the growing season before major stages of senescence. Later in the growing season, when the canopy density was at its highest, a possible overestimation may have occurred. This was most likely due to the chosen flight parameters not providing the best depictions of canopy density with consideration of the LiDAR's perspective, as the ground-based destructive measurements provided lower values of PAI. Additionally, a distinction between total LiDAR-derived PAI, multispectral-derived GAI, and brown area index (BAI) is made to show how the active and passive optical sensor methods used in this study can complement each other throughout the growing season.
BibTeX:
@article{Bates2021,
  author = {Bates, Jordan Steven and Montzka, Carsten and Schmidt, Marius and Jonard, François},
  title = {Estimating Canopy Density Parameters Time-Series for Winter Wheat Using UAS Mounted LiDAR},
  journal = {Remote Sensing},
  year = {2021},
  volume = {13},
  number = {4},
  url = {https://www.mdpi.com/2072-4292/13/4/710},
  doi = {10.3390/rs13040710}
}
Becker M, Olsen A and Reverdin G (2021), "In-air one-point calibration of oxygen optodes in underway systems", Limnology and Oceanography: Methods., may, 2021. Vol. 19(5), pp. 293-302. John Wiley & Sons, Ltd.
Abstract: Abstract Ships of opportunity are a frequently used platform in surface ocean carbon observations and estimating the annual ocean carbon sink. For understanding the drivers behind changes in the ocean carbon system, oxygen measurements alongside the carbon dioxide measurements can be a valuable tool. We developed an in-air calibration system for oxygen optodes in underway systems. The regular measurements of atmospheric oxygen enable us to correct for sensor drift and biofouling. This new system can help to obtain reliable oxygen data from underway applications, especially if the vessel is not easily accessible and a frequent recalibration of the optode is not feasible.
BibTeX:
@article{Becker2021,
  author = {Becker, Meike and Olsen, Are and Reverdin, Gilles},
  title = {In-air one-point calibration of oxygen optodes in underway systems},
  journal = {Limnology and Oceanography: Methods},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {19},
  number = {5},
  pages = {293--302},
  url = {https://doi.org/10.1002/lom3.10423},
  doi = {10.1002/lom3.10423}
}
Bengtsson F, Rydin H, Baltzer JL, Bragazza L, Bu Z-J, Caporn SJM, Dorrepaal E, Flatberg KI, Galanina O, Gałka M, Ganeva A, Goia I, Goncharova N, Hájek M, Haraguchi A, Harris LI, Humphreys E, Jiroušek M, Kajukało K, Karofeld E, Koronatova NG, Kosykh NP, Laine AM, Lamentowicz M, Lapshina E, Limpens J, Linkosalmi M, Ma J-Z, Mauritz M, Mitchell EAD, Munir TM, Natali SM, Natcheva R, Payne RJ, Philippov DA, Rice SK, Robinson S, Robroek BJM, Rochefort L, Singer D, Stenøien HK, Tuittila E-S, Vellak K, Waddington JM and Granath G (2021), "Environmental drivers of Sphagnum growth in peatlands across the Holarctic region", Journal of Ecology., jan, 2021. Vol. 109(1), pp. 417-431. John Wiley & Sons, Ltd.
Abstract: Abstract The relative importance of global versus local environmental factors for growth and thus carbon uptake of the bryophyte genus Sphagnum?the main peat-former and ecosystem engineer in northern peatlands?remains unclear. We measured length growth and net primary production (NPP) of two abundant Sphagnum species across 99 Holarctic peatlands. We tested the importance of previously proposed abiotic and biotic drivers for peatland carbon uptake (climate, N deposition, water table depth and vascular plant cover) on these two responses. Employing structural equation models (SEMs), we explored both indirect and direct effects of drivers on Sphagnum growth. Variation in growth was large, but similar within and between peatlands. Length growth showed a stronger response to predictors than NPP. Moreover, the smaller and denser Sphagnum fuscum growing on hummocks had weaker responses to climatic variation than the larger and looser Sphagnum magellanicum growing in the wetter conditions. Growth decreased with increasing vascular plant cover within a site. Between sites, precipitation and temperature increased growth for S. magellanicum. The SEMs indicate that indirect effects are important. For example, vascular plant cover increased with a deeper water table, increased nitrogen deposition, precipitation and temperature. These factors also influenced Sphagnum growth indirectly by affecting moss shoot density. Synthesis. Our results imply that in a warmer climate, S. magellanicum will increase length growth as long as precipitation is not reduced, while S. fuscum is more resistant to decreased precipitation, but also less able to take advantage of increased precipitation and temperature. Such species-specific sensitivity to climate may affect competitive outcomes in a changing environment, and potentially the future carbon sink function of peatlands.
BibTeX:
@article{Bengtsson2021,
  author = {Bengtsson, Fia and Rydin, Håkan and Baltzer, Jennifer L and Bragazza, Luca and Bu, Zhao-Jun and Caporn, Simon J M and Dorrepaal, Ellen and Flatberg, Kjell Ivar and Galanina, Olga and Gałka, Mariusz and Ganeva, Anna and Goia, Irina and Goncharova, Nadezhda and Hájek, Michal and Haraguchi, Akira and Harris, Lorna I and Humphreys, Elyn and Jiroušek, Martin and Kajukało, Katarzyna and Karofeld, Edgar and Koronatova, Natalia G and Kosykh, Natalia P and Laine, Anna M and Lamentowicz, Mariusz and Lapshina, Elena and Limpens, Juul and Linkosalmi, Maiju and Ma, Jin-Ze and Mauritz, Marguerite and Mitchell, Edward A D and Munir, Tariq M and Natali, Susan M and Natcheva, Rayna and Payne, Richard J and Philippov, Dmitriy A and Rice, Steven K and Robinson, Sean and Robroek, Bjorn J M and Rochefort, Line and Singer, David and Stenøien, Hans K and Tuittila, Eeva-Stiina and Vellak, Kai and Waddington, James Michael and Granath, Gustaf},
  title = {Environmental drivers of Sphagnum growth in peatlands across the Holarctic region},
  journal = {Journal of Ecology},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {109},
  number = {1},
  pages = {417--431},
  url = {https://doi.org/10.1111/1365-2745.13499},
  doi = {10.1111/1365-2745.13499}
}
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}
}
Brovkina O, Hanuš J and Novotný J (2021), "Airborne remote sensing for forest inventory attributes assessment: experience of Flying Laboratory of Imaging Systems (FLIS) in the Czech Republic", IOP Conference Series: Earth and Environmental Science. Vol. 806(1), pp. 12005. IOP Publishing.
Abstract: The paper contributes to the recent studies for forest inventory attributes assessment from airborne data using experience of Flying Laboratory of Imaging Systems (FLIS).The advanced methods of airborne hyperspectral and laser scanning data processing are summarized to demonstrate the applicability of FLIS in assessment of forest inventory attributes for tree and plot levels in selected forest areas in the Czech Republic. Specifically, assessments of tree height, tree position, crown base, crown width, aboveground biomass, species composition, dead trees, and health status are presented.
BibTeX:
@article{Brovkina2021,
  author = {Brovkina, O and Hanuš, J and Novotný, J},
  title = {Airborne remote sensing for forest inventory attributes assessment: experience of Flying Laboratory of Imaging Systems (FLIS) in the Czech Republic},
  journal = {IOP Conference Series: Earth and Environmental Science},
  publisher = {IOP Publishing},
  year = {2021},
  volume = {806},
  number = {1},
  pages = {12005},
  url = {http://dx.doi.org/10.1088/1755-1315/806/1/012005},
  doi = {10.1088/1755-1315/806/1/012005}
}
Brunner C, Brem BT, Collaud Coen M, Conen F, Hervo M, Henne S, Steinbacher M, Gysel-Beer M and Kanji ZA (2021), "The contribution of Saharan dust to the ice-nucleating particle concentrations at the High Altitude Station Jungfraujoch (3580,m,a.s.l.), Switzerland", Atmospheric Chemistry and Physics. Vol. 21(23), pp. 18029-18053.
BibTeX:
@article{Brunner2021,
  author = {Brunner, C and Brem, B T and Collaud Coen, M and Conen, F and Hervo, M and Henne, S and Steinbacher, M and Gysel-Beer, M and Kanji, Z A},
  title = {The contribution of Saharan dust to the ice-nucleating particle concentrations at the High Altitude Station Jungfraujoch (3580,m,a.s.l.), Switzerland},
  journal = {Atmospheric Chemistry and Physics},
  year = {2021},
  volume = {21},
  number = {23},
  pages = {18029--18053},
  url = {https://acp.copernicus.org/articles/21/18029/2021/},
  doi = {10.5194/acp-21-18029-2021}
}
Bukowiecki N, Brem BT, Wehrle G, Močnik G, Affolter S, Leuenberger M, Coen MC, Hervo M, Baltensperger U and Gysel-Beer M (2021), "Elucidating local pollution and site representativeness at the Jungfraujoch, Switzerland through parallel aerosol measurements at an adjacent mountain ridge", Environmental Research Communications. Vol. 3(2), pp. 21001. IOP Publishing.
Abstract: Many long-term air pollution and climate monitoring stations face the issue of increasing anthropogenic activities in their vicinity. Furthermore, the spatial representativeness of the sites is often not entirely understood especially in mountainous terrain with complex topographic features. This study presents a 5-year comparison of parallel aerosol measurements (total particle number concentration and equivalent black carbon mass concentration) at the Jungfraujoch in the Swiss Alps (JFJ, 3580 m a.s.l.), and an adjacent mountain ridge, the Jungfrau East Ridge (JER, 3705 m a.s.l.), in 1000 m air-line distance to the main site. The parallel aerosol measurements reveal characteristic differences in the diurnal variations between the two sites under certain specific meteorological conditions. Our analysis estimates that on 20%–40% of the days local activities at the Jungfraujoch have a clear influence on the measured time series of the total aerosol number concentration and the equivalent black carbon mass concentration. This influence is mainly seen in form of strong isolated spikes rather than by an increase in the on-site background concentration. They can thus be flagged during the data quality assurance process and filtered from those measurement parameters available at high time resolution. Removing the spikes from the original time series results in daily mean values for the total aerosol number concentration and equivalent black carbon mass concentration that are 5%–10% lower compared to the original signals. During nighttime with hardly any local pollution sources that cause spikes this percentage decreases towards 0%. The signal baselines at the Jungfraujoch and Jungfrau East Ridge correlate well during more than 50% of the days.
BibTeX:
@article{Bukowiecki2021,
  author = {Bukowiecki, Nicolas and Brem, Benjamin T and Wehrle, Günther and Močnik, Griša and Affolter, Stéphane and Leuenberger, Markus and Coen, Martine Collaud and Hervo, Maxime and Baltensperger, Urs and Gysel-Beer, Martin},
  title = {Elucidating local pollution and site representativeness at the Jungfraujoch, Switzerland through parallel aerosol measurements at an adjacent mountain ridge},
  journal = {Environmental Research Communications},
  publisher = {IOP Publishing},
  year = {2021},
  volume = {3},
  number = {2},
  pages = {21001},
  url = {http://dx.doi.org/10.1088/2515-7620/abe987},
  doi = {10.1088/2515-7620/abe987}
}
Cael BB, Bisson K, Conte M, Duret MT, Follett CL, Henson SA, Honda MC, Iversen MH, Karl DM, Lampitt RS, Mouw CB, Muller-Karger F, Pebody CA, Smith Jr. KL and Talmy D (2021), "Open Ocean Particle Flux Variability From Surface to Seafloor", Geophysical Research Letters., may, 2021. Vol. 48(9), pp. e2021GL092895. John Wiley & Sons, Ltd.
Abstract: Abstract The sinking of carbon fixed via net primary production (NPP) into the ocean interior is an important part of marine biogeochemical cycles. NPP measurements follow a log-normal probability distribution, meaning NPP variations can be simply described by two parameters despite NPP's complexity. By analyzing a global database of open ocean particle fluxes, we show that this log-normal probability distribution propagates into the variations of near-seafloor fluxes of particulate organic carbon (POC), calcium carbonate, and opal. Deep-sea particle fluxes at subtropical and temperate time-series sites follow the same log-normal probability distribution, strongly suggesting the log-normal description is robust and applies on multiple scales. This log-normality implies that 29% of the highest measurements are responsible for 71% of the total near-seafloor POC flux. We discuss possible causes for the dampening of variability from NPP to deep-sea POC flux, and present an updated relationship predicting POC flux from mineral flux and depth.
BibTeX:
@article{Cael2021,
  author = {Cael, B B and Bisson, Kelsey and Conte, Maureen and Duret, Manon T and Follett, Christopher L and Henson, Stephanie A and Honda, Makio C and Iversen, Morten H and Karl, David M and Lampitt, Richard S and Mouw, Colleen B and Muller-Karger, Frank and Pebody, Corinne A and Smith Jr., Kenneth L and Talmy, David},
  title = {Open Ocean Particle Flux Variability From Surface to Seafloor},
  journal = {Geophysical Research Letters},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {48},
  number = {9},
  pages = {e2021GL092895},
  url = {https://doi.org/10.1029/2021GL092895},
  doi = {10.1029/2021GL092895}
}
Cai Z, Junttila S, Holst J, Jin H, Ardö J, Ibrom A, Peichl M, Mölder M, Jönsson P, Rinne J, Karamihalaki M and Eklundh L (2021), "Modelling Daily Gross Primary Productivity with Sentinel-2 Data in the Nordic Region–Comparison with Data from MODIS", Remote Sensing., jan, 2021. Vol. 13(3), pp. 469.
Abstract: The high-resolution Sentinel-2 data potentially enable the estimation of gross primary productivity (GPP) at finer spatial resolution by better capturing the spatial variation in a heterogeneous landscapes. This study investigates the potential of 10 m resolution reflectance from the Sentinel-2 Multispectral Instrument to improve the accuracy of GPP estimation across Nordic vegetation types, compared with the 250 m and 500 m resolution reflectance from the Moderate Resolution Imaging Spectroradiometer (MODIS). We applied linear regression models with inputs of two-band enhanced vegetation index (EVI2) derived from Sentinel-2 and MODIS reflectance, respectively, together with various environmental drivers to estimate daily GPP at eight Nordic eddy covariance (EC) flux tower sites. Compared with the GPP from EC measurements, the accuracies of modelled GPP were generally high (R2 = 0.84 for Sentinel-2; R2 = 0.83 for MODIS), and the differences between Sentinel-2 and MODIS were minimal. This demonstrates the general consistency in GPP estimates based on the two satellite sensor systems at the Nordic regional scale. On the other hand, the model accuracy did not improve by using the higher spatial-resolution Sentinel-2 data. More analyses of different model formulations, more tests of remotely sensed indices and biophysical parameters, and analyses across a wider range of geographical locations and times will be required to achieve improved GPP estimations from Sentinel-2 satellite data.
BibTeX:
@article{Cai2021,
  author = {Cai, Zhanzhang and Junttila, Sofia and Holst, Jutta and Jin, Hongxiao and Ardö, Jonas and Ibrom, Andreas and Peichl, Matthias and Mölder, Meelis and Jönsson, Per and Rinne, Janne and Karamihalaki, Maria and Eklundh, Lars},
  title = {Modelling Daily Gross Primary Productivity with Sentinel-2 Data in the Nordic Region–Comparison with Data from MODIS},
  journal = {Remote Sensing},
  year = {2021},
  volume = {13},
  number = {3},
  pages = {469},
  url = {https://www.mdpi.com/2072-4292/13/3/469},
  doi = {10.3390/rs13030469}
}
Campeau A, Vachon D, Bishop K, Nilsson MB and Wallin MB (2021), "Autumn destabilization of deep porewater CO2 store in a northern peatland driven by turbulent diffusion", Nature Communications. Vol. 12(1), pp. 6857.
Abstract: The deep porewater of northern peatlands stores large amounts of carbon dioxide (CO2). This store is viewed as a stable feature in the peatland CO2 cycle. Here, we report large and rapid fluctuations in deep porewater CO2 concentration recurring every autumn over four consecutive years in a boreal peatland. Estimates of the vertical diffusion of heat indicate that CO2 diffusion occurs at the turbulent rather than molecular rate. The weakening of porewater thermal stratification in autumn likely increases turbulent diffusion, thus fostering a rapid diffusion of deeper porewater CO2 towards the surface where net losses occur. This phenomenon periodically decreases the peat porewater CO2 store by between 29 and 90 g C m−2 throughout autumn, which is comparable to the peatland's annual C-sink. Our results establish the need to consider the role of turbulent diffusion in regularly destabilizing the CO2 store in peat porewater.
BibTeX:
@article{Campeau2021,
  author = {Campeau, A and Vachon, D and Bishop, K and Nilsson, M B and Wallin, M B},
  title = {Autumn destabilization of deep porewater CO2 store in a northern peatland driven by turbulent diffusion},
  journal = {Nature Communications},
  year = {2021},
  volume = {12},
  number = {1},
  pages = {6857},
  url = {https://doi.org/10.1038/s41467-021-27059-0},
  doi = {10.1038/s41467-021-27059-0}
}
Chan SS, Seidenfaden IK, Jensen KH and Sonnenborg TO (2021), "Climate change impacts and uncertainty on spatiotemporal variations of drought indices for an irrigated catchment", Journal of Hydrology. Vol. 601, pp. 126814.
Abstract: Droughts are responsible for severe vegetation loss and declining agricultural yields. As future climate change projections imply an increased risk of extreme events, the occurrence of droughts is potentially accelerating in the future. The influence of climate change on drought events in a Danish agricultural catchment under the emission scenario RCP8.5 are evaluated by three different drought indices covering soil moisture, groundwater and streamflow deficits. The indices are based on results from a hydrological model forced by downscaled climate outputs from 16 Euro-CORDEX climate models (GCM-RCMs), while considering uncertainties among climate model projections. The hydrological model demonstrated a satisfactory ability in modelling historical drought characteristics. The results from the future projections showed that the intensity and frequency of droughts increased towards the end of the century. The spatial patterns of changes in drought were found to be highly dependent on the climate model results, index formulations and assumptions, as well as the hydrogeological properties of the catchment. Groundwater based irrigation in the agricultural areas effectively mitigates soil moisture drought, leading to lower future uncertainty of the ensemble mean (higher model agreement) for soil moisture droughts at irrigated locations. This is obtained at the cost of lower groundwater levels in both reference and future periods resulting in larger uncertainties on the simulated groundwater droughts, because of the addition of irrigation uncertainty. While the joint impact of greater groundwater abstraction and changing dynamics of precipitation and groundwater recharge also leads to larger streamflow variability between model combinations (standard deviation) under RCP8.5 for the downstream discharge station.
BibTeX:
@article{Chan2021,
  author = {Chan, San Shing and Seidenfaden, Ida Karlsson and Jensen, Karsten Høgh and Sonnenborg, Torben Obel},
  title = {Climate change impacts and uncertainty on spatiotemporal variations of drought indices for an irrigated catchment},
  journal = {Journal of Hydrology},
  year = {2021},
  volume = {601},
  pages = {126814},
  url = {https://www.sciencedirect.com/science/article/pii/S0022169421008647},
  doi = {10.1016/j.jhydrol.2021.126814}
}
Chang K-Y, Riley WJ, Knox SH, Jackson RB, McNicol G, Poulter B, Aurela M, Baldocchi D, Bansal S, Bohrer G, Campbell DI, Cescatti A, Chu H, Delwiche KB, Desai AR, Euskirchen E, Friborg T, Goeckede M, Helbig M, Hemes KS, Hirano T, Iwata H, Kang M, Keenan T, Krauss KW, Lohila A, Mammarella I, Mitra B, Miyata A, Nilsson MB, Noormets A, Oechel WC, Papale D, Peichl M, Reba ML, Rinne J, Runkle BRK, Ryu Y, Sachs T, Schäfer KVR, Schmid HP, Shurpali N, Sonnentag O, Tang ACI, Torn MS, Trotta C, Tuittila E-S, Ueyama M, Vargas R, Vesala T, Windham-Myers L, Zhang Z and Zona D (2021), "Substantial hysteresis in emergent temperature sensitivity of global wetland CH4 emissions", Nature Communications., dec, 2021. Vol. 12(1), pp. 2266.
Abstract: Wetland methane (CH 4 ) emissions ( F_CH_4 F C H 4 ) are important in global carbon budgets and climate change assessments. Currently, F_CH_4 F C H 4 projections rely on prescribed static temperature sensitivity that varies among biogeochemical models. Meta-analyses have proposed a consistent F_CH_4 F C H 4 temperature dependence across spatial scales for use in models; however, site-level studies demonstrate that F_CH_4 F C H 4 are often controlled by factors beyond temperature. Here, we evaluate the relationship between F_CH_4 F C H 4 and temperature using observations from the FLUXNET-CH 4 database. Measurements collected across the globe show substantial seasonal hysteresis between F_CH_4 F C H 4 and temperature, suggesting larger F_CH_4 F C H 4 sensitivity to temperature later in the frost-free season (about 77% of site-years). Results derived from a machine-learning model and several regression models highlight the importance of representing the large spatial and temporal variability within site-years and ecosystem types. Mechanistic advancements in biogeochemical model parameterization and detailed measurements in factors modulating CH 4 production are thus needed to improve global CH 4 budget assessments.
BibTeX:
@article{Chang2021,
  author = {Chang, Kuang-Yu and Riley, William J and Knox, Sara H and Jackson, Robert B and McNicol, Gavin and Poulter, Benjamin and Aurela, Mika and Baldocchi, Dennis and Bansal, Sheel and Bohrer, Gil and Campbell, David I and Cescatti, Alessandro and Chu, Housen and Delwiche, Kyle B and Desai, Ankur R and Euskirchen, Eugenie and Friborg, Thomas and Goeckede, Mathias and Helbig, Manuel and Hemes, Kyle S and Hirano, Takashi and Iwata, Hiroki and Kang, Minseok and Keenan, Trevor and Krauss, Ken W and Lohila, Annalea and Mammarella, Ivan and Mitra, Bhaskar and Miyata, Akira and Nilsson, Mats B and Noormets, Asko and Oechel, Walter C and Papale, Dario and Peichl, Matthias and Reba, Michele L and Rinne, Janne 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 Torn, Margaret S and Trotta, Carlo and Tuittila, Eeva-Stiina and Ueyama, Masahito and Vargas, Rodrigo and Vesala, Timo and Windham-Myers, Lisamarie and Zhang, Zhen and Zona, Donatella},
  title = {Substantial hysteresis in emergent temperature sensitivity of global wetland CH4 emissions},
  journal = {Nature Communications},
  year = {2021},
  volume = {12},
  number = {1},
  pages = {2266},
  url = {http://www.nature.com/articles/s41467-021-22452-1},
  doi = {10.1038/s41467-021-22452-1}
}
Choler P, Bayle A, Carlson BZ, Randin C, Filippa G and Cremonese E (2021), "The tempo of greening in the European Alps: Spatial variations on a common theme", Global Change Biology., nov, 2021. Vol. 27(21), pp. 5614-5628. John Wiley & Sons, Ltd.
Abstract: Abstract The long-term increase in satellite-based proxies of vegetation cover is a well-documented response of seasonally snow-covered ecosystems to climate warming. However, observed greening trends are far from uniform, and substantial uncertainty remains concerning the underlying causes of this spatial variability. Here, we processed surface reflectance of the moderate resolution imaging spectroradiometer (MODIS) to investigate trends and drivers of changes in the annual peak values of the Normalized Difference Vegetation Index (NDVI). Our study focuses on above-treeline ecosystems in the European Alps. NDVI changes in these ecosystems are highly sensitive to land cover and biomass changes and are marginally affected by anthropogenic disturbances. We observed widespread greening for the 2000?2020 period, a pattern that is consistent with the overall increase in summer temperature. At the local scale, the spatial variability of greening was mainly due to the preferential response of north-facing slopes between 1900 and 2400 m. Using high-resolution imagery, we noticed that the presence of screes and outcrops locally magnified this response. At the regional scale, we identified hotspots of greening where vegetation cover is sparser than expected given the elevation and exposure. Most of these hotspots experienced delayed snow melt and green-up dates in recent years. We conclude that the ongoing greening in the Alps primarily reflects the high responsiveness of sparsely vegetated ecosystems that are able to benefit the most from temperature and water-related habitat amelioration above treeline.
BibTeX:
@article{Choler2021,
  author = {Choler, Philippe and Bayle, Arthur and Carlson, Bradley Z and Randin, Christophe and Filippa, Gianluca and Cremonese, Edoardo},
  title = {The tempo of greening in the European Alps: Spatial variations on a common theme},
  journal = {Global Change Biology},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {27},
  number = {21},
  pages = {5614--5628},
  url = {https://doi.org/10.1111/gcb.15820},
  doi = {10.1111/gcb.15820}
}
Christensen TR (2021), "Arctic Permafrost and Ecosystem Functioning". feb, 2021.
Abstract: Summary Permafrost underlies most of the Arctic land mass. The two main climatic parameters that determine the presence or absence of permafrost are air temperature and precipitation (especially in the form of snow). No species is dependent on permafrost, and on a circumarctic scale no ecosystems are restricted by the existence of permafrost because both tundra ecosystems and boreal forest scan occur in the presence or absence of permafrost. One catastrophic impact of changing vegetation on permafrost is likely to be an increased frequency of fires. Wildfire is a major disturbance in the Arctic tundra and boreal forests, which has a significant impact on soil hydrology, carbon cycling, and permafrost dynamics. Thawing permafrost is associated with gradual or episodic disturbance (slumping) of the land surface that can affect large areas. Periglacial processes change land surfaces, which can in turn affect ecosystem function.
BibTeX:
@misc{Christensen2021,
  author = {Christensen, Torben R},
  title = {Arctic Permafrost and Ecosystem Functioning},
  booktitle = {Arctic Ecology},
  year = {2021},
  pages = {81--101},
  url = {https://doi.org/10.1002/9781118846582.ch4},
  doi = {10.1002/9781118846582.ch4}
}
Conte A, Otu-Larbi F, Alivernini A, Hoshika Y, Paoletti E, Ashworth K and Fares S (2021), "Exploring new strategies for ozone-risk assessment: A dynamic-threshold case study", Environmental Pollution. Vol. 287, pp. 117620.
Abstract: Tropospheric ozone is a dangerous atmospheric pollutant for forest ecosystems when it penetrates stomata. Thresholds for ozone-risk assessment are based on accumulated stomatal ozone fluxes such as the Phytotoxic Ozone Dose (POD). In order to identify the effect of ozone on a Holm oak forest in central Italy, four flux-based ozone impact response functions were implemented and tested in a multi-layer canopy model AIRTREE and evaluated against Gross Primary Productivity (GPP) obtained from observations of Eddy Covariance fluxes of CO2. To evaluate if a clear phytotoxic threshold exists and if it changes during the year, six different detoxifying thresholds ranging between 0 and 5 nmol O3 m−2 s−1 were tested. The use of species-specific rather than more general response functions based on plant functional types (PFT) increased model accuracy (RMSE reduced by up to 8.5%). In the case of linear response functions, a threshold of 1 nmol m−2 s−2 produced the best results for simulations of the whole year, although the tolerance to ozone changed seasonally, with higher tolerance (5 nmol m−2 s−1 or no ozone impact) for Winter and Spring and lower thresholds in Summer and Fall (0–1 nmol m−2 s−1). A “dynamic threshold” obtained by extracting the best daily threshold values from a range of different simulations helped reduce model overestimation of GPP by 213 g C m−2 y−1 and reduce RMSE up to 7.7%. Finally, a nonlinear ozone correction based on manipulative experiments produced the best results when no detoxifying threshold was applied (0 nmol O3 m−2 s−1), suggesting that nonlinear functions fully account for ozone detoxification. The evidence of seasonal changes in ozone tolerance points to the need for seasonal thresholds to predict ozone damage and highlights the importance of performing more species-specific manipulative experiments to derive response functions for a broad range of plant species.
BibTeX:
@article{Conte2021,
  author = {Conte, A and Otu-Larbi, F and Alivernini, A and Hoshika, Y and Paoletti, E and Ashworth, K and Fares, S},
  title = {Exploring new strategies for ozone-risk assessment: A dynamic-threshold case study},
  journal = {Environmental Pollution},
  year = {2021},
  volume = {287},
  pages = {117620},
  url = {https://www.sciencedirect.com/science/article/pii/S0269749121012021},
  doi = {10.1016/j.envpol.2021.117620}
}
Crill P, Wik M and Jansen J (2021), "Temperatures in subarctic lakes on the Stordalen Mire, Abisko, Northern Sweden".
BibTeX:
@misc{Crill2021,
  author = {Crill, Patrick and Wik, Martin and Jansen, Joachim},
  title = {Temperatures in subarctic lakes on the Stordalen Mire, Abisko, Northern Sweden},
  publisher = {Bolin Centre Database},
  year = {2021},
  url = {https://bolin.su.se/data/stordalen-lake-temperatures-4},
  doi = {10.17043/STORDALEN-LAKE-TEMPERATURES-4}
}
Cristofanelli P, Arduni J, Serva F, Calzolari F, Bonasoni P, Busetto M, Maione M, Sprenger M, Trisolino P and Putero D (2021), "Negative ozone anomalies at a high mountain site in northern Italy during 2020: a possible role of COVID-19 lockdowns?", Environmental Research Letters. Vol. 16(7), pp. 74029. IOP Publishing.
Abstract: Several studies investigated the possible impacts of the restriction measures related to the containment of the spread of the COrona VIrus Disease (COVID-19) to atmospheric ozone (O3) at global, regional, and local scales during 2020. O3 is a secondary pollutant with adverse effects on population health and ecosystems and with negative impacts on climate, acting as greenhouse gas. Most of these studies focused on spring 2020 (i.e. March–May) and on observations in the planetary boundary layer (PBL), mostly in the vicinity of urban agglomerates. Here, we analyzed the variability of O3 above the PBL of northern Italy in 2020 by using continuous observations carried out at a high mountain WMO/GAW global station in Italy (Mt. Cimone–CMN; 44°12′ N, 10°42′ E, 2165 m a.s.l.). Low O3 monthly anomalies were observed during spring (MAM) and summer (JJA), when periods of low O3 intertwined with periods with higher O3, within climatological ranges. A similar variability was observed for O3 precursors like NO2 and 15 anthropogenic non-methane volatile organic carbons, but the systematic O3 anomalies were not reflected in these variables. The analysis of meteorological variables and diel O3 cycles did not suggest major changes in the vertical transport related to the thermal circulation system in the mountain area. The analysis of five days back-trajectories suggested that the observed O3 anomalies cannot be explained by differences in the synoptic-scale circulation with respect to the previous years alone. On the other hand, the characterization of two transport patterns (i.e. air masses from the regional PBL or from the free troposphere) and the analysis of back-trajectories suggested an important contribution of transport from the continental PBL during the periods with the lowest O3 at CMN. When proxies of air mass transport from the regional PBL are considered, a lower NO x content was pointed out with respect to the previous years, suggesting a lower O3 production in a NO x -limited atmosphere. Our study suggested for the first time that, during MAM and JJA 2020, the reduced anthropogenic emissions related to the COVID-19 restrictions lowered the amount of this short-lived climate forcer/pollutant at remote locations above the PBL over northern Italy. This work suggests the importance of limiting anthropogenic precursor emissions for decreasing the O3 amount at remote locations and in upper atmospheric layers.
BibTeX:
@article{Cristofanelli2021a,
  author = {Cristofanelli, Paolo and Arduni, Jgor and Serva, Federico and Calzolari, Francescopiero and Bonasoni, Paolo and Busetto, Maurizio and Maione, Michela and Sprenger, Michael and Trisolino, Pamela and Putero, Davide},
  title = {Negative ozone anomalies at a high mountain site in northern Italy during 2020: a possible role of COVID-19 lockdowns?},
  journal = {Environmental Research Letters},
  publisher = {IOP Publishing},
  year = {2021},
  volume = {16},
  number = {7},
  pages = {74029},
  url = {http://dx.doi.org/10.1088/1748-9326/ac0b6a},
  doi = {10.1088/1748-9326/ac0b6a}
}
Cristofanelli P, Gutiérrez I, Adame JA, Bonasoni P, Busetto M, Calzolari F, Putero D and Roccato F (2021), "Interannual and seasonal variability of NOx observed at the Mt. Cimone GAW/WMO global station (2165 m a.s.l., Italy)", Atmospheric Environment. Vol. 249, pp. 118245.
Abstract: In this work, we present and analyze a dataset of near-surface NO and NO2 observations carried out at the Mt. Cimone WMO/GAW global station (CMN, Italy, 2165 m a.s.l.) from 2015 to 2019. The purpose of this work is to provide a first characterization of NO and NO2 variability over different time scales, as well as to obtain preliminary information about transport processes able to affect the observed variability. NO was characterized by a peak in February–March (mean value: 0.08 ppb), while in summer the typical levels were near or lower than the detection limit. NO2 values maximized in winter (0.32–0.37 ppb) and minimized in summer (0.21 ppb in June). The evident NO and NO2 diel cycles point towards a joint role of vertical transport of air masses from the regional planetary boundary layer (PBL) and photochemistry. We combined nighttime observations (less affected by direct transport from the regional PBL) and 3D back-trajectories, calculated by the FLEXTRA model (2015 -2018), to analyze how long-range atmospheric circulation could impact NO2 observations. Even if some caveats should be considered when commenting results from back-trajectory analysis (i.e. NOx removal by oxidation processes not represented, possible residual impact of regional PBL air masses, impact of adding/removing a single year from the analysis), some robust outcomes can be considered: the atmospheric transport from northern Africa and the Mediterranean basin was tagged to baseline NO2 values, while the highest values were related to atmospheric circulation overpassing central/western Europe (spring) and North Italy (spring and summer). Less robust relationship were found between high NO2 values and air masses passing over central/western Europe (winter) and eastern Europe (winter and summer). On the other side, mountain thermal wind regime represents an important process for the occurrence of high NO2 events by transporting polluted air masses from the regional PBL to CMN. Our analysis suggested that it is not possible to define a unique set of O3/NOx threshold values able to discriminate the photochemical ages of air masses as done in previous studies; these values must be tuned as a function of the season and, possibly, of the measurement site. Finally, we segregated CMN observations as a function of conditions representative for the presence of free tropospheric- or PBL-affected air masses: higher NOx were observed under conditions representative for the transport of air masses from the regional PBL; the differences between the two regimes are maximized in winter for NO and in summer-autumn for NO2.
BibTeX:
@article{Cristofanelli2021,
  author = {Cristofanelli, P and Gutiérrez, I and Adame, J A and Bonasoni, P and Busetto, M and Calzolari, F and Putero, D and Roccato, F},
  title = {Interannual and seasonal variability of NOx observed at the Mt. Cimone GAW/WMO global station (2165 m a.s.l., Italy)},
  journal = {Atmospheric Environment},
  year = {2021},
  volume = {249},
  pages = {118245},
  url = {https://www.sciencedirect.com/science/article/pii/S1352231021000637},
  doi = {10.1016/j.atmosenv.2021.118245}
}
Curbelo-Hernández D, González-Dávila M, González AG, González-Santana D and Santana-Casiano JM (2021), "CO2 fluxes in the Northeast Atlantic Ocean based on measurements from a surface ocean observation platform", Science of The Total Environment. Vol. 775, pp. 145804.
Abstract: The seasonal and spatial variability of the CO2 system parameters and CO2 air-sea exchange were studied in the Northeast Atlantic Ocean between the northwest African coastal upwelling and the oligotrophic open-ocean waters of the North Atlantic subtropical gyre. Data was collected aboard a volunteer observing ship from February 2019 to February 2020. The seasonal and spatial variability of CO2 fugacity in seawater (fCO2,sw) was strongly driven by the seasonal temperature variation, which increased with latitude and was lower throughout the year in coastal regions where the upwelling and offshore transport was more intense. The thermal to biological effect ratio (T/B) was approximately 2, with minimum values along the African coastline related to higher biological activity in the upwelled waters. The fCO2,sw increased from winter to summer by 11.84 ± 0.28 μatm°C−1 on the inter-island routes and by 11.71 ± 0.25 μatm°C−1 along the northwest African continental shelf. The seasonality of total inorganic carbon normalized to constant salinity of 36.7 (NCT) was studied throughout the region. The effect of biological processes and calcification/dissolution on NCT between February and October represented >90% of the reduction of inorganic carbon while air-sea exchange described <6%. The seasonality of air-sea CO2 exchange was controlled by temperature. The surface waters of the entire region acted as a CO2 sink during the cold months and as a CO2 source during the warm months. The Canary basin acted as a net sink of −0.26 ± 0.04 molC m−2 yr−1. The northwest African continental shelf behaved as a stronger sink at −0.48 ± 0.09 molC m−2 yr−1. The calculated average CO2 flux for the entire area was −2.65 ± 0.44 TgCO2 yr−1 (−0.72 ± 0.12 TgC yr−1).
BibTeX:
@article{CurbeloHernandez2021,
  author = {Curbelo-Hernández, D and González-Dávila, M and González, A G and González-Santana, D and Santana-Casiano, J M},
  title = {CO2 fluxes in the Northeast Atlantic Ocean based on measurements from a surface ocean observation platform},
  journal = {Science of The Total Environment},
  year = {2021},
  volume = {775},
  pages = {145804},
  url = {https://www.sciencedirect.com/science/article/pii/S0048969721008718},
  doi = {10.1016/j.scitotenv.2021.145804}
}
Curbelo-Hernández D, Santana-Casiano JM, González AG and González-Dávila M (2021), "Air-Sea CO2 Exchange in the Strait of Gibraltar", Frontiers in Marine Science. Vol. 8
Abstract: The seasonal and spatial variability of the CO2 system and air-sea fluxes were studied in surface waters of the Strait of Gibraltar between February 2019 and March 2021. High-resolution data was collected by a surface ocean observation platform aboard a volunteer observing ship. The CO2 system was strongly influenced by temperature and salinity fluctuations forced by the seasonal and spatial variability in the depth of the Atlantic–Mediterranean Interface layer and by the tidal and wind-induced upwelling. The changes in seawater CO2 fugacity (fCO2,sw) and fluxes were mainly driven by temperature despite the significant influence of non-thermal processes in the southernmost part. The thermal to non-thermal effect ratio (T/B) reached maximum values in the northern section (>1.8) and minimum values in the southern section (<1.30). The fCO2,sw increased with temperature by 9.02 ± 1.99 μatm °C–1 (r2 = 0.86 and ρ = 0.93) and 4.51 ± 1.66 μatm °C–1 (r2 = 0.48 and ρ = 0.69) in the northern and southern sections, respectively. The annual cycle of total inorganic carbon normalized to a constant salinity of 36.7 (NCT) was assessed. Net community production processes described 93.5–95.6% of the total NCT change, while air-sea exchange and horizontal and vertical advection accounted for <4.6%. The fCO2,sw in the Strait of Gibraltar since 1999 has been fitted to an equation with an interannual trend of 2.35 ± 0.06 μatm year–1 and a standard error of estimate of ±12.8 μatm. The seasonality of the air-sea CO2 fluxes reported the behavior as a strong CO2 sink during the cold months and as a weak CO2 source during the warm months. Both the northern and the southern sections acted as a net CO2 sink of −0.82 and −1.01 mol C m–2 year–1, respectively. The calculated average CO2 flux for the entire area was −7.12 Gg CO2 year–1 (−1.94 Gg C year–1).
BibTeX:
@article{CurbeloHernandez2021a,
  author = {Curbelo-Hernández, David and Santana-Casiano, J Magdalena and González, Aridane González and González-Dávila, Melchor},
  title = {Air-Sea CO2 Exchange in the Strait of Gibraltar},
  journal = {Frontiers in Marine Science},
  year = {2021},
  volume = {8},
  url = {https://www.frontiersin.org/article/10.3389/fmars.2021.745304},
  doi = {10.3389/fmars.2021.745304}
}
Dare-Idowu O, Jarlan L, Le-Dantec V, Rivalland V, Ceschia E, Boone A and Brut A (2021), "Hydrological Functioning of Maize Crops in Southwest France Using Eddy Covariance Measurements and a Land Surface Model".
Abstract: The primary objective of this study is to evaluate the representation of the energy budget for irrigated maize crops in soil–vegetation–atmosphere transfer (SVAT) models. To this end, a comparison between the original version of the interactions between the soil–biosphere–atmosphere (ISBA) model based on a single-surface energy balance and the new ISBA-multi-energy balance (ISBA-MEB) option was carried out. The second objective is to analyze the intra- and inter-seasonal variability of the crop water budget by implementing ISBA and ISBA-MEB over six irrigated maize seasons between 2008 and 2019 in Lamasquère, southwest France. Seasonal dynamics of the convective fluxes were properly reproduced by both models with R2 ranging between 0.66 and 0.80 (RMSE less than 59 W m−2) for the sensible heat flux and between 0.77 and 0.88 (RMSE less than 59 W m−2) for the latent heat flux. Statistical metrics also showed that over the six crop seasons, for the turbulent fluxes, ISBA-MEB was consistently in better agreement with the in situ measurements with RMSE 8–30% lower than ISBA, particularly when the canopy was heterogeneous. The ability of both models to partition the evapotranspiration (ET) term between soil evaporation and plant transpiration was also acceptable as transpiration predictions compared very well with the available sap flow measurements during the summer of 2015; (ISBA-MEB had slightly better statistics than ISBA with R2 of 0.91 and a RMSE value of 0.07 mm h−1). Finally, the results from the analysis of the inter-annual variability of the crop water budget can be summarized as follows: (1) The partitioning of the ET revealed a strong year-to-year variability with transpiration ranging between 40% and 67% of total ET, while soil evaporation was dominant in 2008 and 2010 due to the late and poor canopy development; (2) drainage losses are close to null because of an impervious layer at 60 cm depth; and (3) this very specific condition limited the inter-annual variability of irrigation scheduling as crops can always extract water that is stored in the root zone.
BibTeX:
@misc{DareIdowu2021,
  author = {Dare-Idowu, Oluwakemi and Jarlan, Lionel and Le-Dantec, Valerie and Rivalland, Vincent and Ceschia, Eric and Boone, Aaron and Brut, Aurore},
  title = {Hydrological Functioning of Maize Crops in Southwest France Using Eddy Covariance Measurements and a Land Surface Model},
  booktitle = {Water},
  year = {2021},
  volume = {13},
  number = {11},
  doi = {10.3390/w13111481}
}
Darenova E, Kadavý J, Knott R, Kokrda L and Novotný J (2021), "Effect of tree harvest, silvopastoral practices, and microclimate conditions on forest floor CO2 efflux in a sessile oak (Quercus petraea agg. [Matt.] Liebl.) forest", Annals of Forest Science. Vol. 78(3), pp. 80.
Abstract: Forest floor CO2efflux (Rf; consisted of soil and potential vegetation) increased after forest harvest, but this response was changed by actual weather (especially drought and rains).
BibTeX:
@article{Darenova2021,
  author = {Darenova, Eva and Kadavý, Jan and Knott, Robert and Kokrda, Lukáš and Novotný, Jan},
  title = {Effect of tree harvest, silvopastoral practices, and microclimate conditions on forest floor CO2 efflux in a sessile oak (Quercus petraea agg. [Matt.] Liebl.) forest},
  journal = {Annals of Forest Science},
  year = {2021},
  volume = {78},
  number = {3},
  pages = {80},
  url = {https://doi.org/10.1007/s13595-021-01101-z},
  doi = {10.1007/s13595-021-01101-z}
}
Delwiche KB, Knox SH, Malhotra A, Fluet-Chouinard E, McNicol G, Feron S, Ouyang Z, Papale D, Trotta C, Canfora E, Cheah Y-W, Christianson D, Alberto MCR, Alekseychik P, Aurela M, Baldocchi D, Bansal S, Billesbach DP, Bohrer G, Bracho R, Buchmann N, Campbell DI, Celis G, Chen J, Chen W, Chu H, Dalmagro HJ, Dengel S, Desai AR, Detto M, Dolman H, Eichelmann E, Euskirchen E, Famulari D, Fuchs K, Goeckede M, Gogo S, Gondwe MJ, Goodrich JP, Gottschalk P, Graham SL, Heimann M, Helbig M, Helfter C, Hemes KS, Hirano T, Hollinger D, Hörtnagl L, Iwata H, Jacotot A, Jurasinski G, Kang M, Kasak K, King J, Klatt J, Koebsch F, Krauss KW, Lai DYF, Lohila A, Mammarella I, Belelli Marchesini L, Manca G, Matthes JH, Maximov T, Merbold L, Mitra B, Morin TH, Nemitz E, Nilsson MB, Niu S, Oechel WC, Oikawa PY, Ono K, Peichl M, Peltola O, Reba ML, Richardson AD, Riley W, Runkle BRK, Ryu Y, Sachs T, Sakabe A, Sanchez CR, Schuur EA, Schäfer KVR, Sonnentag O, Sparks JP, Stuart-Haëntjens E, Sturtevant C, Sullivan RC, Szutu DJ, Thom JE, Torn MS, Tuittila E-S, Turner J, Ueyama M, Valach AC, Vargas R, Varlagin A, Vazquez-Lule A, Verfaillie JG, Vesala T, Vourlitis GL, Ward EJ, Wille C, Wohlfahrt G, Wong GX, Zhang Z, Zona D, Windham-Myers L, Poulter B and Jackson RB (2021), "FLUXNET-CH_4: a global, multi-ecosystem dataset and analysis of methane seasonality from freshwater wetlands", Earth System Science Data. Vol. 13(7), pp. 3607-3689.
BibTeX:
@article{Delwiche2021,
  author = {Delwiche, K B and Knox, S H and Malhotra, A and Fluet-Chouinard, E and McNicol, G and Feron, S and Ouyang, Z and Papale, D and Trotta, C and Canfora, E and Cheah, Y.-W. and Christianson, D and Alberto, Ma. C R and Alekseychik, P and Aurela, M and Baldocchi, D and Bansal, S and Billesbach, D P and Bohrer, G and Bracho, R and Buchmann, N and Campbell, D I and Celis, G and Chen, J and Chen, W and Chu, H and Dalmagro, H J and Dengel, S and Desai, A R and Detto, M and Dolman, H and Eichelmann, E and Euskirchen, E and Famulari, D and Fuchs, K and Goeckede, M and Gogo, S and Gondwe, M J and Goodrich, J P and Gottschalk, P and Graham, S L and Heimann, M and Helbig, M and Helfter, C and Hemes, K S and Hirano, T and Hollinger, D and Hörtnagl, L and Iwata, H and Jacotot, A and Jurasinski, G and Kang, M and Kasak, K and King, J and Klatt, J and Koebsch, F and Krauss, K W and Lai, D Y F and Lohila, A and Mammarella, I and Belelli Marchesini, L and Manca, G and Matthes, J H and Maximov, T and Merbold, L and Mitra, B and Morin, T H and Nemitz, E and Nilsson, M B and Niu, S and Oechel, W C and Oikawa, P Y and Ono, K and Peichl, M and Peltola, O and Reba, M L and Richardson, A D and Riley, W and Runkle, B R K and Ryu, Y and Sachs, T and Sakabe, A and Sanchez, C R and Schuur, E A and Schäfer, K V R and Sonnentag, O and Sparks, J P and Stuart-Haëntjens, E and Sturtevant, C and Sullivan, R C and Szutu, D J and Thom, J E and Torn, M S and Tuittila, E.-S. and Turner, J and Ueyama, M and Valach, A C and Vargas, R and Varlagin, A and Vazquez-Lule, A and Verfaillie, J G and Vesala, T and Vourlitis, G L and Ward, E J and Wille, C and Wohlfahrt, G and Wong, G X and Zhang, Z and Zona, D and Windham-Myers, L and Poulter, B and Jackson, R B},
  title = {FLUXNET-CH_4: a global, multi-ecosystem dataset and analysis of methane seasonality from freshwater wetlands},
  journal = {Earth System Science Data},
  year = {2021},
  volume = {13},
  number = {7},
  pages = {3607--3689},
  url = {https://essd.copernicus.org/articles/13/3607/2021/},
  doi = {10.5194/essd-13-3607-2021}
}
Demol M, Calders K, Krishna Moorthy SM, Van den Bulcke J, Verbeeck H and Gielen B (2021), "Consequences of vertical basic wood density variation on the estimation of aboveground biomass with terrestrial laser scanning", Trees. Vol. 35(2), pp. 671-684.
Abstract: Stump-to-tip trends in basic wood density complicate the conversion of tree volume into aboveground biomass. We use 3D tree models from terrestrial laser scanning to obtain tree-level volume-weighted wood density.
BibTeX:
@article{Demol2021,
  author = {Demol, Miro and Calders, Kim and Krishna Moorthy, Sruthi M and Van den Bulcke, Jan and Verbeeck, Hans and Gielen, Bert},
  title = {Consequences of vertical basic wood density variation on the estimation of aboveground biomass with terrestrial laser scanning},
  journal = {Trees},
  year = {2021},
  volume = {35},
  number = {2},
  pages = {671--684},
  url = {https://doi.org/10.1007/s00468-020-02067-7},
  doi = {10.1007/s00468-020-02067-7}
}
Dimitriou K, Bougiatioti A, Ramonet M, Pierros F, Michalopoulos P, Liakakou E, Solomos S, Quehe P-Y, Delmotte M, Gerasopoulos E, Kanakidou M and Mihalopoulos N (2021), "Greenhouse gases (CO2 and CH4) at an urban background site in Athens, Greece: Levels, sources and impact of atmospheric circulation", Atmospheric Environment. Vol. 253, pp. 118372.
Abstract: Year-round carbon dioxide (CO2) and methane (CH4) concentration measurements, performed for the first time in the city of Athens, Greece from December 21, 2018 to December 31, 2019, are presented in this study and analyzed in relation to atmospheric circulation patterns at a local, regional and long-range transport scale. Clear diurnal and seasonal variations of both greenhouse gases were detected. The observed increased levels during night and early morning hours are attributed to traffic/heating emissions and leakages of residential natural gas for CO2 and CH4, respectively. Using CO2 and CH4 levels simultaneously measured at the regional background site at Finokalia (Greece), increments in their levels due to local and regional anthropogenic sources within the city were assessed. For CO2, maximum and minimum increments were clearly observed during winter and summer respectively, suggesting a greater impact of combustion of fossil fuel and especially of biomass on CO2 levels during winter. On the other hand, CH4 increments were similar in all seasons, suggesting that local sources of CH4 remain quite constant year-round. Through the implementation of the Conditional Probability Function (CPF), the emission sources of theses greenhouse gases have been localized to the northern and the eastern domains of the Athens basin. Stagnant atmospheric conditions were also associated with an increased likelihood of CO2 and CH4 episodes. Backward modeling simulations with FLEXPART and HYSPLIT models indicate an industrial zone and a petrochemical zone, situated to the north and to the west of Athens respectively, as possible CH4 regional sources as well as possible CO2 contributions from southern directions attributed to shipping emissions from the port of Piraeus. The present study provides knowledge needed for the determination of greenhouse gas emission mitigation strategies in Athens.
BibTeX:
@article{Dimitriou2021,
  author = {Dimitriou, K and Bougiatioti, A and Ramonet, M and Pierros, F and Michalopoulos, P and Liakakou, E and Solomos, S and Quehe, P.-Y. and Delmotte, M and Gerasopoulos, E and Kanakidou, M and Mihalopoulos, N},
  title = {Greenhouse gases (CO2 and CH4) at an urban background site in Athens, Greece: Levels, sources and impact of atmospheric circulation},
  journal = {Atmospheric Environment},
  year = {2021},
  volume = {253},
  pages = {118372},
  url = {https://www.sciencedirect.com/science/article/pii/S1352231021001916},
  doi = {10.1016/j.atmosenv.2021.118372}
}
Dogniaux M, Crevoisier C, Armante R, Capelle V, Delahaye T, Cassé V, De Mazière M, Deutscher NM, Feist DG, Garcia OE, Griffith DWT, Hase F, Iraci LT, Kivi R, Morino I, Notholt J, Pollard DF, Roehl CM, Shiomi K, Strong K, Té Y, Velazco VA and Warneke T (2021), "The Adaptable 4A Inversion (5AI): description and first X_CO_2 retrievals from Orbiting Carbon Observatory-2 (OCO-2) observations", Atmospheric Measurement Techniques. Vol. 14(6), pp. 4689-4706.
BibTeX:
@article{Dogniaux2021,
  author = {Dogniaux, M and Crevoisier, C and Armante, R and Capelle, V and Delahaye, T and Cassé, V and De Mazière, M and Deutscher, N M and Feist, D G and Garcia, O E and Griffith, D W T and Hase, F and Iraci, L T and Kivi, R and Morino, I and Notholt, J and Pollard, D F and Roehl, C M and Shiomi, K and Strong, K and Té, Y and Velazco, V A and Warneke, T},
  title = {The Adaptable 4A Inversion (5AI): description and first X_CO_2 retrievals from Orbiting Carbon Observatory-2 (OCO-2) observations},
  journal = {Atmospheric Measurement Techniques},
  year = {2021},
  volume = {14},
  number = {6},
  pages = {4689--4706},
  url = {https://amt.copernicus.org/articles/14/4689/2021/},
  doi = {10.5194/amt-14-4689-2021}
}
Dombrowski O, Hendricks Franssen H-J, Brogi C and Bogena HR (2021), "Performance of the ATMOS41 All-in-One Weather Station for Weather Monitoring", Sensors. Vol. 21(3)
Abstract: Affordable and accurate weather monitoring systems are essential in low-income and developing countries and, more recently, are needed in small-scale research such as precision agriculture and urban climate studies. A variety of low-cost solutions are available on the market, but the use of non-standard technologies raises concerns for data quality. Research-grade all-in-one weather stations could present a reliable, cost effective solution while being robust and easy to use. This study evaluates the performance of the commercially available ATMOS41 all-in-one weather station. Three stations were deployed next to a high-performance reference station over a three-month period. The ATMOS41 stations showed good performance compared to the reference, and close agreement among the three stations for most standard weather variables. However, measured atmospheric pressure showed uncertainties >0.6 hPa and solar radiation was underestimated by 3%, which could be corrected with a locally obtained linear regression function. Furthermore, precipitation measurements showed considerable variability, with observed differences of &plusmn;7.5% compared to the reference gauge, which suggests relatively high susceptibility to wind-induced errors. Overall, the station is well suited for private user applications such as farming, while the use in research should consider the limitations of the station, especially regarding precise precipitation measurements.
BibTeX:
@article{Dombrowski2021,
  author = {Dombrowski, Olga and Hendricks Franssen, Harrie-Jan and Brogi, Cosimo and Bogena, Heye Reemt},
  title = {Performance of the ATMOS41 All-in-One Weather Station for Weather Monitoring},
  journal = {Sensors},
  year = {2021},
  volume = {21},
  number = {3},
  url = {https://www.mdpi.com/1424-8220/21/3/741},
  doi = {10.3390/s21030741}
}
Dorigo W, Himmelbauer I, Aberer D, Schremmer L, Petrakovic I, Zappa L, Preimesberger W, Xaver A, Annor F, Ardö J, Baldocchi D, Bitelli M, Blöschl G, Bogena H, Brocca L, Calvet J-C, Camarero JJ, Capello G, Choi M, Cosh MC, van de Giesen N, Hajdu I, Ikonen J, Jensen KH, Kanniah KD, de Kat I, Kirchengast G, Kumar Rai P, Kyrouac J, Larson K, Liu S, Loew A, Moghaddam M, Mart\inez Fernández J, Mattar Bader C, Morbidelli R, Musial JP, Osenga E, Palecki MA, Pellarin T, Petropoulos GP, Pfeil I, Powers J, Robock A, Rüdiger C, Rummel U, Strobel M, Su Z, Sullivan R, Tagesson T, Varlagin A, Vreugdenhil M, Walker J, Wen J, Wenger F, Wigneron JP, Woods M, Yang K, Zeng Y, Zhang X, Zreda M, Dietrich S, Gruber A, van Oevelen P, Wagner W, Scipal K, Drusch M and Sabia R (2021), "The International Soil Moisture Network: serving Earth system science for over a decade", Hydrology and Earth System Sciences. Vol. 25(11), pp. 5749-5804.
BibTeX:
@article{Dorigo2021,
  author = {Dorigo, W and Himmelbauer, I and Aberer, D and Schremmer, L and Petrakovic, I and Zappa, L and Preimesberger, W and Xaver, A and Annor, F and Ardö, J and Baldocchi, D and Bitelli, M and Blöschl, G and Bogena, H and Brocca, L and Calvet, J.-C. and Camarero, J J and Capello, G and Choi, M and Cosh, M C and van de Giesen, N and Hajdu, I and Ikonen, J and Jensen, K H and Kanniah, K D and de Kat, I and Kirchengast, G and Kumar Rai, P and Kyrouac, J and Larson, K and Liu, S and Loew, A and Moghaddam, M and Mart\inez Fernández, J and Mattar Bader, C and Morbidelli, R and Musial, J P and Osenga, E and Palecki, M A and Pellarin, T and Petropoulos, G P and Pfeil, I and Powers, J and Robock, A and Rüdiger, C and Rummel, U and Strobel, M and Su, Z and Sullivan, R and Tagesson, T and Varlagin, A and Vreugdenhil, M and Walker, J and Wen, J and Wenger, F and Wigneron, J P and Woods, M and Yang, K and Zeng, Y and Zhang, X and Zreda, M and Dietrich, S and Gruber, A and van Oevelen, P and Wagner, W and Scipal, K and Drusch, M and Sabia, R},
  title = {The International Soil Moisture Network: serving Earth system science for over a decade},
  journal = {Hydrology and Earth System Sciences},
  year = {2021},
  volume = {25},
  number = {11},
  pages = {5749--5804},
  url = {https://hess.copernicus.org/articles/25/5749/2021/},
  doi = {10.5194/hess-25-5749-2021}
}
Doro L, Wang X, Ammann C, De Antoni Migliorati M, Grünwald T, Klumpp K, Loubet B, Pattey E, Wohlfahrt G, Williams JR and Norfleet ML (2021), "Improving the simulation of soil temperature within the EPIC model", Environmental Modelling & Software. Vol. 144, pp. 105140.
Abstract: Soil temperature is a key driver of several physical, chemical, and biological processes. The Environmental Policy Integrated Climate (EPIC) is a comprehensive ecosystem model that simulates soil temperature dynamics using a cosine function approach driven by daily air temperature and average annual soil temperature at damping depth, which may erroneously predict lower soil temperatures in winter. A new cosine model and a pseudo-heat-transfer model were therefore developed and implemented for simulating soil temperature. The two methods were evaluated by comparing simulated daily soil temperatures with observed data at 24 study sites. Results showed that the two new methods had similar performance and the better statistical results obtained with these new methods demonstrated the ability to better predict the soil temperature for a wide range of pedoclimatic conditions, land management, and land uses. The main reason for the improved performance was due to a better prediction of soil temperature during the winter period.
BibTeX:
@article{Doro2021,
  author = {Doro, Luca and Wang, Xiuying and Ammann, Christof and De Antoni Migliorati, Massimiliano and Grünwald, Thomas and Klumpp, Katja and Loubet, Benjamin and Pattey, Elizabeth and Wohlfahrt, Georg and Williams, Jimmy R and Norfleet, M Lee},
  title = {Improving the simulation of soil temperature within the EPIC model},
  journal = {Environmental Modelling & Software},
  year = {2021},
  volume = {144},
  pages = {105140},
  url = {https://www.sciencedirect.com/science/article/pii/S1364815221001833},
  doi = {10.1016/j.envsoft.2021.105140}
}
Dumortier P, Gourlez de la Motte L, Andriamandroso ALH, Aubinet M, Beckers Y, Bindelle J, De Cock N, Lebeau F and Heinesch B (2021), "Beef cattle methane emission estimation using the eddy covariance technique in combination with geolocation", Agricultural and Forest Meteorology. Vol. 297, pp. 108249.
Abstract: Methane emissions of a grazing herd of Belgian Blue cattle were estimated per individual on the field by combining eddy covariance measurements with geolocation of the cattle and a footprint model. This method allows the measurement of outdoor non-invasive methane emissions but is complex and subject to methodological issues. Estimated emissions were 220 ±35 g CH4 LU−1 day−1 (grams of methane per livestock unit per day), where the uncertainty corresponds to the random error and does not include any possible systematic error. Cattle behavior was also monitored and presented a clear daily pattern of activity with more intense grazing after sunrise and before sunset. However, no significant methane emission pattern could be associated with it, the diurnal emission variation being lower than the measurement precision.
BibTeX:
@article{Dumortier2021,
  author = {Dumortier, P and Gourlez de la Motte, L and Andriamandroso, A L H and Aubinet, M and Beckers, Y and Bindelle, J and De Cock, N and Lebeau, F and Heinesch, B},
  title = {Beef cattle methane emission estimation using the eddy covariance technique in combination with geolocation},
  journal = {Agricultural and Forest Meteorology},
  year = {2021},
  volume = {297},
  pages = {108249},
  url = {https://www.sciencedirect.com/science/article/pii/S0168192320303518},
  doi = {10.1016/j.agrformet.2020.108249}
}
Dušek J, Nguyen VX, Le TX and Pavelka M (2021), "Methane and carbon dioxide emissions from different ecosystems at the end of dry period in South Vietnam", Tropical Ecology. Vol. 62(1), pp. 1-16. Springer India.
Abstract: The carbon cycle includes important fluxes of methane (CH4) and carbon dioxide (CO2) between the ecosystem and the atmosphere. The fluxes may acquire either positive (release) or negative values (consumption). We calculated these fluxes based on short-campaign in situ chamber measurements from four ecosystems of South Vietnam: intact mountain rain forest, rice field, Melaleuca forest and mangroves (different sites with Avicennia or Rhizophora and a typhoon-disturbed gap). Soil measurements were supplemented by chamber measurements of gas fluxes from the tree stems. Measuring CH4 and CO2 together facilitates the assessment of the ratio between these two gases in connection with current conditions and specificity of individual ecosystems. The highest fluxes of CH4 were recorded in the Melaleuca forest, being within the range from 356.7 to 784.2 mg CH4–C m−2 day−1 accompanied by higher fluxes of CH4 release from Melaleuca tree stems (8.0–262.1 mg CH4–C m−2 day−1). Significant negative soil fluxes of CH4 were recorded in the mountain rain forest, within the range from − 0.3 to − 0.8 mg CH4–C m−2 day−1. Fluxes of CO2 indicate prevailing aerobic activity in the soils of the ecosystems investigated. Quite a large variability of CO2 fluxes was recorded in the soil of the Avicennia mangroves. The in situ measurements of different ecosystems are fundamental for follow-up measurements at different levels such as aerial and satellite gas fluxes observations.
BibTeX:
@article{Dusek2021,
  author = {Dušek, Jiří and Nguyen, Vinh Xuan and Le, Thuyen Xuan and Pavelka, Marian},
  title = {Methane and carbon dioxide emissions from different ecosystems at the end of dry period in South Vietnam},
  journal = {Tropical Ecology},
  publisher = {Springer India},
  year = {2021},
  volume = {62},
  number = {1},
  pages = {1--16},
  url = {https://doi.org/10.1007/s42965-020-00118-1},
  doi = {10.1007/s42965-020-00118-1}
}
Dyukarev E, Zarov E, Alekseychik P, Nijp J, Filippova N, Mammarella I, Filippov I, Bleuten W, Khoroshavin V, Ganasevich G, Meshcheryakova A, Vesala T and Lapshina E (2021), "The Multiscale Monitoring of Peatland Ecosystem Carbon Cycling in the Middle Taiga Zone of Western Siberia: The Mukhrino Bog Case Study", Land. Vol. 10(8)
Abstract: The peatlands of the West Siberian Lowlands, comprising the largest pristine peatland area of the world, have not previously been covered by continuous measurement and monitoring programs. The response of peatlands to climate change occurs over several decades. This paper summarizes the results of peatland carbon balance studies collected over ten years at the Mukhrino field station (Mukhrino FS, MFS) operating in the Middle Taiga Zone of Western Siberia. A multiscale approach was applied for the investigations of peatland carbon cycling. Carbon dioxide fluxes at the local scale studied using the chamber method showed net accumulation with rates from 110, to 57.8 gC m−2 at the Sphagnum hollow site. Net CO2 fluxes at the pine-dwarf shrubs-Sphagnum ridge varied from negative (−32.1 gC m−2 in 2019) to positive (13.4 gC m−2 in 2017). The cumulative May-August net ecosystem exchange (NEE) from eddy-covariance (EC) measurements at the ecosystem scale was −202 gC m−2 in 2015, due to the impact of photosynthesis of pine trees which was not registered by the chamber method. The net annual accumulation of carbon in the live part of mosses was estimated at 24–190 gC m−2 depending on the Sphagnum moss species. Long-term carbon accumulation rates obtained by radiocarbon analysis ranged from 28.5 to 57.2 gC m−2 yr−1, with local extremes of up to 176.2 gC m−2 yr−1. The obtained estimates of various carbon fluxes using EC and chamber methods, the accounting for Sphagnum growth and decomposition, and long-term peat accumulation provided information about the functioning of the peatland ecosystems at different spatial and temporal scales. Multiscale carbon flux monitoring reveals useful new information for forecasting the response of northern peatland carbon cycles to climatic changes.
BibTeX:
@article{Dyukarev2021,
  author = {Dyukarev, Egor and Zarov, Evgeny and Alekseychik, Pavel and Nijp, Jelmer and Filippova, Nina and Mammarella, Ivan and Filippov, Ilya and Bleuten, Wladimir and Khoroshavin, Vitaly and Ganasevich, Galina and Meshcheryakova, Anastasiya and Vesala, Timo and Lapshina, Elena},
  title = {The Multiscale Monitoring of Peatland Ecosystem Carbon Cycling in the Middle Taiga Zone of Western Siberia: The Mukhrino Bog Case Study},
  journal = {Land},
  year = {2021},
  volume = {10},
  number = {8},
  url = {https://www.mdpi.com/2073-445X/10/8/824},
  doi = {10.3390/land10080824}
}
Emerson JB, Varner RK, Wik M, Parks DH, Neumann RB, Johnson JE, Singleton CM, Woodcroft BJ, Tollerson R, Owusu-Dommey A, Binder M, Freitas NL, Crill PM, Saleska SR, Tyson GW and Rich VI (2021), "Diverse sediment microbiota shape methane emission temperature sensitivity in Arctic lakes", Nature Communications. Vol. 12(1), pp. 5815.
Abstract: Northern post-glacial lakes are significant, increasing sources of atmospheric carbon through ebullition (bubbling) of microbially-produced methane (CH4) from sediments. Ebullitive CH4 flux correlates strongly with temperature, reflecting that solar radiation drives emissions. However, here we show that the slope of the temperature-CH4 flux relationship differs spatially across two post-glacial lakes in Sweden. We compared these CH4 emission patterns with sediment microbial (metagenomic and amplicon), isotopic, and geochemical data. The temperature-associated increase in CH4 emissions was greater in lake middles—where methanogens were more abundant—than edges, and sediment communities were distinct between edges and middles. Microbial abundances, including those of CH4-cycling microorganisms and syntrophs, were predictive of porewater CH4 concentrations. Results suggest that deeper lake regions, which currently emit less CH4 than shallower edges, could add substantially to CH4 emissions in a warmer Arctic and that CH4 emission predictions may be improved by accounting for spatial variations in sediment microbiota.
BibTeX:
@article{Emerson2021,
  author = {Emerson, Joanne B and Varner, Ruth K and Wik, Martin and Parks, Donovan H and Neumann, Rebecca B and Johnson, Joel E and Singleton, Caitlin M and Woodcroft, Ben J and Tollerson, Rodney and Owusu-Dommey, Akosua and Binder, Morgan and Freitas, Nancy L and Crill, Patrick M and Saleska, Scott R and Tyson, Gene W and Rich, Virginia I},
  title = {Diverse sediment microbiota shape methane emission temperature sensitivity in Arctic lakes},
  journal = {Nature Communications},
  year = {2021},
  volume = {12},
  number = {1},
  pages = {5815},
  url = {https://doi.org/10.1038/s41467-021-25983-9},
  doi = {10.1038/s41467-021-25983-9}
}
Emmerichs T, Kerkweg A, Ouwersloot H, Fares S, Mammarella I and Taraborrelli D (2021), "A revised dry deposition scheme for land--atmosphere exchange of trace gases in ECHAM/MESSy v2.54", Geoscientific Model Development. Vol. 14(1), pp. 495-519.
BibTeX:
@article{Emmerichs2021,
  author = {Emmerichs, T and Kerkweg, A and Ouwersloot, H and Fares, S and Mammarella, I and Taraborrelli, D},
  title = {A revised dry deposition scheme for land--atmosphere exchange of trace gases in ECHAM/MESSy v2.54},
  journal = {Geoscientific Model Development},
  year = {2021},
  volume = {14},
  number = {1},
  pages = {495--519},
  url = {https://gmd.copernicus.org/articles/14/495/2021/},
  doi = {10.5194/gmd-14-495-2021}
}
Ferrara RM, Carozzi M, Decuq C, Loubet B, Finco A, Marzuoli R, Gerosa G, Di Tommasi P, Magliulo V and Rana G (2021), "Ammonia, nitrous oxide, carbon dioxide, and water vapor fluxes after green manuring of faba bean under Mediterranean climate", Agriculture, Ecosystems & Environment. Vol. 315, pp. 107439.
Abstract: Green manuring of legume crops has increased in interest in recent years because of environmental and economic costs of synthetic fertilizers and need of sustainable cropping systems. Climatic conditions can reduce the agronomic and environmental effectiveness of green manuring promoting reactive nitrogen losses, or fostering soil heterotrophic respiration. This study aims to quantify ammonia and nitrous oxide losses, as well as carbon dioxide exchanges following green manuring of faba bean (Vicia faba spp. minor L.) under semi-arid climate conditions, typical of the Mediterranean basin. Ammonia emissions were measured by means of an aerodynamic gradient approach equipped with a multi-channel wet-denuder system (ROSAA), alongside with a concentration-based inverse dispersion modelling assessment. Nitrous oxide losses were measured with an automated chamber system, whereas carbon dioxide and water vapor exchanges were monitored jointly by means of eddy covariance technique. Ammonia volatilization lasted for three weeks and was triggered by the increase of soil water content due to rainfall, occurring 5 days after green manuring. Total emissions were 0.31% of the nitrogen supplied by green manuring (230 kg N ha−1). Nitrous oxide emissions from soil were of low intensity during the measurement period and were directly corelated to the water filled pore space. The biogeochemical model CERES-EGC was validated with the measurements of nitrous oxide, then used to reproduce the dynamic until the sowing of the succeeding crop. Cumulated emissions of nitrous oxide were 1% of the total nitrogen supplied. Soil became a net source both of carbon dioxide and water vapor soon after green manuring, with an emission of 900 kg C-CO2 ha−1 by heterotrophic respiration (23% of added carbon). In terms of water balance, 19 mm of water evaporated from soil surface, originated from the addition of fresh biomass. Green manuring proved to be a significant agronomic strategy to improve soil fertility, limiting reactive nitrogen and carbon losses to the atmosphere.
BibTeX:
@article{Ferrara2021,
  author = {Ferrara, Rossana Monica and Carozzi, Marco and Decuq, Céline and Loubet, Benjamin and Finco, Angelo and Marzuoli, Riccardo and Gerosa, Giacomo and Di Tommasi, Paul and Magliulo, Vincenzo and Rana, Gianfranco},
  title = {Ammonia, nitrous oxide, carbon dioxide, and water vapor fluxes after green manuring of faba bean under Mediterranean climate},
  journal = {Agriculture, Ecosystems & Environment},
  year = {2021},
  volume = {315},
  pages = {107439},
  url = {https://www.sciencedirect.com/science/article/pii/S0167880921001432},
  doi = {10.1016/j.agee.2021.107439}
}
Fischer G, Romero OE, Karstensen J, Baumann K-H, Moradi N, Iversen M, Ruhland G, Klann M and Körtzinger A (2021), "Seasonal flux patterns and carbon transport from low-oxygen eddies at the Cape Verde Ocean Observatory: lessons learned from a time series sediment trap study (2009--2016)", Biogeosciences. Vol. 18(24), pp. 6479-6500.
BibTeX:
@article{Fischer2021,
  author = {Fischer, G and Romero, O E and Karstensen, J and Baumann, K.-H. and Moradi, N and Iversen, M and Ruhland, G and Klann, M and Körtzinger, A},
  title = {Seasonal flux patterns and carbon transport from low-oxygen eddies at the Cape Verde Ocean Observatory: lessons learned from a time series sediment trap study (2009--2016)},
  journal = {Biogeosciences},
  year = {2021},
  volume = {18},
  number = {24},
  pages = {6479--6500},
  url = {https://bg.copernicus.org/articles/18/6479/2021/},
  doi = {10.5194/bg-18-6479-2021}
}
Fodor N, Pásztor L, Szabó B, Laborczi A, Pokovai K, Hidy D, Hollós R, Kristóf E, Kis A, Dobor L, Kern A, Grünwald T and Barcza Z (2021), "Input database related uncertainty of Biome-BGCMuSo agro-environmental model outputs", International Journal of Digital Earth., nov, 2021. Vol. 14(11), pp. 1582-1601. Taylor & Francis.
BibTeX:
@article{Fodor2021,
  author = {Fodor, Nándor and Pásztor, László and Szabó, Brigitta and Laborczi, Annamária and Pokovai, Klára and Hidy, Dóra and Hollós, Roland and Kristóf, Erzsébet and Kis, Anna and Dobor, Laura and Kern, Anikó and Grünwald, Thomas and Barcza, Zoltán},
  title = {Input database related uncertainty of Biome-BGCMuSo agro-environmental model outputs},
  journal = {International Journal of Digital Earth},
  publisher = {Taylor & Francis},
  year = {2021},
  volume = {14},
  number = {11},
  pages = {1582--1601},
  url = {https://doi.org/10.1080/17538947.2021.1953161},
  doi = {10.1080/17538947.2021.1953161}
}
Friedlingstein P, Jones MW, O'Sullivan M, Andrew RM, Bakker DCE, Hauck J, Le Quéré C, Peters GP, Peters W, Pongratz J, Sitch S, Canadell JG, Ciais P, Jackson RB, Alin SR, Anthoni P, Bates NR, Becker M, Bellouin N, Bopp L, Chau TTT, Chevallier F, Chini LP, Cronin M, Currie KI, Decharme B, Djeutchouang L, Dou X, Evans W, Feely RA, Feng L, Gasser T, Gilfillan D, Gkritzalis T, Grassi G, Gregor L, Gruber N, Gürses Ö, Harris I, Houghton RA, Hurtt GC, Iida Y, Ilyina T, Luijkx IT, Jain AK, Jones SD, Kato E, Kennedy D, Klein Goldewijk K, Knauer J, Korsbakken JI, Körtzinger A, Landschützer P, Lauvset SK, Lefèvre N, Lienert S, Liu J, Marland G, McGuire PC, Melton JR, Munro DR, Nabel JEMS, Nakaoka S-I, Niwa Y, Ono T, Pierrot D, Poulter B, Rehder G, Resplandy L, Robertson E, Rödenbeck C, Rosan TM, Schwinger J, Schwingshackl C, Séférian R, Sutton AJ, Sweeney C, Tanhua T, Tans PP, Tian H, Tilbrook B, Tubiello F, van der Werf G, Vuichard N, Wada C, Wanninkhof R, Watson A, Willis D, Wiltshire AJ, Yuan W, Yue C, Yue X, Zaehle S and Zeng J (2021), "Global Carbon Budget 2021", Earth System Science Data Discussions. Vol. 2021, pp. 1-191.
BibTeX:
@article{Friedlingstein2021,
  author = {Friedlingstein, P and Jones, M W and O'Sullivan, M and Andrew, R M and Bakker, D C E and Hauck, J and Le Quéré, C and Peters, G P and Peters, W and Pongratz, J and Sitch, S and Canadell, J G and Ciais, P and Jackson, R B and Alin, S R and Anthoni, P and Bates, N R and Becker, M and Bellouin, N and Bopp, L and Chau, T T T and Chevallier, F and Chini, L P and Cronin, M and Currie, K I and Decharme, B and Djeutchouang, L and Dou, X and Evans, W and Feely, R A and Feng, L and Gasser, T and Gilfillan, D and Gkritzalis, T and Grassi, G and Gregor, L and Gruber, N and Gürses, Ö and Harris, I and Houghton, R A and Hurtt, G C and Iida, Y and Ilyina, T and Luijkx, I T and Jain, A K and Jones, S D and Kato, E and Kennedy, D and Klein Goldewijk, K and Knauer, J and Korsbakken, J I and Körtzinger, A and Landschützer, P and Lauvset, S K and Lefèvre, N and Lienert, S and Liu, J and Marland, G and McGuire, P C and Melton, J R and Munro, D R and Nabel, J E M S and Nakaoka, S.-I. and Niwa, Y and Ono, T and Pierrot, D and Poulter, B and Rehder, G and Resplandy, L and Robertson, E and Rödenbeck, C and Rosan, T M and Schwinger, J and Schwingshackl, C and Séférian, R and Sutton, A J and Sweeney, C and Tanhua, T and Tans, P P and Tian, H and Tilbrook, B and Tubiello, F and van der Werf, G and Vuichard, N and Wada, C and Wanninkhof, R and Watson, A and Willis, D and Wiltshire, A J and Yuan, W and Yue, C and Yue, X and Zaehle, S and Zeng, J},
  title = {Global Carbon Budget 2021},
  journal = {Earth System Science Data Discussions},
  year = {2021},
  volume = {2021},
  pages = {1--191},
  url = {https://essd.copernicus.org/preprints/essd-2021-386/},
  doi = {10.5194/essd-2021-386}
}
Gałkowski M, Jordan A, Rothe M, Marshall J, Koch F-T, Chen J, Agusti-Panareda A, Fix A and Gerbig C (2021), "In situ observations of greenhouse gases over Europe during the CoMet 1.0 campaign aboard the HALO aircraft", Atmospheric Measurement Techniques. Vol. 14(2), pp. 1525-1544.
BibTeX:
@article{Galkowski2021,
  author = {Gałkowski, M and Jordan, A and Rothe, M and Marshall, J and Koch, F.-T. and Chen, J and Agusti-Panareda, A and Fix, A and Gerbig, C},
  title = {In situ observations of greenhouse gases over Europe during the CoMet 1.0 campaign aboard the HALO aircraft},
  journal = {Atmospheric Measurement Techniques},
  year = {2021},
  volume = {14},
  number = {2},
  pages = {1525--1544},
  url = {https://amt.copernicus.org/articles/14/1525/2021/},
  doi = {10.5194/amt-14-1525-2021}
}
George J-P, Yang W, Kobayashi H, Biermann T, Carrara A, Cremonese E, Cuntz M, Fares S, Gerosa G, Grünwald T, Hase N, Heliasz M, Ibrom A, Knohl A, Kruijt B, Lange H, Limousin J-M, Loustau D, Lukeš P, Marzuoli R, Mölder M, Montagnani L, Neirynck J, Peichl M, Rebmann C, Schmidt M, Serrano FRL, Soudani K, Vincke C and Pisek J (2021), "Method comparison of indirect assessments of understory leaf area index (LAIu): A case study across the extended network of ICOS forest ecosystem sites in Europe", Ecological Indicators., sep, 2021. Vol. 128, pp. 107841.
BibTeX:
@article{George2021,
  author = {George, Jan-Peter and Yang, Wei and Kobayashi, Hideki and Biermann, Tobias and Carrara, Arnaud and Cremonese, Edoardo and Cuntz, Matthias and Fares, Silvano and Gerosa, Giacomo and Grünwald, Thomas and Hase, Niklas and Heliasz, Michael and Ibrom, Andreas and Knohl, Alexander and Kruijt, Bart and Lange, Holger and Limousin, Jean-Marc and Loustau, Denis and Lukeš, Petr and Marzuoli, Riccardo and Mölder, Meelis and Montagnani, Leonardo and Neirynck, Johan and Peichl, Matthias and Rebmann, Corinna and Schmidt, Marius and Serrano, Francisco Ramon Lopez and Soudani, Kamel and Vincke, Caroline and Pisek, Jan},
  title = {Method comparison of indirect assessments of understory leaf area index (LAIu): A case study across the extended network of ICOS forest ecosystem sites in Europe},
  journal = {Ecological Indicators},
  year = {2021},
  volume = {128},
  pages = {107841},
  url = {https://linkinghub.elsevier.com/retrieve/pii/S1470160X21005069},
  doi = {10.1016/j.ecolind.2021.107841}
}
Gharun M, Klesse S, Tomlinson G, Waldner P, Stocker B, Rihm B, Siegwolf R and Buchmann N (2021), "Effect of nitrogen deposition on centennial forest water-use efficiency", Environmental Research Letters. Vol. 16(11), pp. 114036. IOP Publishing.
Abstract: The uptake of carbon dioxide (CO2) from the atmosphere through photosynthesis is accompanied by an inevitable loss of water vapor through the stomata of leaves. The rate of leaf-level CO2 assimilation per unit stomatal conductance, i.e. intrinsic water-use efficiency (WUEi), is thus a key characteristic of terrestrial ecosystem functioning that is central to the global hydroclimate system. Empirical evidence and theory suggest a positive response of forest WUE to increased CO2 levels globally. Although evidence exists for a positive effect of ecosystem nitrogen (N) inputs on WUEi, it is not clear how trends in atmospheric N deposition have affected WUEi in the past. Here we combine twentieth-century climate and nitrogen deposition with stable isotope signature in tree rings and document a WUEi trend reversal at two sites in Switzerland, that matches the timing of a trend reversal in atmospheric N deposition. Using generalized additive models (GAMs), we fitted observed WUEi time series to multiple environmental covariates. This suggested N deposition to have a significant effect on long-term WUEi at the site that was exposed to higher N deposition levels. The ratio of the increase in WUEi in response to increase in CO2 (dWUEi/dCO2) declined by 96% after 1980 (from 0.53 to 0.02) in the beech forest and declined by 72% in the spruce forest (from 0.46 to 0.13) concurrent with a sharp decline in N deposition. Using the GAM model for two scenarios, we show that had N deposition levels not declined after 1980s, WUEi would have increased more strongly in response to increasing CO2. Although the increase in N deposition was limited to the 1950–1980 decades and the signals have declined with improvements in air quality across Europe, the role of atmospheric pollution must be reconsidered in interpretation of tree ring studies and for building environmental proxies that are pivotal to understanding future sink capacity of terrestrial ecosystems in response to climate change.
BibTeX:
@article{Gharun2021,
  author = {Gharun, Mana and Klesse, Stefan and Tomlinson, Gregory and Waldner, Peter and Stocker, Benjamin and Rihm, Beat and Siegwolf, Rolf and Buchmann, Nina},
  title = {Effect of nitrogen deposition on centennial forest water-use efficiency},
  journal = {Environmental Research Letters},
  publisher = {IOP Publishing},
  year = {2021},
  volume = {16},
  number = {11},
  pages = {114036},
  url = {http://dx.doi.org/10.1088/1748-9326/ac30f9},
  doi = {10.1088/1748-9326/ac30f9}
}
Gomez LG, Loubet B, Lafouge F, Ciuraru R, Bsaibes S, Kammer J, Buysse P, Durand B, Gueudet J-C, Fanucci O, Zurfluh O, Decuq C, Truong F, Gros V and Boissard C (2021), "Effect of senescence on biogenic volatile organic compound fluxes in wheat plants", Atmospheric Environment. Vol. 266, pp. 118665.
Abstract: Exchanges of biogenic volatile organic compounds (BVOC) between plants and the atmosphere are likely to vary, in amount and composition, between different plant species but also for a single plant during its development. However, the effect of plant development stages, including senescence, on BVOC exchanges remains poorly investigated, especially in the case of crop plants. We investigated the BVOC exchange patterns for wheat plants, the most grown crop species worldwide, during seed maturation, senescence and after harvest. Fluxes were measured online, in situ, at the plant scale by combining automated chambers and a Proton Transfer - Reaction - Quadrupole ion guide - Time of Flight - Mass Spectrometer (PTR-Qi-Tof-MS). The high resolution and sensitivity of this method enabled the measurement of a large mass spectrum of compounds emitted at very small amounts, allowing a precise characterization of BVOC exchanges. We found that the overall BVOC emissions increased twofold during the senescence stage compared to the maturation stage. Methanol was found to be the most emitted compound (49–60% of the overall flux on a molar basis) followed by acetone (7.5–8.2% of the overall flux on a molar basis) during each developmental stage investigated. Acetaldehyde was another major emitted compound contributing mainly during late senescence to the overall flux (9.7%). When normalized for temperature and light conditions, most BVOC emissions increased during senescence, showing a clear effect of senescence on BVOC exchanges. Chamber emissions were comparable to whole ecosystem fluxes measured at the same site by eddy covariance the previous year. The OH reactivity of the emitted compounds was evaluated based on known reaction rate constants and was the largest during the first senescence stage, peaking at 12 s−1 in the chambers. The results of this study show the need for considering plant phenology when computing BVOC emissions from crops.
BibTeX:
@article{Gomez2021,
  author = {Gomez, Lais Gonzaga and Loubet, Benjamin and Lafouge, Florence and Ciuraru, Raluca and Bsaibes, Sandy and Kammer, Julien and Buysse, Pauline and Durand, Brigitte and Gueudet, Jean-Christophe and Fanucci, Olivier and Zurfluh, Olivier and Decuq, Céline and Truong, François and Gros, Valérie and Boissard, Christophe},
  title = {Effect of senescence on biogenic volatile organic compound fluxes in wheat plants},
  journal = {Atmospheric Environment},
  year = {2021},
  volume = {266},
  pages = {118665},
  url = {https://www.sciencedirect.com/science/article/pii/S1352231021004878},
  doi = {10.1016/j.atmosenv.2021.118665}
}
Grönholm T, Mäkelä T, Hatakka J, Jalkanen J-P, Kuula J, Laurila T, Laakso L and Kukkonen J (2021), "Evaluation of Methane Emissions Originating from LNG Ships Based on the Measurements at a Remote Marine Station", Environmental Science & Technology., oct, 2021. Vol. 55(20), pp. 13677-13686. American Chemical Society.
BibTeX:
@article{Groenholm2021,
  author = {Grönholm, Tiia and Mäkelä, Timo and Hatakka, Juha and Jalkanen, Jukka-Pekka and Kuula, Joel and Laurila, Tuomas and Laakso, Lauri and Kukkonen, Jaakko},
  title = {Evaluation of Methane Emissions Originating from LNG Ships Based on the Measurements at a Remote Marine Station},
  journal = {Environmental Science & Technology},
  publisher = {American Chemical Society},
  year = {2021},
  volume = {55},
  number = {20},
  pages = {13677--13686},
  url = {https://doi.org/10.1021/acs.est.1c03293},
  doi = {10.1021/acs.est.1c03293}
}
Groß-Schmölders M, Klein K, Birkholz A, Leifeld J and Alewell C (2021), "Rewetting and Drainage of Nutrient-Poor Peatlands Indicated by Specific Bacterial Membrane Fatty Acids and a Repeated Sampling of Stable Isotopes (δ15N, δ13C)", Frontiers in Environmental Science. Vol. 9
Abstract: Peatland degradation impairs soil functions such as carbon storage and the existence of biodiversity hotspots. Therefore, and in view of the ongoing climate change, an efficient method of evaluating peatland hydrology and the success of restoration efforts is needed. To understand the role of microbial groups in biogeochemical cycling, gaseous loss and isotopic fractionation that lead to specific isotopic depth patterns (δ13C, δ15N), we integrated previously published stable isotope data with a membrane fatty acid (mFA) analysis related to various microbial groups that are known to be common in peatlands. We performed two sampling campaigns to verify the observed stable isotope depth trends in nutrient-poor peatlands in Northern Europe. Cores were taken from adjacent drained (or rewetted) and undrained sites. Fungal-derived mFA abundance was highest in the uppermost part of the drained layer. We found increasing bacterial-derived mFA concentrations with depth peaking in the middle of the drained layers, which correlates with a δ15N peak of bulk material. The results support our hypothesis that changing peatland hydrology induce a shift in microbial community and metabolism processes and is therefore also imprinted in stable isotope values. Under waterlogged conditions overall levels of microbial-derived mFAs were generally low. Drained layers showed simultaneous changes in microbial abundance and composition and depth trends in stable isotope bulk values. Bacteria, particularly acidobacteria, can be expected to dominate increased denitrification with low oxygen saturation accompanied by increased δ15N bulk values in the remaining substrate. Interestingly, cores from recent rewetted peatlands show no depth trend of δ15N in the layers grown under rewetting conditions; this is congruent with relatively low concentrations of microbial-derived mFAs. Hence, we conclude that stable isotopes, especially δ15N values, reflect changing microbial metabolic processes, which differ between drained and undrained - and especially also for recent rewetted–peatlands. As today stable isotope measurements are routine measurements, these findings enable us to get cost- and time efficient reliable information of drainage and restoration success.
BibTeX:
@article{GrossSchmoelders2021,
  author = {Groß-Schmölders, Miriam and Klein, Kristy and Birkholz, Axel and Leifeld, Jens and Alewell, Christine},
  title = {Rewetting and Drainage of Nutrient-Poor Peatlands Indicated by Specific Bacterial Membrane Fatty Acids and a Repeated Sampling of Stable Isotopes (δ15N, δ13C)},
  journal = {Frontiers in Environmental Science},
  year = {2021},
  volume = {9},
  url = {https://www.frontiersin.org/article/10.3389/fenvs.2021.730106},
  doi = {10.3389/fenvs.2021.730106}
}
Gu C, Tang Q, Zhu G, Ma J, Gu C, Zhang K, Sun S, Yu Q and Niu S (2021), "Discrepant responses between evapotranspiration- and transpiration-based ecosystem water use efficiency to interannual precipitation fluctuations", Agricultural and Forest Meteorology. Vol. 303, pp. 108385.
Abstract: Climate change intensifies precipitation fluctuation and increases drought frequency around the globe. Water use efficiency (WUE) has proven to be a crucial metric to quantify the trade-off linking global carbon and water cycles in many aspects of terrestrial ecosystem function. Investigating the response of ecosystem WUE to multiannual precipitation fluctuations has major implications for our understanding of ecosystem carbon and water dynamics. However, the impacts of water availability variation on evapotranspiration- and transpiration-based ecosystem WUE and their mechanisms are poorly understood due to limited observations. We investigated ecosystem WUE in response to interannual precipitation fluctuations in order to reveal the regularity underlying WUE changes under different levels of water stress. We optimized the parameters of two remote sensing models (PT-JPL and PM) based on different biophysical processes using the differential-evolution Markov Chain (DE-MC) method. We investigated ecosystem WUEET (GPP/ET) and WUET (GPP/T) in response to interannual precipitation fluctuations at 73 sites. We found ecosystem WUET appears to decline during drought years and to increase in wet years contrasting with WUEET, which was mostly attributable to differing sensitivities of GPP, ET and T to multiannual precipitation fluctuations. The vegetation generally consumes more T to improve ecosystem GPP during dry years, meanwhile, no apparent change in WUEET during dry years because of the trade of between GPP/T and T/ET. The replenishment of soil moisture to ecosystem transpiration is higher than we thought during dry years. This was masked in analysis that considered the responses of GPP and T to annual precipitation changes separately, but was revealed by the changes in ecosystem WUET. This research advances our understanding of the consequences of water fluctuation on ecosystem carbon and water exchange.
BibTeX:
@article{Gu2021,
  author = {Gu, Chunjie and Tang, Qiuhong and Zhu, Gaofeng and Ma, Jinzhu and Gu, Chunli and Zhang, Kun and Sun, Shuang and Yu, Qiang and Niu, Shuli},
  title = {Discrepant responses between evapotranspiration- and transpiration-based ecosystem water use efficiency to interannual precipitation fluctuations},
  journal = {Agricultural and Forest Meteorology},
  year = {2021},
  volume = {303},
  pages = {108385},
  url = {https://www.sciencedirect.com/science/article/pii/S016819232100068X},
  doi = {10.1016/j.agrformet.2021.108385}
}
Guseva S, Aurela M, Cortés A, Kivi R, Lotsari E, MacIntyre S, Mammarella I, Ojala A, Stepanenko V, Uotila P, Vähä A, Vesala T, Wallin MB and Lorke A (2021), "Variable Physical Drivers of Near-Surface Turbulence in a Regulated River", Water Resources Research., nov, 2021. Vol. 57(11), pp. e2020WR027939. John Wiley & Sons, Ltd.
Abstract: Abstract Inland waters, such as lakes, reservoirs and rivers, are important sources of climate forcing trace gases. A key parameter that regulates the gas exchange between water and the atmosphere is the gas transfer velocity, which itself is controlled by near-surface turbulence in the water. While in lakes and reservoirs, near-surface turbulence is mainly driven by atmospheric forcing, in shallow rivers and streams it is generated by bottom friction of gravity-forced flow. Large rivers represent a transition between these two cases. Near-surface turbulence has rarely been measured in rivers and the drivers of turbulence have not been quantified. We analyzed continuous measurements of flow velocity and quantified turbulence as the rate of dissipation of turbulent kinetic energy over the ice-free season in a large regulated river in Northern Finland. Measured dissipation rates agreed with predictions from bulk parameters, including mean flow velocity, wind speed, surface heat flux, and with a one-dimensional numerical turbulence model. Values ranged from to . Atmospheric forcing or gravity was the dominant driver of near-surface turbulence for similar fraction of the time. Large variability in near-surface dissipation rate occurred at diel time scales, when the flow velocity was strongly affected by downstream dam operation. By combining scaling relations for boundary-layer turbulence at the river bed and at the air-water interface, we derived a simple model for estimating the relative contributions of wind speed and bottom friction of river flow as a function of depth.
BibTeX:
@article{Guseva2021,
  author = {Guseva, S and Aurela, M and Cortés, A and Kivi, R and Lotsari, E and MacIntyre, S and Mammarella, I and Ojala, A and Stepanenko, V and Uotila, P and Vähä, A and Vesala, T and Wallin, M B and Lorke, A},
  title = {Variable Physical Drivers of Near-Surface Turbulence in a Regulated River},
  journal = {Water Resources Research},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {57},
  number = {11},
  pages = {e2020WR027939},
  url = {https://doi.org/10.1029/2020WR027939},
  doi = {10.1029/2020WR027939}
}
Gutiérrez-Loza L, Wallin MB, Sahlée E, Holding T, Shutler JD, Rehder G and Rutgersson A (2021), "Air–sea CO2 exchange in the Baltic Sea—A sensitivity analysis of the gas transfer velocity", Journal of Marine Systems. Vol. 222, pp. 103603.
Abstract: Air–sea gas fluxes are commonly estimated using wind-based parametrizations of the gas transfer velocity. However, neglecting gas exchange forcing mechanisms – other than wind speed – may lead to large uncertainties in the flux estimates and the carbon budgets, in particular, in heterogeneous environments such as marginal seas and coastal areas. In this study we investigated the impact of including relevant processes to the air–sea CO2 flux parametrization for the Baltic Sea. We used six parametrizations of the gas transfer velocity to evaluate the effect of precipitation, water-side convection, and surfactants on the net CO2 flux at regional and sub-regional scale. The differences both in the mean CO2 fluxes and the integrated net fluxes were small between the different cases. However, the implications on the seasonal variability were shown to be significant. The inter-annual and spatial variability were also found to be associated with the forcing mechanisms evaluated in the study. In addition to wind, water-side convection was the most relevant parameter controlling the air–sea gas exchange at seasonal and inter-annual scales. The effect of precipitation and surfactants seemed negligible in terms of the inter-annual variability. The effect of water-side convection and surfactants resulted in a reduction of the downward fluxes, while precipitation was the only parameter that resulted in an enhancement of the net uptake in the Baltic Sea.
BibTeX:
@article{GutierrezLoza2021,
  author = {Gutiérrez-Loza, Lucía and Wallin, Marcus B and Sahlée, Erik and Holding, Thomas and Shutler, Jamie D and Rehder, Gregor and Rutgersson, Anna},
  title = {Air–sea CO2 exchange in the Baltic Sea—A sensitivity analysis of the gas transfer velocity},
  journal = {Journal of Marine Systems},
  year = {2021},
  volume = {222},
  pages = {103603},
  url = {https://www.sciencedirect.com/science/article/pii/S0924796321001007},
  doi = {10.1016/j.jmarsys.2021.103603}
}
Haesen S, Lembrechts JJ, De Frenne P, Lenoir J, Aalto J, Ashcroft MB, Kopecký M, Luoto M, Maclean I, Nijs I, Niittynen P, van den Hoogen J, Arriga N, Brůna J, Buchmann N, Čiliak M, Collalti A, De Lombaerde E, Descombes P, Gharun M, Goded I, Govaert S, Greiser C, Grelle A, Gruening C, Hederová L, Hylander K, Kreyling J, Kruijt B, Macek M, Máliš F, Man M, Manca G, Matula R, Meeussen C, Merinero S, Minerbi S, Montagnani L, Muffler L, Ogaya R, Penuelas J, Plichta R, Portillo-Estrada M, Schmeddes J, Shekhar A, Spicher F, Ujházyová M, Vangansbeke P, Weigel R, Wild J, Zellweger F and Van Meerbeek K (2021), "ForestTemp – Sub-canopy microclimate temperatures of European forests", Global Change Biology., dec, 2021. Vol. 27(23), pp. 6307-6319. John Wiley & Sons, Ltd.
Abstract: Abstract Ecological research heavily relies on coarse-gridded climate data based on standardized temperature measurements recorded at 2 m height in open landscapes. However, many organisms experience environmental conditions that differ substantially from those captured by these macroclimatic (i.e. free air) temperature grids. In forests, the tree canopy functions as a thermal insulator and buffers sub-canopy microclimatic conditions, thereby affecting biological and ecological processes. To improve the assessment of climatic conditions and climate-change-related impacts on forest-floor biodiversity and functioning, high-resolution temperature grids reflecting forest microclimates are thus urgently needed. Combining more than 1200 time series of in situ near-surface forest temperature with topographical, biological and macroclimatic variables in a machine learning model, we predicted the mean monthly offset between sub-canopy temperature at 15 cm above the surface and free-air temperature over the period 2000?2020 at a spatial resolution of 25 m across Europe. This offset was used to evaluate the difference between microclimate and macroclimate across space and seasons and finally enabled us to calculate mean annual and monthly temperatures for European forest understories. We found that sub-canopy air temperatures differ substantially from free-air temperatures, being on average 2.1°C (standard deviation ± 1.6°C) lower in summer and 2.0°C higher (±0.7°C) in winter across Europe. Additionally, our high-resolution maps expose considerable microclimatic variation within landscapes, not captured by the gridded macroclimatic products. The provided forest sub-canopy temperature maps will enable future research to model below-canopy biological processes and patterns, as well as species distributions more accurately.
BibTeX:
@article{Haesen2021,
  author = {Haesen, Stef and Lembrechts, Jonas J and De Frenne, Pieter and Lenoir, Jonathan and Aalto, Juha and Ashcroft, Michael B and Kopecký, Martin and Luoto, Miska and Maclean, Ilya and Nijs, Ivan and Niittynen, Pekka and van den Hoogen, Johan and Arriga, Nicola and Brůna, Josef and Buchmann, Nina and Čiliak, Marek and Collalti, Alessio and De Lombaerde, Emiel and Descombes, Patrice and Gharun, Mana and Goded, Ignacio and Govaert, Sanne and Greiser, Caroline and Grelle, Achim and Gruening, Carsten and Hederová, Lucia and Hylander, Kristoffer and Kreyling, Jürgen and Kruijt, Bart and Macek, Martin and Máliš, František and Man, Matěj and Manca, Giovanni and Matula, Radim and Meeussen, Camille and Merinero, Sonia and Minerbi, Stefano and Montagnani, Leonardo and Muffler, Lena and Ogaya, Romà and Penuelas, Josep and Plichta, Roman and Portillo-Estrada, Miguel and Schmeddes, Jonas and Shekhar, Ankit and Spicher, Fabien and Ujházyová, Mariana and Vangansbeke, Pieter and Weigel, Robert and Wild, Jan and Zellweger, Florian and Van Meerbeek, Koenraad},
  title = {ForestTemp – Sub-canopy microclimate temperatures of European forests},
  journal = {Global Change Biology},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {27},
  number = {23},
  pages = {6307--6319},
  url = {https://doi.org/10.1111/gcb.15892},
  doi = {10.1111/gcb.15892}
}
Hamard S, Céréghino R, Barret M, Sytiuk A, Lara E, Dorrepaal E, Kardol P, Küttim M, Lamentowicz M, Leflaive J, Le Roux G, Tuittila E-S and Jassey VEJ (2021), "Contribution of microbial photosynthesis to peatland carbon uptake along a latitudinal gradient", Journal of Ecology., sep, 2021. Vol. 109(9), pp. 3424-3441. John Wiley & Sons, Ltd.
Abstract: Abstract Phototrophic microbes, also known as micro-algae, display a high abundance in many terrestrial surface soils. They contribute to atmospheric carbon dioxide fluxes through their photosynthesis, and thus regulate climate similar to plants. However, microbial photosynthesis remains overlooked in most terrestrial ecosystems. Here, we hypothesise that phototrophic microbes significantly contribute to peatland C uptake, unless environmental conditions limit their development and their photosynthetic activity. To test our hypothesis, we studied phototrophic microbial communities in five peatlands distributed along a latitudinal gradient in Europe. By means of metabarcoding, microscopy and cytometry analyses, as well as measures of photosynthesis, we investigated the diversity, absolute abundance and photosynthetic rates of the phototrophic microbial communities. We identified 351 photosynthetic prokaryotic and eukaryotic operational taxonomic units (OTUs) across the five peatlands. We found that water availability and plant composition were important determinants of the composition and the structure of phototrophic microbial communities. Despite environmental shifts in community structure and composition, we showed that microbial C fixation rates remained similar along the latitudinal gradient. Our results further revealed that phototrophic microbes accounted for approximately 10% of peatland C uptake. Synthesis. Our findings show that phototrophic microbes are extremely diverse and abundant in peatlands. While species turnover with environmental conditions, microbial photosynthesis similarly contributed to peatland C uptake at all latitudes. We estimate that phototrophic microbes take up around 75 MT CO2 per year in northern peatlands. This amount roughly equals the magnitude of projected peatland C loss due to climate warming and highlights the importance of phototrophic microbes for the peatland C cycle.
BibTeX:
@article{Hamard2021,
  author = {Hamard, Samuel and Céréghino, Regis and Barret, Maialen and Sytiuk, Anna and Lara, Enrique and Dorrepaal, Ellen and Kardol, Paul and Küttim, Martin and Lamentowicz, Mariusz and Leflaive, Joséphine and Le Roux, Gaël and Tuittila, Eeva-Stiina and Jassey, Vincent E J},
  title = {Contribution of microbial photosynthesis to peatland carbon uptake along a latitudinal gradient},
  journal = {Journal of Ecology},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {109},
  number = {9},
  pages = {3424--3441},
  url = {https://doi.org/10.1111/1365-2745.13732},
  doi = {10.1111/1365-2745.13732}
}
Han Q, Wang T, Wang L, Smettem K, Mai M and Chen X (2021), "Comparison of Nighttime With Daytime Evapotranspiration Responses to Environmental Controls Across Temporal Scales Along a Climate Gradient", Water Resources Research., jul, 2021. Vol. 57(7), pp. e2021WR029638. John Wiley & Sons, Ltd.
Abstract: Abstract Understanding daytime (ETD) and nighttime (ETN) evapotranspiration is critical for accurately evaluating terrestrial water and carbon cycles. However, unlike ETD, the factors influencing ETN remain poorly understood. Here, long-term ETD and ETN data from five FLUXNET sites along a climate gradient in Northern Australia were analyzed to compare their responses to environmental drivers at different temporal scales. We found that (a) across the sites, mean annual ETN/ETD (/) ranged between 5.1% and 11.7%, which was mainly determined by variations. Particularly, vegetation and meteorological variables mostly controlled , while was largely related to air temperature and net radiation (Rn) due to lower nighttime atmospheric water demands; (b) At individual sites, ETD and ETN exhibited higher correlations with meteorological and vegetation variables at monthly timescales than at annual timescales. Monthly ETD and ETN were also strongly coupled, especially under drier climatic conditions. At daily timescales, leaf area index and soil water content (SWC) controlled ETD with SWC being more important at drier sites; whereas, SWC was the dominant factor controlling ETN. At half-hourly timescales, the boosted regression tree method quantitively showed that ETD and ETN were controlled by Rn and SWC, respectively. Overall, the results showed that ETN was less responsive to environmental variables, illustrating that ETD and ETN responded differently to diverse climate regimes and ecosystems at varying temporal scales. These findings provide a critical evaluation for contrasting ETD and ETN interactions in constantly changing environments, which has important implications for ecosystem water balance and land surface processes modeling.
BibTeX:
@article{Han2021,
  author = {Han, Qiong and Wang, Tiejun and Wang, Lichun and Smettem, Keith and Mai, Mai and Chen, Xi},
  title = {Comparison of Nighttime With Daytime Evapotranspiration Responses to Environmental Controls Across Temporal Scales Along a Climate Gradient},
  journal = {Water Resources Research},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {57},
  number = {7},
  pages = {e2021WR029638},
  url = {https://doi.org/10.1029/2021WR029638},
  doi = {10.1029/2021WR029638}
}
Harper AB, Williams KE, McGuire PC, Duran Rojas MC, Hemming D, Verhoef A, Huntingford C, Rowland L, Marthews T, Breder Eller C, Mathison C, Nobrega RLB, Gedney N, Vidale PL, Otu-Larbi F, Pandey D, Garrigues S, Wright A, Slevin D, De Kauwe MG, Blyth E, Ardö J, Black A, Bonal D, Buchmann N, Burban B, Fuchs K, de Grandcourt A, Mammarella I, Merbold L, Montagnani L, Nouvellon Y, Restrepo-Coupe N and Wohlfahrt G (2021), "Improvement of modeling plant responses to low soil moisture in JULESvn4.9 and evaluation against flux tower measurements", Geoscientific Model Development. Vol. 14(6), pp. 3269-3294.
BibTeX:
@article{Harper2021,
  author = {Harper, A B and Williams, K E and McGuire, P C and Duran Rojas, M C and Hemming, D and Verhoef, A and Huntingford, C and Rowland, L and Marthews, T and Breder Eller, C and Mathison, C and Nobrega, R L B and Gedney, N and Vidale, P L and Otu-Larbi, F and Pandey, D and Garrigues, S and Wright, A and Slevin, D and De Kauwe, M G and Blyth, E and Ardö, J and Black, A and Bonal, D and Buchmann, N and Burban, B and Fuchs, K and de Grandcourt, A and Mammarella, I and Merbold, L and Montagnani, L and Nouvellon, Y and Restrepo-Coupe, N and Wohlfahrt, G},
  title = {Improvement of modeling plant responses to low soil moisture in JULESvn4.9 and evaluation against flux tower measurements},
  journal = {Geoscientific Model Development},
  year = {2021},
  volume = {14},
  number = {6},
  pages = {3269--3294},
  url = {https://gmd.copernicus.org/articles/14/3269/2021/},
  doi = {10.5194/gmd-14-3269-2021}
}
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}
}
Haszpra L and Prácser E (2021), "Uncertainty of hourly-average concentration values derived from non-continuous measurements", Atmospheric Measurement Techniques. Vol. 14(5), pp. 3561-3571.
BibTeX:
@article{Haszpra2021,
  author = {Haszpra, L and Prácser, E},
  title = {Uncertainty of hourly-average concentration values derived from non-continuous measurements},
  journal = {Atmospheric Measurement Techniques},
  year = {2021},
  volume = {14},
  number = {5},
  pages = {3561--3571},
  url = {https://amt.copernicus.org/articles/14/3561/2021/},
  doi = {10.5194/amt-14-3561-2021}
}
He Q, Ju W, Dai S, He W, Song L, Wang S, Li X and Mao G (2021), "Drought Risk of Global Terrestrial Gross Primary Productivity Over the Last 40 Years Detected by a Remote Sensing-Driven Process Model", Journal of Geophysical Research: Biogeosciences., jun, 2021. Vol. 126(6), pp. e2020JG005944. John Wiley & Sons, Ltd.
Abstract: Abstract Gross primary productivity (GPP) is the largest flux in the global terrestrial carbon cycle. Drought has significantly impacted global terrestrial GPP in recent decades, and has been projected to occur with increasing frequency and intensity. However, the drought risk of global terrestrial GPP has not been well investigated. In this study, global terrestrial GPP during 1981?2016 was simulated with the process-based Boreal Ecosystem Productivity Simulator model. Then, the drought risk of GPP was quantified as the product of drought probability and reduction of GPP caused by drought, which was determined using the standardized precipitation evapotranspiration index. During the study period, the drought risk of GPP was high in the southeastern United States, most of South America, southern Europe, central and eastern Africa, eastern and southeastern Asia, and eastern Australia. It was low at some high latitudes of the Northern Hemisphere and in part of tropical South America, where terrestrial GPP increased slightly in drought years. The drought risk of terrestrial GPP was greater during 2000?2016 than during 1981?1999 in 21 out of 24 climatic zones. The global mean drought risk of GPP increased from 13.6 g C m?2 yr?1 during 1981?1999 to 19.3 g C m?2 yr?1 during 2000?2016. The increase in drought risk of GPP was mainly caused by the increase in drought vulnerability. Simulation experiments indicated that the drought vulnerability of GPP was mainly induced by climatic variability. This study advances our understanding on the impact of drought on GPP over the globe.
BibTeX:
@article{He2021,
  author = {He, Qiaoning and Ju, Weimin and Dai, Shengpei and He, Wei and Song, Lian and Wang, Songhan and Li, Xinchuan and Mao, Guangxiong},
  title = {Drought Risk of Global Terrestrial Gross Primary Productivity Over the Last 40 Years Detected by a Remote Sensing-Driven Process Model},
  journal = {Journal of Geophysical Research: Biogeosciences},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {126},
  number = {6},
  pages = {e2020JG005944},
  url = {https://doi.org/10.1029/2020JG005944},
  doi = {10.1029/2020JG005944}
}
Heiskanen J, Brümmer C, Buchmann N, Calfapietra C, Chen H, Gielen B, Gkritzalis T, Hammer S, Hartman S, Herbst M, Janssens IA, Jordan A, Juurola E, Karstens U, Kasurinen V, Kruijt B, Lankreijer H, Levin I, Linderson M-L, Loustau D, Merbold L, Myhre CL, Papale D, Pavelka M, Pilegaard K, Ramonet M, Rebmann C, Rinne J, Rivier L, Saltikoff E, Sanders R, Steinbacher M, Steinhoff T, Watson A, Vermeulen AT, Vesala T, Vítková G and Kutsch W (2021), "The Integrated Carbon Observation System in Europe", Bulletin of the American Meteorological Society., oct, 2021. , pp. 1-54.
Abstract: Since 1750, land use change and fossil fuel combustion has led to a 46 % increase in the atmospheric carbon dioxide (CO 2 ) concentrations, causing global warming with substantial societal consequences. The Paris Agreement aims to limiting global temperature increases to well below 2°C above pre-industrial levels. Increasing levels of CO 2 and other greenhouse gases (GHGs), such as methane (CH 4 ) and nitrous oxide (N 2 O), in the atmosphere are the primary cause of climate change. Approximately half of the carbon emissions to the atmosphere is sequestered by ocean and land sinks, leading to ocean acidification but also slowing the rate of global warming. However, there are significant uncertainties in the future global warming scenarios due to uncertainties in the size, nature and stability of these sinks. Quantifying and monitoring the size and timing of natural sinks and the impact of climate change on ecosystems are important information to guide policy-makers' decisions and strategies on reductions in emissions. Continuous, long-term observations are required to quantify GHG emissions, sinks, and their impacts on Earth systems. The Integrated Carbon Observation System (ICOS) was designed as the European in situ observation and information system to support science and society in their efforts to mitigate climate change. It provides standardized and open data currently from over 140 measurement stations across 12 European countries. The stations observe GHG concentrations in the atmosphere and carbon and GHG fluxes between the atmosphere, land surface and the oceans. This article describes how ICOS fulfills its mission to harmonize these observations, ensure the related long-term financial commitments, provide easy access to well-documented and reproducible high-quality data and related protocols and tools for scientific studies, and deliver information and GHG-related products to stakeholders in society and policy.
BibTeX:
@article{Heiskanen2021,
  author = {Heiskanen, Jouni and Brümmer, Christian and Buchmann, Nina and Calfapietra, Carlo and Chen, Huilin and Gielen, Bert and Gkritzalis, Thanos and Hammer, Samuel and Hartman, Susan and Herbst, Mathias and Janssens, Ivan A and Jordan, Armin and Juurola, Eija and Karstens, Ute and Kasurinen, Ville and Kruijt, Bart and Lankreijer, Harry and Levin, Ingeborg and Linderson, Maj-Lena and Loustau, Denis and Merbold, Lutz and Myhre, Cathrine Lund and Papale, Dario and Pavelka, Marian and Pilegaard, Kim and Ramonet, Michel and Rebmann, Corinna and Rinne, Janne and Rivier, Léonard and Saltikoff, Elena and Sanders, Richard and Steinbacher, Martin and Steinhoff, Tobias and Watson, Andrew and Vermeulen, Alex T and Vesala, Timo and Vítková, Gabriela and Kutsch, Werner},
  title = {The Integrated Carbon Observation System in Europe},
  journal = {Bulletin of the American Meteorological Society},
  year = {2021},
  pages = {1--54},
  url = {https://journals.ametsoc.org/view/journals/bams/aop/BAMS-D-19-0364.1/BAMS-D-19-0364.1.xml},
  doi = {10.1175/BAMS-D-19-0364.1}
}
Heiskanen L, Tuovinen J-P, Räsänen A, Virtanen T, Juutinen S, Lohila A, Penttilä T, Linkosalmi M, Mikola J, Laurila T and Aurela M (2021), "Carbon dioxide and methane exchange of a patterned subarctic fen during two contrasting growing seasons", Biogeosciences. Vol. 18(3), pp. 873-896.
BibTeX:
@article{Heiskanen2021a,
  author = {Heiskanen, L and Tuovinen, J.-P. and Räsänen, A and Virtanen, T and Juutinen, S and Lohila, A and Penttilä, T and Linkosalmi, M and Mikola, J and Laurila, T and Aurela, M},
  title = {Carbon dioxide and methane exchange of a patterned subarctic fen during two contrasting growing seasons},
  journal = {Biogeosciences},
  year = {2021},
  volume = {18},
  number = {3},
  pages = {873--896},
  url = {https://bg.copernicus.org/articles/18/873/2021/},
  doi = {10.5194/bg-18-873-2021}
}
Helbig M, Gerken T, Beamesderfer ER, Baldocchi DD, Banerjee T, Biraud SC, Brown WOJ, Brunsell NA, Burakowski EA, Burns SP, Butterworth BJ, Chan WS, Davis KJ, Desai AR, Fuentes JD, Hollinger DY, Kljun N, Mauder M, Novick KA, Perkins JM, Rahn DA, Rey-Sanchez C, Santanello JA, Scott RL, Seyednasrollah B, Stoy PC, Sullivan RC, de Arellano JV-G, Wharton S, Yi C and Richardson AD (2021), "Integrating continuous atmospheric boundary layer and tower-based flux measurements to advance understanding of land-atmosphere interactions", Agricultural and Forest Meteorology. Vol. 307, pp. 108509.
Abstract: The atmospheric boundary layer mediates the exchange of energy, matter, and momentum between the land surface and the free troposphere, integrating a range of physical, chemical, and biological processes and is defined as the lowest layer of the atmosphere (ranging from a few meters to 3 km). In this review, we investigate how continuous, automated observations of the atmospheric boundary layer can enhance the scientific value of co-located eddy covariance measurements of land-atmosphere fluxes of carbon, water, and energy, as are being made at FLUXNET sites worldwide. We highlight four key opportunities to integrate tower-based flux measurements with continuous, long-term atmospheric boundary layer measurements: (1) to interpret surface flux and atmospheric boundary layer exchange dynamics and feedbacks at flux tower sites, (2) to support flux footprint modelling, the interpretation of surface fluxes in heterogeneous and mountainous terrain, and quality control of eddy covariance flux measurements, (3) to support regional-scale modeling and upscaling of surface fluxes to continental scales, and (4) to quantify land-atmosphere coupling and validate its representation in Earth system models. Adding a suite of atmospheric boundary layer measurements to eddy covariance flux tower sites, and supporting the sharing of these data to tower networks, would allow the Earth science community to address new emerging research questions, better interpret ongoing flux tower measurements, and would present novel opportunities for collaborations between FLUXNET scientists and atmospheric and remote sensing scientists.
BibTeX:
@article{Helbig2021,
  author = {Helbig, Manuel and Gerken, Tobias and Beamesderfer, Eric R and Baldocchi, Dennis D and Banerjee, Tirtha and Biraud, Sébastien C and Brown, William O J and Brunsell, Nathaniel A and Burakowski, Elizabeth A and Burns, Sean P and Butterworth, Brian J and Chan, W Stephen and Davis, Kenneth J and Desai, Ankur R and Fuentes, Jose D and Hollinger, David Y and Kljun, Natascha and Mauder, Matthias and Novick, Kimberly A and Perkins, John M and Rahn, David A and Rey-Sanchez, Camilo and Santanello, Joseph A and Scott, Russell L and Seyednasrollah, Bijan and Stoy, Paul C and Sullivan, Ryan C and de Arellano, Jordi Vilà-Guerau and Wharton, Sonia and Yi, Chuixiang and Richardson, Andrew D},
  title = {Integrating continuous atmospheric boundary layer and tower-based flux measurements to advance understanding of land-atmosphere interactions},
  journal = {Agricultural and Forest Meteorology},
  year = {2021},
  volume = {307},
  pages = {108509},
  url = {https://www.sciencedirect.com/science/article/pii/S0168192321001933},
  doi = {10.1016/j.agrformet.2021.108509}
}
Hermanns F, Pohl F, Rebmann C, Schulz G, Werban U and Lausch A (2021), "Inferring Grassland Drought Stress with Unsupervised Learning from Airborne Hyperspectral VNIR Imagery".
Abstract: The 2018–2019 Central European drought had a grave impact on natural and managed ecosystems, affecting their health and productivity. We examined patterns in hyperspectral VNIR imagery using an unsupervised learning approach to improve ecosystem monitoring and the understanding of grassland drought responses. The main objectives of this study were (1) to evaluate the application of simplex volume maximisation (SiVM), an unsupervised learning method, for the detection of grassland drought stress in high-dimensional remote sensing data at the ecosystem scale and (2) to analyse the contributions of different spectral plant and soil traits to the computed stress signal. The drought status of the research site was assessed with a non-parametric standardised precipitation–evapotranspiration index (SPEI) and soil moisture measurements. We used airborne HySpex VNIR-1800 data from spring 2018 and 2019 to compare vegetation condition at the onset of the drought with the state after one year. SiVM, an interpretable matrix factorisation technique, was used to derive typical extreme spectra (archetypes) from the hyperspectral data. The classification of archetypes allowed for the inference of qualitative drought stress levels. The results were evaluated using a set of geophysical measurements and vegetation indices as proxy variables for drought-inhibited vegetation growth. The successful application of SiVM for grassland stress detection at the ecosystem canopy scale was verified in a correlation analysis. The predictor importance was assessed with boosted beta regression. In the resulting interannual stress model, carotenoid-related variables had among the highest coefficient values. The significance of the photochemical reflectance index that uses 512 nm as reference wavelength (PRI512) demonstrates the value of combining imaging spectrometry and unsupervised learning for the monitoring of vegetation stress. It also shows the potential of archetypical reflectance spectra to be used for the remote estimation of photosynthetic efficiency. More conclusive results could be achieved by using vegetation measurements instead of proxy variables for evaluation. It must also be investigated how the method can be generalised across ecosystems.
BibTeX:
@misc{Hermanns2021,
  author = {Hermanns, Floris and Pohl, Felix and Rebmann, Corinna and Schulz, Gundula and Werban, Ulrike and Lausch, Angela},
  title = {Inferring Grassland Drought Stress with Unsupervised Learning from Airborne Hyperspectral VNIR Imagery},
  booktitle = {Remote Sensing},
  year = {2021},
  volume = {13},
  number = {10},
  doi = {10.3390/rs13101885}
}
Holik L, Vranova V, Foltynova L and Acosta M (2021), "Forest soil properties under elevated CO2: A five-year experiment", European Journal of Soil Biology. Vol. 106, pp. 103346.
Abstract: Whether rising carbon dioxide (CO2) is causing changes in soil properties remains unclear. Therefore, the objective of our study was to determine the effects of elevated CO2 concentration on a mountain forest soil with respect to soil organic matter content and its quality, cation exchange capacity, nutrient availability and quantity, and activity of soil microbes. In our study, a young mountain beech–spruce forest soil was exposed to ambient (385 ppm) and elevated CO2 (700 ppm) concentrations for a 5-year period. We found that exposure of beech–spruce forest soil to elevated. CO2 over a 5-year period had no effect on the quantity of soil organic carbon or nitrogen or on the availability of nutrients. The cation exchange capacity decreased under both conditions, ambient and elevated CO2 (over a 5-year period). Changes in soil organic matter content, nutrient availability, and soil enzyme activities showed positive trend. Nevertheless, our results overall showed no significant impact of elevated CO2 on mountain beech-spruce forest soil through 5 years of exposure.
BibTeX:
@article{Holik2021,
  author = {Holik, Ladislav and Vranova, Valerie and Foltynova, Lenka and Acosta, Manuel},
  title = {Forest soil properties under elevated CO2: A five-year experiment},
  journal = {European Journal of Soil Biology},
  year = {2021},
  volume = {106},
  pages = {103346},
  url = {https://www.sciencedirect.com/science/article/pii/S1164556321000820},
  doi = {10.1016/j.ejsobi.2021.103346}
}
Holtmann A, Huth A, Pohl F, Rebmann C and Fischer R (2021), "Carbon Sequestration in Mixed Deciduous Forests: The Influence of Tree Size and Species Composition Derived from Model Experiments".
Abstract: Forests play an important role in climate regulation due to carbon sequestration. However, a deeper understanding of forest carbon flux dynamics is often missing due to a lack of information about forest structure and species composition, especially for non-even-aged and species-mixed forests. In this study, we integrated field inventory data of a species-mixed deciduous forest in Germany into an individual-based forest model to investigate daily carbon fluxes and to examine the role of tree size and species composition for stand productivity. This approach enables to reproduce daily carbon fluxes derived from eddy covariance measurements (R2 of 0.82 for gross primary productivity and 0.77 for ecosystem respiration). While medium-sized trees (stem diameter 30–60 cm) account for the largest share (66%) of total productivity at the study site, small (0–30 cm) and large trees (>60 cm) contribute less with 8.3% and 25.5% respectively. Simulation experiments indicate that vertical stand structure and shading influence forest productivity more than species composition. Hence, it is important to incorporate small-scale information about forest stand structure into modelling studies to decrease uncertainties of carbon dynamic predictions.
BibTeX:
@misc{Holtmann2021,
  author = {Holtmann, Anne and Huth, Andreas and Pohl, Felix and Rebmann, Corinna and Fischer, Rico},
  title = {Carbon Sequestration in Mixed Deciduous Forests: The Influence of Tree Size and Species Composition Derived from Model Experiments},
  booktitle = {Forests},
  year = {2021},
  volume = {12},
  number = {6},
  doi = {10.3390/f12060726}
}
Hrachowitz M, Stockinger M, Coenders-Gerrits M, van der Ent R, Bogena H, Lücke A and Stumpp C (2021), "Reduction of vegetation-accessible water storage capacity after deforestation affects catchment travel time distributions and increases young water fractions in a headwater catchment", Hydrology and Earth System Sciences. Vol. 25(9), pp. 4887-4915.
BibTeX:
@article{Hrachowitz2021,
  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 = {Reduction of vegetation-accessible water storage capacity after deforestation affects catchment travel time distributions and increases young water fractions in a headwater catchment},
  journal = {Hydrology and Earth System Sciences},
  year = {2021},
  volume = {25},
  number = {9},
  pages = {4887--4915},
  url = {https://hess.copernicus.org/articles/25/4887/2021/},
  doi = {10.5194/hess-25-4887-2021}
}
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}
}
Irvin J, Zhou S, McNicol G, Lu F, Liu V, Fluet-Chouinard E, Ouyang Z, Knox SH, Lucas-Moffat A, Trotta C, Papale D, Vitale D, Mammarella I, Alekseychik P, Aurela M, Avati A, Baldocchi D, Bansal S, Bohrer G, Campbell DI, Chen J, Chu H, Dalmagro HJ, Delwiche KB, Desai AR, Euskirchen E, Feron S, Goeckede M, Heimann M, Helbig M, Helfter C, Hemes KS, Hirano T, Iwata H, Jurasinski G, Kalhori A, Kondrich A, Lai DYF, Lohila A, Malhotra A, Merbold L, Mitra B, Ng A, Nilsson MB, Noormets A, Peichl M, Rey-Sanchez AC, Richardson AD, Runkle BRK, Schäfer KVR, Sonnentag O, Stuart-Haëntjens E, Sturtevant C, Ueyama M, Valach AC, Vargas R, Vourlitis GL, Ward EJ, Wong GX, Zona D, Alberto MCR, Billesbach DP, Celis G, Dolman H, Friborg T, Fuchs K, Gogo S, Gondwe MJ, Goodrich JP, Gottschalk P, Hörtnagl L, Jacotot A, Koebsch F, Kasak K, Maier R, Morin TH, Nemitz E, Oechel WC, Oikawa PY, Ono K, Sachs T, Sakabe A, Schuur EA, Shortt R, Sullivan RC, Szutu DJ, Tuittila E-S, Varlagin A, Verfaillie JG, Wille C, Windham-Myers L, Poulter B and Jackson RB (2021), "Gap-filling eddy covariance methane fluxes: Comparison of machine learning model predictions and uncertainties at FLUXNET-CH4 wetlands", Agricultural and Forest Meteorology. Vol. 308-309, pp. 108528.
Abstract: Time series of wetland methane fluxes measured by eddy covariance require gap-filling to estimate daily, seasonal, and annual emissions. Gap-filling methane fluxes is challenging because of high variability and complex responses to multiple drivers. To date, there is no widely established gap-filling standard for wetland methane fluxes, with regards both to the best model algorithms and predictors. This study synthesizes results of different gap-filling methods systematically applied at 17 wetland sites spanning boreal to tropical regions and including all major wetland classes and two rice paddies. Procedures are proposed for: 1) creating realistic artificial gap scenarios, 2) training and evaluating gap-filling models without overstating performance, and 3) predicting half-hourly methane fluxes and annual emissions with realistic uncertainty estimates. Performance is compared between a conventional method (marginal distribution sampling) and four machine learning algorithms. The conventional method achieved similar median performance as the machine learning models but was worse than the best machine learning models and relatively insensitive to predictor choices. Of the machine learning models, decision tree algorithms performed the best in cross-validation experiments, even with a baseline predictor set, and artificial neural networks showed comparable performance when using all predictors. Soil temperature was frequently the most important predictor whilst water table depth was important at sites with substantial water table fluctuations, highlighting the value of data on wetland soil conditions. Raw gap-filling uncertainties from the machine learning models were underestimated and we propose a method to calibrate uncertainties to observations. The python code for model development, evaluation, and uncertainty estimation is publicly available. This study outlines a modular and robust machine learning workflow and makes recommendations for, and evaluates an improved baseline of, methane gap-filling models that can be implemented in multi-site syntheses or standardized products from regional and global flux networks (e.g., FLUXNET).
BibTeX:
@article{Irvin2021,
  author = {Irvin, Jeremy and Zhou, Sharon and McNicol, Gavin and Lu, Fred and Liu, Vincent and Fluet-Chouinard, Etienne and Ouyang, Zutao and Knox, Sara Helen and Lucas-Moffat, Antje and Trotta, Carlo and Papale, Dario and Vitale, Domenico and Mammarella, Ivan and Alekseychik, Pavel and Aurela, Mika and Avati, Anand and Baldocchi, Dennis and Bansal, Sheel and Bohrer, Gil and Campbell, David I and Chen, Jiquan and Chu, Housen and Dalmagro, Higo J and Delwiche, Kyle B and Desai, Ankur R and Euskirchen, Eugenie and Feron, Sarah and Goeckede, Mathias and Heimann, Martin and Helbig, Manuel and Helfter, Carole and Hemes, Kyle S and Hirano, Takashi and Iwata, Hiroki and Jurasinski, Gerald and Kalhori, Aram and Kondrich, Andrew and Lai, Derrick Y F and Lohila, Annalea and Malhotra, Avni and Merbold, Lutz and Mitra, Bhaskar and Ng, Andrew and Nilsson, Mats B and Noormets, Asko and Peichl, Matthias and Rey-Sanchez, A Camilo and Richardson, Andrew D and Runkle, Benjamin R K and Schäfer, Karina V R and Sonnentag, Oliver and Stuart-Haëntjens, Ellen and Sturtevant, Cove and Ueyama, Masahito and Valach, Alex C and Vargas, Rodrigo and Vourlitis, George L and Ward, Eric J and Wong, Guan Xhuan and Zona, Donatella and Alberto, Ma. Carmelita R and Billesbach, David P and Celis, Gerardo and Dolman, Han and Friborg, Thomas and Fuchs, Kathrin and Gogo, Sébastien and Gondwe, Mangaliso J and Goodrich, Jordan P and Gottschalk, Pia and Hörtnagl, Lukas and Jacotot, Adrien and Koebsch, Franziska and Kasak, Kuno and Maier, Regine and Morin, Timothy H and Nemitz, Eiko and Oechel, Walter C and Oikawa, Patricia Y and Ono, Keisuke and Sachs, Torsten and Sakabe, Ayaka and Schuur, Edward A and Shortt, Robert and Sullivan, Ryan C and Szutu, Daphne J and Tuittila, Eeva-Stiina and Varlagin, Andrej and Verfaillie, Joeseph G and Wille, Christian and Windham-Myers, Lisamarie and Poulter, Benjamin and Jackson, Robert B},
  title = {Gap-filling eddy covariance methane fluxes: Comparison of machine learning model predictions and uncertainties at FLUXNET-CH4 wetlands},
  journal = {Agricultural and Forest Meteorology},
  year = {2021},
  volume = {308-309},
  pages = {108528},
  url = {https://www.sciencedirect.com/science/article/pii/S0168192321002124},
  doi = {10.1016/j.agrformet.2021.108528}
}
Jackson TD, Sethi S, Dellwik E, Angelou N, Bunce A, van Emmerik T, Duperat M, Ruel J-C, Wellpott A, Van Bloem S, Achim A, Kane B, Ciruzzi DM, Loheide II SP, James K, Burcham D, Moore J, Schindler D, Kolbe S, Wiegmann K, Rudnicki M, Lieffers VJ, Selker J, Gougherty AV, Newson T, Koeser A, Miesbauer J, Samelson R, Wagner J, Ambrose AR, Detter A, Rust S, Coomes D and Gardiner B (2021), "The motion of trees in the wind: a data synthesis", Biogeosciences. Vol. 18(13), pp. 4059-4072.
BibTeX:
@article{Jackson2021,
  author = {Jackson, T D and Sethi, S and Dellwik, E and Angelou, N and Bunce, A and van Emmerik, T and Duperat, M and Ruel, J.-C. and Wellpott, A and Van Bloem, S and Achim, A and Kane, B and Ciruzzi, D M and Loheide II, S P and James, K and Burcham, D and Moore, J and Schindler, D and Kolbe, S and Wiegmann, K and Rudnicki, M and Lieffers, V J and Selker, J and Gougherty, A V and Newson, T and Koeser, A and Miesbauer, J and Samelson, R and Wagner, J and Ambrose, A R and Detter, A and Rust, S and Coomes, D and Gardiner, B},
  title = {The motion of trees in the wind: a data synthesis},
  journal = {Biogeosciences},
  year = {2021},
  volume = {18},
  number = {13},
  pages = {4059--4072},
  url = {https://bg.copernicus.org/articles/18/4059/2021/},
  doi = {10.5194/bg-18-4059-2021}
}
Jacobs E, Bittig HC, Gräwe U, Graves CA, Glockzin M, Müller JD, Schneider B and Rehder G (2021), "Upwelling-induced trace gas dynamics in the Baltic Sea inferred from 8∼years of autonomous measurements on a ship of opportunity", Biogeosciences. Vol. 18(8), pp. 2679-2709.
BibTeX:
@article{Jacobs2021,
  author = {Jacobs, E and Bittig, H C and Gräwe, U and Graves, C A and Glockzin, M and Müller, J D and Schneider, B and Rehder, G},
  title = {Upwelling-induced trace gas dynamics in the Baltic Sea inferred from 8∼years of autonomous measurements on a ship of opportunity},
  journal = {Biogeosciences},
  year = {2021},
  volume = {18},
  number = {8},
  pages = {2679--2709},
  url = {https://bg.copernicus.org/articles/18/2679/2021/},
  doi = {10.5194/bg-18-2679-2021}
}
Johnston ASA, Meade A, Ardö J, Arriga N, Black A, Blanken PD, Bonal D, Brümmer C, Cescatti A, Dušek J, Graf A, Gioli B, Goded I, Gough CM, Ikawa H, Jassal R, Kobayashi H, Magliulo V, Manca G, Montagnani L, Moyano FE, Olesen JE, Sachs T, Shao C, Tagesson T, Wohlfahrt G, Wolf S, Woodgate W, Varlagin A and Venditti C (2021), "Temperature thresholds of ecosystem respiration at a global scale", Nature Ecology & Evolution., apr, 2021. Vol. 5(4), pp. 487-494.
BibTeX:
@article{Johnston2021,
  author = {Johnston, Alice S A and Meade, Andrew and Ardö, Jonas and Arriga, Nicola and Black, Andy and Blanken, Peter D and Bonal, Damien and Brümmer, Christian and Cescatti, Alessandro and Dušek, Jiří and Graf, Alexander and Gioli, Beniamino and Goded, Ignacio and Gough, Christopher M and Ikawa, Hiroki and Jassal, Rachhpal and Kobayashi, Hideki and Magliulo, Vincenzo and Manca, Giovanni and Montagnani, Leonardo and Moyano, Fernando E and Olesen, Jørgen E and Sachs, Torsten and Shao, Changliang and Tagesson, Torbern and Wohlfahrt, Georg and Wolf, Sebastian and Woodgate, William and Varlagin, Andrej and Venditti, Chris},
  title = {Temperature thresholds of ecosystem respiration at a global scale},
  journal = {Nature Ecology & Evolution},
  year = {2021},
  volume = {5},
  number = {4},
  pages = {487--494},
  url = {http://www.nature.com/articles/s41559-021-01398-z},
  doi = {10.1038/s41559-021-01398-z}
}
Junttila S, Kelly J, Kljun N, Aurela M, Klemedtsson L, Lohila A, Nilsson M, Rinne J, Tuittila E-S, Vestin P, Weslien P and Eklundh L (2021), "Upscaling Northern Peatland CO2 Fluxes Using Satellite Remote Sensing Data", Remote Sensing., feb, 2021. Vol. 13(4), pp. 818.
Abstract: Peatlands play an important role in the global carbon cycle as they contain a large soil carbon stock. However, current climate change could potentially shift peatlands from being carbon sinks to carbon sources. Remote sensing methods provide an opportunity to monitor carbon dioxide (CO2) exchange in peatland ecosystems at large scales under these changing conditions. In this study, we developed empirical models of the CO2 balance (net ecosystem exchange, NEE), gross primary production (GPP), and ecosystem respiration (ER) that could be used for upscaling CO2 fluxes with remotely sensed data. Two to three years of eddy covariance (EC) data from five peatlands in Sweden and Finland were compared to modelled NEE, GPP and ER based on vegetation indices from 10 m resolution Sentinel-2 MSI and land surface temperature from 1 km resolution MODIS data. To ensure a precise match between the EC data and the Sentinel-2 observations, a footprint model was applied to derive footprint-weighted daily means of the vegetation indices. Average model parameters for all sites were acquired with a leave-one-out-cross-validation procedure. Both the GPP and the ER models gave high agreement with the EC-derived fluxes (R2 = 0.70 and 0.56, NRMSE = 14% and 15%, respectively). The performance of the NEE model was weaker (average R2 = 0.36 and NRMSE = 13%). Our findings demonstrate that using optical and thermal satellite sensor data is a feasible method for upscaling the GPP and ER of northern boreal peatlands, although further studies are needed to investigate the sources of the unexplained spatial and temporal variation of the CO2 fluxes.
BibTeX:
@article{Junttila2021,
  author = {Junttila, Sofia and Kelly, Julia and Kljun, Natascha and Aurela, Mika and Klemedtsson, Leif and Lohila, Annalea and Nilsson, Mats and Rinne, Janne and Tuittila, Eeva-Stiina and Vestin, Patrik and Weslien, Per and Eklundh, Lars},
  title = {Upscaling Northern Peatland CO2 Fluxes Using Satellite Remote Sensing Data},
  journal = {Remote Sensing},
  year = {2021},
  volume = {13},
  number = {4},
  pages = {818},
  url = {https://www.mdpi.com/2072-4292/13/4/818},
  doi = {10.3390/rs13040818}
}
Jurečka F, Fischer M, Hlavinka P, Balek J, Semerádová D, Bláhová M, Anderson MC, Hain C, Žalud Z and Trnka M (2021), "Potential of water balance and remote sensing-based evapotranspiration models to predict yields of spring barley and winter wheat in the Czech Republic", Agricultural Water Management. Vol. 256, pp. 107064.
Abstract: Indicators based on evapotranspiration (ET) provide useful information about surface water status, response of vegetation to drought stress, and potential growth limitations. The capability of ET-based indicators, including actual ET and the evaporative stress index (ESI), to predict crop yields of spring barley and winter wheat was analyzed for 33 districts of the Czech Republic. In this study, the ET-based indicators were computed using two different approaches: (i) a prognostic model, SoilClim, which computes the water balance based on ground weather observations and information about soil and land cover; (ii) the diagnostic Atmosphere–Land Exchange Inverse (ALEXI) model based primarily on remotely sensed land surface temperature data. The capability of both sets of indicators to predict yields of spring barley and winter wheat was tested using artificial neural networks (ANNs) applied to the adjusting number and timeframe of inputs during the growing season. Yield predictions based on ANNs were computed for both crops for all districts together, as well as for individual districts. The root mean square error (RMSE) and coefficient of determination (R2) between observed and predicted yields varied with date within the growing season and with the number of ANN inputs used for yield prediction. The period with the highest predictive capability started from early-June to mid-June. This optimal period for yield prediction was identifiable already at the lower number of ANN inputs, nevertheless, the accuracy of the prediction improved as more inputs were included within ANNs.The RMSE values for individual districts varied between 0.4 and 0.7 t ha–1 while R2 reached values of 0.5–0.8 during the optimal period. Results of the study demonstrated that ET-based indicators can be used for yield prediction in real time during the growing season and therefore have great potential for decision making at regional and district levels.
BibTeX:
@article{Jurecka2021,
  author = {Jurečka, František and Fischer, Milan and Hlavinka, Petr and Balek, Jan and Semerádová, Daniela and Bláhová, Monika and Anderson, Martha C and Hain, Christopher and Žalud, Zdeněk and Trnka, Miroslav},
  title = {Potential of water balance and remote sensing-based evapotranspiration models to predict yields of spring barley and winter wheat in the Czech Republic},
  journal = {Agricultural Water Management},
  year = {2021},
  volume = {256},
  pages = {107064},
  url = {https://www.sciencedirect.com/science/article/pii/S0378377421003292},
  doi = {10.1016/j.agwat.2021.107064}
}
Keane JB, Toet S, Ineson P, Weslien P, Stockdale JE and Klemedtsson L (2021), "Carbon Dioxide and Methane Flux Response and Recovery From Drought in a Hemiboreal Ombrotrophic Fen", Frontiers in Earth Science. Vol. 8
Abstract: Globally peatlands store 500 Gt carbon (C), with northern blanket bogs accumulating 23 g C m−2 y−1 due to cool wet conditions. As a sink of carbon dioxide (CO2) peat bogs slow anthropogenic climate change, but warming climate increases the likelihood of drought which may reduce net ecosystem exchange (NEE) and increase soil respiration, tipping C sinks to sources. High water tables make bogs a globally important source of methane (CH4), another greenhouse gas (GHG) with a global warming potential (GWP) 34 times that of CO2. Warming may increase CH4 emissions, but drying may cause a reduction. Predicted species composition changes may also influence GHG balance, due to different traits such as erenchyma, e.g., Eriophorum vaginatum (eriophorum) and non-aerenchymatous species, e.g., Calluna vulgaris (heather). To understand how these ecosystems will respond to climate change, it is vital to measure GHG responses to drought at the species level. An automated chamber system, SkyLine2D, measured NEE and CH4 fluxes near-continuously from an ombrotrophic fen from August 2017 to September 2019. Four ecotypes were identified: sphagnum (Sphagnum spp), eriophorum, heather and water, hypothesizing that fluxes would significantly differ between ecotypes. The 2018 drought allowed comparison of fluxes between drought and non-drought years (May to September), and their recovery the following year. Methane emissions differed between ecotypes (p < 0.02), ordered high to low: eriophorum > sphagnum > water > heather, ranging from 23 to 8 mg CH4-C m−2 d−1. Daily NEE was similar between ecotypes (p > 0.7), but under 2018 drought conditions all ecotypes were greater sources of CO2 compared to 2019, losing 1.14 g and 0.24 g CO2-C m−2 d−1 respectively (p < 0.001). CH4 emissions were ca. 40% higher during 2018 than 2019, 17 mg compared to 12 mg CH4-C m−2 d−1 (p < 0.0001), and fluxes exhibited hysteresis with water table depth. A lag of 84–88 days was observed between rising water table and increased CH4 emissions. A significant interaction between ecotype and year showed fluxes from open water did not return to pre-drought levels. Our findings suggest that short-term drought may lead to a net increase in C emissions from northern wetlands.
BibTeX:
@article{Keane2021,
  author = {Keane, J B and Toet, S and Ineson, P and Weslien, P and Stockdale, J E and Klemedtsson, L},
  title = {Carbon Dioxide and Methane Flux Response and Recovery From Drought in a Hemiboreal Ombrotrophic Fen},
  journal = {Frontiers in Earth Science},
  year = {2021},
  volume = {8},
  url = {https://www.frontiersin.org/article/10.3389/feart.2020.562401},
  doi = {10.3389/feart.2020.562401}
}
Kelly J, Kljun N, Eklundh L, Klemedtsson L, Liljebladh B, Olsson P-O, Weslien P and Xie X (2021), "Modelling and upscaling ecosystem respiration using thermal cameras and UAVs: Application to a peatland during and after a hot drought", Agricultural and Forest Meteorology., apr, 2021. Vol. 300, pp. 108330.
BibTeX:
@article{Kelly2021,
  author = {Kelly, Julia and Kljun, Natascha and Eklundh, Lars and Klemedtsson, Leif and Liljebladh, Bengt and Olsson, Per-Ola and Weslien, Per and Xie, Xianghua},
  title = {Modelling and upscaling ecosystem respiration using thermal cameras and UAVs: Application to a peatland during and after a hot drought},
  journal = {Agricultural and Forest Meteorology},
  year = {2021},
  volume = {300},
  pages = {108330},
  url = {https://linkinghub.elsevier.com/retrieve/pii/S0168192321000137},
  doi = {10.1016/j.agrformet.2021.108330}
}
Kim D, Baik J, Umair M and Choi M (2021), "Water use efficiency in terrestrial ecosystem over East Asia: Effects of climate regimes and land cover types", Science of The Total Environment. Vol. 773, pp. 145519.
Abstract: Water use efficiency (WUE) is an environmental factor to account for the metabolism of terrestrial ecosystems using various climate systems and vegetation types. It is estimated by the ratio of gross primary productivity (GPP) to evapotranspiration (ET), the largest carbon and water fluxes with respect to plant respiration. In this study, the WUE was calculated using GPP and ET from the community land model version 4.0 (CLM4.0), inclusive of the prognostic carbon-nitrogen model in the community earth system model (CESM). The estimated WUE in East Asia was analyzed for climate zones, land cover types, and water- and energy-limited zones, with aridity index (AI). Spatial variations from 2001 to 2015 in annual WUE gradually increased as latitude decreased, though small year-to-year differences appeared between monthly GPP and ET. Monthly WUE was lower in summer than fall because the water loss rate in summer was higher than the carbon assimilation increase. The WUE under arid conditions (AI<0.5) was lower than under humid conditions. The GPP, ET, and WUE were higher in the forest, savannas, cropland, and permanent wetland with dense vegetation or abundant water resources than in other land cover types. The WUE was lower in water-limited zones than in energy-limited zones due to the low amount of water to use for the physical processes of GPP and ET. Based on this study, we identified general spatial and temporal variations of carbon fluxes in East Asia with various climate zones and land cover types.
BibTeX:
@article{Kim2021,
  author = {Kim, Daeun and Baik, Jongjin and Umair, Muhammad and Choi, Minha},
  title = {Water use efficiency in terrestrial ecosystem over East Asia: Effects of climate regimes and land cover types},
  journal = {Science of The Total Environment},
  year = {2021},
  volume = {773},
  pages = {145519},
  url = {https://www.sciencedirect.com/science/article/pii/S0048969721005878},
  doi = {10.1016/j.scitotenv.2021.145519}
}
Kluge M, Wauthy M, Clemmensen KE, Wurzbacher C, Hawkes JA, Einarsdottir K, Rautio M, Stenlid J and Peura S (2021), "Declining fungal diversity in Arctic freshwaters along a permafrost thaw gradient", Global Change Biology., nov, 2021. Vol. 27(22), pp. 5889-5906. John Wiley & Sons, Ltd.
Abstract: Abstract Climate change?driven permafrost thaw has a strong influence on pan-Arctic regions, via, for example, the formation of thermokarst ponds. These ponds are hotspots of microbial carbon cycling and greenhouse gas production, and efforts have been put on disentangling the role of bacteria and archaea in recycling the increasing amounts of carbon arriving to the ponds from degrading watersheds. However, despite the well-established role of fungi in carbon cycling in the terrestrial environments, the interactions between permafrost thaw and fungal communities in Arctic freshwaters have remained unknown. We integrated data from 60 ponds in Arctic hydro-ecosystems, representing a gradient of permafrost integrity and spanning over five regions, namely Alaska, Greenland, Canada, Sweden, and Western Siberia. The results revealed that differences in pH and organic matter quality and availability were linked to distinct fungal community compositions and that a large fraction of the community represented unknown fungal phyla. Results display a 16%?19% decrease in fungal diversity, assessed by beta diversity, across ponds in landscapes with more degraded permafrost. At the same time, sites with similar carbon quality shared more species, aligning a shift in species composition with the quality and availability of terrestrial dissolved organic matter. We demonstrate that the degradation of permafrost has a strong negative impact on aquatic fungal diversity, likely via interactions with the carbon pool released from ancient deposits. This is expected to have implications for carbon cycling and climate feedback loops in the rapidly warming Arctic.
BibTeX:
@article{Kluge2021,
  author = {Kluge, Mariana and Wauthy, Maxime and Clemmensen, Karina Engelbrecht and Wurzbacher, Christian and Hawkes, Jeffrey A and Einarsdottir, Karolina and Rautio, Milla and Stenlid, Jan and Peura, Sari},
  title = {Declining fungal diversity in Arctic freshwaters along a permafrost thaw gradient},
  journal = {Global Change Biology},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {27},
  number = {22},
  pages = {5889--5906},
  url = {https://doi.org/10.1111/gcb.15852},
  doi = {10.1111/gcb.15852}
}
Kluge M, Wurzbacher C, Wauthy M, Clemmensen KE, Hawkes JA, Einarsdottir K, Stenlid J and Peura S (2021), "Community composition of aquatic fungi across the thawing Arctic", Scientific Data. Vol. 8(1), pp. 221.
Abstract: Thermokarst activity at permafrost sites releases considerable amounts of ancient carbon to the atmosphere. A large part of this carbon is released via thermokarst ponds, and fungi could be an important organismal group enabling its recycling. However, our knowledge about aquatic fungi in thermokarstic systems is extremely limited. In this study, we collected samples from five permafrost sites distributed across circumpolar Arctic and representing different stages of permafrost integrity. Surface water samples were taken from the ponds and, additionally, for most of the ponds also the detritus and sediment samples were taken. All the samples were extracted for total DNA, which was then amplified for the fungal ITS2 region of the ribosomal genes. These amplicons were sequenced using PacBio technology. Water samples were also collected to analyze the chemical conditions in the ponds, including nutrient status and the quality and quantity of dissolved organic carbon. This dataset gives a unique overview of the impact of the thawing permafrost on fungal communities and their potential role on carbon recycling.
BibTeX:
@article{Kluge2021a,
  author = {Kluge, Mariana and Wurzbacher, Christian and Wauthy, Maxime and Clemmensen, Karina Engelbrecht and Hawkes, Jeffrey Alistair and Einarsdottir, Karolina and Stenlid, Jan and Peura, Sari},
  title = {Community composition of aquatic fungi across the thawing Arctic},
  journal = {Scientific Data},
  year = {2021},
  volume = {8},
  number = {1},
  pages = {221},
  url = {https://doi.org/10.1038/s41597-021-01005-7},
  doi = {10.1038/s41597-021-01005-7}
}
Knox SH, Bansal S, McNicol G, Schafer K, Sturtevant C, Ueyama M, Valach AC, Baldocchi D, Delwiche K, Desai AR, Euskirchen E, Liu J, Lohila A, Malhotra A, Melling L, Riley W, Runkle BRK, Turner J, Vargas R, Zhu Q, Alto T, Fluet-Chouinard E, Goeckede M, Melton JR, Sonnentag O, Vesala T, Ward E, Zhang Z, Feron S, Ouyang Z, Alekseychik P, Aurela M, Bohrer G, Campbell DI, Chen J, Chu H, Dalmagro HJ, Goodrich JP, Gottschalk P, Hirano T, Iwata H, Jurasinski G, Kang M, Koebsch F, Mammarella I, Nilsson MB, Ono K, Peichl M, Peltola O, Ryu Y, Sachs T, Sakabe A, Sparks JP, Tuittila E-S, Vourlitis GL, Wong GX, Windham-Myers L, Poulter B and Jackson RB (2021), "Identifying dominant environmental predictors of freshwater wetland methane fluxes across diurnal to seasonal time scales", Global Change Biology., aug, 2021. Vol. 27(15), pp. 3582-3604. John Wiley & Sons, Ltd.
Abstract: Abstract While wetlands are the largest natural source of methane (CH4) to the atmosphere, they represent a large source of uncertainty in the global CH4 budget due to the complex biogeochemical controls on CH4 dynamics. Here we present, to our knowledge, the first multi-site synthesis of how predictors of CH4 fluxes (FCH4) in freshwater wetlands vary across wetland types at diel, multiday (synoptic), and seasonal time scales. We used several statistical approaches (correlation analysis, generalized additive modeling, mutual information, and random forests) in a wavelet-based multi-resolution framework to assess the importance of environmental predictors, nonlinearities and lags on FCH4 across 23 eddy covariance sites. Seasonally, soil and air temperature were dominant predictors of FCH4 at sites with smaller seasonal variation in water table depth (WTD). In contrast, WTD was the dominant predictor for wetlands with smaller variations in temperature (e.g., seasonal tropical/subtropical wetlands). Changes in seasonal FCH4 lagged fluctuations in WTD by ∼17 ± 11 days, and lagged air and soil temperature by median values of 8 ± 16 and 5 ± 15 days, respectively. Temperature and WTD were also dominant predictors at the multiday scale. Atmospheric pressure (PA) was another important multiday scale predictor for peat-dominated sites, with drops in PA coinciding with synchronous releases of CH4. At the diel scale, synchronous relationships with latent heat flux and vapor pressure deficit suggest that physical processes controlling evaporation and boundary layer mixing exert similar controls on CH4 volatilization, and suggest the influence of pressurized ventilation in aerenchymatous vegetation. In addition, 1- to 4-h lagged relationships with ecosystem photosynthesis indicate recent carbon substrates, such as root exudates, may also control FCH4. By addressing issues of scale, asynchrony, and nonlinearity, this work improves understanding of the predictors and timing of wetland FCH4 that can inform future studies and models, and help constrain wetland CH4 emissions.
BibTeX:
@article{Knox2021,
  author = {Knox, Sara H and Bansal, Sheel and McNicol, Gavin and Schafer, Karina and Sturtevant, Cove and Ueyama, Masahito and Valach, Alex C and Baldocchi, Dennis and Delwiche, Kyle and Desai, Ankur R and Euskirchen, Eugenie and Liu, Jinxun and Lohila, Annalea and Malhotra, Avni and Melling, Lulie and Riley, William and Runkle, Benjamin R K and Turner, Jessica and Vargas, Rodrigo and Zhu, Qing and Alto, Tuula and Fluet-Chouinard, Etienne and Goeckede, Mathias and Melton, Joe R and Sonnentag, Oliver and Vesala, Timo and Ward, Eric and Zhang, Zhen and Feron, Sarah and Ouyang, Zutao and Alekseychik, Pavel and Aurela, Mika and Bohrer, Gil and Campbell, David I and Chen, Jiquan and Chu, Housen and Dalmagro, Higo J and Goodrich, Jordan P and Gottschalk, Pia and Hirano, Takashi and Iwata, Hiroki and Jurasinski, Gerald and Kang, Minseok and Koebsch, Franziska and Mammarella, Ivan and Nilsson, Mats B and Ono, Keisuke and Peichl, Matthias and Peltola, Olli and Ryu, Youngryel and Sachs, Torsten and Sakabe, Ayaka and Sparks, Jed P and Tuittila, Eeva-Stiina and Vourlitis, George L and Wong, Guan X and Windham-Myers, Lisamarie and Poulter, Benjamin and Jackson, Robert B},
  title = {Identifying dominant environmental predictors of freshwater wetland methane fluxes across diurnal to seasonal time scales},
  journal = {Global Change Biology},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {27},
  number = {15},
  pages = {3582--3604},
  url = {https://doi.org/10.1111/gcb.15661},
  doi = {10.1111/gcb.15661}
}
Kooijmans LMJ, Cho A, Ma J, Kaushik A, Haynes KD, Baker I, Luijkx IT, Groenink M, Peters W, Miller JB, Berry JA, Ogée J, Meredith LK, Sun W, Kohonen K-M, Vesala T, Mammarella I, Chen H, Spielmann FM, Wohlfahrt G, Berkelhammer M, Whelan ME, Maseyk K, Seibt U, Commane R, Wehr R and Krol M (2021), "Evaluation of carbonyl sulfide biosphere exchange in the Simple Biosphere Model (SiB4)", Biogeosciences. Vol. 18(24), pp. 6547-6565.
BibTeX:
@article{Kooijmans2021,
  author = {Kooijmans, L M J and Cho, A and Ma, J and Kaushik, A and Haynes, K D and Baker, I and Luijkx, I T and Groenink, M and Peters, W and Miller, J B and Berry, J A and Ogée, J and Meredith, L K and Sun, W and Kohonen, K.-M. and Vesala, T and Mammarella, I and Chen, H and Spielmann, F M and Wohlfahrt, G and Berkelhammer, M and Whelan, M E and Maseyk, K and Seibt, U and Commane, R and Wehr, R and Krol, M},
  title = {Evaluation of carbonyl sulfide biosphere exchange in the Simple Biosphere Model (SiB4)},
  journal = {Biogeosciences},
  year = {2021},
  volume = {18},
  number = {24},
  pages = {6547--6565},
  url = {https://bg.copernicus.org/articles/18/6547/2021/},
  doi = {10.5194/bg-18-6547-2021}
}
Krich C, Migliavacca M, Miralles DG, Kraemer G, El-Madany TS, Reichstein M, Runge J and Mahecha MD (2021), "Functional convergence of biosphere--atmosphere interactions in response to meteorological conditions", Biogeosciences. Vol. 18(7), pp. 2379-2404.
BibTeX:
@article{Krich2021,
  author = {Krich, C and Migliavacca, M and Miralles, D G and Kraemer, G and El-Madany, T S and Reichstein, M and Runge, J and Mahecha, M D},
  title = {Functional convergence of biosphere--atmosphere interactions in response to meteorological conditions},
  journal = {Biogeosciences},
  year = {2021},
  volume = {18},
  number = {7},
  pages = {2379--2404},
  url = {https://bg.copernicus.org/articles/18/2379/2021/},
  doi = {10.5194/bg-18-2379-2021}
}
Lammirato C, Wallman M, Weslien P, Klemedtsson L and Rütting T (2021), "Measuring frequency and accuracy of annual nitrous oxide emission estimates", Agricultural and Forest Meteorology. Vol. 310, pp. 108624.
Abstract: Accurate estimates of cumulative N2O fluxes from agricultural soil are essential for quantifying global N2O emissions and for identifying effective mitigation strategies. This study focuses on the short term temporal variability of N2O fluxes, and on how the accuracy of annual cumulative estimates is affected by different (simulated) measuring frequencies of an automatic system based on the closed chamber method. Fluxes were measured with high temporal resolution (24 per day) for approximately one year on agricultural soil in the southwest of Sweden. The short-term temporal variability of N2O fluxes was considerable: the predictive power of measured fluxes decreased to negligible levels in a time frame of 4-5 h, and large intraday flux ranges were observed frequently, particularly in days with soil temperatures below 0∘C. A time of day well suited for consistently providing good estimates of the mean daily flux could not be identified. Consequently, the accuracy of annual emission estimates strongly depended on the measuring frequency. Multiple measurements per day were necessary for consistently quantifying annual emission estimates with accuracy. Accuracy improved with measuring frequency increasing up to four times per day, and higher frequencies generated negligible further improvements. Based on this study the following recommendations are made with regard to measuring frequency: i) measure four times per day for maximum accuracy and ii) measure twice per day for a good compromise between accuracy and the number of plots that can be monitored.
BibTeX:
@article{Lammirato2021,
  author = {Lammirato, C and Wallman, M and Weslien, P and Klemedtsson, L and Rütting, T},
  title = {Measuring frequency and accuracy of annual nitrous oxide emission estimates},
  journal = {Agricultural and Forest Meteorology},
  year = {2021},
  volume = {310},
  pages = {108624},
  url = {https://www.sciencedirect.com/science/article/pii/S0168192321003105},
  doi = {10.1016/j.agrformet.2021.108624}
}
Lau DCP, Jonsson A, Isles PDF, Creed IF and Bergström A (2021), "Lowered nutritional quality of plankton caused by global environmental changes", Global Change Biology., dec, 2021. Vol. 27(23), pp. 6294-6306. John Wiley & Sons, Ltd.
Abstract: Abstract Global environmental changes are causing widespread nutrient depletion, declines in the ratio of dissolved inorganic nitrogen (N) to total phosphorus (DIN:TP), and increases in both water temperature and terrestrial colored dissolved organic carbon (DOC) concentration (browning) in high-latitude northern lakes. Declining lake DIN:TP, warming, and browning alter the nutrient limitation regime and biomass of phytoplankton, but how these stressors together affect the nutritional quality in terms of polyunsaturated fatty acid (PUFA) contents of the pelagic food web components remains unknown. We assessed the fatty acid compositions of seston and zooplankton in 33 lakes across south-to-north and boreal-to-subarctic gradients in Sweden. Data showed higher lake DIN:TP in the south than in the north, and that boreal lakes were warmer and browner than subarctic lakes. Lake DIN:TP strongly affected the PUFA contents?especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)?in seston, calanoids, and copepods (as a group), but not in cladocerans. The EPA+DHA contents increased by 123% in seston, 197% in calanoids, and 230% in copepods across a lake molar DIN:TP gradient from 0.17 to 14.53, indicating lower seston and copepod nutritional quality in the more N-limited lakes (those with lower DIN:TP). Water temperature affected EPA+DHA contents of zooplankton, especially cladocerans, but not seston. Cladoceran EPA+DHA contents were reduced by ca. 6% for every 1°C increase in surface water. Also, the EPA, DHA, or EPA+DHA contents of Bosmina, cyclopoids, and copepods increased in lakes with higher DOC concentrations or aromaticity. Our findings indicate that zooplankton food quality for higher consumers will decrease with warming alone (for cladocerans) or in combination with declining lake DIN:TP (for copepods), but impacts of these stressors are moderated by lake browning. Global environmental changes that drive northern lakes toward more N-limited, warmer, and browner conditions will reduce PUFA availability and nutritional quality of the pelagic food web components.
BibTeX:
@article{Lau2021,
  author = {Lau, Danny C P and Jonsson, Anders and Isles, Peter D F and Creed, Irena F and Bergström, Ann‑Kristin},
  title = {Lowered nutritional quality of plankton caused by global environmental changes},
  journal = {Global Change Biology},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {27},
  number = {23},
  pages = {6294--6306},
  url = {https://doi.org/10.1111/gcb.15887},
  doi = {10.1111/gcb.15887}
}
Laudon H, Hasselquist EM, Peichl M, Lindgren K, Sponseller R, Lidman F, Kuglerová L, Hasselquist NJ, Bishop K, Nilsson MB and Ågren AM (2021), "Northern landscapes in transition: Evidence, approach and ways forward using the Krycklan Catchment Study", Hydrological Processes., apr, 2021. Vol. 35(4), pp. e14170. John Wiley & Sons, Ltd.
Abstract: Abstract Improving our ability to detect changes in terrestrial and aquatic systems is a grand challenge in the environmental sciences. In a world experiencing increasingly rapid rates of climate change and ecosystem transformation, our ability to understand and predict how, when, where, and why changes occur is essential for adapting and mitigating human behaviours. In this context, long-term field research infrastructures have a fundamentally important role to play. For northern boreal landscapes, the Krycklan Catchment Study (KCS) has supported monitoring and research aimed at revealing these changes since it was initiated in 1980. Early studies focused on forest regeneration and microclimatic conditions, nutrient balances and forest hydrology, which included monitoring climate variables, water balance components, and stream water chemistry. The research infrastructure has expanded over the years to encompass a 6790?ha catchment, which currently includes 11 gauged streams, ca. 1000 soil lysimeters, 150 groundwater wells, >500 permanent forest inventory plots, and a 150 m tall tower (a combined ecosystem-atmosphere station of the ICOS, Integrated Carbon Observation System) for measurements of atmospheric gas concentrations and biosphere-atmosphere exchanges of carbon, water, and energy. In addition, the KCS has also been the focus of numerous high resolution multi-spectral LiDAR measurements and large scale experiments. This large collection of equipment and data generation supports a range of disciplinary studies, but more importantly fosters multi-, trans-, and interdisciplinary research opportunities. The KCS attracts a broad collection of scientists, including biogeochemists, ecologists, foresters, geologists, hydrologists, limnologists, soil scientists, and social scientists, all of whom bring their knowledge and experience to the site. The combination of long-term monitoring, shorter-term research projects, and large-scale experiments, including manipulations of climate and various forest management practices, has contributed much to our understanding of boreal landscape functioning, while also supporting the development of models and guidelines for research, policy, and management.
BibTeX:
@article{Laudon2021,
  author = {Laudon, Hjalmar and Hasselquist, Eliza Maher and Peichl, Matthias and Lindgren, Kim and Sponseller, Ryan and Lidman, Fredrik and Kuglerová, Lenka and Hasselquist, Niles J and Bishop, Kevin and Nilsson, Mats B and Ågren, Anneli M},
  title = {Northern landscapes in transition: Evidence, approach and ways forward using the Krycklan Catchment Study},
  journal = {Hydrological Processes},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {35},
  number = {4},
  pages = {e14170},
  url = {https://doi.org/10.1002/hyp.14170},
  doi = {10.1002/hyp.14170}
}
Lembrechts JJ, van den Hoogen J, Aalto J, Ashcroft MB, De Frenne P, Kemppinen J, Kopecký M, Luoto M, Maclean IMD, Crowther TW, Bailey JJ, Haesen S, Klinges DH, Niittynen P, Scheffers BR, Van Meerbeek K, Aartsma P, Abdalaze O, Abedi M, Aerts R, Ahmadian N, Ahrends A, Alatalo JM, Alexander JM, Allonsius CN, Altman J, Ammann C, Andres C, Andrews C, Ardö J, Arriga N, Arzac A, Aschero V, Assis RL, Assmann JJ, Bader MY, Bahalkeh K, Barančok P, Barrio IC, Barros A, Barthel M, Basham EW, Bauters M, Bazzichetto M, Marchesini LB, Bell MC, Benavides JC, Benito Alonso JL, Berauer BJ, Bjerke JW, Björk RG, Björkman MP, Björnsdóttir K, Blonder B, Boeckx P, Boike J, Bokhorst S, Brum BNS, Brůna J, Buchmann N, Buysse P, Camargo JL, Campoe OC, Candan O, Canessa R, Cannone N, Carbognani M, Carnicer J, Casanova-Katny A, Cesarz S, Chojnicki B, Choler P, Chown SL, Cifuentes EF, Čiliak M, Contador T, Convey P, Cooper EJ, Cremonese E, Curasi SR, Curtis R, Cutini M, Dahlberg CJ, Daskalova GN, de Pablo MA, Della Chiesa S, Dengler J, Deronde B, Descombes P, Di Cecco V, Di Musciano M, Dick J, Dimarco RD, Dolezal J, Dorrepaal E, Dušek J, Eisenhauer N, Eklundh L, Erickson TE, Erschbamer B, Eugster W, Ewers RM, Exton DA, Fanin N, Fazlioglu F, Feigenwinter I, Fenu G, Ferlian O, Fernández Calzado MR, Fernández-Pascual E, Finckh M, Higgens RF, Forte TGW, Freeman EC, Frei ER, Fuentes-Lillo E, García RA, García MB, Géron C, Gharun M, Ghosn D, Gigauri K, Gobin A, Goded I, Goeckede M, Gottschall F, Goulding K, Govaert S, Graae BJ, Greenwood S, Greiser C, Grelle A, Guénard B, Guglielmin M, Guillemot J, Haase P, Haider S, Halbritter AH, Hamid M, Hammerle A, Hampe A, Haugum SV, Hederová L, Heinesch B, Helfter C, Hepenstrick D, Herberich M, Herbst M, Hermanutz L, Hik DS, Hoffrén R, Homeier J, Hörtnagl L, Høye TT, Hrbacek F, Hylander K, Iwata H, Jackowicz-Korczynski MA, Jactel H, Järveoja J, Jastrzebowski S, Jentsch A, Jiménez JJ, Jónsdóttir IS, Jucker T, Jump AS, Juszczak R, Kanka R, Kašpar V, Kazakis G, Kelly J, Khuroo AA, Klemedtsson L, Klisz M, Kljun N, Knohl A, Kobler J, Kollár J, Kotowska MM, Kovács B, Kreyling J, Lamprecht A, Lang SI, Larson C, Larson K, Laska K, le Maire G, Leihy RI, Lens L, Liljebladh B, Lohila A, Lorite J, Loubet B, Lynn J, Macek M, Mackenzie R, Magliulo E, Maier R, Malfasi F, Máliš F, Man M, Manca G, Manco A, Manise T, Manolaki P, Marciniak F, Matula R, Mazzolari AC, Medinets S, Medinets V, Meeussen C, Merinero S, Mesquita RdCG, Meusburger K, Meysman FJR, Michaletz ST, Milbau A, Moiseev D, Moiseev P, Mondoni A, Monfries R, Montagnani L, Moriana-Armendariz M, Morra di Cella U, Mörsdorf M, Mosedale JR, Muffler L, Muñoz-Rojas M, Myers JA, Myers-Smith IH, Nagy L, Nardino M, Naujokaitis-Lewis I, Newling E, Nicklas L, Niedrist G, Niessner A, Nilsson MB, Normand S, Nosetto MD, Nouvellon Y, Nuñez MA, Ogaya R, Ogée J, Okello J, Olejnik J, Olesen JE, Opedal ØH, Orsenigo S, Palaj A, Pampuch T, Panov AV, Pärtel M, Pastor A, Pauchard A, Pauli H, Pavelka M, Pearse WD, Peichl M, Pellissier L, Penczykowski RM, Penuelas J, Petit Bon M, Petraglia A, Phartyal SS, Phoenix GK, Pio C, Pitacco A, Pitteloud C, Plichta R, Porro F, Portillo-Estrada M, Poulenard J, Poyatos R, Prokushkin AS, Puchalka R, Pușcaș M, Radujković D, Randall K, Ratier Backes A, Remmele S, Remmers W, Renault D, Risch AC, Rixen C, Robinson SA, Robroek BJM, Rocha AV, Rossi C, Rossi G, Roupsard O, Rubtsov AV, Saccone P, Sagot C, Sallo Bravo J, Santos CC, Sarneel JM, Scharnweber T, Schmeddes J, Schmidt M, Scholten T, Schuchardt M, Schwartz N, Scott T, Seeber J, Segalin de Andrade AC, Seipel T, Semenchuk P, Senior RA, Serra-Diaz JM, Sewerniak P, Shekhar A, Sidenko NV, Siebicke L, Siegwart Collier L, Simpson E, Siqueira DP, Sitková Z, Six J, Smiljanic M, Smith SW, Smith-Tripp S, Somers B, Sørensen MV, Souza JJLL, Souza BI, Souza Dias A, Spasojevic MJ, Speed JDM, Spicher F, Stanisci A, Steinbauer K, Steinbrecher R, Steinwandter M, Stemkovski M, Stephan JG, Stiegler C, Stoll S, Svátek M, Svoboda M, Tagesson T, Tanentzap AJ, Tanneberger F, Theurillat J-P, Thomas HJD, Thomas AD, Tielbörger K, Tomaselli M, Treier UA, Trouillier M, Turtureanu PD, Tutton R, Tyystjärvi VA, Ueyama M, Ujházy K, Ujházyová M, Uogintas D, Urban AV, Urban J, Urbaniak M, Ursu T-M, Vaccari FP, Van de Vondel S, van den Brink L, Van Geel M, Vandvik V, Vangansbeke P, Varlagin A, Veen GF, Veenendaal E, Venn SE, Verbeeck H, Verbrugggen E, Verheijen FGA, Villar L, Vitale L, Vittoz P, Vives-Ingla M, von Oppen J, Walz J, Wang R, Wang Y, Way RG, Wedegärtner REM, Weigel R, Wild J, Wilkinson M, Wilmking M, Wingate L, Winkler M, Wipf S, Wohlfahrt G, Xenakis G, Yang Y, Yu Z, Yu K, Zellweger F, Zhang J, Zhang Z, Zhao P, Ziembliʼnska K, Zimmermann R, Zong S, Zyryanov VI, Nijs I and Lenoir J (2021), "Global maps of soil temperature", Global Change Biology., dec, 2021. Vol. n/a(n/a) John Wiley & Sons, Ltd.
Abstract: Abstract Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km2 resolution for 0?5 and 5?15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km2 pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (?0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications.
BibTeX:
@article{Lembrechts2021,
  author = {Lembrechts, Jonas J and van den Hoogen, Johan and Aalto, Juha and Ashcroft, Michael B and De Frenne, Pieter and Kemppinen, Julia and Kopecký, Martin and Luoto, Miska and Maclean, Ilya M D and Crowther, Thomas W and Bailey, Joseph J and Haesen, Stef and Klinges, David H and Niittynen, Pekka and Scheffers, Brett R and Van Meerbeek, Koenraad and Aartsma, Peter and Abdalaze, Otar and Abedi, Mehdi and Aerts, Rien and Ahmadian, Negar and Ahrends, Antje and Alatalo, Juha M and Alexander, Jake M and Allonsius, Camille Nina and Altman, Jan and Ammann, Christof and Andres, Christian and Andrews, Christopher and Ardö, Jonas and Arriga, Nicola and Arzac, Alberto and Aschero, Valeria and Assis, Rafael L and Assmann, Jakob Johann and Bader, Maaike Y and Bahalkeh, Khadijeh and Barančok, Peter and Barrio, Isabel C and Barros, Agustina and Barthel, Matti and Basham, Edmund W and Bauters, Marijn and Bazzichetto, Manuele and Marchesini, Luca Belelli and Bell, Michael C and Benavides, Juan C and Benito Alonso, José Luis and Berauer, Bernd J and Bjerke, Jarle W and Björk, Robert G and Björkman, Mats P and Björnsdóttir, Katrin and Blonder, Benjamin and Boeckx, Pascal and Boike, Julia and Bokhorst, Stef and Brum, Bárbara N S and Brůna, Josef and Buchmann, Nina and Buysse, Pauline and Camargo, José Luís and Campoe, Otávio C and Candan, Onur and Canessa, Rafaella and Cannone, Nicoletta and Carbognani, Michele and Carnicer, Jofre and Casanova-Katny, Angélica and Cesarz, Simone and Chojnicki, Bogdan and Choler, Philippe and Chown, Steven L and Cifuentes, Edgar F and Čiliak, Marek and Contador, Tamara and Convey, Peter and Cooper, Elisabeth J and Cremonese, Edoardo and Curasi, Salvatore R and Curtis, Robin and Cutini, Maurizio and Dahlberg, C Johan and Daskalova, Gergana N and de Pablo, Miguel Angel and Della Chiesa, Stefano and Dengler, Jürgen and Deronde, Bart and Descombes, Patrice and Di Cecco, Valter and Di Musciano, Michele and Dick, Jan and Dimarco, Romina D and Dolezal, Jiri and Dorrepaal, Ellen and Dušek, Jiří and Eisenhauer, Nico and Eklundh, Lars and Erickson, Todd E and Erschbamer, Brigitta and Eugster, Werner and Ewers, Robert M and Exton, Dan A and Fanin, Nicolas and Fazlioglu, Fatih and Feigenwinter, Iris and Fenu, Giuseppe and Ferlian, Olga and Fernández Calzado, M Rosa and Fernández-Pascual, Eduardo and Finckh, Manfred and Higgens, Rebecca Finger and Forte, T'ai G W and Freeman, Erika C and Frei, Esther R and Fuentes-Lillo, Eduardo and García, Rafael A and García, María B and Géron, Charly and Gharun, Mana and Ghosn, Dany and Gigauri, Khatuna and Gobin, Anne and Goded, Ignacio and Goeckede, Mathias and Gottschall, Felix and Goulding, Keith and Govaert, Sanne and Graae, Bente Jessen and Greenwood, Sarah and Greiser, Caroline and Grelle, Achim and Guénard, Benoit and Guglielmin, Mauro and Guillemot, Joannès and Haase, Peter and Haider, Sylvia and Halbritter, Aud H and Hamid, Maroof and Hammerle, Albin and Hampe, Arndt and Haugum, Siri V and Hederová, Lucia and Heinesch, Bernard and Helfter, Carole and Hepenstrick, Daniel and Herberich, Maximiliane and Herbst, Mathias and Hermanutz, Luise and Hik, David S and Hoffrén, Raúl and Homeier, Jürgen and Hörtnagl, Lukas and Høye, Toke T and Hrbacek, Filip and Hylander, Kristoffer and Iwata, Hiroki and Jackowicz-Korczynski, Marcin Antoni and Jactel, Hervé and Järveoja, Järvi and Jastrzebowski, Szymon and Jentsch, Anke and Jiménez, Juan J and Jónsdóttir, Ingibjörg S and Jucker, Tommaso and Jump, Alistair S and Juszczak, Radoslaw and Kanka, Róbert and Kašpar, Vít and Kazakis, George and Kelly, Julia and Khuroo, Anzar A and Klemedtsson, Leif and Klisz, Marcin and Kljun, Natascha and Knohl, Alexander and Kobler, Johannes and Kollár, Jozef and Kotowska, Martyna M and Kovács, Bence and Kreyling, Juergen and Lamprecht, Andrea and Lang, Simone I and Larson, Christian and Larson, Keith and Laska, Kamil and le Maire, Guerric and Leihy, Rachel I and Lens, Luc and Liljebladh, Bengt and Lohila, Annalea and Lorite, Juan and Loubet, Benjamin and Lynn, Joshua and Macek, Martin and Mackenzie, Roy and Magliulo, Enzo and Maier, Regine and Malfasi, Francesco and Máliš, František and Man, Matěj and Manca, Giovanni and Manco, Antonio and Manise, Tanguy and Manolaki, Paraskevi and Marciniak, Felipe and Matula, Radim and Mazzolari, Ana Clara and Medinets, Sergiy and Medinets, Volodymyr and Meeussen, Camille and Merinero, Sonia and Mesquita, Rita de Cássia Guimarães and Meusburger, Katrin and Meysman, Filip J R and Michaletz, Sean T and Milbau, Ann and Moiseev, Dmitry and Moiseev, Pavel and Mondoni, Andrea and Monfries, Ruth and Montagnani, Leonardo and Moriana-Armendariz, Mikel and Morra di Cella, Umberto and Mörsdorf, Martin and Mosedale, Jonathan R and Muffler, Lena and Muñoz-Rojas, Miriam and Myers, Jonathan A and Myers-Smith, Isla H and Nagy, Laszlo and Nardino, Marianna and Naujokaitis-Lewis, Ilona and Newling, Emily and Nicklas, Lena and Niedrist, Georg and Niessner, Armin and Nilsson, Mats B and Normand, Signe and Nosetto, Marcelo D and Nouvellon, Yann and Nuñez, Martin A and Ogaya, Romà and Ogée, Jérôme and Okello, Joseph and Olejnik, Janusz and Olesen, Jørgen Eivind and Opedal, Øystein H and Orsenigo, Simone and Palaj, Andrej and Pampuch, Timo and Panov, Alexey V and Pärtel, Meelis and Pastor, Ada and Pauchard, Aníbal and Pauli, Harald and Pavelka, Marian and Pearse, William D and Peichl, Matthias and Pellissier, Loïc and Penczykowski, Rachel M and Penuelas, Josep and Petit Bon, Matteo and Petraglia, Alessandro and Phartyal, Shyam S and Phoenix, Gareth K and Pio, Casimiro and Pitacco, Andrea and Pitteloud, Camille and Plichta, Roman and Porro, Francesco and Portillo-Estrada, Miguel and Poulenard, Jérôme and Poyatos, Rafael and Prokushkin, Anatoly S and Puchalka, Radoslaw and Pușcaș, Mihai and Radujković, Dajana and Randall, Krystal and Ratier Backes, Amanda and Remmele, Sabine and Remmers, Wolfram and Renault, David and Risch, Anita C and Rixen, Christian and Robinson, Sharon A and Robroek, Bjorn J M and Rocha, Adrian V and Rossi, Christian and Rossi, Graziano and Roupsard, Olivier and Rubtsov, Alexey V and Saccone, Patrick and Sagot, Clotilde and Sallo Bravo, Jhonatan and Santos, Cinthya C and Sarneel, Judith M and Scharnweber, Tobias and Schmeddes, Jonas and Schmidt, Marius and Scholten, Thomas and Schuchardt, Max and Schwartz, Naomi and Scott, Tony and Seeber, Julia and Segalin de Andrade, Ana Cristina and Seipel, Tim and Semenchuk, Philipp and Senior, Rebecca A and Serra-Diaz, Josep M and Sewerniak, Piotr and Shekhar, Ankit and Sidenko, Nikita V and Siebicke, Lukas and Siegwart Collier, Laura and Simpson, Elizabeth and Siqueira, David P and Sitková, Zuzana and Six, Johan and Smiljanic, Marko and Smith, Stuart W and Smith-Tripp, Sarah and Somers, Ben and Sørensen, Mia Vedel and Souza, José João L L and Souza, Bartolomeu Israel and Souza Dias, Arildo and Spasojevic, Marko J and Speed, James D M and Spicher, Fabien and Stanisci, Angela and Steinbauer, Klaus and Steinbrecher, Rainer and Steinwandter, Michael and Stemkovski, Michael and Stephan, Jörg G and Stiegler, Christian and Stoll, Stefan and Svátek, Martin and Svoboda, Miroslav and Tagesson, Torbern and Tanentzap, Andrew J and Tanneberger, Franziska and Theurillat, Jean-Paul and Thomas, Haydn J D and Thomas, Andrew D and Tielbörger, Katja and Tomaselli, Marcello and Treier, Urs Albert and Trouillier, Mario and Turtureanu, Pavel Dan and Tutton, Rosamond and Tyystjärvi, Vilna A and Ueyama, Masahito and Ujházy, Karol and Ujházyová, Mariana and Uogintas, Domas and Urban, Anastasiya V and Urban, Josef and Urbaniak, Marek and Ursu, Tudor-Mihai and Vaccari, Francesco Primo and Van de Vondel, Stijn and van den Brink, Liesbeth and Van Geel, Maarten and Vandvik, Vigdis and Vangansbeke, Pieter and Varlagin, Andrej and Veen, G F and Veenendaal, Elmar and Venn, Susanna E and Verbeeck, Hans and Verbrugggen, Erik and Verheijen, Frank G A and Villar, Luis and Vitale, Luca and Vittoz, Pascal and Vives-Ingla, Maria and von Oppen, Jonathan and Walz, Josefine and Wang, Runxi and Wang, Yifeng and Way, Robert G and Wedegärtner, Ronja E M and Weigel, Robert and Wild, Jan and Wilkinson, Matthew and Wilmking, Martin and Wingate, Lisa and Winkler, Manuela and Wipf, Sonja and Wohlfahrt, Georg and Xenakis, Georgios and Yang, Yan and Yu, Zicheng and Yu, Kailiang and Zellweger, Florian and Zhang, Jian and Zhang, Zhaochen and Zhao, Peng and Ziembliʼnska, Klaudia and Zimmermann, Reiner and Zong, Shengwei and Zyryanov, Viacheslav I and Nijs, Ivan and Lenoir, Jonathan},
  title = {Global maps of soil temperature},
  journal = {Global Change Biology},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {n/a},
  number = {n/a},
  url = {https://doi.org/10.1111/gcb.16060},
  doi = {10.1111/gcb.16060}
}
Levin I, Hammer S, Kromer B, Preunkert S, Weller R and Worthy DE (2021), "RADIOCARBON IN GLOBAL TROPOSPHERIC CARBON DIOXIDE", Radiocarbon. , pp. 1-11. Cambridge University Press.
Abstract: Since the 1950s, observations of radiocarbon (14C) in tropospheric carbon dioxide (CO2) have been conducted in both hemispheres, documenting the so-called nuclear “bomb spike” and its transfer into the oceans and the terrestrial biosphere, the two compartments permanently exchanging carbon with the atmosphere. Results from the Heidelberg global network of Δ14C-CO2 observations are revisited here with respect to the insights and quantitative constraints they provided on these carbon exchange fluxes. The recent development of global and hemispheric trends of Δ14C-CO2 are further discussed in regard to their suitability to continue providing constraints for 14C-free fossil CO2 emission changes on the global and regional scale.
BibTeX:
@article{Levin2021,
  author = {Levin, Ingeborg and Hammer, Samuel and Kromer, Bernd and Preunkert, Susanne and Weller, Rolf and Worthy, Douglas E},
  title = {RADIOCARBON IN GLOBAL TROPOSPHERIC CARBON DIOXIDE},
  journal = {Radiocarbon},
  publisher = {Cambridge University Press},
  year = {2021},
  pages = {1--11},
  edition = {2021/12/23},
  url = {https://www.cambridge.org/core/article/radiocarbon-in-global-tropospheric-carbon-dioxide/2FB547BD4488086C216BBD60A13740C3},
  doi = {10.1017/RDC.2021.102}
}
Levin I, Karstens U, Hammer S, DellaColetta J, Maier F and Gachkivskyi M (2021), "Limitations of the radon tracer method (RTM) to estimate regional greenhouse gas (GHG) emissions -- a case study for methane in Heidelberg", Atmospheric Chemistry and Physics. Vol. 21(23), pp. 17907-17926.
BibTeX:
@article{Levin2021a,
  author = {Levin, I and Karstens, U and Hammer, S and DellaColetta, J and Maier, F and Gachkivskyi, M},
  title = {Limitations of the radon tracer method (RTM) to estimate regional greenhouse gas (GHG) emissions -- a case study for methane in Heidelberg},
  journal = {Atmospheric Chemistry and Physics},
  year = {2021},
  volume = {21},
  number = {23},
  pages = {17907--17926},
  url = {https://acp.copernicus.org/articles/21/17907/2021/},
  doi = {10.5194/acp-21-17907-2021}
}
Li H, Claremar B, Wu L, Hallgren C, Körnich H, Ivanell S and Sahlée E (2021), "A sensitivity study of the WRF model in offshore wind modeling over the Baltic Sea", Geoscience Frontiers. Vol. 12(6), pp. 101229.
Abstract: Accurate wind modeling is important for wind resources assessment and wind power forecasting. To improve the WRF model configuration for the offshore wind modeling over the Baltic Sea, this study performed a sensitivity study of the WRF model to multiple model configurations, including domain setup, grid resolution, sea surface temperature, land surface data, and atmosphere-wave coupling. The simulated offshore wind was evaluated against LiDAR observations under different wind directions, atmospheric stabilities, and sea status. Generally, the simulated wind profiles matched observations, despite systematic underestimations. Strengthening the forcing from the reanalysis data through reducing the number of nested domains played the largest role in improving wind modeling. Atmosphere-wave coupling further improved the simulated wind, especially under the growing and mature sea conditions. Increasing the vertical resolution, and updating the sea surface temperature and the land surface information only had a slight impact, mainly visible during very stable conditions. Increasing the horizontal resolution also only had a slight impact, most visible during unstable conditions. Our study can help to improve the wind resources assessment and wind power forecasting over the Baltic Sea.
BibTeX:
@article{Li2021,
  author = {Li, Huidong and Claremar, Björn and Wu, Lichuan and Hallgren, Christoffer and Körnich, Heiner and Ivanell, Stefan and Sahlée, Erik},
  title = {A sensitivity study of the WRF model in offshore wind modeling over the Baltic Sea},
  journal = {Geoscience Frontiers},
  year = {2021},
  volume = {12},
  number = {6},
  pages = {101229},
  url = {https://www.sciencedirect.com/science/article/pii/S1674987121000931},
  doi = {10.1016/j.gsf.2021.101229}
}
Lian J, Bréon F-M, Broquet G, Lauvaux T, Zheng B, Ramonet M, Xueref-Remy I, Kotthaus S, Haeffelin M and Ciais P (2021), "Sensitivity to the sources of uncertainties in the modeling of atmospheric CO_2 concentration within and in the vicinity of Paris", Atmospheric Chemistry and Physics. Vol. 21(13), pp. 10707-10726.
BibTeX:
@article{Lian2021,
  author = {Lian, J and Bréon, F.-M. and Broquet, G and Lauvaux, T and Zheng, B and Ramonet, M and Xueref-Remy, I and Kotthaus, S and Haeffelin, M and Ciais, P},
  title = {Sensitivity to the sources of uncertainties in the modeling of atmospheric CO_2 concentration within and in the vicinity of Paris},
  journal = {Atmospheric Chemistry and Physics},
  year = {2021},
  volume = {21},
  number = {13},
  pages = {10707--10726},
  url = {https://acp.copernicus.org/articles/21/10707/2021/},
  doi = {10.5194/acp-21-10707-2021}
}
Lin S, Li J, Liu Q, Gioli B, Paul-Limoges E, Buchmann N, Gharun M, Hörtnagl L, Foltýnová L, Dušek J, Li L and Yuan W (2021), "Improved global estimations of gross primary productivity of natural vegetation types by incorporating plant functional type", International Journal of Applied Earth Observation and Geoinformation. Vol. 100, pp. 102328.
Abstract: Satellite-based light use efficiency (LUE) models are important tools for estimating regional and global vegetation gross primary productivity (GPP). However, all LUE models assume a constant value of maximum LUE at canopy scale (LUEmaxcanopy) over a given vegetation type. This assumption is not supported by observed plant traits regulating LUEmaxcanopy, which varies greatly even within the same ecosystem type. In this study, we developed an improved satellite data driven GPP model by identifying the potential maximal GPP (GPPPOT) and their dominant climate control factor in various plant functional types (PFT), which takes into account both plant trait and climatic control inter-dependence. We selected 161 sites from the FLUXNET2015 dataset with eddy covariance CO2 flux data and continuous meteorology to derive GPPPOT and their dominant climate control factor of vegetation growth for 42 natural PFTs. Results showed that (1) under the same phenology and incident photosynthetic active radiation, the maximal variance of GPPPOT is found in different PFTs of forests (10.9 g C m−2 day−1) and in different climatic zones of grasslands (>10 g C m−2 day−1); (2) intra-annual change of GPP in tropical and arid climate zones is mostly driven by vapor pressure deficit (VPD) changes, while temperature is the dominant climate control factor in temperate, boreal and polar climate zones; even under the same climate condition, physiological stress in photosynthesis is different across PFTs; (3) the model that takes into account the plant trait difference across PFTs had a higher agreement with flux tower-based GPP data (GPPflux) than the GPP products that omit PFT differences. Such agreement was highest for natural vegetation cover sites (R2 = 0.77, RMSE = 1.79 g C m−2 day−1). These results suggest that global scale GPP models should incorporate both plant traits and their dominant climate control factor variance in various PFT to reduce the uncertainties in terrestrial carbon assessments.
BibTeX:
@article{Lin2021,
  author = {Lin, Shangrong and Li, Jing and Liu, Qinhuo and Gioli, Beniamino and Paul-Limoges, Eugenie and Buchmann, Nina and Gharun, Mana and Hörtnagl, Lukas and Foltýnová, Lenka and Dušek, Jiří and Li, Longhui and Yuan, Wenping},
  title = {Improved global estimations of gross primary productivity of natural vegetation types by incorporating plant functional type},
  journal = {International Journal of Applied Earth Observation and Geoinformation},
  year = {2021},
  volume = {100},
  pages = {102328},
  url = {https://www.sciencedirect.com/science/article/pii/S0303243421000350},
  doi = {10.1016/j.jag.2021.102328}
}
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}
}
Liu Y, Wu C, Liu L, Gu C, Andrew Black T, Jassal RS, Hörtnagl L, Montagnani L, Moyano F, Varlagin A, Altaf Arain M and Govind A (2021), "Interannual and spatial variability of net ecosystem production in forests explained by an integrated physiological indicator in summer", Ecological Indicators. Vol. 129, pp. 107982.
Abstract: Understanding the feedback of ecosystem carbon uptake on climate change at temporal and spatial scales is crucial for developing ecosystem models. Previous studies have focused on the role of spring and autumn phenology in regulating carbon sequestration in forest stands, but few on the impact of physiological status in summer. However, plant accumulated the most carbon in summer compared with spring and autumn, therefore, it is of great significance to explore the role of summer phenological metrics on the variability of carbon sequestration. Using 514 site-years of flux data obtained at 40 FLUXNET sites including three forest ecosystems (i.e. evergreen needleleaf forest (ENF), deciduous broadleaf forest (DBF) and mixed forest (MF)) in Europe and North America, we compared the potential of physiological and phenological metrics of Gross Primary Production (GPP) and Ecosystem Respiration (RECO) in explaining the interannual and spatial variability (IAV and SV) of forest net ecosystem production (NEP). In view of the better performance of physiological metrics, we developed the maximum carbon uptake index (MCUI), which integrated the physiology metrics of photosynthesis and respiration in summer, and further explored its ability in explaining the IAV and SV of NEP. The results suggest that the MCUI had a better ability than respiration-growth length ratio (RGR) in predicting NEP for all three forest types. The interpretation of MCUI based on meteorological variables illustrated that the controlling meteorological factors of MCUI differed substantially among ecosystems. The summer shortwave radiation had the greatest influence on MCUI at DBF sites, while the soil water content played an important but opposite role at ENF and DBF sites, and no significant meteorological driver was found at MF sites. The higher potential of MCUI in explaining IAV and SV of NEP highlights the importance of summer physiology in controlling the forest carbon sequestration, and further confirms the significant role of peak plant growth in regulating carbon cycle of forest ecosystems. Understanding the drivers of peak plant growth is therefore of a great significance for further improving the precious of ecosystem model in the future.
BibTeX:
@article{Liu2021,
  author = {Liu, Ying and Wu, Chaoyang and Liu, Lin and Gu, Chengyan and Andrew Black, T and Jassal, Rachhpal S and Hörtnagl, Lukas and Montagnani, Leonardo and Moyano, Fernando and Varlagin, Andrej and Altaf Arain, M and Govind, Ajit},
  title = {Interannual and spatial variability of net ecosystem production in forests explained by an integrated physiological indicator in summer},
  journal = {Ecological Indicators},
  year = {2021},
  volume = {129},
  pages = {107982},
  url = {https://www.sciencedirect.com/science/article/pii/S1470160X21006476},
  doi = {10.1016/j.ecolind.2021.107982}
}
Lunt MF, Manning AJ, Allen G, Arnold T, Bauguitte SJ-B, Boesch H, Ganesan AL, Grant A, Helfter C, Nemitz E, O'Doherty SJ, Palmer PI, Pitt JR, Rennick C, Say D, Stanley KM, Stavert AR, Young D and Rigby M (2021), "Atmospheric observations consistent with reported decline in the UK's methane emissions (2013--2020)", Atmospheric Chemistry and Physics. Vol. 21(21), pp. 16257-16276.
BibTeX:
@article{Lunt2021,
  author = {Lunt, M F and Manning, A J and Allen, G and Arnold, T and Bauguitte, S J.-B. and Boesch, H and Ganesan, A L and Grant, A and Helfter, C and Nemitz, E and O'Doherty, S J and Palmer, P I and Pitt, J R and Rennick, C and Say, D and Stanley, K M and Stavert, A R and Young, D and Rigby, M},
  title = {Atmospheric observations consistent with reported decline in the UK's methane emissions (2013--2020)},
  journal = {Atmospheric Chemistry and Physics},
  year = {2021},
  volume = {21},
  number = {21},
  pages = {16257--16276},
  url = {https://acp.copernicus.org/articles/21/16257/2021/},
  doi = {10.5194/acp-21-16257-2021}
}
Mahrt L, Nilsson E, Rutgersson A and Pettersson H (2021), "Vertical Divergence of the Atmospheric Momentum Flux near the Sea Surface at a Coastal Site", Journal of Physical Oceanography. Boston MA, USA Vol. 51(11), pp. 3529-3537. American Meteorological Society.
BibTeX:
@article{Mahrt2021,
  author = {Mahrt, L and Nilsson, Erik and Rutgersson, Anna and Pettersson, Heidi},
  title = {Vertical Divergence of the Atmospheric Momentum Flux near the Sea Surface at a Coastal Site},
  journal = {Journal of Physical Oceanography},
  publisher = {American Meteorological Society},
  year = {2021},
  volume = {51},
  number = {11},
  pages = {3529--3537},
  url = {https://journals.ametsoc.org/view/journals/phoc/51/11/JPO-D-21-0081.1.xml},
  doi = {10.1175/JPO-D-21-0081.1}
}
Maignan F, Abadie C, Remaud M, Kooijmans LMJ, Kohonen K-M, Commane R, Wehr R, Campbell JE, Belviso S, Montzka SA, Raoult N, Seibt U, Shiga YP, Vuichard N, Whelan ME and Peylin P (2021), "Carbonyl sulfide: comparing a mechanistic representation of the vegetation uptake in a land surface model and the leaf relative uptake approach", Biogeosciences. Vol. 18(9), pp. 2917-2955.
BibTeX:
@article{Maignan2021,
  author = {Maignan, F and Abadie, C and Remaud, M and Kooijmans, L M J and Kohonen, K.-M. and Commane, R and Wehr, R and Campbell, J E and Belviso, S and Montzka, S A and Raoult, N and Seibt, U and Shiga, Y P and Vuichard, N and Whelan, M E and Peylin, P},
  title = {Carbonyl sulfide: comparing a mechanistic representation of the vegetation uptake in a land surface model and the leaf relative uptake approach},
  journal = {Biogeosciences},
  year = {2021},
  volume = {18},
  number = {9},
  pages = {2917--2955},
  url = {https://bg.copernicus.org/articles/18/2917/2021/},
  doi = {10.5194/bg-18-2917-2021}
}
Manco A, Brilli F, Famulari D, Gasbarra D, Gioli B, Vitale L, di Tommasi P, Loubet B, Arena C and Magliulo V (2021), "Cross-correlations of Biogenic Volatile Organic Compounds (BVOC) emissions typify different phenological stages and stressful events in a Mediterranean Sorghum plantation", Agricultural and Forest Meteorology. Vol. 303, pp. 108380.
Abstract: Climate change will affect the growing season and increase the occurrence of extreme stressful events, thus altering crop phenological phases and the associated emission of biogenic volatile organic compounds (BVOC). BVOC exchange has been poorly investigated in field crops, especially in the Mediterranean area. In this study we report continuous measurements of BVOC fluxes and CO2 net ecosystem exchange (NEE), together with environmental variables, green area index (GAI) and aboveground biomass (AGB) during a whole growing season in a grain sorghum (Sorghum bicolor x Sorghum sudangrass., cv. Nicol, Pioneer) plantation located in Southern Europe. Results of this intensive field campaign showed that, while the bare soil of our site was a sink of BVOC, the sorghum plantation became a source of oxygenated BVOC, mainly methanol and acetaldehyde, which were emitted over the season at an average rate of 0.137 ± 0.013 and 0.070 ± 0.004 nmol m−2 s−1, respectively. In addition, the application of the advanced data mining method of Self-Organizing Maps (SOM) revealed distinctive patterns of BVOC fluxes correlating with sorghum growth stages (GS): in the first stage (GS1), developing plantlets emitted a mixture of BVOC uniquely characterized by monoterpenes; in GS2, adult plants forming an homogeneous dense canopy emitted the most abundant fluxes of a mixture of oxygenated BVOC comprising methanol, acetaldehyde, formic acid, acetone, acetic acid and n-pentenol; once plants entered the flowering stage (in GS3), only a few BVOC continued to be emitted at the highest rates (i.e. formic acid, acetone, acetic acid, n-pentenol). Moreover, the application of SOM to a sub-set of BVOC fluxes highlighted the possibility to qualitatively differentiate stressful events of plant lodging and harvest cutting. In fact, enhanced emission of acetaldehyde distinguished the BVOC mixture emitted from lodged rather than from cut and harvested sorghum plants in the field.
BibTeX:
@article{Manco2021,
  author = {Manco, Antonio and Brilli, Federico and Famulari, Daniela and Gasbarra, Daniele and Gioli, Beniamino and Vitale, Luca and di Tommasi, Paul and Loubet, Benjamin and Arena, Carmen and Magliulo, Vincenzo},
  title = {Cross-correlations of Biogenic Volatile Organic Compounds (BVOC) emissions typify different phenological stages and stressful events in a Mediterranean Sorghum plantation},
  journal = {Agricultural and Forest Meteorology},
  year = {2021},
  volume = {303},
  pages = {108380},
  url = {https://www.sciencedirect.com/science/article/pii/S0168192321000630},
  doi = {10.1016/j.agrformet.2021.108380}
}
Manning AJ, Redington AL, Say D, O'Doherty S, Young D, Simmonds PG, Vollmer MK, Mühle J, Arduini J, Spain G, Wisher A, Maione M, Schuck TJ, Stanley K, Reimann S, Engel A, Krummel PB, Fraser PJ, Harth CM, Salameh PK, Weiss RF, Gluckman R, Brown PN, Watterson JD and Arnold T (2021), "Evidence of a recent decline in UK emissions of hydrofluorocarbons determined by the InTEM inverse model and atmospheric measurements", Atmospheric Chemistry and Physics. Vol. 21(16), pp. 12739-12755.
BibTeX:
@article{Manning2021,
  author = {Manning, A J and Redington, A L and Say, D and O'Doherty, S and Young, D and Simmonds, P G and Vollmer, M K and Mühle, J and Arduini, J and Spain, G and Wisher, A and Maione, M and Schuck, T J and Stanley, K and Reimann, S and Engel, A and Krummel, P B and Fraser, P J and Harth, C M and Salameh, P K and Weiss, R F and Gluckman, R and Brown, P N and Watterson, J D and Arnold, T},
  title = {Evidence of a recent decline in UK emissions of hydrofluorocarbons determined by the InTEM inverse model and atmospheric measurements},
  journal = {Atmospheric Chemistry and Physics},
  year = {2021},
  volume = {21},
  number = {16},
  pages = {12739--12755},
  url = {https://acp.copernicus.org/articles/21/12739/2021/},
  doi = {10.5194/acp-21-12739-2021}
}
Marañón-Jiménez S, Radujković D, Verbruggen E, Grau O, Cuntz M, Peñuelas J, Richter A, Schrumpf M and Rebmann C (2021), "Shifts in the Abundances of Saprotrophic and Ectomycorrhizal Fungi With Altered Leaf Litter Inputs", Frontiers in Plant Science. Vol. 12
Abstract: Ectomycorrhizal (EcM) and saprotrophic fungi interact in the breakdown of organic matter, but the mechanisms underlying the EcM role on organic matter decomposition are not totally clear. We hypothesized that the ecological relations between EcM and saprotroph fungi are modulated by resources availability and accessibility, determining decomposition rates. We manipulated the amount of leaf litter inputs (No-Litter, Control Litter, Doubled Litter) on Trenched (root exclusion) and Non-Trenched plots (with roots) in a temperate deciduous forest of EcM-associated trees. Resultant shifts in soil fungal communities were determined by phospholipid fatty acids and DNA sequencing after 3 years, and CO2 fluxes were measured throughout this period. Different levels of leaf litter inputs generated a gradient of organic substrate availability and accessibility, altering the composition and ecological relations between EcM and saprotroph fungal communities. EcM fungi dominated at low levels of fresh organic substrates and lower organic matter quality, where short-distances exploration types seem to be better competitors, whereas saprotrophs and longer exploration types of EcM fungi tended to dominate at high levels of leaf litter inputs, where labile organic substrates were easily accessible. We were, however, not able to detect unequivocal signs of competition between these fungal groups for common resources. These results point to the relevance of substrate quality and availability as key factors determining the role of EcM and saprotroph fungi on litter and soil organic matter decay and represent a path forward on the capacity of organic matter decomposition of different exploration types of EcM fungi.
BibTeX:
@article{MaranonJimenez2021,
  author = {Marañón-Jiménez, Sara and Radujković, Dajana and Verbruggen, Erik and Grau, Oriol and Cuntz, Matthias and Peñuelas, Josep and Richter, Andreas and Schrumpf, Marion and Rebmann, Corinna},
  title = {Shifts in the Abundances of Saprotrophic and Ectomycorrhizal Fungi With Altered Leaf Litter Inputs},
  journal = {Frontiers in Plant Science},
  year = {2021},
  volume = {12},
  url = {https://www.frontiersin.org/article/10.3389/fpls.2021.682142},
  doi = {10.3389/fpls.2021.682142}
}
Marshall JD, Laudon H, Mäkelä A, Peichl M, Hasselquist N and Näsholm T (2021), "Isotopic Branchpoints: Linkages and Efficiencies in Carbon and Water Budgets", Journal of Geophysical Research: Biogeosciences., jan, 2021. Vol. 126(1), pp. e2020JG006043. John Wiley & Sons, Ltd.
Abstract: Abstract Forests pass water and carbon through while converting portions to streamflow, soil organic matter, wood production, and other ecosystem services. The efficiencies of these transfers are but poorly quantified. New theory and new instruments have made it possible to use stable isotope composition to provide this quantification of efficiencies wherever there is a measurable difference between the branches of a branchpoint. We present a linked conceptual model that relies on isotopes of hydrogen, carbon, and oxygen to describe these branchpoints along the pathway from precipitation to soil and biomass carbon sequestration and illustrate how it can be tested and generalized.
BibTeX:
@article{Marshall2021,
  author = {Marshall, John D and Laudon, Hjalmar and Mäkelä, Annikki and Peichl, Matthias and Hasselquist, Niles and Näsholm, Torgny},
  title = {Isotopic Branchpoints: Linkages and Efficiencies in Carbon and Water Budgets},
  journal = {Journal of Geophysical Research: Biogeosciences},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {126},
  number = {1},
  pages = {e2020JG006043},
  url = {https://doi.org/10.1029/2020JG006043},
  doi = {10.1029/2020JG006043}
}
Marttila H, Aurela M, Büngener L, Rossi PM, Lohila A, Postila H, Saari M, Penttilä T and Kløve B (2021), "Quantifying groundwater fluxes from an aapa mire to a riverside esker formation", Hydrology Research., mar, 2021. Vol. 52(2), pp. 585-596.
Abstract: Water flows in peatland margins is an under-researched topic. This study examines recharge from a peatland to an esker aquifer in an aapa mire complex of northern Finland. Our objective was to study how the aapa mire margin is hydrogeologically connected to the riverside aquifer and spatial and temporal variations in the recharge of peatland water to groundwater (GW). Following geophysical studies and monitoring of the saturated zone, a GW model (MODFLOW) was used in combination with stable isotopes to quantify GW flow volumes and directions. Peatland water recharge to the sandy aquifer indicated a strong connection at the peatland–aquifer boundary. Recharge volumes from peatland to esker were high and rather constant (873 m3 d−1) and dominated esker recharge at the study site. The peat water recharging the esker boundary was rich in dissolved organic carbon (DOC). Stable isotope studies on water (δ18O, δ2H, and d-excess) from GW wells verified the recharge of DOC-rich water from peatlands to mineral soil esker. Biogeochemical analysis revealed changes from DOC to dissolved inorganic carbon in the flow pathway from peatland margin to the river Kitinen. This study highlights the importance of careful investigation of aapa mire margin areas and their potential role in regional GW recharge patterns.
BibTeX:
@article{Marttila2021,
  author = {Marttila, H and Aurela, M and Büngener, L and Rossi, P M and Lohila, A and Postila, H and Saari, M and Penttilä, T and Kløve, B},
  title = {Quantifying groundwater fluxes from an aapa mire to a riverside esker formation},
  journal = {Hydrology Research},
  year = {2021},
  volume = {52},
  number = {2},
  pages = {585--596},
  url = {https://doi.org/10.2166/nh.2021.064},
  doi = {10.2166/nh.2021.064}
}
Marttila H, Lohila A, Ala-Aho P, Noor K, Welker JM, Croghan D, Mustonen K, Meriö L-J, Autio A, Muhic F, Bailey H, Aurela M, Vuorenmaa J, Penttilä T, Hyöky V, Klein E, Kuzmin A, Korpelainen P, Kumpula T, Rauhala A and Kløve B (2021), "Subarctic catchment water storage and carbon cycling – Leading the way for future studies using integrated datasets at Pallas, Finland", Hydrological Processes., sep, 2021. Vol. 35(9), pp. e14350. John Wiley & Sons, Ltd.
Abstract: Abstract Subarctic ecohydrological processes are changing rapidly, but detailed and integrated ecohydrological investigations are not as widespread as necessary. We introduce an integrated research catchment site (Pallas) for atmosphere, ecosystems, and ecohydrology studies in subarctic conditions in Finland that can be used for a new set of comparative catchment investigations. The Pallas site provides unique observational data and high-intensity field measurement datasets over long periods. The infrastructure for atmosphere- to landscape-scale research in ecosystem processes in a subarctic landscape has recently been complemented with detailed ecohydrological measurements. We identify three dominant processes in subarctic ecohydrology: (a) strong seasonality drives ecohydrological regimes, (b) limited dynamic storage causes rapid stream response to water inputs (snowmelt and intensive storms), and (c) hydrological state of the system regulates catchment-scale dissolved carbon dynamics and greenhouse (GHG) fluxes. Surface water and groundwater interactions play an important role in regulating catchment-scale carbon balances and ecosystem respiration within subarctic peatlands, particularly their spatial variability in the landscape. Based on our observations from Pallas, we highlight key research gaps in subarctic ecohydrology and propose several ways forward. We also demonstrate that the Pallas catchment meets the need for sustaining and pushing the boundaries of critical long-term integrated ecohydrological research in high-latitude environments.
BibTeX:
@article{Marttila2021a,
  author = {Marttila, Hannu and Lohila, Annalea and Ala-Aho, Pertti and Noor, Kashif and Welker, Jeffrey M and Croghan, Danny and Mustonen, Kaisa and Meriö, Leo-Juhani and Autio, Anna and Muhic, Filip and Bailey, Hannah and Aurela, Mika and Vuorenmaa, Jussi and Penttilä, Timo and Hyöky, Valtteri and Klein, Eric and Kuzmin, Anton and Korpelainen, Pasi and Kumpula, Timo and Rauhala, Anssi and Kløve, Bjørn},
  title = {Subarctic catchment water storage and carbon cycling – Leading the way for future studies using integrated datasets at Pallas, Finland},
  journal = {Hydrological Processes},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {35},
  number = {9},
  pages = {e14350},
  url = {https://doi.org/10.1002/hyp.14350},
  doi = {10.1002/hyp.14350}
}
Matkala L, Kulmala L, Kolari P, Aurela M and Bäck J (2021), "Resilience of subarctic Scots pine and Norway spruce forests to extreme weather events", Agricultural and Forest Meteorology. Vol. 296, pp. 108239.
Abstract: We studied the occurrence of extreme weather events and their effects on the carbon dioxide and water exchange of two subarctic forest stands. One study site was a Scots pine site in eastern Finnish Lapland (Värriö), and the other was a Norway spruce site in western Finnish Lapland (Kenttärova). We compared short-term meteorological data with long-term data and found that the pine forest had experienced extremely warm, wet and dry years as well as cold spells during the growing season in the studied period of 2012–2018. The spruce forest was studied during the period 2003–2013, during which time it experienced extremely warm and wet summers, and dry periods, although the dry times were not statistically defined as such. The spruce forest was less resilient to warm and dry periods, as its total ecosystem respiration and respiration potential decreased during warm and dry summers, while the same effect was not seen in the pine forest. The decreased respiration values may have occurred due to slowed decomposition of organic matter. The pine forest experienced two cold spells during the studied period. One of these cold periods was more of a continuation of the previous cold spring and late start of the growing season in 2017, while the other one occurred after a warm period in 2014. The ecosystem respiration rates and gross primary production in 2017 remained low for the whole July–August time period likely due to cold-inhibited growth of ground vegetation, while in 2014 no such effect could be seen. We saw no effect of extreme weather events in the water exchange related measurements in either of the forests. Overall, both forests, especially the trees, were resilient to the weather extremes and experienced no long-term damage.
BibTeX:
@article{Matkala2021,
  author = {Matkala, L and Kulmala, L and Kolari, P and Aurela, M and Bäck, J},
  title = {Resilience of subarctic Scots pine and Norway spruce forests to extreme weather events},
  journal = {Agricultural and Forest Meteorology},
  year = {2021},
  volume = {296},
  pages = {108239},
  url = {https://www.sciencedirect.com/science/article/pii/S0168192320303415},
  doi = {10.1016/j.agrformet.2020.108239}
}
Mauder M, Ibrom A, Wanner L, De Roo F, Brugger P, Kiese R and Pilegaard K (2021), "Options to correct local turbulent flux measurements for large-scale fluxes using an approach based on large-eddy simulation", Atmospheric Measurement Techniques. Vol. 14(12), pp. 7835-7850.
BibTeX:
@article{Mauder2021,
  author = {Mauder, M and Ibrom, A and Wanner, L and De Roo, F and Brugger, P and Kiese, R and Pilegaard, K},
  title = {Options to correct local turbulent flux measurements for large-scale fluxes using an approach based on large-eddy simulation},
  journal = {Atmospheric Measurement Techniques},
  year = {2021},
  volume = {14},
  number = {12},
  pages = {7835--7850},
  url = {https://amt.copernicus.org/articles/14/7835/2021/},
  doi = {10.5194/amt-14-7835-2021}
}
Mbengue S, Zikova N, Schwarz J, Vodička P, Šmejkalová AH and Holoubek I (2021), "Mass absorption cross-section and absorption enhancement from long term black and elemental carbon measurements: A rural background station in Central Europe", Science of The Total Environment. Vol. 794, pp. 148365.
Abstract: Black carbon (BC) is a dominant aerosol light absorber, and its brown carbon (BrC) coating can enhance absorption and lead to uncertainties concerning the radiative forcing estimation. This study investigates the mass absorption cross-section of equivalent BC (MACeBC) during a long-term field measurement (2013–2017) at a rural Central European site. The MAC enhancement factor (Eabs) and the contribution of BrC coatings to the absorption coefficient (Babs) were estimated by combining different approaches. The annual mean Babs and MACeBC values decreased slightly over the measurement period associated with change in the submicron aerosol size distribution. Regardless of the wavelength, Babs exhibited clear seasonal and diurnal variations, with higher values in winter when a higher absorption Ångström exponent (1.4) was observed due to the local biomass burning (BB). In contrast, MACeBC did not have a distinct temporal trend at 600 nm (7.84 ± 2.79 m2 g−1), while it showed a seasonal trend at 370 nm with higher values in winter (15.64 ± 4.77 m2 g−1). During this season, Eabs_660 was 1.18 ± 0.27 and did not exhibit any clear wavelength dependence, despite the influence of BB. During the study period, BrC-attributed absorption was observed in 31% of the samples, with a contribution of up to 40% of total Babs. In summer, the Eabs_660 increased to 1.59 ± 0.60, when a larger BC coating could be formed by secondary aerosol fractions. During this season, MACeBC_660 and Eabs_660 showed comparable source profiles that were mainly associated with aged air masses over central Europe, thereby supporting the fact that characteristics of coating materials formed during atmospheric aging are a major factor driving the MACeBC_660 measured at the regional background site. Further field investigations of the composition of BC coatings would help to better understand and estimate uncertainties related to the radiative effect of aerosols.
BibTeX:
@article{Mbengue2021,
  author = {Mbengue, Saliou and Zikova, Nadezda and Schwarz, Jaroslav and Vodička, Petr and Šmejkalová, Adéla Holubová and Holoubek, Ivan},
  title = {Mass absorption cross-section and absorption enhancement from long term black and elemental carbon measurements: A rural background station in Central Europe},
  journal = {Science of The Total Environment},
  year = {2021},
  volume = {794},
  pages = {148365},
  url = {https://www.sciencedirect.com/science/article/pii/S0048969721034367},
  doi = {10.1016/j.scitotenv.2021.148365}
}
Mejdová M, Dušek J, Foltýnová L, Macálková L and Čížková H (2021), "Photosynthetic parameters of a sedge-grass marsh as a big-leaf: effect of plant species composition", Scientific Reports. Vol. 11(1), pp. 3723.
Abstract: The study estimates the parameters of the photosynthesis–irradiance relationship (PN/I) of a sedge-grass marsh (Czech Republic, Europe), represented as an active “green” surface—a hypothetical “big-leaf”. Photosynthetic parameters of the “big-leaf” are based on in situ measurements of the leaf PN/I curves of the dominant plant species. The non-rectangular hyperbola was selected as the best model for fitting the PN/I relationships. The plant species had different parameters of this relationship. The highest light-saturated rate of photosynthesis (Asat) was recorded for Glyceria maxima and Acorus calamus followed by Carex acuta and Phalaris arundinacea. The lowest Asat was recorded for Calamagrostis canescens. The parameters of the PN/I relationship were calculated also for different growth periods. The highest Asat was calculated for the spring period followed by the summer and autumn periods. The effect of the species composition of the local plant community on the photosynthetic parameters of the “big-leaf” was addressed by introducing both real (recorded) and hypothetical species compositions corresponding to “wet” and “dry” hydrological conditions. We can conclude that the species composition (or diversity) is essential for reaching a high Asat of the “big-leaf ”representing the sedge-grass marsh in different growth periods.
BibTeX:
@article{Mejdova2021,
  author = {Mejdová, Markéta and Dušek, Jiří and Foltýnová, Lenka and Macálková, Lenka and Čížková, Hana},
  title = {Photosynthetic parameters of a sedge-grass marsh as a big-leaf: effect of plant species composition},
  journal = {Scientific Reports},
  year = {2021},
  volume = {11},
  number = {1},
  pages = {3723},
  url = {https://doi.org/10.1038/s41598-021-82382-2},
  doi = {10.1038/s41598-021-82382-2}
}
Mengen D, Montzka C, Jagdhuber T, Fluhrer A, Brogi C, Baum S, Schüttemeyer D, Bayat B, Bogena H, Coccia A, Masalias G, Trinkel V, Jakobi J, Jonard F, Ma Y, Mattia F, Palmisano D, Rascher U, Satalino G, Schumacher M, Koyama C, Schmidt M and Vereecken H (2021), "The SARSense Campaign: Air- and Space-Borne C- and L-Band SAR for the Analysis of Soil and Plant Parameters in Agriculture", Remote Sensing. Vol. 13(4)
Abstract: With the upcoming L-band Synthetic Aperture Radar (SAR) satellite mission Radar Observing System for Europe L-band SAR (ROSE-L) and its integration into existing C-band satellite missions such as Sentinel-1, multi-frequency SAR observations with high temporal and spatial resolution will become available. The SARSense campaign was conducted between June and August 2019 to investigate the potential for estimating soil and plant parameters at the agricultural test site in Selhausen (Germany). It included C- and L-band air- and space-borne observations accompanied by extensive in situ soil and plant sampling as well as unmanned aerial system (UAS) based multispectral and thermal infrared measurements. In this regard, we introduce a new publicly available SAR data set and present the first analysis of C- and L-band co- and cross-polarized backscattering signals regarding their sensitivity to soil and plant parameters. Results indicate that a multi-frequency approach is relevant to disentangle soil and plant contributions to the SAR signal and to identify specific scattering mechanisms associated with the characteristics of different crop type, especially for root crops and cereals.
BibTeX:
@article{Mengen2021,
  author = {Mengen, David and Montzka, Carsten and Jagdhuber, Thomas and Fluhrer, Anke and Brogi, Cosimo and Baum, Stephani and Schüttemeyer, Dirk and Bayat, Bagher and Bogena, Heye and Coccia, Alex and Masalias, Gerard and Trinkel, Verena and Jakobi, Jannis and Jonard, François and Ma, Yueling and Mattia, Francesco and Palmisano, Davide and Rascher, Uwe and Satalino, Giuseppe and Schumacher, Maike and Koyama, Christian and Schmidt, Marius and Vereecken, Harry},
  title = {The SARSense Campaign: Air- and Space-Borne C- and L-Band SAR for the Analysis of Soil and Plant Parameters in Agriculture},
  journal = {Remote Sensing},
  year = {2021},
  volume = {13},
  number = {4},
  url = {https://www.mdpi.com/2072-4292/13/4/825},
  doi = {10.3390/rs13040825}
}
Mensah C, Šigut L, Fischer M, Foltýnová L, Jocher G, Acosta M, Kowalska N, Kokrda L, Pavelka M, Marshall JD, Nyantakyi EK and Marek MV (2021), "Assessing the Contrasting Effects of the Exceptional 2015 Drought on the Carbon Dynamics in Two Norway Spruce Forest Ecosystems", Atmosphere. Vol. 12(8)
Abstract: The occurrence of extreme drought poses a severe threat to forest ecosystems and reduces their capability to sequester carbon dioxide. This study analysed the impacts of a central European summer drought in 2015 on gross primary productivity (GPP) at two Norway spruce forest sites representing two contrasting climatic conditions—cold and humid climate at Bílý Kříž (CZ-BK1) vs. moderately warm and dry climate at Rájec (CZ-RAJ). The comparative analyses of GPP was based on a three-year eddy covariance dataset, where 2014 and 2016 represented years with normal conditions, while 2015 was characterized by dry conditions. A significant decline in the forest GPP was found during the dry year of 2015, reaching 14% and 6% at CZ-BK1 and CZ-RAJ, respectively. The reduction in GPP coincided with high ecosystem respiration (Reco) during the dry year period, especially during July and August, when several heat waves hit the region. Additional analyses of GPP decline during the dry year period suggested that a vapour pressure deficit played a more important role than the soil volumetric water content at both investigated sites, highlighting the often neglected importance of considering the species hydraulic strategy (isohydric vs. anisohydric) in drought impact assessments. The study indicates the high vulnerability of the Norway spruce forest to drought stress, especially at sites with precipitation equal or smaller than the atmospheric evaporative demand. Since central Europe is currently experiencing large-scale dieback of Norway spruce forests in lowlands and uplands (such as for CZ-RAJ conditions), the findings of this study may help to quantitatively assess the fate of these widespread cultures under future climate projections, and may help to delimitate the areas of their sustainable production.
BibTeX:
@article{Mensah2021,
  author = {Mensah, Caleb and Šigut, Ladislav and Fischer, Milan and Foltýnová, Lenka and Jocher, Georg and Acosta, Manuel and Kowalska, Natalia and Kokrda, Lukáš and Pavelka, Marian and Marshall, John David and Nyantakyi, Emmanuel K and Marek, Michal V},
  title = {Assessing the Contrasting Effects of the Exceptional 2015 Drought on the Carbon Dynamics in Two Norway Spruce Forest Ecosystems},
  journal = {Atmosphere},
  year = {2021},
  volume = {12},
  number = {8},
  url = {https://www.mdpi.com/2073-4433/12/8/988},
  doi = {10.3390/atmos12080988}
}
Mensah C, Šigut L, Fischer M, Foltýnová L, Jocher G, Urban O, Wemegah CS, Nyantakyi EK, Chawla S, Pavelka M and Marek MV (2021), "Environmental Effects on Normalized Gross Primary Productivity in Beech and Norway Spruce Forests", Atmosphere. Vol. 12(9)
Abstract: The strong effects of climate change are expected to negatively impact the long-term resilience and function of forest ecosystems, which could lead to changes in forest carbon balance and productivity. However, these forest responses may vary with local conditions and forest types. Accordingly, this study was carried out to determine gross primary productivity (GPP) sensitivity to changes in environmental parameters. Central European beech (at Štítná) and spruce species (at Bílý Kr̆íz̆ and Rájec), growing under contrasting climatic conditions, were studied. The comparative analyses of GPP were based on a five-year-long dataset of eddy covariance fluxes during the main growing season (2012–2016). Results of forest GPP responses with changes in environmental factors from a traditional Stepwise multiple linear regression model (SMLR) were used and compared with Random forest (RF) analyses. To demonstrate how actual GPP trends compare to potential GPP (GPPpot) courses expected under near-optimal environmental conditions, we computed normalized GPP (GPPnorm) with values between 0 and 1 as the ratio of the estimated daily sum of GPP to GPPpot. The study confirmed the well-known effect of total intensity of the photosynthetically active radiation and its diffuse fraction on GPPnorm across all the forest types. However, the study also showed the secondary effects of other environmental variables on forest productivity depending on the species and local climatic conditions. The reduction in forest productivity at the beech forest in Štítná was presumed to be mainly induced by edaphic drought (anisohydric behaviour). In contrast, reduced forest productivity at the spruce forest sites was presumably induced by both meteorological and hydrological drought events, especially at the moderately dry climate in Rájec. Overall, our analyses call for more studies on forest productivity across different forest types and contrasting climatic conditions, as this productivity is strongly dependent on species type and site-specific environmental conditions.
BibTeX:
@article{Mensah2021a,
  author = {Mensah, Caleb and Šigut, Ladislav and Fischer, Milan and Foltýnová, Lenka and Jocher, Georg and Urban, Otmar and Wemegah, Cosmos Senyo and Nyantakyi, Emmanuel K and Chawla, Shilpi and Pavelka, Marian and Marek, Michal V},
  title = {Environmental Effects on Normalized Gross Primary Productivity in Beech and Norway Spruce Forests},
  journal = {Atmosphere},
  year = {2021},
  volume = {12},
  number = {9},
  url = {https://www.mdpi.com/2073-4433/12/9/1128},
  doi = {10.3390/atmos12091128}
}
Merbold L, Scholes RJ, Acosta M, Beck J, Bombelli A, Fiedler B, Grieco E, Helmschrot J, Hugo W, Kasurinen V, Kim D-G, Körtzinger A, Leitner S, López-Ballesteros A, Ndisi M, Nickless A, Salmon E, Saunders M, Skjelvan I, Vermeulen AT and Kutsch WL (2021), "Opportunities for an African greenhouse gas observation system", Regional Environmental Change., dec, 2021. Vol. 21(4), pp. 104.
Abstract: Global population projections foresee the biggest increase to occur in Africa with most of the available uncultivated land to ensure food security remaining on the continent. Simultaneously, greenhouse gas emissions are expected to rise due to ongoing land use change, industrialisation, and transport amongst other reasons with Africa becoming a major emitter of greenhouse gases globally. However, distinct knowledge on greenhouse gas emissions sources and sinks as well as their variability remains largely unknown caused by its vast size and diversity and an according lack of observations across the continent. Thus, an environmental research infrastructure—as being setup in other regions—is more needed than ever. Here, we present the results of a design study that developed a blueprint for establishing such an environmental research infrastructure in Africa. The blueprint comprises an inventory of already existing observations, the spatial disaggregation of locations that will enable to reduce the uncertainty in climate forcing's in Africa and globally as well as an overall estimated cost for such an endeavour of about 550 M€ over the next 30 years. We further highlight the importance of the development of an e-infrastructure, the necessity for capacity development and the inclusion of all stakeholders to ensure African ownership.
BibTeX:
@article{Merbold2021,
  author = {Merbold, Lutz and Scholes, Robert J and Acosta, Manuel and Beck, Johannes and Bombelli, Antonio and Fiedler, Bjoern and Grieco, Elisa and Helmschrot, Joerg and Hugo, Wim and Kasurinen, Ville and Kim, Dong-Gill and Körtzinger, Arne and Leitner, Sonja and López-Ballesteros, Ana and Ndisi, Mylene and Nickless, Aecia and Salmon, Emmanuel and Saunders, Matthew and Skjelvan, Ingunn and Vermeulen, Alexander T and Kutsch, Werner L},
  title = {Opportunities for an African greenhouse gas observation system},
  journal = {Regional Environmental Change},
  year = {2021},
  volume = {21},
  number = {4},
  pages = {104},
  url = {https://link.springer.com/10.1007/s10113-021-01823-w},
  doi = {10.1007/s10113-021-01823-w}
}
Migliavacca M, Musavi T, Mahecha MD, Nelson JA, Knauer J, Baldocchi DD, Perez-Priego O, Christiansen R, Peters J, Anderson K, Bahn M, Black TA, Blanken PD, Bonal D, Buchmann N, Caldararu S, Carrara A, Carvalhais N, Cescatti A, Chen J, Cleverly J, Cremonese E, Desai AR, El-Madany TS, Farella MM, Fernández-Martínez M, Filippa G, Forkel M, Galvagno M, Gomarasca U, Gough CM, Göckede M, Ibrom A, Ikawa H, Janssens IA, Jung M, Kattge J, Keenan TF, Knohl A, Kobayashi H, Kraemer G, Law BE, Liddell MJ, Ma X, Mammarella I, Martini D, Macfarlane C, Matteucci G, Montagnani L, Pabon-Moreno DE, Panigada C, Papale D, Pendall E, Penuelas J, Phillips RP, Reich PB, Rossini M, Rotenberg E, Scott RL, Stahl C, Weber U, Wohlfahrt G, Wolf S, Wright IJ, Yakir D, Zaehle S and Reichstein M (2021), "The three major axes of terrestrial ecosystem function", Nature. Vol. 598(7881), pp. 468-472.
Abstract: The leaf economics spectrum1,2 and the global spectrum of plant forms and functions3 revealed fundamental axes of variation in plant traits, which represent different ecological strategies that are shaped by the evolutionary development of plant species2. Ecosystem functions depend on environmental conditions and the traits of species that comprise the ecological communities4. However, the axes of variation of ecosystem functions are largely unknown, which limits our understanding of how ecosystems respond as a whole to anthropogenic drivers, climate and environmental variability4,5. Here we derive a set of ecosystem functions6 from a dataset of surface gas exchange measurements across major terrestrial biomes. We find that most of the variability within ecosystem functions (71.8%) is captured by three key axes. The first axis reflects maximum ecosystem productivity and is mostly explained by vegetation structure. The second axis reflects ecosystem water-use strategies and is jointly explained by variation in vegetation height and climate. The third axis, which represents ecosystem carbon-use efficiency, features a gradient related to aridity, and is explained primarily by variation in vegetation structure. We show that two state-of-the-art land surface models reproduce the first and most important axis of ecosystem functions. However, the models tend to simulate more strongly correlated functions than those observed, which limits their ability to accurately predict the full range of responses to environmental changes in carbon, water and energy cycling in terrestrial ecosystems7,8.
BibTeX:
@article{Migliavacca2021,
  author = {Migliavacca, Mirco and Musavi, Talie and Mahecha, Miguel D and Nelson, Jacob A and Knauer, Jürgen and Baldocchi, Dennis D and Perez-Priego, Oscar and Christiansen, Rune and Peters, Jonas and Anderson, Karen and Bahn, Michael and Black, T Andrew and Blanken, Peter D and Bonal, Damien and Buchmann, Nina and Caldararu, Silvia and Carrara, Arnaud and Carvalhais, Nuno and Cescatti, Alessandro and Chen, Jiquan and Cleverly, Jamie and Cremonese, Edoardo and Desai, Ankur R and El-Madany, Tarek S and Farella, Martha M and Fernández-Martínez, Marcos and Filippa, Gianluca and Forkel, Matthias and Galvagno, Marta and Gomarasca, Ulisse and Gough, Christopher M and Göckede, Mathias and Ibrom, Andreas and Ikawa, Hiroki and Janssens, Ivan A and Jung, Martin and Kattge, Jens and Keenan, Trevor F and Knohl, Alexander and Kobayashi, Hideki and Kraemer, Guido and Law, Beverly E and Liddell, Michael J and Ma, Xuanlong and Mammarella, Ivan and Martini, David and Macfarlane, Craig and Matteucci, Giorgio and Montagnani, Leonardo and Pabon-Moreno, Daniel E and Panigada, Cinzia and Papale, Dario and Pendall, Elise and Penuelas, Josep and Phillips, Richard P and Reich, Peter B and Rossini, Micol and Rotenberg, Eyal and Scott, Russell L and Stahl, Clement and Weber, Ulrich and Wohlfahrt, Georg and Wolf, Sebastian and Wright, Ian J and Yakir, Dan and Zaehle, Sönke and Reichstein, Markus},
  title = {The three major axes of terrestrial ecosystem function},
  journal = {Nature},
  year = {2021},
  volume = {598},
  number = {7881},
  pages = {468--472},
  url = {https://doi.org/10.1038/s41586-021-03939-9},
  doi = {10.1038/s41586-021-03939-9}
}
Moderow U, Grünwald T, Queck R, Spank U and Bernhofer C (2021), "Energy balance closure and advective fluxes at ADVEX sites", Theoretical and Applied Climatology. Vol. 143(1), pp. 761-779.
Abstract: When measuring the energy balance at the earth's surface using the Eddy covariance technique, the obtained budgets seldom produce a closed energy balance. The measurements often miss some of the energy fluxes. A possible reason is the neglect of non-turbulent surface fluxes of latent heat and sensible heat, i.e. advective fluxes of these quantities. We present estimates of advective latent and sensible heat fluxes for three different sites across Europe based on the ADVEX dataset. The obtained horizontal and vertical advective fluxes were site-specific and characterized by large scatter. In relative terms, the data indicated that the sensible heat budget was less affected by advection than the latent heat budget during nighttime; this is because vertical turbulent latent heat fluxes were very small or close to zero during the night. The results further showed that the additional energy gain by sensible heat advection might have triggered enhanced evaporation for two sites during nighttime. Accounting for advective fluxes improved the energy balance closure for one of the three ADVEX sites. However, the energy balance closure of the other two sites did not improve overall. A comparison with energy balance residuals (energy missed by the measurements without accounting for advection) indicated a large influence of systematic errors. An inspection of the energy balance for the sloped site of the ADVEX dataset underlined the necessity of slope-parallel measurement of radiation.
BibTeX:
@article{Moderow2021,
  author = {Moderow, Uta and Grünwald, Thomas and Queck, Ronald and Spank, Uwe and Bernhofer, Christian},
  title = {Energy balance closure and advective fluxes at ADVEX sites},
  journal = {Theoretical and Applied Climatology},
  year = {2021},
  volume = {143},
  number = {1},
  pages = {761--779},
  url = {https://doi.org/10.1007/s00704-020-03412-z},
  doi = {10.1007/s00704-020-03412-z}
}
Mohammad Harmay NS, Kim D and Choi M (2021), "Urban Heat Island associated with Land Use/Land Cover and climate variations in Melbourne, Australia", Sustainable Cities and Society. Vol. 69, pp. 102861.
Abstract: Urbanization is known as one of the most prominent global problems that alter the atmosphere and land surface properties. The intensity of Urban Heat Island (UHI) associated with surface temperature and component attributes were assessed using the Community Land Model (CLM). The variations of UHI with Land Use/Land Cover (LULC) and climate variations were also investigated to provide a link among urbanization, surface energy balance interactions, and extreme hydroclimatic events which are drought (‘big dry' and ‘angry summer') and heavy rainfall (‘big wet') in Melbourne, Australia. Generally, UHI demonstrated a uniform increasing trend with an ∼1.20 ± 0.20 °C increment, along with urbanization expansion of +14.93 % from 2001 to 2014. Furthermore, urban area showed positive contribution to UHI based on Land Contribution Index (LCI). High surface temperatures also resulted in higher sensible heat flux (Qh) and lower latent heat flux (Qle). During the multiple extreme climate events, the UHI biophysical drivers were majorly related to the convection reduction during ‘big dry' (2001−2009), surface evaporative cooling during ‘big wet' (2010−2011), and heat storage release during ‘angry summer' (2012–2013). Overall, this analysis demonstrated correlation of UHI intensity and its component attributes with urban expansion, which was associated with LULC and climate variations in Melbourne.
BibTeX:
@article{MohammadHarmay2021,
  author = {Mohammad Harmay, Nurul Syahira and Kim, Daeun and Choi, Minha},
  title = {Urban Heat Island associated with Land Use/Land Cover and climate variations in Melbourne, Australia},
  journal = {Sustainable Cities and Society},
  year = {2021},
  volume = {69},
  pages = {102861},
  url = {https://www.sciencedirect.com/science/article/pii/S2210670721001517},
  doi = {10.1016/j.scs.2021.102861}
}
Montzka C, Bogena HR, Herbst M, Cosh MH, Jagdhuber T and Vereecken H (2021), "Estimating the Number of Reference Sites Necessary for the Validation of Global Soil Moisture Products", IEEE Geoscience and Remote Sensing Letters. Vol. 18(9), pp. 1530-1534.
BibTeX:
@article{Montzka2021,
  author = {Montzka, Carsten and Bogena, Heye R and Herbst, Michael and Cosh, Michael H and Jagdhuber, Thomas and Vereecken, Harry},
  title = {Estimating the Number of Reference Sites Necessary for the Validation of Global Soil Moisture Products},
  journal = {IEEE Geoscience and Remote Sensing Letters},
  year = {2021},
  volume = {18},
  number = {9},
  pages = {1530--1534},
  doi = {10.1109/LGRS.2020.3005730}
}
Mowlem M, Beaton A, Pascal R, Schaap A, Loucaides S, Monk S, Morris A, Cardwell CL, Fowell SE, Patey MD and López-García P (2021), "Industry Partnership: Lab on Chip Chemical Sensor Technology for Ocean Observing", Frontiers in Marine Science. Vol. 8
Abstract: We introduce for the first time a new product line able to make high accuracy measurements of a number of water chemistry parameters in situ: i.e., submerged in the environment including in the deep sea (to 6,000 m). This product is based on the developments of in situ lab on chip technology at the National Oceanography Centre (NOC), and the University of Southampton and is produced under license by Clearwater Sensors Ltd., a start-up and industrial partner in bringing this technology to global availability and further developing its potential. The technology has already been deployed by the NOC, and with their partners worldwide over 200 times including to depths of ∼4,800 m, in turbid estuaries and rivers, and for up to a year in seasonally ice-covered regions of the arctic. The technology is capable of making accurate determinations of chemical and biological parameters that require reagents and which produce an electrical, absorbance, fluorescence, or luminescence signal. As such it is suitable for a wide range of environmental measurements. Whilst further parameters are in development across this partnership, Nitrate, Nitrite, Phosphate, Silicate, Iron, and pH sensors are currently available commercially. Theses sensors use microfluidics and optics combined in an optofluidic chip with electromechanical valves and pumps mounted upon it to mix water samples with reagents and measure the optical response. An overview of the sensors and the underlying components and technologies is given together with examples of deployments and integrations with observing platforms such as gliders, autonomous underwater vehicles and moorings.
BibTeX:
@article{Mowlem2021,
  author = {Mowlem, Matt and Beaton, Alexander and Pascal, Robin and Schaap, Allison and Loucaides, Socratis and Monk, Sam and Morris, Andrew and Cardwell, Christopher L and Fowell, Sara E and Patey, Matthew D and López-García, Patricia},
  title = {Industry Partnership: Lab on Chip Chemical Sensor Technology for Ocean Observing},
  journal = {Frontiers in Marine Science},
  year = {2021},
  volume = {8},
  url = {https://www.frontiersin.org/article/10.3389/fmars.2021.697611},
  doi = {10.3389/fmars.2021.697611}
}
Müller JD, Schneider B, Gräwe U, Fietzek P, Wallin MB, Rutgersson A, Wasmund N, Krüger S and Rehder G (2021), "Cyanobacteria net community production in the Baltic Sea as inferred from profiling pCO_2 measurements", Biogeosciences. Vol. 18(17), pp. 4889-4917.
BibTeX:
@article{Mueller2021,
  author = {Müller, J D and Schneider, B and Gräwe, U and Fietzek, P and Wallin, M B and Rutgersson, A and Wasmund, N and Krüger, S and Rehder, G},
  title = {Cyanobacteria net community production in the Baltic Sea as inferred from profiling pCO_2 measurements},
  journal = {Biogeosciences},
  year = {2021},
  volume = {18},
  number = {17},
  pages = {4889--4917},
  url = {https://bg.copernicus.org/articles/18/4889/2021/},
  doi = {10.5194/bg-18-4889-2021}
}
Nadal-Sala D, Grote R, Birami B, Lintunen A, Mammarella I, Preisler Y, Rotenberg E, Salmon Y, Tatarinov F, Yakir D and Ruehr NK (2021), "Assessing model performance via the most limiting environmental driver in two differently stressed pine stands", Ecological Applications., jun, 2021. Vol. 31(4), pp. e02312. John Wiley & Sons, Ltd.
Abstract: Abstract Climate change will impact forest productivity worldwide. Forecasting the magnitude of such impact, with multiple environmental stressors changing simultaneously, is only possible with the help of process-based models. In order to assess their performance, such models require careful evaluation against measurements. However, direct comparison of model outputs against observational data is often not reliable, as models may provide the right answers due to the wrong reasons. This would severely hinder forecasting abilities under unprecedented climate conditions. Here, we present a methodology for model assessment, which supplements the traditional output-to-observation model validation. It evaluates model performance through its ability to reproduce observed seasonal changes of the most limiting environmental driver (MLED) for a given process, here daily gross primary productivity (GPP). We analyzed seasonal changes of the MLED for GPP in two contrasting pine forests, the Mediterranean Pinus halepensis Mill. Yatir (Israel) and the boreal Pinus sylvestris L. Hyytiälä (Finland) from three years of eddy-covariance flux data. Then, we simulated the same period with a state-of-the-art process-based simulation model (LandscapeDNDC). Finally, we assessed if the model was able to reproduce both GPP observations and MLED seasonality. We found that the model reproduced the seasonality of GPP in both stands, but it was slightly overestimated without site-specific fine-tuning. Interestingly, although LandscapeDNDC properly captured the main MLED in Hyytiälä (temperature) and in Yatir (soil water availability), it failed to reproduce high-temperature and high-vapor pressure limitations of GPP in Yatir during spring and summer. We deduced that the most likely reason for this divergence is an incomplete description of stomatal behavior. In summary, this study validates the MLED approach as a model evaluation tool, and opens up new possibilities for model improvement.
BibTeX:
@article{NadalSala2021,
  author = {Nadal-Sala, Daniel and Grote, Rüdiger and Birami, Benjamin and Lintunen, Anna and Mammarella, Ivan and Preisler, Yakir and Rotenberg, Eyal and Salmon, Yann and Tatarinov, Fedor and Yakir, Dan and Ruehr, Nadine K},
  title = {Assessing model performance via the most limiting environmental driver in two differently stressed pine stands},
  journal = {Ecological Applications},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {31},
  number = {4},
  pages = {e02312},
  url = {https://doi.org/10.1002/eap.2312},
  doi = {10.1002/eap.2312}
}
Nerobelov G, Timofeyev Y, Smyshlyaev S, Foka S, Mammarella I and Virolainen Y (2021), "Validation of WRF-Chem Model and CAMS Performance in Estimating Near-Surface Atmospheric CO2 Mixing Ratio in the Area of Saint Petersburg (Russia)", Atmosphere. Vol. 12(3)
Abstract: Nowadays, different approaches for CO2 anthropogenic emission estimation are applied to control agreements on greenhouse gas reduction. Some methods are based on the inverse modelling of emissions using various measurements and the results of numerical chemistry transport models (CTMs). Since the accuracy and precision of CTMs largely determine errors in the approaches for emission estimation, it is crucial to validate the performance of such models through observations. In the current study, the near-surface CO2 mixing ratio simulated by the CTM Weather Research and Forecasting—Chemistry (WRF-Chem) at a high spatial resolution (3 km) using three different sets of CO2 fluxes (anthropogenic + biogenic fluxes, time-varying and constant anthropogenic emissions) and from Copernicus Atmosphere Monitoring Service (CAMS) datasets have been validated using in situ observations near the Saint Petersburg megacity (Russia) in March and April 2019. It was found that CAMS reanalysis data with a low spatial resolution (1.9° × 3.8°) can match the observations better than CAMS analysis data with a high resolution (0.15° × 0.15°). The CAMS analysis significantly overestimates the observed near-surface CO2 mixing ratio in Peterhof in March and April 2019 (by more than 10 ppm). The best match for the CAMS reanalysis and observations was observed in March, when the wind was predominantly opposite to the Saint Petersburg urbanized area. In contrast, the CAMS analysis fits the observed trend of the mixing ratio variation in April better than the reanalysis with the wind directions from the Saint Petersburg urban zone. Generally, the WRF-Chem predicts the observed temporal variations in the near-surface CO2 reasonably well (mean bias ≈ (−0.3) − (−0.9) ppm, RMSD ≈ 8.7 ppm, correlation coefficient ≈ 0.61 ± 0.04). The WRF-Chem data where anthropogenic and biogenic fluxes were used match the observations a bit better than the WRF-Chem data without biogenic fluxes. The diurnal time variation in the anthropogenic emissions influenced the WRF-Chem data insignificantly. However, in general, the data of all three WRF-Chem model runs give almost the same CO2 temporal variation in Peterhof in March and April 2019. This could be related to the late start of the growing season, which influences biogenic CO2 fluxes, inaccuracies in the estimation of the biogenic fluxes, and the simplified time variation pattern of the CO2 anthropogenic emissions.
BibTeX:
@article{Nerobelov2021,
  author = {Nerobelov, Georgy and Timofeyev, Yuri and Smyshlyaev, Sergei and Foka, Stefani and Mammarella, Ivan and Virolainen, Yana},
  title = {Validation of WRF-Chem Model and CAMS Performance in Estimating Near-Surface Atmospheric CO2 Mixing Ratio in the Area of Saint Petersburg (Russia)},
  journal = {Atmosphere},
  year = {2021},
  volume = {12},
  number = {3},
  url = {https://www.mdpi.com/2073-4433/12/3/387},
  doi = {10.3390/atmos12030387}
}
Neuwirth B, Rabbel I, Bendix J, Bogena HR and Thies B (2021), "The European Heat Wave 2018: The Dendroecological Response of Oak and Spruce in Western Germany", Forests. Vol. 12(3)
Abstract: The European heat wave of 2018 was characterized by extraordinarily dry and hot spring and summer conditions in many central and northern European countries. The average temperatures from June to August 2018 were the second highest since 1881. Accordingly, many plants, especially trees, were pushed to their physiological limits. However, while the drought and heat response of field crops and younger trees have been well investigated in laboratory experiments, little is known regarding the drought and heat response of mature forest trees. In this study, we compared the response of a coniferous and a deciduous tree species, located in western and central–western Germany, to the extreme environmental conditions during the European heat wave of 2018. Combining classic dendroecological techniques (tree–ring analysis) with measurements of the intra–annual stem expansion (dendrometers) and tree water uptake (sap flow sensors), we found contrasting responses of spruce and oak trees. While spruce trees developed a narrow tree ring in 2018 combined with decreasing correlations of daily sap flow and dendrometer parameters to the climatic parameters, oak trees developed a ring with above–average tree–ring width combined with increasing correlations between the daily climatic parameters and the parameters derived from sap flow and the dendrometer sensors. In conclusion, spruce trees reacted to the 2018 heat wave with the early completion of their growth activities, whereas oaks appeared to intensify their activities based on the water content in their tree stems.
BibTeX:
@article{Neuwirth2021,
  author = {Neuwirth, Burkhard and Rabbel, Inken and Bendix, Jörg and Bogena, Heye R and Thies, Boris},
  title = {The European Heat Wave 2018: The Dendroecological Response of Oak and Spruce in Western Germany},
  journal = {Forests},
  year = {2021},
  volume = {12},
  number = {3},
  url = {https://www.mdpi.com/1999-4907/12/3/283},
  doi = {10.3390/f12030283}
}
Nilsson H, Pilesjö P, Hasan A and Persson A (2021), "Dynamic spatio-temporal flow modeling with raster DEMs", Transactions in GIS., nov, 2021. Vol. n/a(n/a) John Wiley & Sons, Ltd.
Abstract: Abstract A user-friendly high-resolution intermediate complexity dynamic and spatially distributed flow model is crucial in urban flood modeling. Planners and consultants need to improve the accuracy of floods and estimation of risks. A new flow model will serve as a rapid tool to improve identification of these. This article provides a detailed explanation of a model based on a multiple flow algorithm. Model testing was performed on selected urban and rural areas. Additionally, a sensitivity analysis is conducted to analyze functionality. The model includes basic hydrological processes and is therefore less complex than fully physical models. The data needed to set up and run the new model include spatially and temporally distributed basic geometric and hydrologic variables (i.e., digital elevation model, precipitation, infiltration, and surface roughness). The model is implemented using open-source coding and can easily be applied to any selected area. Outputs are water volumes, depths, and velocities at different modeling times. Using GIS, results can be visualized and utilized for further analyses. The test, applied in urban as well as rural areas, demonstrates its user-friendliness, and that the estimated distributed water depths and water velocity at any time step can be saved and visualized.
BibTeX:
@article{Nilsson2021,
  author = {Nilsson, Hampus and Pilesjö, Petter and Hasan, Abdulghani and Persson, Andreas},
  title = {Dynamic spatio-temporal flow modeling with raster DEMs},
  journal = {Transactions in GIS},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {n/a},
  number = {n/a},
  url = {https://doi.org/10.1111/tgis.12870},
  doi = {10.1111/tgis.12870}
}
Oddi L, Cremonese E, Ascari L, Filippa G, Galvagno M, Serafino D and di Cella UM (2021), "Using UAV Imagery to Detect and Map Woody Species Encroachment in a Subalpine Grassland: Advantages and Limits", Remote Sensing. Vol. 13(7)
Abstract: Woody species encroachment on grassland ecosystems is occurring worldwide with both negative and positive consequences for biodiversity conservation and ecosystem services. Remote sensing and image analysis represent useful tools for the monitoring of this process. In this paper, we aimed at evaluating quantitatively the potential of using high-resolution UAV imagery to monitor the encroachment process during its early development and at comparing the performance of manual and semi-automatic classification methods. The RGB images of an abandoned subalpine grassland on the Western Italian Alps were acquired by drone and then classified through manual photo-interpretation, with both pixel- and object-based semi-automatic models, using machine-learning algorithms. The classification techniques were applied at different resolution levels and tested for their accuracy against reference data including measurements of tree dimensions collected in the field. Results showed that the most accurate method was the photo-interpretation (≈99%), followed by the pixel-based approach (≈86%) that was faster than the manual technique and more accurate than the object-based one (≈78%). The dimensional threshold for juvenile tree detection was lower for the photo-interpretation but comparable to the pixel-based one. Therefore, for the encroachment mapping at its early stages, the pixel-based approach proved to be a promising and pragmatic choice.
BibTeX:
@article{Oddi2021,
  author = {Oddi, Ludovica and Cremonese, Edoardo and Ascari, Lorenzo and Filippa, Gianluca and Galvagno, Marta and Serafino, Davide and di Cella, Umberto Morra},
  title = {Using UAV Imagery to Detect and Map Woody Species Encroachment in a Subalpine Grassland: Advantages and Limits},
  journal = {Remote Sensing},
  year = {2021},
  volume = {13},
  number = {7},
  url = {https://www.mdpi.com/2072-4292/13/7/1239},
  doi = {10.3390/rs13071239}
}
Ogundare MO, Fransson A, Chierici M, Joubert WR and Roychoudhury AN (2021), "Variability of Sea-Air Carbon Dioxide Flux in Autumn Across the Weddell Gyre and Offshore Dronning Maud Land in the Southern Ocean", Frontiers in Marine Science. Vol. 7
Abstract: Sea surface fugacity of carbon dioxide (fCO2ssw) was measured across the Weddell gyre and the eastern sector in the Atlantic Southern Ocean in autumn. During the occupation between February and April 2019, the region of the study transect was a potential ocean CO2 sink. A net CO2 flux (FCO2) of −6.2 (± 8; sink) mmol m–2 d–1 was estimated for the entire study region, with the largest average CO2 sink of −10.0 (± 8) mmol m–2 d–1 in the partly ice-covered Astrid Ridge (AR) region near the coast at 68°S and −6.1 (± 8) mmol m–2d–1 was observed in the Maud Rise (MR) region. A CO2 sink was also observed south of 66°S in the Weddell Sea (WS). To assess the main drivers describing the variability of fCO2ssw, a correlation model using fCO2 and oxygen saturation was considered. Spatial distributions of the fCO2 saturation/O2 saturation correlations, described relative to the surface water properties of the controlling variables (chlorophyll a, apparent oxygen utilization (AOU), sea surface temperature, and sea surface salinity) further constrained the interplay of the processes driving the fCO2ssw distributions. Photosynthetic CO2 drawdown significantly offsets the influence of the upwelling of CO2-rich waters in the central Weddell gyre and enhanced the CO2 sink in the region. FCO2 of −6.9 mmol m–2 d–1 estimated for the Weddell gyre in this study was different from FCO2 of −2.5 mmol m–2 d–1 in autumn estimated in a previous study. Due to low CO2 data coverage during autumn, limited sea-air CO2 flux estimates from direct sea-surface CO2 observations particularly for the Weddell gyre region are available with which to compare the values estimated in this study. This highlights the importance of increasing seasonal CO2 observations especially during autumn/winter to improving the seasonal coverage of flux estimates in the seasonal sea ice-covered regions of the Southern Ocean.
BibTeX:
@article{Ogundare2021,
  author = {Ogundare, Margaret Ojone and Fransson, Agneta and Chierici, Melissa and Joubert, Warren R and Roychoudhury, Alakendra N},
  title = {Variability of Sea-Air Carbon Dioxide Flux in Autumn Across the Weddell Gyre and Offshore Dronning Maud Land in the Southern Ocean},
  journal = {Frontiers in Marine Science},
  year = {2021},
  volume = {7},
  url = {https://www.frontiersin.org/article/10.3389/fmars.2020.614263},
  doi = {10.3389/fmars.2020.614263}
}
Öhrn P, Berlin M, Elfstrand M, Krokene P and Jönsson AM (2021), "Seasonal variation in Norway spruce response to inoculation with bark beetle-associated bluestain fungi one year after a severe drought", Forest Ecology and Management. Vol. 496, pp. 119443.
Abstract: In 2018, up to 4 million m3 Norway spruce was killed by the spruce bark beetle Ips typographus in Sweden. The event was unique for Sweden, in terms of both affected volume and the fact that it was triggered by severe drought stress, not by ample availability of relatively defenseless storm-felled trees. The outbreak continued in 2019 and 2020, each year with twice as many trees killed as in 2018. The aim of this study was to quantify seasonal variation and potential lag-effects in tree defense capacity the year after a severe drought stress. Inoculation with a bark beetle-associated bluestain fungus, repeated four times with one-month-intervals between May and August 2019, were carried out at three field sites with spruce provenances of Swedish and East European origin representing early and late bud burst, respectively. All sites had experienced moderate to severe drought stress in 2018, and site-specific defense capacity correlated positively with the cumulative precipitation two months before inoculation. Sites with two-month precipitation levels <100 mm had larger necrotic lesions in the phloem following inoculation, an indication of lower tree defense capacity. Lesion size did not differ between provenances, and all trees were able to confine fungal infection successfully. There were some seasonal differences in necrotic lesion size, with the sites Skärsnäs and Norberg having significantly larger lesions in June than in May, and site Lugnet having large lesions also in May. Lesions were generally smaller in July and August than in June. The cross-sectional area and number of traumatic resin ducts was measured in sapwood samples from one site, Lugnet, to quantify an additional aspect of tree defenses. The area of resin ducts produced in May and June were larger than that in July and August. This is in line with a positive correlation between lesion area and resin duct area, indicating that a stronger fungal infection following inoculation in spring triggered a stronger induced defense response. The East European provenances had more resin ducts than Swedish provenances, but the area of resin ducts did not differ significantly between provenances.
BibTeX:
@article{Oehrn2021,
  author = {Öhrn, Petter and Berlin, Mats and Elfstrand, Malin and Krokene, Paal and Jönsson, Anna Maria},
  title = {Seasonal variation in Norway spruce response to inoculation with bark beetle-associated bluestain fungi one year after a severe drought},
  journal = {Forest Ecology and Management},
  year = {2021},
  volume = {496},
  pages = {119443},
  url = {https://www.sciencedirect.com/science/article/pii/S0378112721005326},
  doi = {10.1016/j.foreco.2021.119443}
}
Ollivier C, Olioso A, Carrière SD, Boulet G, Chalikakis K, Chanzy A, Charlier J-B, Combemale D, Davi H, Emblanch C, Marloie O, Martin-StPaul N, Mazzilli N, Simioni G and Weiss M (2021), "An evapotranspiration model driven by remote sensing data for assessing groundwater resource in karst watershed", Science of The Total Environment. Vol. 781, pp. 146706.
Abstract: Aquifer recharge may depend mainly on the difference between precipitation and evapotranspiration. Hydrological models used to estimate groundwater reserves use evapotranspiration models that are mainly determined by climate demand. In particular, mechanisms of plant transpiration are neglected, although transpiration constitutes 70% of evapotranspiration. This is problematic when considering karst watershed, which are poorly documented at the interface between soil and atmosphere where vegetation and soil properties control water flows. To fill this gap, we propose an evapotranspiration model that integrates the processes of plant transpiration and soil evaporation. The dynamics of vegetation is evaluated using the Enhanced Vegetation Indexes from the Terra and Aqua Moderate Resolution Imaging Spectroradiometers. The soil evaporation calculation account for the impact of coarse elements at soil surface. The “Simple Crop coefficient for Evapotranspiration” (SimpKcET) model is tested at flux tower sites over forest of Font-Blanche, Puechabon and the agricultural area of Avignon. The simulated daily evapotranspirations are very close to the observations (RMSE ∼0.5 mm.d-1), while the model is simple compared to other models proposed in the literature. The SimpKcET is implemented in a karst hydrological model to evaluate the impact of evapotranspiration estimation on the aquifer flow rate simulation. This approach is applied to the vast watershed of Fontaine de Vaucluse. In comparison to the water bucket model that is frequently used in karst models, SimpKcET provide ET simulations that are more in line with ET processes. A cross wavelet analysis highlighted the improvement of the simulated recharge and observed flow rate relationship brought by the consideration of evaporation and transpiration processes. The use of remote sensing data related to plant activity makes it possible to propose a parsimonious model that can be applied to all types of vegetation (agricultural, natural, mixed forest) and that can be transferred to other karst models.
BibTeX:
@article{Ollivier2021,
  author = {Ollivier, Chloé and Olioso, Albert and Carrière, Simon Damien and Boulet, Gilles and Chalikakis, Konstantinos and Chanzy, André and Charlier, Jean-Baptiste and Combemale, David and Davi, Hendrik and Emblanch, Christophe and Marloie, Olivier and Martin-StPaul, Nicolas and Mazzilli, Naomi and Simioni, Guillaume and Weiss, Marie},
  title = {An evapotranspiration model driven by remote sensing data for assessing groundwater resource in karst watershed},
  journal = {Science of The Total Environment},
  year = {2021},
  volume = {781},
  pages = {146706},
  url = {https://www.sciencedirect.com/science/article/pii/S0048969721017745},
  doi = {10.1016/j.scitotenv.2021.146706}
}
Osterwalder S, Nerentorp M, Zhu W, Jiskra M, Nilsson E, Nilsson MB, Rutgersson A, Soerensen AL, Sommar J, Wallin MB, Wängberg I and Bishop K (2021), "Critical Observations of Gaseous Elemental Mercury Air-Sea Exchange", Global Biogeochemical Cycles., aug, 2021. Vol. 35(8), pp. e2020GB006742. John Wiley & Sons, Ltd.
Abstract: Abstract Air-sea exchange of gaseous elemental mercury (Hg0) is not well constrained, even though it is a major component of the global Hg cycle. Lack of Hg0 flux measurements to validate parameterizations of the Hg0 transfer velocity contributes to this uncertainty. We measured the Hg0 flux on the Baltic Sea coast using micrometeorological methods (gradient-based and relaxed eddy accumulation [REA]) and also simulated the flux with a gas exchange model. The coastal waters were typically supersaturated with Hg0 (mean ± 1σ = 13.5 ± 3.5 ng m?3; ca. 10% of total Hg) compared to the atmosphere (1.3 ± 0.2 ng m?3). The Hg0 flux calculated using the gas exchange model ranged from 0.1?1.3 ng m?2 h?1 (10th and 90th percentile) over the course of the campaign (May 10?June 20, 2017) and showed a distinct diel fluctuation. The mean coastal Hg0 fluxes determined with the two gradient-based approaches and REA were 0.3, 0.5, and 0.6 ng m?2 h?1, respectively. In contrast, the mean open sea Hg0 flux measured with REA was larger (6.3 ng m?2 h?1). The open sea Hg0 flux indicated a stronger wind speed dependence for the Hg0 transfer velocity compared to commonly used parameterizations. Although based on a limited data set, we suggest that the wind speed dependence of the Hg0 transfer velocity is more consistent with gases that have less water solubility than CO2 (e.g., O2). These pioneering flux measurements using micrometeorological techniques show that more such measurements would improve our understanding of air-sea Hg exchange.
BibTeX:
@article{Osterwalder2021,
  author = {Osterwalder, S and Nerentorp, M and Zhu, W and Jiskra, M and Nilsson, E and Nilsson, M B and Rutgersson, A and Soerensen, A L and Sommar, J and Wallin, M B and Wängberg, I and Bishop, K},
  title = {Critical Observations of Gaseous Elemental Mercury Air-Sea Exchange},
  journal = {Global Biogeochemical Cycles},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {35},
  number = {8},
  pages = {e2020GB006742},
  url = {https://doi.org/10.1029/2020GB006742},
  doi = {10.1029/2020GB006742}
}
Otu-Larbi F, Conte A, Fares S, Wild O and Ashworth K (2021), "FORCAsT-gs: Importance of Stomatal Conductance Parameterization to Estimated Ozone Deposition Velocity", Journal of Advances in Modeling Earth Systems., sep, 2021. Vol. 13(9), pp. e2021MS002581. John Wiley & Sons, Ltd.
Abstract: Abstract The role of stomata in regulating photosynthesis and transpiration, and hence governing global biogeochemical cycles and climate, is well-known. Less well-understood, however, is the importance of stomatal control to the exchange of other trace gases between terrestrial vegetation and the atmosphere. Yet these gases determine atmospheric composition, and hence air quality and climate, on scales ranging from local to global, and seconds to decades. Vegetation is a major sink for ground-level ozone via the process of dry deposition and the primary source of many biogenic volatile organic compounds (BVOCs). The rate of dry deposition is largely controlled by the rate of diffusion of a gas through the stomata, and this also governs the emission rate of some key BVOCs. It is critical therefore that canopy-atmosphere exchange models capture the physiological processes controlling stomatal conductance and the transfer of trace gases other than carbon dioxide and water vapor. We incorporate three of the most widely used coupled stomatal conductance-photosynthesis models into the one-dimensional multi-layer FORest Canopy-Atmosphere Transfer (FORCAsT1.0) model to assess the importance of choice of parameterization on simulated ozone deposition rates. Modeled GPP and stomatal conductance across a broad range of ecosystems differ by up to a factor of two between the best and worst performing model configurations. This leads to divergences in seasonal and diel profiles of ozone deposition velocity of up to 30% and deposition rate of up to 13%, demonstrating that the choice of stomatal conductance parameterization is critical in accurate quantification of ozone deposition.
BibTeX:
@article{OtuLarbi2021,
  author = {Otu-Larbi, Frederick and Conte, Adriano and Fares, Silvano and Wild, Oliver and Ashworth, Kirsti},
  title = {FORCAsT-gs: Importance of Stomatal Conductance Parameterization to Estimated Ozone Deposition Velocity},
  journal = {Journal of Advances in Modeling Earth Systems},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {13},
  number = {9},
  pages = {e2021MS002581},
  url = {https://doi.org/10.1029/2021MS002581},
  doi = {10.1029/2021MS002581}
}
Oulehle F, Fischer M, Hruška J, Chuman T, Krám P, Navrátil T, Tesař M and Trnka M (2021), "The GEOMON network of Czech catchments provides long-term insights into altered forest biogeochemistry: From acid atmospheric deposition to climate change", Hydrological Processes., may, 2021. Vol. 35(5), pp. e14204. John Wiley & Sons, Ltd.
Abstract: Abstract In 1994, a network of small catchments (GEOMON) was established in the Czech Republic to determine input?output element fluxes in semi-natural forest ecosystems recovering from anthropogenic acidification. The network consists from 16 catchments and the primary observations of elements fluxes were complemented by monitoring of biomass stock, element pools in soil and vegetation, and the main water balance components. Over last three decades, reductions of SO2, NOx and NH3 emissions were followed by sulphur (S) and nitrogen (N) deposition reductions of 75% and 30%, respectively. Steeper declines of strong acid anion concentrations compared to cations (Ca, Mg, Na, K, NH4) in precipitation resulted in precipitation pH increase from 4.5 to 5.2 in bulk precipitation and from 4.0 to 5.1 in spruce throughfall. Stream chemistry responded to changes in deposition: S leaching declined. However at majority of catchments soils acted as a net source of S to runoff, delaying recovery. Stream pH increased at acidic streams (pH?
BibTeX:
@article{Oulehle2021,
  author = {Oulehle, Filip and Fischer, Milan and Hruška, Jakub and Chuman, Tomáš and Krám, Pavel and Navrátil, Tomáš and Tesař, Miroslav and Trnka, Miroslav},
  title = {The GEOMON network of Czech catchments provides long-term insights into altered forest biogeochemistry: From acid atmospheric deposition to climate change},
  journal = {Hydrological Processes},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {35},
  number = {5},
  pages = {e14204},
  url = {https://doi.org/10.1002/hyp.14204},
  doi = {10.1002/hyp.14204}
}
Pace R, Guidolotti G, Baldacchini C, Pallozzi E, Grote R, Nowak DJ and Calfapietra C (2021), "Comparing i-Tree Eco Estimates of Particulate Matter Deposition with Leaf and Canopy Measurements in an Urban Mediterranean Holm Oak Forest", Environmental Science & Technology., may, 2021. Vol. 55(10), pp. 6613-6622. American Chemical Society.
BibTeX:
@article{Pace2021,
  author = {Pace, Rocco and Guidolotti, Gabriele and Baldacchini, Chiara and Pallozzi, Emanuele and Grote, Rüdiger and Nowak, David J and Calfapietra, Carlo},
  title = {Comparing i-Tree Eco Estimates of Particulate Matter Deposition with Leaf and Canopy Measurements in an Urban Mediterranean Holm Oak Forest},
  journal = {Environmental Science & Technology},
  publisher = {American Chemical Society},
  year = {2021},
  volume = {55},
  number = {10},
  pages = {6613--6622},
  url = {https://doi.org/10.1021/acs.est.0c07679},
  doi = {10.1021/acs.est.0c07679}
}
Pallandt M, Kumar J, Mauritz M, Schuur E, Virkkala A-M, Celis G, Hoffman F and Göckede M (2021), "Representativeness assessment of the pan-Arctic eddy-covariance site network, and optimized future enhancements", Biogeosciences Discussions. , pp. 1-42.
Abstract: Large changes in the Arctic carbon balance are expected as warming linked to climate change threatens to 15 destabilize ancient permafrost carbon stocks. The eddy covariance (EC) method is an established technique to quantify net losses and gains of carbon between the biosphere and atmosphere at high spatio-temporal resolution. Over the past decades, a growing network of terrestrial EC tower sites has been established across the Arctic, but a comprehensive assessment of the network's representativeness within the heterogeneous Arctic region is still lacking. This creates additional uncertainties when integrating flux data across sites, for example when upscaling fluxes to constrain pan-Arctic carbon budgets, and 20 changes therein. This study provides an inventory of Arctic (here >= 60 O N) EC sites, which has also been made available online (https://cosima.nceas.ucsb.edu/carbon-flux-sites/). Our database currently comprises 120 EC sites, but only 83 are listed as active, and just 25 of these active sites remain operational throughout the winter. To map the representativeness of this EC network, based on 18 bioclimatic and edaphic variables, we evaluated the similarity between environmental conditions 25 observed at the tower locations and those within the larger Arctic study domain. With the majority of sites located in Fennoscandia and Alaska, these regions were assigned the highest level of network representativeness, while large parts of Siberia and patches of Canada were classified as under-represented. This division between regions is further emphasized for
BibTeX:
@article{Pallandt2021,
  author = {Pallandt, Martijn and Kumar, Jitendra and Mauritz, Marguerite and Schuur, Edward and Virkkala, Anna-Maria and Celis, Gerardo and Hoffman, Forrest and Göckede, Mathias},
  title = {Representativeness assessment of the pan-Arctic eddy-covariance site network, and optimized future enhancements},
  journal = {Biogeosciences Discussions},
  year = {2021},
  pages = {1--42},
  doi = {10.5194/bg-2021-133}
}
Park S-B, Knohl A, Migliavacca M, Thum T, Vesala T, Peltola O, Mammarella I, Prokushkin A, Kolle O, Lavrič J, Park SS and Heimann M (2021), "Temperature Control of Spring CO2 Fluxes at a Coniferous Forest and a Peat Bog in Central Siberia", Atmosphere. Vol. 12(8)
Abstract: Climate change impacts the characteristics of the vegetation carbon-uptake process in the northern Eurasian terrestrial ecosystem. However, the currently available direct CO2 flux measurement datasets, particularly for central Siberia, are insufficient for understanding the current condition in the northern Eurasian carbon cycle. Here, we report daily and seasonal interannual variations in CO2 fluxes and associated abiotic factors measured using eddy covariance in a coniferous forest and a bog near Zotino, Krasnoyarsk Krai, Russia, for April to early June, 2013–2017. Despite the snow not being completely melted, both ecosystems became weak net CO2 sinks if the air temperature was warm enough for photosynthesis. The forest became a net CO2 sink 7–16 days earlier than the bog. After the surface soil temperature exceeded ∼1 °C, the ecosystems became persistent net CO2 sinks. Net ecosystem productivity was highest in 2015 for both ecosystems because of the anomalously high air temperature in May compared with other years. Our findings demonstrate that long-term monitoring of flux measurements at the site level, particularly during winter and its transition to spring, is essential for understanding the responses of the northern Eurasian ecosystem to spring warming.
BibTeX:
@article{Park2021,
  author = {Park, Sung-Bin and Knohl, Alexander and Migliavacca, Mirco and Thum, Tea and Vesala, Timo and Peltola, Olli and Mammarella, Ivan and Prokushkin, Anatoly and Kolle, Olaf and Lavrič, Jošt and Park, Sang Seo and Heimann, Martin},
  title = {Temperature Control of Spring CO2 Fluxes at a Coniferous Forest and a Peat Bog in Central Siberia},
  journal = {Atmosphere},
  year = {2021},
  volume = {12},
  number = {8},
  url = {https://www.mdpi.com/2073-4433/12/8/984},
  doi = {10.3390/atmos12080984}
}
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, Reichstein M, Ribeca A, van Ingen C, Vuichard N, 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, Rebmann C, 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, 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 (2021), "Author Correction: The FLUXNET2015 dataset and the ONEFlux processing pipeline for eddy covariance data", Scientific Data. Vol. 8(1), pp. 72.
Abstract: A Correction to this paper has been published: https://doi.org/10.1038/s41597-021-00851-9.
BibTeX:
@article{Pastorello2021,
  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 Reichstein, Markus and Ribeca, Alessio and van Ingen, Catharine and Vuichard, Nicolas 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, Jiří 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 Rebmann, Corinna 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 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 = {Author Correction: The FLUXNET2015 dataset and the ONEFlux processing pipeline for eddy covariance data},
  journal = {Scientific Data},
  year = {2021},
  volume = {8},
  number = {1},
  pages = {72},
  url = {https://doi.org/10.1038/s41597-021-00851-9},
  doi = {10.1038/s41597-021-00851-9}
}
Peltola O, Aslan T, Ibrom A, Nemitz E, Rannik Ü and Mammarella I (2021), "The high-frequency response correction of eddy covariance fluxes -- Part 1: An experimental approach and its interdependence with the time-lag estimation", Atmospheric Measurement Techniques. Vol. 14(7), pp. 5071-5088.
BibTeX:
@article{Peltola2021,
  author = {Peltola, O and Aslan, T and Ibrom, A and Nemitz, E and Rannik, Ü and Mammarella, I},
  title = {The high-frequency response correction of eddy covariance fluxes -- Part 1: An experimental approach and its interdependence with the time-lag estimation},
  journal = {Atmospheric Measurement Techniques},
  year = {2021},
  volume = {14},
  number = {7},
  pages = {5071--5088},
  url = {https://amt.copernicus.org/articles/14/5071/2021/},
  doi = {10.5194/amt-14-5071-2021}
}
Petrescu AMR, Qiu C, Ciais P, Thompson RL, Peylin P, McGrath MJ, Solazzo E, Janssens-Maenhout G, Tubiello FN, Bergamaschi P, Brunner D, Peters GP, Höglund-Isaksson L, Regnier P, Lauerwald R, Bastviken D, Tsuruta A, Winiwarter W, Patra PK, Kuhnert M, Oreggioni GD, Crippa M, Saunois M, Perugini L, Markkanen T, Aalto T, Groot Zwaaftink CD, Tian H, Yao Y, Wilson C, Conchedda G, Günther D, Leip A, Smith P, Haussaire J-M, Leppänen A, Manning AJ, McNorton J, Brockmann P and Dolman AJ (2021), "The consolidated European synthesis of CH_{4} and N_{2}O emissions for the European Union and United Kingdom: 1990--2017", Earth System Science Data. Vol. 13(5), pp. 2307-2362.
BibTeX:
@article{Petrescu2021,
  author = {Petrescu, A M R and Qiu, C and Ciais, P and Thompson, R L and Peylin, P and McGrath, M J and Solazzo, E and Janssens-Maenhout, G and Tubiello, F N and Bergamaschi, P and Brunner, D and Peters, G P and Höglund-Isaksson, L and Regnier, P and Lauerwald, R and Bastviken, D and Tsuruta, A and Winiwarter, W and Patra, P K and Kuhnert, M and Oreggioni, G D and Crippa, M and Saunois, M and Perugini, L and Markkanen, T and Aalto, T and Groot Zwaaftink, C D and Tian, H and Yao, Y and Wilson, C and Conchedda, G and Günther, D and Leip, A and Smith, P and Haussaire, J.-M. and Leppänen, A and Manning, A J and McNorton, J and Brockmann, P and Dolman, A J},
  title = {The consolidated European synthesis of CH_{4} and N_{2}O emissions for the European Union and United Kingdom: 1990--2017},
  journal = {Earth System Science Data},
  year = {2021},
  volume = {13},
  number = {5},
  pages = {2307--2362},
  url = {https://essd.copernicus.org/articles/13/2307/2021/},
  doi = {10.5194/essd-13-2307-2021}
}
Pisek J, Erb A, Korhonen L, Biermann T, Carrara A, Cremonese E, Cuntz M, Fares S, Gerosa G, Grünwald T, Hase N, Heliasz M, Ibrom A, Knohl A, Kobler J, Kruijt B, Lange H, Leppänen L, Limousin J-M, Serrano FRL, Loustau D, Lukeš P, Lundin L, Marzuoli R, Mölder M, Montagnani L, Neirynck J, Peichl M, Rebmann C, Rubio E, Santos-Reis M, Schaaf C, Schmidt M, Simioni G, Soudani K and Vincke C (2021), "Retrieval and validation of forest background reflectivity from daily Moderate Resolution Imaging Spectroradiometer (MODIS) bidirectional reflectance distribution function (BRDF) data across European forests", Biogeosciences., jan, 2021. Vol. 18(2), pp. 621-635.
BibTeX:
@article{Pisek2021,
  author = {Pisek, Jan and Erb, Angela and Korhonen, Lauri and Biermann, Tobias and Carrara, Arnaud and Cremonese, Edoardo and Cuntz, Matthias and Fares, Silvano and Gerosa, Giacomo and Grünwald, Thomas and Hase, Niklas and Heliasz, Michal and Ibrom, Andreas and Knohl, Alexander and Kobler, Johannes and Kruijt, Bart and Lange, Holger and Leppänen, Leena and Limousin, Jean-Marc and Serrano, Francisco Ramon Lopez and Loustau, Denis and Lukeš, Petr and Lundin, Lars and Marzuoli, Riccardo and Mölder, Meelis and Montagnani, Leonardo and Neirynck, Johan and Peichl, Matthias and Rebmann, Corinna and Rubio, Eva and Santos-Reis, Margarida and Schaaf, Crystal and Schmidt, Marius and Simioni, Guillaume and Soudani, Kamel and Vincke, Caroline},
  title = {Retrieval and validation of forest background reflectivity from daily Moderate Resolution Imaging Spectroradiometer (MODIS) bidirectional reflectance distribution function (BRDF) data across European forests},
  journal = {Biogeosciences},
  year = {2021},
  volume = {18},
  number = {2},
  pages = {621--635},
  url = {https://bg.copernicus.org/articles/18/621/2021/},
  doi = {10.5194/bg-18-621-2021}
}
Platt SM, Hov Ø, Berg T, Breivik K, Eckhardt S, Eleftheriadis K, Evangeliou N, Fiebig M, Fisher R, Hansen G, Hansson H-C, Heintzenberg J, Hermansen O, Heslin-Rees D, Holmén K, Hudson S, Kallenborn R, Krejci R, Krognes T, Larssen S, Lowry D, Lund Myhre C, Lunder C, Nisbet E, Nizetto PB, Park K-T, Pedersen CA, Aspmo Pfaffhuber K, Röckmann T, Schmidbauer N, Solberg S, Stohl A, Ström J, Svendby T, Tunved P, Tørnkvist K, van der Veen C, Vratolis S, Yoon YJ, Yttri KE, Zieger P, Aas W and Tørseth K (2021), "Atmospheric composition in the European Arctic and 30 years of the Zeppelin Observatory, Ny-Ålesund", Atmospheric Chemistry and Physics Discussions. Vol. 2021, pp. 1-80.
BibTeX:
@article{Platt2021,
  author = {Platt, S M and Hov, Ø and Berg, T and Breivik, K and Eckhardt, S and Eleftheriadis, K and Evangeliou, N and Fiebig, M and Fisher, R and Hansen, G and Hansson, H.-C. and Heintzenberg, J and Hermansen, O and Heslin-Rees, D and Holmén, K and Hudson, S and Kallenborn, R and Krejci, R and Krognes, T and Larssen, S and Lowry, D and Lund Myhre, C and Lunder, C and Nisbet, E and Nizetto, P B and Park, K.-T. and Pedersen, C A and Aspmo Pfaffhuber, K and Röckmann, T and Schmidbauer, N and Solberg, S and Stohl, A and Ström, J and Svendby, T and Tunved, P and Tørnkvist, K and van der Veen, C and Vratolis, S and Yoon, Y J and Yttri, K E and Zieger, P and Aas, W and Tørseth, K},
  title = {Atmospheric composition in the European Arctic and 30 years of the Zeppelin Observatory, Ny-Ålesund},
  journal = {Atmospheric Chemistry and Physics Discussions},
  year = {2021},
  volume = {2021},
  pages = {1--80},
  url = {https://acp.copernicus.org/preprints/acp-2021-505/},
  doi = {10.5194/acp-2021-505}
}
Pold G, Baillargeon N, Lepe A, Rastetter EB and Sistla SA (2021), "Warming effects on arctic tundra biogeochemistry are limited but habitat-dependent: a meta-analysis", Ecosphere., oct, 2021. Vol. 12(10), pp. e03777. John Wiley & Sons, Ltd.
Abstract: Abstract Arctic tundra consists of diverse habitats that differ in dominant vegetation, soil moisture regimes, and relative importance of organic vs. inorganic nutrient cycling. The Arctic is also the most rapidly warming global area, with winter warming dominating. This warming is expected to have dramatic effects on tundra carbon and nutrient dynamics. We completed a meta-analysis of 166 experimental warming study papers to evaluate the hypotheses that warming changes tundra biogeochemical cycles in a habitat- and seasonally specific manner and that the carbon (C), nitrogen (N), and phosphorus (P) cycles will be differentially accelerated, leading to decoupling of elemental cycles. We found that nutrient availability and plant leaf stoichiometry responses to experimental warming were variable and overall weak, but that both gross primary productivity and the plant C pool tended to increase with growing season warming. The effects of winter warming on C fluxes did not extend into the growing season. Overall, although warming led to more consistent increases in C fluxes compared to N or P fluxes, evidence for decoupling of biogeochemical cycles is weak and any effect appears limited to heath habitats. However, data on many habitats are too sparse to be able to generalize how warming might decouple biogeochemical cycles, and too few year-round warming studies exist to ascertain whether the season under which warming occurs alters how ecosystems respond to warming. Coordinated field campaigns are necessary to more robustly document tundra habitat-specific responses to realistic climate warming scenarios in order to better understand the mechanisms driving this heterogeneity and identify the tundra habitats, communities, and soil pools most susceptible to warming.
BibTeX:
@article{Pold2021,
  author = {Pold, Grace and Baillargeon, Natalie and Lepe, Adan and Rastetter, Edward B and Sistla, Seeta A},
  title = {Warming effects on arctic tundra biogeochemistry are limited but habitat-dependent: a meta-analysis},
  journal = {Ecosphere},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {12},
  number = {10},
  pages = {e03777},
  url = {https://doi.org/10.1002/ecs2.3777},
  doi = {10.1002/ecs2.3777}
}
Poyatos R, Granda V, Flo V, Adams MA, Adorján B, Aguadé D, Aidar MPM, Allen S, Alvarado-Barrientos MS, Anderson-Teixeira KJ, Aparecido LM, Arain MA, Aranda I, Asbjornsen H, Baxter R, Beamesderfer E, Berry ZC, Berveiller D, Blakely B, Boggs J, Bohrer G, Bolstad PV, Bonal D, Bracho R, Brito P, Brodeur J, Casanoves F, Chave J, Chen H, Cisneros C, Clark K, Cremonese E, Dang H, David JS, David TS, Delpierre N, Desai AR, Do FC, Dohnal M, Domec J-C, Dzikiti S, Edgar C, Eichstaedt R, El-Madany TS, Elbers J, Eller CB, Euskirchen ES, Ewers B, Fonti P, Forner A, Forrester DI, Freitas HC, Galvagno M, Garcia-Tejera O, Ghimire CP, Gimeno TE, Grace J, Granier A, Griebel A, Guangyu Y, Gush MB, Hanson PJ, Hasselquist NJ, Heinrich I, Hernandez-Santana V, Herrmann V, Hölttä T, Holwerda F, Irvine J, Isarangkool Na Ayutthaya S, Jarvis PG, Jochheim H, Joly CA, Kaplick J, Kim HS, Klemedtsson L, Kropp H, Lagergren F, Lane P, Lang P, Lapenas A, Lechuga V, Lee M, Leuschner C, Limousin J-M, Linares JC, Linderson M-L, Lindroth A, Llorens P, López-Bernal Á, Loranty MM, Lüttschwager D, Macinnis-Ng C, Maréchaux I, Martin TA, Matheny A, McDowell N, McMahon S, Meir P, Mészáros I, Migliavacca M, Mitchell P, Mölder M, Montagnani L, Moore GW, Nakada R, Niu F, Nolan RH, Norby R, Novick K, Oberhuber W, Obojes N, Oishi AC, Oliveira RS, Oren R, Ourcival J-M, Paljakka T, Perez-Priego O, Peri PL, Peters RL, Pfautsch S, Pockman WT, Preisler Y, Rascher K, Robinson G, Rocha H, Rocheteau A, Röll A, Rosado BHP, Rowland L, Rubtsov AV, Sabaté S, Salmon Y, Salomón RL, Sánchez-Costa E, Schäfer KVR, Schuldt B, Shashkin A, Stahl C, Stojanović M, Suárez JC, Sun G, Szatniewska J, Tatarinov F, Tesař M, Thomas FM, Tor-ngern P, Urban J, Valladares F, van der Tol C, van Meerveld I, Varlagin A, Voigt H, Warren J, Werner C, Werner W, Wieser G, Wingate L, Wullschleger S, Yi K, Zweifel R, Steppe K, Mencuccini M and Martínez-Vilalta J (2021), "Global transpiration data from sap flow measurements: the SAPFLUXNET database", Earth System Science Data., jun, 2021. Vol. 13(6), pp. 2607-2649.
BibTeX:
@article{Poyatos2021,
  author = {Poyatos, Rafael and Granda, Víctor and Flo, Víctor and Adams, Mark A and Adorján, Balázs and Aguadé, David and Aidar, Marcos P M and Allen, Scott and Alvarado-Barrientos, M Susana and Anderson-Teixeira, Kristina J and Aparecido, Luiza Maria and Arain, M Altaf and Aranda, Ismael and Asbjornsen, Heidi and Baxter, Robert and Beamesderfer, Eric and Berry, Z Carter and Berveiller, Daniel and Blakely, Bethany and Boggs, Johnny and Bohrer, Gil and Bolstad, Paul V and Bonal, Damien and Bracho, Rosvel and Brito, Patricia and Brodeur, Jason and Casanoves, Fernando and Chave, Jérôme and Chen, Hui and Cisneros, Cesar and Clark, Kenneth and Cremonese, Edoardo and Dang, Hongzhong and David, Jorge S and David, Teresa S and Delpierre, Nicolas and Desai, Ankur R and Do, Frederic C and Dohnal, Michal and Domec, Jean-Christophe and Dzikiti, Sebinasi and Edgar, Colin and Eichstaedt, Rebekka and El-Madany, Tarek S and Elbers, Jan and Eller, Cleiton B and Euskirchen, Eugénie S and Ewers, Brent and Fonti, Patrick and Forner, Alicia and Forrester, David I and Freitas, Helber C and Galvagno, Marta and Garcia-Tejera, Omar and Ghimire, Chandra Prasad and Gimeno, Teresa E and Grace, John and Granier, André and Griebel, Anne and Guangyu, Yan and Gush, Mark B and Hanson, Paul J and Hasselquist, Niles J and Heinrich, Ingo and Hernandez-Santana, Virginia and Herrmann, Valentine and Hölttä, Teemu and Holwerda, Friso and Irvine, James and Isarangkool Na Ayutthaya, Supat and Jarvis, Paul G and Jochheim, Hubert and Joly, Carlos A and Kaplick, Julia and Kim, Hyun Seok and Klemedtsson, Leif and Kropp, Heather and Lagergren, Fredrik and Lane, Patrick and Lang, Petra and Lapenas, Andrei and Lechuga, Víctor and Lee, Minsu and Leuschner, Christoph and Limousin, Jean-Marc and Linares, Juan Carlos and Linderson, Maj-Lena and Lindroth, Anders and Llorens, Pilar and López-Bernal, Álvaro and Loranty, Michael M and Lüttschwager, Dietmar and Macinnis-Ng, Cate and Maréchaux, Isabelle and Martin, Timothy A and Matheny, Ashley and McDowell, Nate and McMahon, Sean and Meir, Patrick and Mészáros, Ilona and Migliavacca, Mirco and Mitchell, Patrick and Mölder, Meelis and Montagnani, Leonardo and Moore, Georgianne W and Nakada, Ryogo and Niu, Furong and Nolan, Rachael H and Norby, Richard and Novick, Kimberly and Oberhuber, Walter and Obojes, Nikolaus and Oishi, A Christopher and Oliveira, Rafael S and Oren, Ram and Ourcival, Jean-Marc and Paljakka, Teemu and Perez-Priego, Oscar and Peri, Pablo L and Peters, Richard L and Pfautsch, Sebastian and Pockman, William T and Preisler, Yakir and Rascher, Katherine and Robinson, George and Rocha, Humberto and Rocheteau, Alain and Röll, Alexander and Rosado, Bruno H P and Rowland, Lucy and Rubtsov, Alexey V and Sabaté, Santiago and Salmon, Yann and Salomón, Roberto L and Sánchez-Costa, Elisenda and Schäfer, Karina V R and Schuldt, Bernhard and Shashkin, Alexandr and Stahl, Clément and Stojanović, Marko and Suárez, Juan Carlos and Sun, Ge and Szatniewska, Justyna and Tatarinov, Fyodor and Tesař, Miroslav and Thomas, Frank M and Tor-ngern, Pantana and Urban, Josef and Valladares, Fernando and van der Tol, Christiaan and van Meerveld, Ilja and Varlagin, Andrej and Voigt, Holm and Warren, Jeffrey and Werner, Christiane and Werner, Willy and Wieser, Gerhard and Wingate, Lisa and Wullschleger, Stan and Yi, Koong and Zweifel, Roman and Steppe, Kathy and Mencuccini, Maurizio and Martínez-Vilalta, Jordi},
  title = {Global transpiration data from sap flow measurements: the SAPFLUXNET database},
  journal = {Earth System Science Data},
  year = {2021},
  volume = {13},
  number = {6},
  pages = {2607--2649},
  url = {https://essd.copernicus.org/articles/13/2607/2021/},
  doi = {10.5194/essd-13-2607-2021}
}
Qiao W, Wu L, Song J, Li X, Qiao F and Rutgersson A (2021), "Momentum Flux Balance at the Air-Sea Interface", Journal of Geophysical Research: Oceans., feb, 2021. Vol. 126(2), pp. e2020JC016563. John Wiley & Sons, Ltd.
Abstract: Abstract Ocean waves can spatiotemporally redistribute the momentum flux at the air-sea interface, which varies with the sea state. Traditional atmosphere-ocean coupled systems assume the ocean-side stress (τoc) to be identical to the air-side stress (τa); consequently, the role of ocean waves is neglected. In this study, the wave impacts on the air-sea momentum flux are investigated based on 1-year high-resolution model simulations in the Baltic Sea using an atmosphere-wave coupled model (Uppsala University-Coupled Model, UU-CM). The simulation results show that τoc can differ significantly from τa in both direction and magnitude. The direction difference between τoc and τa (DD(τoc, τa)) and the normalized momentum flux () decrease with increasing inverse wave age. In general, and DD(τoc, τa) are pronounced under wind-following swell and wind-crossing swell conditions, respectively. The occurrence frequencies of large and DD(τoc, τa) are higher nearer the coast; statistically, both decrease significantly with increasing water depth because of the joint effect of dissipation processes. Based on four selected areas, we find that alongshore winds (winds blowing parallel to the coastline) are favorable for large angular differences between τoc and τa (DD(τoc, τa) > 5°). However, onshore winds predominate at . The τa in the wave model is generally less than that obtained from the atmospheric model under low-moderate wind conditions if the wave model feeds only the Charnock coefficient (roughness length) back to the atmospheric model in coupled systems.
BibTeX:
@article{Qiao2021,
  author = {Qiao, Wenli and Wu, Lichuan and Song, Jinbao and Li, Xue and Qiao, Fangli and Rutgersson, Anna},
  title = {Momentum Flux Balance at the Air-Sea Interface},
  journal = {Journal of Geophysical Research: Oceans},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {126},
  number = {2},
  pages = {e2020JC016563},
  url = {https://doi.org/10.1029/2020JC016563},
  doi = {10.1029/2020JC016563}
}
Qu Z-L, Santalahti M, Köster K, Berninger F, Pumpanen J, Heinonsalo J and Sun H (2021), "Soil Fungal Community Structure in Boreal Pine Forests: From Southern to Subarctic Areas of Finland", Frontiers in Microbiology. Vol. 12
Abstract: The boreal forest environment plays an important role in the global C cycle due to its high carbon storage capacity. However, relatively little is known about the forest fungal community at a regional scale in boreal forests. In the present study, we have re-analyzed the data from our previous studies and highlighted the core fungal community composition and potential functional groups in three forests dominated by Scots pine (Pinus sylvestris L.) in Finland, and identified the fungal generalists that appear across geographic locations despite differences in local conditions. The three forests represent subarctic, northern and southern boreal forest, and are all in an un-managed state without human interference or management. The subarctic and northern areas are subject to reindeer grazing. The results showed that the three locations formed distinct fungal community structures (P < 0.05). Compared to the two northern locations, the southern boreal forest harbored a greater abundance of Zygomycota, Lactarius, Mortierella Umbelopsis, and Tylospora, in which aspect there were no differences between the two northern forests. Cortinarius, Piloderma, and Suillus were the core fungal genera in the boreal Scots pine forest. Functionally, the southern boreal forest harbored a greater abundance of saprotroph, endophytes and fungal parasite-lichen, whereas a greater abundance of ectomycorrhizal fungi was observed in the northern boreal forests. Moreover, the pathotroph and wood saprotrophs were commonly present in these three regions. The three locations formed two distinct fungal community functional structures, by which the southern forest was clearly separated from the two northern forests, suggesting a distance–decay relationship via geographic location. This study provides useful information for better understanding the common fungal communities and functions in boreal forests in different geographical locations.
BibTeX:
@article{Qu2021,
  author = {Qu, Zhao-Lei and Santalahti, Minna and Köster, Kajar and Berninger, Frank and Pumpanen, Jukka and Heinonsalo, Jussi and Sun, Hui},
  title = {Soil Fungal Community Structure in Boreal Pine Forests: From Southern to Subarctic Areas of Finland},
  journal = {Frontiers in Microbiology},
  year = {2021},
  volume = {12},
  url = {https://www.frontiersin.org/article/10.3389/fmicb.2021.653896},
  doi = {10.3389/fmicb.2021.653896}
}
Raoult N, Ottlé C, Peylin P, Bastrikov V and Maugis P (2021), "Evaluating and Optimizing Surface Soil Moisture Drydowns in the ORCHIDEE Land Surface Model at In Situ Locations", Journal of Hydrometeorology. Boston MA, USA Vol. 22(4), pp. 1025-1043. American Meteorological Society.
BibTeX:
@article{Raoult2021,
  author = {Raoult, Nina and Ottlé, Catherine and Peylin, Philippe and Bastrikov, Vladislav and Maugis, Pascal},
  title = {Evaluating and Optimizing Surface Soil Moisture Drydowns in the ORCHIDEE Land Surface Model at In Situ Locations},
  journal = {Journal of Hydrometeorology},
  publisher = {American Meteorological Society},
  year = {2021},
  volume = {22},
  number = {4},
  pages = {1025--1043},
  url = {https://journals.ametsoc.org/view/journals/hydr/22/4/JHM-D-20-0115.1.xml},
  doi = {10.1175/JHM-D-20-0115.1}
}
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}
}
Resovsky A, Ramonet M, Rivier L, Tarniewicz J, Ciais P, Steinbacher M, Mammarella I, Mölder M, Heliasz M, Kubistin D, Lindauer M, Müller-Williams J, Conil S and Engelen R (2021), "An algorithm to detect non-background signals in greenhouse gas time series from European tall tower and mountain stations", Atmospheric Measurement Techniques. Vol. 14(9), pp. 6119-6135.
BibTeX:
@article{Resovsky2021,
  author = {Resovsky, A and Ramonet, M and Rivier, L and Tarniewicz, J and Ciais, P and Steinbacher, M and Mammarella, I and Mölder, M and Heliasz, M and Kubistin, D and Lindauer, M and Müller-Williams, J and Conil, S and Engelen, R},
  title = {An algorithm to detect non-background signals in greenhouse gas time series from European tall tower and mountain stations},
  journal = {Atmospheric Measurement Techniques},
  year = {2021},
  volume = {14},
  number = {9},
  pages = {6119--6135},
  url = {https://amt.copernicus.org/articles/14/6119/2021/},
  doi = {10.5194/amt-14-6119-2021}
}
Reuter M, Bovensmann H, Buchwitz M, Borchardt J, Krautwurst S, Gerilowski K, Lindauer M, Kubistin D and Burrows JP (2021), "Development of a small unmanned aircraft system to derive CO_2 emissions of anthropogenic point sources", Atmospheric Measurement Techniques. Vol. 14(1), pp. 153-172.
BibTeX:
@article{Reuter2021,
  author = {Reuter, M and Bovensmann, H and Buchwitz, M and Borchardt, J and Krautwurst, S and Gerilowski, K and Lindauer, M and Kubistin, D and Burrows, J P},
  title = {Development of a small unmanned aircraft system to derive CO_2 emissions of anthropogenic point sources},
  journal = {Atmospheric Measurement Techniques},
  year = {2021},
  volume = {14},
  number = {1},
  pages = {153--172},
  url = {https://amt.copernicus.org/articles/14/153/2021/},
  doi = {10.5194/amt-14-153-2021}
}
Rivera Martinez R, Santaren D, Laurent O, Cropley F, Mallet C, Ramonet M, Caldow C, Rivier L, Broquet G, Bouchet C, Juery C and Ciais P (2021), "The Potential of Low-Cost Tin-Oxide Sensors Combined with Machine Learning for Estimating Atmospheric CH4 Variations around Background Concentration".
Abstract: Continued developments in instrumentation and modeling have driven progress in monitoring methane (CH4) emissions at a range of spatial scales. The sites that emit CH4 such as landfills, oil and gas extraction or storage infrastructure, intensive livestock farms account for a large share of global emissions, and need to be monitored on a continuous basis to verify the effectiveness of reductions policies. Low cost sensors are valuable to monitor methane (CH4) around such facilities because they can be deployed in a large number to sample atmospheric plumes and retrieve emission rates using dispersion models. Here we present two tests of three different versions of Figaro&reg; TGS tin-oxide sensors for estimating CH4 concentrations variations, at levels similar to current atmospheric values, with a sought accuracy of 0.1 to 0.2 ppm. In the first test, we characterize the variation of the resistance of the tin-oxide semi-conducting sensors to controlled levels of CH4, H2O and CO in the laboratory, to analyze cross-sensitivities. In the second test, we reconstruct observed CH4 variations in a room, that ranged from 1.9 and 2.4 ppm during a three month experiment from observed time series of resistances and other variables. To do so, a machine learning model is trained against true CH4 recorded by a high precision instrument. The machine-learning model using 30% of the data for training reconstructs CH4 within the target accuracy of 0.1 ppm only if training variables are representative of conditions during the testing period. The model-derived sensitivities of the sensors resistance to H2O compared to CH4 are larger than those observed under controlled conditions, which deserves further characterization of all the factors influencing the resistance of the sensors.
BibTeX:
@misc{RiveraMartinez2021,
  author = {Rivera Martinez, Rodrigo and Santaren, Diego and Laurent, Olivier and Cropley, Ford and Mallet, Cécile and Ramonet, Michel and Caldow, Christopher and Rivier, Leonard and Broquet, Gregoire and Bouchet, Caroline and Juery, Catherine and Ciais, Philippe},
  title = {The Potential of Low-Cost Tin-Oxide Sensors Combined with Machine Learning for Estimating Atmospheric CH4 Variations around Background Concentration},
  booktitle = {Atmosphere},
  year = {2021},
  volume = {12},
  number = {1},
  doi = {10.3390/atmos12010107}
}
Robroek BJM, Martí M, Svensson BH, Dumont MG, Veraart AJ and Jassey VEJ (2021), "Rewiring of peatland plant–microbe networks outpaces species turnover", Oikos., mar, 2021. Vol. 130(3), pp. 339-353. John Wiley & Sons, Ltd.
Abstract: Enviro?climatic changes are thought to be causing alterations in ecosystem processes through shifts in plant and microbial communities; however, how links between plant and microbial communities change with enviro?climatic change is likely to be less straightforward but may be fundamental for many ecological processes. To address this, we assessed the composition of the plant community and the prokaryotic community ? using amplicon-based sequencing ? of three European peatlands that were distinct in enviro?climatic conditions. Bipartite networks were used to construct site-specific plant?prokaryote co-occurrence networks. Our data show that between sites, plant and prokaryotic communities differ and that turnover in interactions between the communities was complex. Essentially, turnover in plant?microbial interactions is much faster than turnover in the respective communities. Our findings suggest that network rewiring does largely result from novel or different interactions between species common to all realised networks. Hence, turnover in network composition is largely driven by the establishment of new interactions between a core community of plants and microorganisms that are shared among all sites. Taken together our results indicate that plant?microbe associations are context dependent, and that changes in enviro?climatic conditions will likely lead to network rewiring. Integrating turnover in plant?microbe interactions into studies that assess the impact of enviro?climatic change on peatland ecosystems is essential to understand ecosystem dynamics and must be combined with studies on the impact of these changes on ecosystem processes.
BibTeX:
@article{Robroek2021,
  author = {Robroek, Bjorn J M and Martí, Magalí and Svensson, Bo H and Dumont, Marc G and Veraart, Annelies J and Jassey, Vincent E J},
  title = {Rewiring of peatland plant–microbe networks outpaces species turnover},
  journal = {Oikos},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {130},
  number = {3},
  pages = {339--353},
  url = {https://doi.org/10.1111/oik.07635},
  doi = {10.1111/oik.07635}
}
Rothfuss Y, Quade M, Brüggemann N, Graf A, Vereecken H and Dubbert M (2021), "Reviews and syntheses: Gaining insights into evapotranspiration partitioning with novel isotopic monitoring methods", Biogeosciences. Vol. 18(12), pp. 3701-3732.
BibTeX:
@article{Rothfuss2021,
  author = {Rothfuss, Y and Quade, M and Brüggemann, N and Graf, A and Vereecken, H and Dubbert, M},
  title = {Reviews and syntheses: Gaining insights into evapotranspiration partitioning with novel isotopic monitoring methods},
  journal = {Biogeosciences},
  year = {2021},
  volume = {18},
  number = {12},
  pages = {3701--3732},
  url = {https://bg.copernicus.org/articles/18/3701/2021/},
  doi = {10.5194/bg-18-3701-2021}
}
Saiz E, Sgouridis F, Drijfhout FP, Peichl M, Nilsson MB and Ullah S (2021), "Chronic Atmospheric Reactive Nitrogen Deposition Suppresses Biological Nitrogen Fixation in Peatlands", Environmental Science & Technology., jan, 2021. Vol. 55(2), pp. 1310-1318. American Chemical Society.
BibTeX:
@article{Saiz2021,
  author = {Saiz, Ernesto and Sgouridis, Fotis and Drijfhout, Falko P and Peichl, Matthias and Nilsson, Mats B and Ullah, Sami},
  title = {Chronic Atmospheric Reactive Nitrogen Deposition Suppresses Biological Nitrogen Fixation in Peatlands},
  journal = {Environmental Science & Technology},
  publisher = {American Chemical Society},
  year = {2021},
  volume = {55},
  number = {2},
  pages = {1310--1318},
  url = {https://doi.org/10.1021/acs.est.0c04882},
  doi = {10.1021/acs.est.0c04882}
}
dos Santos T, Keppel-Aleks G, De Roo R and Steiner A (2021), "Can Land Surface Models Capture the Observed Soil Moisture Control of Water and Carbon Fluxes in Temperate To Boreal Forests?", Journal of Geophysical Research (Biogeosciences)., apr, 2021. Vol. 126(4), pp. e05999.
BibTeX:
@article{Santos2021,
  author = {dos Santos, T and Keppel-Aleks, G and De Roo, R and Steiner, A.∼L.},
  title = {Can Land Surface Models Capture the Observed Soil Moisture Control of Water and Carbon Fluxes in Temperate To Boreal Forests?},
  journal = {Journal of Geophysical Research (Biogeosciences)},
  year = {2021},
  volume = {126},
  number = {4},
  pages = {e05999},
  doi = {10.1029/2020JG005999}
}
Sathyanadh A, Monteil G, Scholze M, Klosterhalfen A, Laudon H, Wu Z, Gerbig C, Peters W, Bastrikov V, Nilsson MB and Peichl M (2021), "Reconciling the Carbon Balance of Northern Sweden Through Integration of Observations and Modelling", Journal of Geophysical Research: Atmospheres., dec, 2021. Vol. 126(23), pp. e2021JD035185. John Wiley & Sons, Ltd.
Abstract: Abstract The boreal biome plays an important role in the global carbon cycle. However, current estimates of its sink-source strength and responses to changes in climate are primarily derived from models and thus remain uncertain. A major challenge is the validation of these models at a regional scale since empirical flux estimates are typically confined to ecosystem or continental scales. The Integrated Carbon Observation System (ICOS)-Svartberget atmospheric station (SVB) provides observations including tall tower eddy covariance (EC) and atmospheric concentration measurements that can contribute to such validation in Northern Sweden. Thus, the overall aim of this study was to quantify the carbon balance in Northern Sweden region by integrating land-atmosphere fluxes and atmospheric carbon dioxide (CO2) concentrations. There were three specific objectives. First, to compare flux estimates from four models (VPRM, LPJ-GUESS, ORCHIDEE, and SiBCASA) to tall tower EC measurements at SVB during the years 2016?2018. Second to assess the fluxes' impact on atmospheric CO2 concentrations using a regional transport model. Third, to assess the impact of the drought in 2018. The comparison of estimated concentrations with ICOS observations helped the evaluation of the models' regional scale performance. Both the simulations and observations indicate there were similar reductions in the net CO2 uptake during drought. All the models (except for SiBCASA) and observations indicated the region was a net carbon sink during the 3-year study period. Our study highlights a need to improve vegetation models through comparisons with empirical data and demonstrate the ICOS network's potential utility for constraining CO2 fluxes in the region.
BibTeX:
@article{Sathyanadh2021,
  author = {Sathyanadh, Anusha and Monteil, Guillaume and Scholze, Marko and Klosterhalfen, Anne and Laudon, Hjalmar and Wu, Zhendong and Gerbig, Christoph and Peters, Wouter and Bastrikov, Vladislav and Nilsson, Mats B and Peichl, Matthias},
  title = {Reconciling the Carbon Balance of Northern Sweden Through Integration of Observations and Modelling},
  journal = {Journal of Geophysical Research: Atmospheres},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {126},
  number = {23},
  pages = {e2021JD035185},
  url = {https://doi.org/10.1029/2021JD035185},
  doi = {10.1029/2021JD035185}
}
Say D, Manning AJ, Western LM, Young D, Wisher A, Rigby M, Reimann S, Vollmer MK, Maione M, Arduini J, Krummel PB, Mühle J, Harth CM, Evans B, Weiss RF, Prinn RG and O'Doherty S (2021), "Global trends and European emissions of tetrafluoromethane (CF_4), hexafluoroethane (C_2F_6) and octafluoropropane (C_3F_8)", Atmospheric Chemistry and Physics. Vol. 21(3), pp. 2149-2164.
BibTeX:
@article{Say2021,
  author = {Say, D and Manning, A J and Western, L M and Young, D and Wisher, A and Rigby, M and Reimann, S and Vollmer, M K and Maione, M and Arduini, J and Krummel, P B and Mühle, J and Harth, C M and Evans, B and Weiss, R F and Prinn, R G and O'Doherty, S},
  title = {Global trends and European emissions of tetrafluoromethane (CF_4), hexafluoroethane (C_2F_6) and octafluoropropane (C_3F_8)},
  journal = {Atmospheric Chemistry and Physics},
  year = {2021},
  volume = {21},
  number = {3},
  pages = {2149--2164},
  url = {https://acp.copernicus.org/articles/21/2149/2021/},
  doi = {10.5194/acp-21-2149-2021}
}
Scheller JH, Mastepanov M, Christiansen HH and Christensen TR (2021), "Methane in Zackenberg Valley, NE Greenland: multidecadal growing season fluxes of a high-Arctic tundra", Biogeosciences. Vol. 18(23), pp. 6093-6114.
BibTeX:
@article{Scheller2021,
  author = {Scheller, J H and Mastepanov, M and Christiansen, H H and Christensen, T R},
  title = {Methane in Zackenberg Valley, NE Greenland: multidecadal growing season fluxes of a high-Arctic tundra},
  journal = {Biogeosciences},
  year = {2021},
  volume = {18},
  number = {23},
  pages = {6093--6114},
  url = {https://bg.copernicus.org/articles/18/6093/2021/},
  doi = {10.5194/bg-18-6093-2021}
}
Schiestl-Aalto P, Stangl ZR, Tarvainen L, Wallin G, Marshall J and Mäkelä A (2021), "Linking canopy-scale mesophyll conductance and phloem sugar δ13C using empirical and modelling approaches", New Phytologist., mar, 2021. Vol. 229(6), pp. 3141-3155. John Wiley & Sons, Ltd.
Abstract: Summary Interpreting phloem carbohydrate or xylem tissue carbon isotopic composition as measures of water-use efficiency or past tree productivity requires in-depth knowledge of the factors altering the isotopic composition within the pathway from ambient air to phloem contents and tree ring. One of least understood of these factors is mesophyll conductance (gm). We formulated a dynamic model describing the leaf photosynthetic pathway including seven alternative gm descriptions and a simple transport of sugars from foliage down the trunk. We parameterised the model for a boreal Scots pine stand and compared simulated gm responses with weather variations. We further compared the simulated δ13C of new photosynthates among the different gm descriptions and against measured phloem sugar δ13C. Simulated gm estimates of the seven descriptions varied according to weather conditions, resulting in varying estimates of phloem δ13C during cold/moist and warm/dry periods. The model succeeded in predicting a drought response and a postdrought release in phloem sugar δ13C indicating suitability of the model for inverse prediction of leaf processes from phloem isotopic composition. We suggest short-interval phloem sampling during and after extreme weather conditions to distinguish between mesophyll conductance drivers for future model development.
BibTeX:
@article{SchiestlAalto2021,
  author = {Schiestl-Aalto, Pauliina and Stangl, Zsofia R and Tarvainen, Lasse and Wallin, Göran and Marshall, John and Mäkelä, Annikki},
  title = {Linking canopy-scale mesophyll conductance and phloem sugar δ13C using empirical and modelling approaches},
  journal = {New Phytologist},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {229},
  number = {6},
  pages = {3141--3155},
  url = {https://doi.org/10.1111/nph.17094},
  doi = {10.1111/nph.17094}
}
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}
}
Schneider M, Ertl B, Diekmann CJ, Khosrawi F, Röhling AN, Hase F, Dubravica D, Garc\ia OE, Sepúlveda E, Borsdorff T, Landgraf J, Lorente A, Chen H, Kivi R, Laemmel T, Ramonet M, Crevoisier C, Pernin J, Steinbacher M, Meinhardt F, Deutscher NM, Griffith DWT, Velazco VA and Pollard DF (2021), "Synergetic use of IASI and TROPOMI space borne sensors for generating a tropospheric methane profile product", Atmospheric Measurement Techniques Discussions. Vol. 2021, pp. 1-37.
BibTeX:
@article{Schneider2021a,
  author = {Schneider, M and Ertl, B and Diekmann, C J and Khosrawi, F and Röhling, A N and Hase, F and Dubravica, D and Garc\ia, O E and Sepúlveda, E and Borsdorff, T and Landgraf, J and Lorente, A and Chen, H and Kivi, R and Laemmel, T and Ramonet, M and Crevoisier, C and Pernin, J and Steinbacher, M and Meinhardt, F and Deutscher, N M and Griffith, D W T and Velazco, V A and Pollard, D F},
  title = {Synergetic use of IASI and TROPOMI space borne sensors for generating a tropospheric methane profile product},
  journal = {Atmospheric Measurement Techniques Discussions},
  year = {2021},
  volume = {2021},
  pages = {1--37},
  url = {https://amt.copernicus.org/preprints/amt-2021-31/},
  doi = {10.5194/amt-2021-31}
}
Seiler C, Melton JR, Arora VK and Wang L (2021), "CLASSIC v1.0: the open-source community successor to the Canadian Land Surface Scheme (CLASS) and the Canadian Terrestrial Ecosystem Model (CTEM) -- Part 2: Global benchmarking", Geoscientific Model Development. Vol. 14(5), pp. 2371-2417.
BibTeX:
@article{Seiler2021,
  author = {Seiler, C and Melton, J R and Arora, V K and Wang, L},
  title = {CLASSIC v1.0: the open-source community successor to the Canadian Land Surface Scheme (CLASS) and the Canadian Terrestrial Ecosystem Model (CTEM) -- Part 2: Global benchmarking},
  journal = {Geoscientific Model Development},
  year = {2021},
  volume = {14},
  number = {5},
  pages = {2371--2417},
  url = {https://gmd.copernicus.org/articles/14/2371/2021/},
  doi = {10.5194/gmd-14-2371-2021}
}
Serk H, Nilsson MB, Figueira J, Wieloch T and Schleucher J (2021), "CO2 fertilization of Sphagnum peat mosses is modulated by water table level and other environmental factors", Plant, Cell & Environment., jun, 2021. Vol. 44(6), pp. 1756-1768. John Wiley & Sons, Ltd.
Abstract: Abstract Sphagnum mosses account for most accumulated dead organic matter in peatlands. Therefore, understanding their responses to increasing atmospheric CO2 is needed for estimating peatland C balances under climate change. A key process is photorespiration: a major determinant of net photosynthetic C assimilation that depends on the CO2 to O2 ratio. We used climate chambers to investigate photorespiratory responses of Sphagnum fuscum hummocks to recent increases in atmospheric CO2 (from 280 to 400?ppm) under different water table, temperature, and light intensity levels. We tested the photorespiratory variability using a novel method based on deuterium isotopomers (D6S/D6R ratio) of photosynthetic glucose. The effect of elevated CO2 on photorespiration was highly dependent on water table. At low water table (?20?cm), elevated CO2 suppressed photorespiration relative to C assimilation, thus substantially increasing the net primary production potential. In contrast, a high water table (∼0 cm) favored photorespiration and abolished this CO2 effect. The response was further tested for Sphagnum majus lawns at typical water table levels (∼0 and ?7 cm), revealing no effect of CO2 under those conditions. Our results indicate that hummocks, which typically experience low water table levels, benefit from the 20th century's increase in atmospheric CO2.
BibTeX:
@article{Serk2021,
  author = {Serk, Henrik and Nilsson, Mats B and Figueira, João and Wieloch, Thomas and Schleucher, Jürgen},
  title = {CO2 fertilization of Sphagnum peat mosses is modulated by water table level and other environmental factors},
  journal = {Plant, Cell & Environment},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {44},
  number = {6},
  pages = {1756--1768},
  url = {https://doi.org/10.1111/pce.14043},
  doi = {10.1111/pce.14043}
}
Siewert MB and Olofsson J (2021), "UAV reveals substantial but heterogeneous effects of herbivores on Arctic vegetation", Scientific Reports. Vol. 11(1), pp. 19468.
Abstract: Understanding how herbivores shape plant biomass and distribution is a core challenge in ecology. Yet, the lack of suitable remote sensing technology limits our knowledge of temporal and spatial impacts of mammal herbivores in the Earth system. The regular interannual density fluctuations of voles and lemmings are exceptional with their large reduction of plant biomass in Arctic landscapes during peak years (12–24%) as previously shown at large spatial scales using satellites. This provides evidence that herbivores are important drivers of observed global changes in vegetation productivity. Here, we use a novel approach with repeated unmanned aerial vehicle (UAV) flights, to map vegetation impact by rodents, indicating that many important aspects of vegetation dynamics otherwise hidden by the coarse resolution of satellite images, including plant–herbivore interactions, can be revealed using UAVs. We quantify areas impacted by rodents at four complex Arctic landscapes with very high spatial resolution UAV imagery to get a new perspective on how herbivores shape Arctic ecosystems. The area impacted by voles and lemmings is indeed substantial, larger at higher altitude tundra environments, varies between habitats depending on local snow cover and plant community composition, and is heterogeneous even within habitats at submeter scales. Coupling this with spectral reflectance of vegetation (NDVI), we can show that the impact on central ecosystem properties like GPP and biomass is stronger than currently accounted for in Arctic ecosystems. As an emerging technology, UAVs will allow us to better disentangle important information on how herbivores maintain spatial heterogeneity, function and diversity in natural ecosystems.
BibTeX:
@article{Siewert2021,
  author = {Siewert, Matthias B and Olofsson, Johan},
  title = {UAV reveals substantial but heterogeneous effects of herbivores on Arctic vegetation},
  journal = {Scientific Reports},
  year = {2021},
  volume = {11},
  number = {1},
  pages = {19468},
  url = {https://doi.org/10.1038/s41598-021-98497-5},
  doi = {10.1038/s41598-021-98497-5}
}
Sim TG, Swindles GT, Morris PJ, Baird AJ, Cooper CL, Gallego-Sala AV, Charman DJ, Roland TP, Borken W, Mullan DJ, Aquino-López MA and Gałka M (2021), "Divergent responses of permafrost peatlands to recent climate change", Environmental Research Letters., feb, 2021. Vol. 16(3), pp. 34001. IOP Publishing.
Abstract: Permafrost peatlands are found in high-latitude regions and store globally-important amounts of soil organic carbon. These regions are warming at over twice the global average rate, causing permafrost thaw, and exposing previously inert carbon to decomposition and emission to the atmosphere as greenhouse gases. However, it is unclear how peatland hydrological behaviour, vegetation structure and carbon balance, and the linkages between them, will respond to permafrost thaw in a warming climate. Here we show that permafrost peatlands follow divergent ecohydrological trajectories in response to recent climate change within the same rapidly warming region (northern Sweden). Whether a site becomes wetter or drier depends on local factors and the autogenic response of individual peatlands. We find that bryophyte-dominated vegetation demonstrates resistance, and in some cases resilience, to climatic and hydrological shifts. Drying at four sites is clearly associated with reduced carbon sequestration, while no clear relationship at wetting sites is observed. We highlight the complex dynamics of permafrost peatlands and warn against an overly-simple approach when considering their ecohydrological trajectories and role as C sinks under a warming climate.
BibTeX:
@article{Sim2021,
  author = {Sim, Thomas G and Swindles, Graeme T and Morris, Paul J and Baird, Andy J and Cooper, Claire L and Gallego-Sala, Angela V and Charman, Dan J and Roland, Thomas P and Borken, Werner and Mullan, Donal J and Aquino-López, Marco A and Gałka, Mariusz},
  title = {Divergent responses of permafrost peatlands to recent climate change},
  journal = {Environmental Research Letters},
  publisher = {IOP Publishing},
  year = {2021},
  volume = {16},
  number = {3},
  pages = {34001},
  url = {https://doi.org/10.1088/1748-9326/abe00b},
  doi = {10.1088/1748-9326/abe00b}
}
Simin T, Tang J, Holst T and Rinnan R (2021), "Volatile organic compound emission in tundra shrubs – Dependence on species characteristics and the near-surface environment", Environmental and Experimental Botany. Vol. 184, pp. 104387.
Abstract: Temperature is one of the key abiotic factors during the life of plants, especially in the Arctic region which is currently experiencing rapid climate change. We evaluated plant traits and environmental variables determining leaf temperature in tundra shrubs and volatile organic compound (VOC) emissions with field measurements on deciduous tundra shrubs, Salix myrsinites and Betula nana, and evergreen Cassiope tetragona and Rhododendron lapponicum. Higher leaf-to-air temperature difference was observed in evergreen, compared to deciduous shrubs. Evergreen shrubs also showed continuously increasing photosynthesis with increasing temperature, suggesting high thermal tolerance. For the deciduous species, the optimum temperature for net photosynthesis was between our measurement temperatures of 24 °C and 38 °C. Air temperature and vapor pressure deficit were the most important variables influencing leaf temperature and VOC emissions in all the studied plants, along with stomatal density and specific leaf area in the deciduous shrubs. Using climate data and emission factors from our measurements, we modelled total seasonal tundra shrub VOC emissions of 0.3–2.3 g m−2 over the main growing season. Our results showed higher-than-expected temperature optima for photosynthesis and VOC emission and demonstrated the relative importance of plant traits and local environments in determining leaf temperature and VOC emissions in a subarctic tundra.
BibTeX:
@article{Simin2021,
  author = {Simin, Tihomir and Tang, Jing and Holst, Thomas and Rinnan, Riikka},
  title = {Volatile organic compound emission in tundra shrubs – Dependence on species characteristics and the near-surface environment},
  journal = {Environmental and Experimental Botany},
  year = {2021},
  volume = {184},
  pages = {104387},
  url = {https://www.sciencedirect.com/science/article/pii/S0098847221000162},
  doi = {10.1016/j.envexpbot.2021.104387}
}
Simpson JE, Holman F, Nieto H, Voelksch I, Mauder M, Klatt J, Fiener P and Kaplan JO (2021), "High Spatial and Temporal Resolution Energy Flux Mapping of Different Land Covers Using an Off-the-Shelf Unmanned Aerial System".
Abstract: With the development of low-cost, lightweight, integrated thermal infrared-multispectral cameras, unmanned aerial systems (UAS) have recently become a flexible complement to eddy covariance (EC) station methods for mapping surface energy fluxes of vegetated areas. These sensors facilitate the measurement of several site characteristics in one flight (e.g., radiometric temperature, vegetation indices, vegetation structure), which can be used alongside in-situ meteorology data to provide spatially-distributed estimates of energy fluxes at very high resolution. Here we test one such system (MicaSense Altum) integrated into an off-the-shelf long-range vertical take-off and landing (VTOL) unmanned aerial vehicle, and apply and evaluate our method by comparing flux estimates with EC-derived data, with specific and novel focus on heterogeneous vegetation communities at three different sites in Germany. Firstly, we present an empirical method for calibrating airborne radiometric temperature in standard units (K) using the Altum multispectral and thermal infrared instrument. Then we provide detailed methods using the two-source energy balance model (TSEB) for mapping net radiation (Rn), sensible (H), latent (LE) and ground (G) heat fluxes at <0.82 m resolution, with root mean square errors (RMSE) less than 45, 37, 39, 52 W m−2 respectively. Converting to radiometric temperature using our empirical method resulted in a 19% reduction in RMSE across all fluxes compared to the standard conversion equation provided by the manufacturer. Our results show the potential of this UAS for mapping energy fluxes at high resolution over large areas in different conditions, but also highlight the need for further surveys of different vegetation types and land uses.
BibTeX:
@misc{Simpson2021,
  author = {Simpson, Jake E and Holman, Fenner and Nieto, Hector and Voelksch, Ingo and Mauder, Matthias and Klatt, Janina and Fiener, Peter and Kaplan, Jed O},
  title = {High Spatial and Temporal Resolution Energy Flux Mapping of Different Land Covers Using an Off-the-Shelf Unmanned Aerial System},
  booktitle = {Remote Sensing},
  year = {2021},
  volume = {13},
  number = {7},
  doi = {10.3390/rs13071286}
}
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}
}
Sun J, Hermann M, Yuan Y, Birmili W, Collaud Coen M, Weinhold K, Madueño L, Poulain L, Tuch T, Ries L, Sohmer R, Couret C, Frank G, Brem BT, Gysel-Beer M, Ma N and Wiedensohler A (2021), "Long-term trends of black carbon and particle number concentration in the lower free troposphere in Central Europe", Environmental Sciences Europe. Vol. 33(1), pp. 47.
Abstract: The implementation of emission mitigation policies in Europe over the last two decades has generally improved the air quality, which resulted in lower aerosol particle mass, particle number, and black carbon mass concentration. However, little is known whether the decreasing particle concentrations at a lower-altitude level can be observed in the free troposphere (FT), an important layer of the atmosphere, where aerosol particles have a longer lifetime and may affect climate dynamics. In this study, we used data from two high-Alpine observatories, Zugspitze-Schneefernerhaus (ZSF) and Jungfraujoch (JFJ), to assess the long-term trends on size-resolved particle number concentrations (PNCs) and equivalent black carbon (eBC) mass concentration separated for undisturbed lower FT conditions and under the influence of air from the planetary boundary layer (PBL) from 2009 to 2018.
BibTeX:
@article{Sun2021,
  author = {Sun, Jia and Hermann, Markus and Yuan, Ye and Birmili, Wolfram and Collaud Coen, Martine and Weinhold, Kay and Madueño, Leizel and Poulain, Laurent and Tuch, Thomas and Ries, Ludwig and Sohmer, Ralf and Couret, Cedric and Frank, Gabriele and Brem, Benjamin Tobias and Gysel-Beer, Martin and Ma, Nan and Wiedensohler, Alfred},
  title = {Long-term trends of black carbon and particle number concentration in the lower free troposphere in Central Europe},
  journal = {Environmental Sciences Europe},
  year = {2021},
  volume = {33},
  number = {1},
  pages = {47},
  url = {https://doi.org/10.1186/s12302-021-00488-w},
  doi = {10.1186/s12302-021-00488-w}
}
Tang Y, Xu X, Zhou Z, Qu Y and Sun Y (2021), "Estimating global maximum gross primary productivity of vegetation based on the combination of MODIS greenness and temperature data", Ecological Informatics. Vol. 63, pp. 101307.
Abstract: Accurate estimation of the spatial-temporal variation of the maximum gross primary productivity (GPPmax) of vegetation is of great significance for predicting carbon fluxes and vegetation-climate feedback. In this study, the GPPmax estimation models were constructed based on driving variables derived from the MODIS enhanced vegetation index (EVI) and land surface temperature (LST) time series data using a stepwise regression analysis. The models were calibrated and validated with the observed GPPmax from 145 FLUXNET sites with 734 site-year data from 2000 to 2014. The GPPmax estimates and the changes in their trends at the global scale were also compared with other GPPmax products from the vegetation photosynthesis model and the eddy covariance-light use efficiency model. The results showed that the GPPmax for both forest and non-forest vegetation types were estimated well, with R2 of 0.47–0.86 and 0.47–0.95 and relative root mean square error of 10.14–35.14% and 11.25–30.02% for calibration and validation data, respectively. Summer EVI and spring EVI and LST played important roles in explaining the variation in GPPmax. The GPPmax estimates from this study and the changes in their trends were highly correlated with GPPmax estimates from the vegetation photosynthesis model, with R2 > 0.70 for most vegetation types. The GPPmax significantly increased in western North America, northern Europe, and eastern China, but decreased in tropical regions. This study concluded that the variation in GPPmax for various vegetation types on a global scale can be accurately estimated based on MODIS EVI and LST time series data, which provides a simple but effective way for large-scale estimation of GPPmax.
BibTeX:
@article{Tang2021,
  author = {Tang, Yan and Xu, Xiaojun and Zhou, Zhongsheng and Qu, Yiling and Sun, Yue},
  title = {Estimating global maximum gross primary productivity of vegetation based on the combination of MODIS greenness and temperature data},
  journal = {Ecological Informatics},
  year = {2021},
  volume = {63},
  pages = {101307},
  url = {https://www.sciencedirect.com/science/article/pii/S1574954121000984},
  doi = {10.1016/j.ecoinf.2021.101307}
}
Tarvainen L, Wallin G, Linder S, Näsholm T, Oren R, Ottosson Löfvenius M, Räntfors M, Tor-Ngern P and Marshall JD (2021), "Limited vertical CO2 transport in stems of mature boreal Pinus sylvestris trees", Tree Physiology., jan, 2021. Vol. 41(1), pp. 63-75.
Abstract: Several studies have suggested that CO2 transport in the transpiration stream can considerably bias estimates of root and stem respiration in ring-porous and diffuse-porous tree species. Whether this also happens in species with tracheid xylem anatomy and lower sap flow rates, such as conifers, is currently unclear. We infused 13C-labelled solution into the xylem near the base of two 90-year-old Pinus sylvestris L. trees. A custom-built gas exchange system and an online isotopic analyser were used to sample the CO2 efflux and its isotopic composition continuously from four positions along the bole and one upper canopy shoot in each tree. Phloem and needle tissue 13C enrichment was also evaluated at these positions. Most of the 13C label was lost by diffusion within a few metres of the infusion point indicating rapid CO2 loss during vertical xylem transport. No 13C enrichment was detected in the upper bole needle tissues. Furthermore, mass balance calculations showed that c. 97% of the locally respired CO2 diffused radially to the atmosphere. Our results support the notion that xylem CO2 transport is of limited magnitude in conifers. This implies that the concerns that stem transport of CO2 derived from root respiration biases chamber-based estimates of forest carbon cycling may be unwarranted for mature conifer stands.
BibTeX:
@article{Tarvainen2021,
  author = {Tarvainen, Lasse and Wallin, Göran and Linder, Sune and Näsholm, Torgny and Oren, Ram and Ottosson Löfvenius, Mikaell and Räntfors, Mats and Tor-Ngern, Pantana and Marshall, John D},
  editor = {Steppe, Kathy},
  title = {Limited vertical CO2 transport in stems of mature boreal Pinus sylvestris trees},
  journal = {Tree Physiology},
  year = {2021},
  volume = {41},
  number = {1},
  pages = {63--75},
  url = {https://academic.oup.com/treephys/article/41/1/63/5898915},
  doi = {10.1093/treephys/tpaa113}
}
Tenkanen M, Tsuruta A, Rautiainen K, Kangasaho V, Ellul R and Aalto T (2021), "Utilizing Earth Observations of Soil Freeze/Thaw Data and Atmospheric Concentrations to Estimate Cold Season Methane Emissions in the Northern High Latitudes".
Abstract: The northern wetland methane emission estimates have large uncertainties. Inversion models are a qualified method to estimate the methane fluxes and emissions in northern latitudes but when atmospheric observations are sparse, the models are only as good as their a priori estimates. Thus, improving a priori estimates is a competent way to reduce uncertainties and enhance emission estimates in the sparsely sampled regions. Here, we use a novel way to integrate remote sensing soil freeze/thaw (F/T) status from SMOS satellite to better capture the seasonality of methane emissions in the northern high latitude. The SMOS F/T data provide daily information of soil freezing state in the northern latitudes, and in this study, the data is used to define the cold season in the high latitudes and, thus, improve our knowledge of the seasonal cycle of biospheric methane fluxes. The SMOS F/T data is implemented to LPX-Bern DYPTOP model estimates and the modified fluxes are used as a biospheric a priori in the inversion model CarbonTracker Europe-CH4. The implementation of the SMOS F/T soil state is shown to be beneficial in improving the inversion model&rsquo;s cold season biospheric flux estimates. Our results show that cold season biospheric CH4 emissions in northern high latitudes are approximately 0.60 Tg lower than previously estimated, which corresponds to 17% reduction in the cold season biospheric emissions. This reduction is partly compensated by increased anthropogenic emissions in the same area (0.23 Tg), and the results also indicates that the anthropogenic emissions could have even larger contribution in cold season than estimated here.
BibTeX:
@misc{Tenkanen2021,
  author = {Tenkanen, Maria and Tsuruta, Aki and Rautiainen, Kimmo and Kangasaho, Vilma and Ellul, Raymond and Aalto, Tuula},
  title = {Utilizing Earth Observations of Soil Freeze/Thaw Data and Atmospheric Concentrations to Estimate Cold Season Methane Emissions in the Northern High Latitudes},
  booktitle = {Remote Sensing},
  year = {2021},
  volume = {13},
  number = {24},
  doi = {10.3390/rs13245059}
}
Trepekli K and Friborg T (2021), "Deriving Aerodynamic Roughness Length at Ultra-High Resolution in Agricultural Areas Using UAV-Borne LiDAR", Remote Sensing. Vol. 13(17)
Abstract: The aerodynamic roughness length (Z0) and surface geometry at ultra-high resolution in precision agriculture and agroforestry have substantial potential to improve aerodynamic process modeling for sustainable farming practices and recreational activities. We explored the potential of unmanned aerial vehicle (UAV)-borne LiDAR systems to provide Z0 maps with the level of spatiotemporal resolution demanded by precision agriculture by generating the 3D structure of vegetated surfaces and linking the derived geometry with morphometric roughness models. We evaluated the performance of three filtering algorithms to segment the LiDAR-derived point clouds into vegetation and ground points in order to obtain the vegetation height metrics and density at a 0.10 m resolution. The effectiveness of three morphometric models to determine the Z0 maps of Danish cropland and the surrounding evergreen trees was assessed by comparing the results with corresponding Z0 values from a nearby eddy covariance tower (Z0_EC). A morphological filter performed satisfactorily over a homogeneous surface, whereas the progressive triangulated irregular network densification algorithm produced fewer errors with a heterogeneous surface. Z0 from UAV-LiDAR-driven models converged with Z0_EC at the source area scale. The Raupach roughness model appropriately simulated temporal variations in Z0 conditioned by vertical and horizontal vegetation density. The Z0 calculated as a fraction of vegetation height or as a function of vegetation height variability resulted in greater differences with the Z0_EC. Deriving Z0 in this manner could be highly useful in the context of surface energy balance and wind profile estimations for micrometeorological, hydrologic, and ecologic applications in similar sites.
BibTeX:
@article{Trepekli2021,
  author = {Trepekli, Katerina and Friborg, Thomas},
  title = {Deriving Aerodynamic Roughness Length at Ultra-High Resolution in Agricultural Areas Using UAV-Borne LiDAR},
  journal = {Remote Sensing},
  year = {2021},
  volume = {13},
  number = {17},
  url = {https://www.mdpi.com/2072-4292/13/17/3538},
  doi = {10.3390/rs13173538}
}
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}
}
Vainio E, Peltola O, Kasurinen V, Kieloaho A-J, Tuittila E-S and Pihlatie M (2021), "Topography-based statistical modelling reveals high spatial variability and seasonal emission patches in forest floor methane flux", Biogeosciences. Vol. 18(6), pp. 2003-2025.
BibTeX:
@article{Vainio2021,
  author = {Vainio, E and Peltola, O and Kasurinen, V and Kieloaho, A.-J. and Tuittila, E.-S. and Pihlatie, M},
  title = {Topography-based statistical modelling reveals high spatial variability and seasonal emission patches in forest floor methane flux},
  journal = {Biogeosciences},
  year = {2021},
  volume = {18},
  number = {6},
  pages = {2003--2025},
  url = {https://bg.copernicus.org/articles/18/2003/2021/},
  doi = {10.5194/bg-18-2003-2021}
}
Van Dam B, Polsenaere P, Barreras-Apodaca A, Lopes C, Sanchez-Mejia Z, Tokoro T, Kuwae T, Loza LG, Rutgersson A, Fourqurean J and Thomas H (2021), "Global Trends in Air-Water CO2 Exchange Over Seagrass Meadows Revealed by Atmospheric Eddy Covariance", Global Biogeochemical Cycles., apr, 2021. Vol. 35(4), pp. e2020GB006848. John Wiley & Sons, Ltd.
Abstract: Abstract Coastal vegetated habitats like seagrass meadows can mitigate anthropogenic carbon emissions by sequestering CO2 as ?blue carbon? (BC). Already, some coastal ecosystems are actively managed to enhance BC storage, with associated BC stocks included in national greenhouse gas inventories. However, the extent to which BC burial fluxes are enhanced or counteracted by other carbon fluxes, especially air-water CO2 flux (FCO2) remains poorly understood. In this study, we synthesized all available direct FCO2 measurements over seagrass meadows made using atmospheric Eddy Covariance, across a globally representative range of ecotypes. Of the four sites with seasonal data coverage, two were net CO2 sources, with average FCO2 equivalent to 44%?115% of the global average BC burial rate. At the remaining sites, net CO2 uptake was 101%?888% of average BC burial. A wavelet coherence analysis demonstrated that FCO2 was most strongly related to physical factors like temperature, wind, and tides. In particular, tidal forcing was a key driver of global-scale patterns in FCO2, likely due to a combination of lateral carbon exchange, bottom-driven turbulence, and pore-water pumping. Lastly, sea-surface drag coefficients were always greater than the prediction for the open ocean, supporting a universal enhancement of gas-transfer in shallow coastal waters. Our study points to the need for a more comprehensive approach to BC assessments, considering not only organic carbon storage, but also air-water CO2 exchange, and its complex biogeochemical and physical drivers.
BibTeX:
@article{VanDam2021,
  author = {Van Dam, Bryce and Polsenaere, Pierre and Barreras-Apodaca, Aylin and Lopes, Christian and Sanchez-Mejia, Zulia and Tokoro, Tatsuki and Kuwae, Tomohiro and Loza, Lucia Gutiérrez and Rutgersson, Anna and Fourqurean, James and Thomas, Helmuth},
  title = {Global Trends in Air-Water CO2 Exchange Over Seagrass Meadows Revealed by Atmospheric Eddy Covariance},
  journal = {Global Biogeochemical Cycles},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {35},
  number = {4},
  pages = {e2020GB006848},
  url = {https://doi.org/10.1029/2020GB006848},
  doi = {10.1029/2020GB006848}
}
Vanikiotis T, Stagakis S and Kyparissis A (2021), "MODIS PRI performance to track Light Use Efficiency of a Mediterranean coniferous forest: Determinants, restrictions and the role of LUE range", Agricultural and Forest Meteorology. Vol. 307, pp. 108518.
Abstract: The relationship between the Photochemical Reflectance Index (PRI) and Light Use Efficiency (LUE) is well established at leaf and small canopy scales, but upscaling to ecosystem level is still a challenge. Only few studies have applied satellite-derived PRI to estimate LUE, mostly using MODIS, and although the results are promising, many external factors have been identified affecting PRI performance. The present study investigates determinants and restrictions of MODIS-derived PRI potential to follow the LUE variability of a Mediterranean coniferous forest. Daily and half-hour LUE values were calculated from eddy covariance measurements, dividing GPP by either Photosynthetically Active Radiation (PAR) or the absorbed fraction of PAR (APAR). Also, various PRI datasets were created based on different sensor (Terra, Aqua, Both), reference band (1, 12, 13) and observation/illumination angles. Overall, PRI correlated better with LUE calculated using PAR instead of APAR and Aqua PRI yielded better results than Terra. Restricting acquisitions according to observation/illumination angles improves the PRI:LUE relationship (maximum R2 = 0.512), with backscatter observations yielding the best correlations. Our findings suggest that MODIS-derived PRI is more sensitive to relatively large seasonal LUE changes, but is unable to closely follow severe drought events. Among the tested reference bands, the best results were derived using band 12 (546 - 556 nm), although the optimum reference band seems to depend on viewing conditions. The PRI:LUE relationship was further improved when half-hour LUE of the satellite overpass was used instead of daily LUE. However, it was found that the PRI:LUE relationships for the different datasets were strongly affected by the range of LUE values corresponding to each PRI group, with lower LUE variability resulting to weaker PRI:LUE correlations. LUE range effect should be accounted for in future studies, when different PRI datasets are compared and might explain the contradicting findings in the existing literature.
BibTeX:
@article{Vanikiotis2021,
  author = {Vanikiotis, Theofilos and Stagakis, Stavros and Kyparissis, Aris},
  title = {MODIS PRI performance to track Light Use Efficiency of a Mediterranean coniferous forest: Determinants, restrictions and the role of LUE range},
  journal = {Agricultural and Forest Meteorology},
  year = {2021},
  volume = {307},
  pages = {108518},
  url = {https://www.sciencedirect.com/science/article/pii/S0168192321002021},
  doi = {10.1016/j.agrformet.2021.108518}
}
Virkkala A-M, Aalto J, Rogers BM, Tagesson T, Treat CC, Natali SM, Watts JD, Potter S, Lehtonen A, Mauritz M, Schuur EAG, Kochendorfer J, Zona D, Oechel W, Kobayashi H, Humphreys E, Goeckede M, Iwata H, Lafleur PM, Euskirchen ES, Bokhorst S, Marushchak M, Martikainen PJ, Elberling B, Voigt C, Biasi C, Sonnentag O, Parmentier F-JW, Ueyama M, Celis G, St.Louis VL, Emmerton CA, Peichl M, Chi J, Järveoja J, Nilsson MB, Oberbauer SF, Torn MS, Park S-J, Dolman H, Mammarella I, Chae N, Poyatos R, López-Blanco E, Christensen TR, Kwon MJ, Sachs T, Holl D and Luoto M (2021), "Statistical upscaling of ecosystem CO2 fluxes across the terrestrial tundra and boreal domain: Regional patterns and uncertainties", Global Change Biology., sep, 2021. Vol. 27(17), pp. 4040-4059. John Wiley & Sons, Ltd.
Abstract: Abstract The regional variability in tundra and boreal carbon dioxide (CO2) fluxes can be high, complicating efforts to quantify sink-source patterns across the entire region. Statistical models are increasingly used to predict (i.e., upscale) CO2 fluxes across large spatial domains, but the reliability of different modeling techniques, each with different specifications and assumptions, has not been assessed in detail. Here, we compile eddy covariance and chamber measurements of annual and growing season CO2 fluxes of gross primary productivity (GPP), ecosystem respiration (ER), and net ecosystem exchange (NEE) during 1990?2015 from 148 terrestrial high-latitude (i.e., tundra and boreal) sites to analyze the spatial patterns and drivers of CO2 fluxes and test the accuracy and uncertainty of different statistical models. CO2 fluxes were upscaled at relatively high spatial resolution (1 km2) across the high-latitude region using five commonly used statistical models and their ensemble, that is, the median of all five models, using climatic, vegetation, and soil predictors. We found the performance of machine learning and ensemble predictions to outperform traditional regression methods. We also found the predictive performance of NEE-focused models to be low, relative to models predicting GPP and ER. Our data compilation and ensemble predictions showed that CO2 sink strength was larger in the boreal biome (observed and predicted average annual NEE ?46 and ?29 g C m?2 yr?1, respectively) compared to tundra (average annual NEE +10 and ?2 g C m?2 yr?1). This pattern was associated with large spatial variability, reflecting local heterogeneity in soil organic carbon stocks, climate, and vegetation productivity. The terrestrial ecosystem CO2 budget, estimated using the annual NEE ensemble prediction, suggests the high-latitude region was on average an annual CO2 sink during 1990?2015, although uncertainty remains high.
BibTeX:
@article{Virkkala2021,
  author = {Virkkala, Anna-Maria and Aalto, Juha and Rogers, Brendan M and Tagesson, Torbern and Treat, Claire C and Natali, Susan M and Watts, Jennifer D and Potter, Stefano and Lehtonen, Aleksi and Mauritz, Marguerite and Schuur, Edward A G and Kochendorfer, John and Zona, Donatella and Oechel, Walter and Kobayashi, Hideki and Humphreys, Elyn and Goeckede, Mathias and Iwata, Hiroki and Lafleur, Peter M and Euskirchen, Eugenie S and Bokhorst, Stef and Marushchak, Maija and Martikainen, Pertti J and Elberling, Bo and Voigt, Carolina and Biasi, Christina and Sonnentag, Oliver and Parmentier, Frans-Jan W and Ueyama, Masahito and Celis, Gerardo and St.Louis, Vincent L and Emmerton, Craig A and Peichl, Matthias and Chi, Jinshu and Järveoja, Järvi and Nilsson, Mats B and Oberbauer, Steven F and Torn, Margaret S and Park, Sang-Jong and Dolman, Han and Mammarella, Ivan and Chae, Namyi and Poyatos, Rafael and López-Blanco, Efrén and Christensen, Torben Røjle and Kwon, Min Jung and Sachs, Torsten and Holl, David and Luoto, Miska},
  title = {Statistical upscaling of ecosystem CO2 fluxes across the terrestrial tundra and boreal domain: Regional patterns and uncertainties},
  journal = {Global Change Biology},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {27},
  number = {17},
  pages = {4040--4059},
  url = {https://doi.org/10.1111/gcb.15659},
  doi = {10.1111/gcb.15659}
}
Wang F, Maksyutov S, Janardanan R, Tsuruta A, Ito A, Morino I, Yoshida Y, Tohjima Y, Kaiser JW, Janssens-Maenhout G, Lan X, Mammarella I, Lavric JV and Matsunaga T (2021), "Interannual variability on methane emissions in monsoon Asia derived from GOSAT and surface observations", Environmental Research Letters. Vol. 16(2), pp. 24040. IOP Publishing.
Abstract: In Asia, much effort is put into reducing methane (CH4) emissions due to the region's contribution to the recent rapid global atmospheric CH4 concentration growth. Accurate quantification of Asia's CH4 budgets is critical for conducting global stocktake and achieving the long-term temperature goal of the Paris Agreement. In this study, we present top-down estimates of CH4 emissions from 2009 to 2018 deduced from atmospheric observations from surface network and GOSAT satellite with the high-resolution global inverse model NIES-TM-FLEXPART-VAR. The optimized average CH4 budgets are 63.40 ± 10.52 Tg y−1 from East Asia (EA), 45.20 ± 6.22 Tg y−1 from Southeast Asia (SEA), and 64.35 ± 9.28 Tg y−1 from South Asia (SA) within the 10 years. We analyzed two 5 years CH4 emission budgets for three subregions and 13 top-emitting countries with an emission budget larger than 1 Tg y−1, and interannual variabilities for these subregions. Statistically significant increasing trends in emissions are found in EA with a lower emission growth rate during 2014–2018 compared to that during 2009–2013, while trends in SEA are not significant. In contrast to the prior emission, the posterior emission shows a significant decreasing trend in SA. The flux decrease is associated with the transition from strong La Ninña (2010–2011) to strong El Ninño (2015–2016) events, which modulate the surface air temperature and rainfall patterns. The interannual variability in CH4 flux anomalies was larger in SA compared to EA and SEA. The Southern Oscillation Index correlates strongly with interannual CH4 flux anomalies for SA. Our findings suggest that the interannual variability in the total CH4 flux is dominated by climate variability in SA. The contribution of climate variability driving interannual variability in natural and anthropogenic CH4 emissions should be further quantified, especially for tropical countries. Accounting for climate variability may be necessary to improve anthropogenic emission inventories.
BibTeX:
@article{Wang2021,
  author = {Wang, Fenjuan and Maksyutov, Shamil and Janardanan, Rajesh and Tsuruta, Aki and Ito, Akihiko and Morino, Isamu and Yoshida, Yukio and Tohjima, Yasunori and Kaiser, Johannes W and Janssens-Maenhout, Greet and Lan, Xin and Mammarella, Ivan and Lavric, Jost V and Matsunaga, Tsuneo},
  title = {Interannual variability on methane emissions in monsoon Asia derived from GOSAT and surface observations},
  journal = {Environmental Research Letters},
  publisher = {IOP Publishing},
  year = {2021},
  volume = {16},
  number = {2},
  pages = {24040},
  url = {http://dx.doi.org/10.1088/1748-9326/abd352},
  doi = {10.1088/1748-9326/abd352}
}
Wang J, Bogena H, Süß T, Graf A, Weuthen A and Brüggemann N (2021), "Investigating the controls on greenhouse gas emission in the riparian zone of a small headwater catchment using an automated monitoring system", Vadose Zone Journal., sep, 2021. Vol. 20(5), pp. e20149. John Wiley & Sons, Ltd.
Abstract: Abstract Riparian zones as the transition zone between terrestrial and aquatic ecosystems play an important role in C and N cycling and greenhouse gas (GHG) emissions. As such, they may help to mitigate climate change but could also accelerate it, depending on the particular processes affected by changes in the hydrologic regime. Hydrological observations indicated frequent shallow groundwater in the riparian zone, especially near the stream and during the wet winter and spring seasons with consequently frequent occurrence of soil water saturation. The redox potential was mainly governed by the soil water regime: under water saturation conditions, the redox potential of the soil decreased and returned to the oxic state after soil drainage. We found that soil temperature and soil water content were the main drivers of the variations in CO2 fluxes, with highest CO2 emission during summer and the lowest emissions in the winter period (162.2?5.4 mg CO2?C m?2 h?1). The annual average daily N2O emission rate was low (2.3 ?g N2O-N m?2 h?1), with the highest average daily N2O emission in March as a result of low temperature and partial soil saturation after heavy precipitation events (37.5 ?g N2O-N m?2 h?1). Our study showed that continuous measurement of redox potential, soil temperature, and soil water content can improve the understanding of GHG emissions in riparian zones.
BibTeX:
@article{Wang2021a,
  author = {Wang, Jihuan and Bogena, Heye and Süß, Thomas and Graf, Alexander and Weuthen, Ansgar and Brüggemann, Nicolas},
  title = {Investigating the controls on greenhouse gas emission in the riparian zone of a small headwater catchment using an automated monitoring system},
  journal = {Vadose Zone Journal},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {20},
  number = {5},
  pages = {e20149},
  url = {https://doi.org/10.1002/vzj2.20149},
  doi = {10.1002/vzj2.20149}
}
Wilson RM, Zayed AA, Crossen KB, Woodcroft B, Tfaily MM, Emerson J, Raab N, Hodgkins SB, Verbeke B, Tyson G, Crill P, Saleska S, Chanton JP, Rich VI, Coordinators IP and Team IPF (2021), "Functional capacities of microbial communities to carry out large scale geochemical processes are maintained during ex situ anaerobic incubation", PLOS ONE. Vol. 16(2), pp. 1-33. Public Library of Science.
Abstract: Mechanisms controlling CO2 and CH4 production in wetlands are central to understanding carbon cycling and greenhouse gas exchange. However, the volatility of these respiration products complicates quantifying their rates of production in the field. Attempts to circumvent the challenges through closed system incubations, from which gases cannot escape, have been used to investigate bulk in situ geochemistry. Efforts towards mapping mechanistic linkages between geochemistry and microbiology have raised concern regarding sampling and incubation-induced perturbations. Microorganisms are impacted by oxygen exposure, increased temperatures and accumulation of metabolic products during handling, storage, and incubation. We probed the extent of these perturbations, and their influence on incubation results, using high-resolution geochemical and microbial gene-based community profiling of anaerobically incubated material from three wetland habitats across a permafrost peatland. We compared the original field samples to the material anaerobically incubated over 50 days. Bulk geochemistry and phylum-level microbiota in incubations largely reflected field observations, but divergence between field and incubations occurred in both geochemistry and lineage-level microbial composition when examined at closer resolution. Despite the changes in representative lineages over time, inferred metabolic function with regards to carbon cycling largely reproduced field results suggesting functional consistency. Habitat differences among the source materials remained the largest driver of variation in geochemical and microbial differences among the samples in both incubations and field results. While incubations may have limited usefulness for identifying specific mechanisms, they remain a viable tool for probing bulk-scale questions related to anaerobic C cycling, including CO2 and CH4 dynamics.
BibTeX:
@article{Wilson2021,
  author = {Wilson, R M and Zayed, A A and Crossen, K B and Woodcroft, B and Tfaily, M M and Emerson, J and Raab, N and Hodgkins, S B and Verbeke, B and Tyson, G and Crill, P and Saleska, S and Chanton, J P and Rich, V I and Coordinators, IsoGenie Project and Team, IsoGenie Project Field},
  title = {Functional capacities of microbial communities to carry out large scale geochemical processes are maintained during ex situ anaerobic incubation},
  journal = {PLOS ONE},
  publisher = {Public Library of Science},
  year = {2021},
  volume = {16},
  number = {2},
  pages = {1--33},
  url = {https://doi.org/10.1371/journal.pone.0245857},
  doi = {10.1371/journal.pone.0245857}
}
Wu D, Liu S, Wu X, Yang X, Xu T, Xu Z and Shi H (2021), "Diagnosing the Temperature Sensitivity of Ecosystem Respiration in Northern High Latitude Regions", Journal of Geophysical Research (Biogeosciences). AA(State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing, China), AB(State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing, China), AC(State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing, China), AD(State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing, China), AE(State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing, China), AF(State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing, China), AG(State Key Laboratory of Remote Sensing Science, Faculty of Geographical Science, Beijing Normal University, Beijing, China), apr, 2021. Vol. 126, pp. e05998.
Abstract: The accurate estimation of the temperature sensitivity of ecosystem respiration (Q10) is important to understanding the terrestrial ecosystem carbon cycle, especially in northern high latitude regions (NHLs). Q10 estimated by the conventional approach at the annual scale is influenced by seasonal confounding effects. Based on singular spectrum analysis, scale dependent parameter estimation (SCAPE) is considered an effective approach to eliminate confounding effects. Nevertheless, the performance of the decomposition and reconstruction schemes in the SCAPE approach in Q10 estimation remains limited, which hampers its further application in larger scale systems. In this study, we utilized an improved scale dependent parameter estimation (iSCAPE) approach to analyze trends of the unconfounded Q10 and its environmental controls in NHLs. The results showed that in NHLs, the confounding effects in forest ecosystems were smaller than those in cropland and grassland ecosystems. The apparent Q10 estimated by the conventional approach varied among 32 sites with a mean value of 2.82 (95% confidence interval (CI): 2.72-2.91), while the mean intrinsic Q10 estimated by the iSCAPE approach across the 32 sites was 1.53 (95% CI: 1.48-1.57). The apparent Q10 increased with the annual mean temperature. The intrinsic Q10 decreased with the increasing of spatial temperature gradient. The current study indicates that ecosystem respiration in NHLs is less sensitive to climate warming than previously reported. The seasonality of ecosystem respiration should be eliminated when estimating Q10 to avoid overestimating climate carbon cycle feedback.
BibTeX:
@article{Wu2021,
  author = {Wu, Dongxing and Liu, Shaomin and Wu, Xiuchen and Yang, Xiaofan and Xu, Tongren and Xu, Ziwei and Shi, Hanyu},
  title = {Diagnosing the Temperature Sensitivity of Ecosystem Respiration in Northern High Latitude Regions},
  journal = {Journal of Geophysical Research (Biogeosciences)},
  year = {2021},
  volume = {126},
  pages = {e05998},
  url = {https://ui.adsabs.harvard.edu/abs/2021JGRG..12605998W},
  doi = {10.1029/2020JG005998}
}
Wu J, Peichl M, Luan J, Connolly J and Xu L (2021), "Editorial: Wetland Ecology and Biogeochemistry Under Natural and Human Disturbance", Frontiers in Earth Science. Vol. 9
BibTeX:
@article{Wu2021a,
  author = {Wu, Jianghua and Peichl, Matthias and Luan, Junwei and Connolly, John and Xu, Ligang},
  title = {Editorial: Wetland Ecology and Biogeochemistry Under Natural and Human Disturbance},
  journal = {Frontiers in Earth Science},
  year = {2021},
  volume = {9},
  url = {https://www.frontiersin.org/article/10.3389/feart.2021.752101},
  doi = {10.3389/feart.2021.752101}
}
Yazbeck T, Bohrer G, Gentine P, Ye L, Arriga N, Bernhofer C, Blanken PD, Desai AR, Durden D, Knohl A, Kowalska N, Metzger S, Mölder M, Noormets A, Novick K, Scott RL, Šigut L, Soudani K, Ueyama M and Varlagin A (2021), "Site Characteristics Mediate the Relationship Between Forest Productivity and Satellite Measured Solar Induced Fluorescence", Frontiers in Forests and Global Change. Vol. 4
Abstract: Solar-Induced Chlorophyll Fluorescence (SIF) can provide key information about the state of photosynthesis and offers the prospect of defining remote sensing-based estimation of Gross Primary Production (GPP). There is strong theoretical support for the link between SIF and GPP and this relationship has been empirically demonstrated using ground-based, airborne, and satellite-based SIF observations, as well as modeling. However, most evaluations have been based on monthly and annual scales, yet the GPP:SIF relations can be strongly influenced by both vegetation structure and physiology. At the monthly timescales, the structural response often dominates but short-term physiological variations can strongly impact the GPP:SIF relations. Here, we test how well SIF can predict the inter-daily variation of GPP during the growing season and under stress conditions, while taking into account the local effect of sites and abiotic conditions. We compare the accuracy of GPP predictions from SIF at different timescales (half-hourly, daily, and weekly), while evaluating effect of adding environmental variables to the relationship. We utilize observations for years 2018–2019 at 31 mid-latitudes, forested, eddy covariance (EC) flux sites in North America and Europe and use TROPOMI satellite data for SIF. Our results show that SIF is a good predictor of GPP, when accounting for inter-site variation, probably due to differences in canopy structure. Seasonally averaged leaf area index, fraction of absorbed photosynthetically active radiation (fPAR) and canopy conductance provide a predictor to the site-level effect. We show that fPAR is the main factor driving errors in the linear model at high temporal resolution. Adding water stress indicators, namely canopy conductance, to a multi-linear SIF-based GPP model provides the best improvement in the model precision at the three considered timescales, showing the importance of accounting for water stress in GPP predictions, independent of the SIF signal. SIF is a promising predictor for GPP among other remote sensing variables, but more focus should be placed on including canopy structure, and water stress effects in the relationship, especially when considering intra-seasonal, and inter- and intra-daily resolutions.
BibTeX:
@article{Yazbeck2021,
  author = {Yazbeck, Theresia and Bohrer, Gil and Gentine, Pierre and Ye, Luping and Arriga, Nicola and Bernhofer, Christian and Blanken, Peter D and Desai, Ankur R and Durden, David and Knohl, Alexander and Kowalska, Natalia and Metzger, Stefan and Mölder, Meelis and Noormets, Asko and Novick, Kim and Scott, Russell L and Šigut, Ladislav and Soudani, Kamel and Ueyama, Masahito and Varlagin, Andrej},
  title = {Site Characteristics Mediate the Relationship Between Forest Productivity and Satellite Measured Solar Induced Fluorescence},
  journal = {Frontiers in Forests and Global Change},
  year = {2021},
  volume = {4},
  url = {https://www.frontiersin.org/article/10.3389/ffgc.2021.695269},
  doi = {10.3389/ffgc.2021.695269}
}
Yin T, Papadimitriou S, Rérolle VMC, Arundell M, Cardwell CL, Walk J, Palmer MR, Fowell SE, Schaap A, Mowlem MC and Loucaides S (2021), "A Novel Lab-on-Chip Spectrophotometric pH Sensor for Autonomous In Situ Seawater Measurements to 6000 m Depth on Stationary and Moving Observing Platforms", Environmental Science & Technology., nov, 2021. Vol. 55(21), pp. 14968-14978. American Chemical Society.
BibTeX:
@article{Yin2021,
  author = {Yin, Tianya and Papadimitriou, Stathys and Rérolle, Victoire M C and Arundell, Martin and Cardwell, Christopher L and Walk, John and Palmer, Martin R and Fowell, Sara E and Schaap, Allison and Mowlem, Matthew C and Loucaides, Socratis},
  title = {A Novel Lab-on-Chip Spectrophotometric pH Sensor for Autonomous In Situ Seawater Measurements to 6000 m Depth on Stationary and Moving Observing Platforms},
  journal = {Environmental Science & Technology},
  publisher = {American Chemical Society},
  year = {2021},
  volume = {55},
  number = {21},
  pages = {14968--14978},
  url = {https://doi.org/10.1021/acs.est.1c03517},
  doi = {10.1021/acs.est.1c03517}
}
Yver-Kwok C, Philippon C, Bergamaschi P, Biermann T, Calzolari F, Chen H, Conil S, Cristofanelli P, Delmotte M, Hatakka J, Heliasz M, Hermansen O, Kominkova K, Kubistin D, Kumps N, Laurent O, Laurila T, Lehner I, Levula J, Lindauer M, Lopez M, Mammarella I, Manca G, Marklund P, Metzger JM, Mölder M, Platt SM, Ramonet M, Rivier L, Scheeren B, Kumar Sha M, Smith P, Steinbacher M, Vítková G and Wyss S (2021), "Evaluation and optimization of ICOS atmosphere station data as part of the labeling process", Atmospheric Measurement Techniques. Vol. 14(1), pp. 89-116.
Abstract:

The Integrated Carbon Observation System (ICOS) is a pan-European research infrastructure which provides harmonized and high-precision scientific data on the carbon cycle and the greenhouse gas budget. All stations have to undergo a rigorous assessment before being labeled, i.e., receiving approval to join the network. In this paper, we present the labeling process for the ICOS atmosphere network through the 23 stations that were labeled between November 2017 and November 2019. We describe the labeling steps, as well as the quality controls, used to verify that the ICOS data (CO2, CH4, CO and meteorological measurements) attain the expected quality level defined within ICOS. To ensure the quality of the greenhouse gas data, three to four calibration gases and two target gases are measured: one target two to three times a day, the other gases twice a month. The data are verified on a weekly basis, and tests on the station sampling lines are performed twice a year. From these high-quality data, we conclude that regular calibrations of the CO2, CH4 and CO analyzers used here (twice a month) are important in particular for carbon monoxide (CO) due to the analyzer's variability and that reducing the number of calibration injections (from four to three) in a calibration sequence is possible, saving gas and extending the calibration gas lifespan. We also show that currently, the on-site water vapor correction test does not deliver quantitative results possibly due to environmental factors. Thus the use of a drying system is strongly recommended. Finally, the mandatory regular intake line tests are shown to be useful in detecting artifacts and leaks, as shown here via three different examples at the stations.

.
BibTeX:
@article{YverKwok2021,
  author = {Yver-Kwok, Camille and Philippon, Carole and Bergamaschi, Peter and Biermann, Tobias and Calzolari, Francescopiero and Chen, Huilin and Conil, Sebastien and Cristofanelli, Paolo and Delmotte, Marc and Hatakka, Juha and Heliasz, Michal and Hermansen, Ove and Kominkova, Katerina and Kubistin, Dagmar and Kumps, Nicolas and Laurent, Olivier and Laurila, Tuomas and Lehner, Irene and Levula, Janne and Lindauer, Matthias and Lopez, Morgan and Mammarella, Ivan and Manca, Giovanni and Marklund, Per and Metzger, Jean Marc and Mölder, Meelis and Platt, Stephen M. and Ramonet, Michel and Rivier, Leonard and Scheeren, Bert and Kumar Sha, Mahesh and Smith, Paul and Steinbacher, Martin and Vítková, Gabriela and Wyss, Simon},
  title = {Evaluation and optimization of ICOS atmosphere station data as part of the labeling process},
  journal = {Atmospheric Measurement Techniques},
  year = {2021},
  volume = {14},
  number = {1},
  pages = {89--116},
  doi = {10.5194/amt-14-89-2021}
}
Zhang H, Tuittila E-S, Korrensalo A, Laine AM, Uljas S, Welti N, Kerttula J, Maljanen M, Elliott D, Vesala T and Lohila A (2021), "Methane production and oxidation potentials along a fen-bog gradient from southern boreal to subarctic peatlands in Finland", Global Change Biology., sep, 2021. Vol. 27(18), pp. 4449-4464. John Wiley & Sons, Ltd.
Abstract: Abstract Methane (CH4) emissions from northern peatlands are projected to increase due to climate change, primarily because of projected increases in soil temperature. Yet, the rates and temperature responses of the two CH4 emission-related microbial processes (CH4 production by methanogens and oxidation by methanotrophs) are poorly known. Further, peatland sites within a fen-bog gradient are known to differ in the variables that regulate these two mechanisms, yet the interaction between peatland type and temperature lacks quantitative understanding. Here, we investigated potential CH4 production and oxidation rates for 14 peatlands in Finland located between c. 60 and 70°N latitude, representing bogs, poor fens, and rich fens. Potentials were measured at three different temperatures (5, 17.5, and 30?) using the laboratory incubation method. We linked CH4 production and oxidation patterns to their methanogen and methanotroph abundance, peat properties, and plant functional types. We found that the rich fen-bog gradient-related nutrient availability and methanogen abundance increased the temperature response of CH4 production, with rich fens exhibiting the greatest production potentials. Oxidation potential showed a steeper temperature response than production, which was explained by aerenchymous plant cover, peat water holding capacity, peat nitrogen, and sulfate content. The steeper temperature response of oxidation suggests that, at higher temperatures, CH4 oxidation might balance increased CH4 production. Predicting net CH4 fluxes as an outcome of the two mechanisms is complicated due to their different controls and temperature responses. The lack of correlation between field CH4 fluxes and production/oxidation potentials, and the positive correlation with aerenchymous plants points toward the essential role of CH4 transport for emissions. The scenario of drying peatlands under climate change, which is likely to promote Sphagnum establishment over brown mosses in many places, will potentially reduce the predicted warming-related increase in CH4 emissions by shifting rich fens to Sphagnum-dominated systems.
BibTeX:
@article{Zhang2021,
  author = {Zhang, Hui and Tuittila, Eeva-Stiina and Korrensalo, Aino and Laine, Anna M and Uljas, Salli and Welti, Nina and Kerttula, Johanna and Maljanen, Marja and Elliott, David and Vesala, Timo and Lohila, Annalea},
  title = {Methane production and oxidation potentials along a fen-bog gradient from southern boreal to subarctic peatlands in Finland},
  journal = {Global Change Biology},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {27},
  number = {18},
  pages = {4449--4464},
  url = {https://doi.org/10.1111/gcb.15740},
  doi = {10.1111/gcb.15740}
}
Zhang S, Rutgersson A, Philipson P and Wallin MB (2021), "Remote Sensing Supported Sea Surface pCO2 Estimation and Variable Analysis in the Baltic Sea", Remote Sensing. Vol. 13(2)
Abstract: Marginal seas are a dynamic and still to large extent uncertain component of the global carbon cycle. The large temporal and spatial variations of sea-surface partial pressure of carbon dioxide (pCO2) in these areas are driven by multiple complex mechanisms. In this study, we analyzed the variable importance for the sea surface pCO2 estimation in the Baltic Sea and derived monthly pCO2 maps for the marginal sea during the period of July 2002&ndash;October 2011. We used variables obtained from remote sensing images and numerical models. The random forest algorithm was employed to construct regression models for pCO2 estimation and produce the importance of different input variables. The study found that photosynthetically available radiation (PAR) was the most important variable for the pCO2 estimation across the entire Baltic Sea, followed by sea surface temperature (SST), absorption of colored dissolved organic matter (aCDOM), and mixed layer depth (MLD). Interestingly, Chlorophyll-a concentration (Chl-a) and the diffuse attenuation coefficient for downwelling irradiance at 490 nm (Kd_490nm) showed relatively low importance for the pCO2 estimation. This was mainly attributed to the high correlation of Chl-a and Kd_490nm to other pCO2-relevant variables (e.g., aCDOM), particularly in the summer months. In addition, the variables&rsquo; importance for pCO2 estimation varied between seasons and sub-basins. For example, the importance of aCDOM were large in the Gulf of Finland but marginal in other sub-basins. The model for pCO2 estimate in the entire Baltic Sea explained 63% of the variation and had a root of mean squared error (RMSE) of 47.8 &micro;atm. The pCO2 maps derived with this model displayed realistic seasonal variations and spatial features of sea surface pCO2 in the Baltic Sea. The spatially and seasonally varying variables&rsquo; importance for the pCO2 estimation shed light on the heterogeneities in the biogeochemical and physical processes driving the carbon cycling in the Baltic Sea and can serve as an important basis for future pCO2 estimation in marginal seas using remote sensing techniques. The pCO2 maps derived in this study provided a robust benchmark for understanding the spatiotemporal patterns of CO2 air-sea exchange in the Baltic Sea.
BibTeX:
@article{Zhang2021b,
  author = {Zhang, Shuping and Rutgersson, Anna and Philipson, Petra and Wallin, Marcus B},
  title = {Remote Sensing Supported Sea Surface pCO2 Estimation and Variable Analysis in the Baltic Sea},
  journal = {Remote Sensing},
  year = {2021},
  volume = {13},
  number = {2},
  url = {https://www.mdpi.com/2072-4292/13/2/259},
  doi = {10.3390/rs13020259}
}
Zhang Z, Zhang H, Cui Z, Tao F, Chen Z, Chang Y, Magliulo V, Wohlfahrt G and Zhao D (2021), "Global consistency in response of terrestrial ecosystem respiration to temperature", Agricultural and Forest Meteorology. Vol. 308-309, pp. 108576.
Abstract: Many studies have been carried out to quantify the trend of terrestrial ecosystem respiration (Re) in a warming world, but a conclusive answer has not yet been confirmed because the temperature sensitivity of Re was found inconsistent under different scales or regarding different types of respiratory flux. Aiming at reconciling the relationship between temperature and Re across different scales (i.e., short-term and site-to-site), we proposed a method to reduce noises of half-hourly Re measurements and applied nine empirical models to a 1387 site-year FLUXNET datasets. Regarding the temperature sensitivity of half-hourly Re records, we found a surprisingly consistent result that the sigmoid functions outcompeted other statistical models in 82% of site-year combinations, and on average, achieved a staggering R2 value of 0.92, indicating the positive correlation between Re and temperature on fine time scale (within one site-year dataset). Even though Re of all biomes followed sigmoid functions, the parameters of the S-curve varied strongly across sites or years. This explains why measured Q10 value (an index denote temperature sensitivity) largely depends on observation season and site. Furthermore, on the interannual variation of Re, we did not find any relationship between mean annual temperature (MAT) and mean annual Re within any site, which implies that the small year-to-year variation of the sigmoid pattern is large enough to counteract the warming effect on Re. This study brings up a conceptual framework to integrate the relationship between temperature and Re under short-term or site-to-site scales. It also provided evidence to support the argument that the relationship between MAT and mean annual Re by using data across multiple sites should not be used to interpret the response of respiration under global warming.
BibTeX:
@article{Zhang2021a,
  author = {Zhang, Zhiyuan and Zhang, Huanyuan and Cui, Zikun and Tao, Feng and Chen, Ziwei and Chang, Yaxuan and Magliulo, Vincenzo and Wohlfahrt, Georg and Zhao, Dongsheng},
  title = {Global consistency in response of terrestrial ecosystem respiration to temperature},
  journal = {Agricultural and Forest Meteorology},
  year = {2021},
  volume = {308-309},
  pages = {108576},
  url = {https://www.sciencedirect.com/science/article/pii/S0168192321002604},
  doi = {10.1016/j.agrformet.2021.108576}
}
Zhou H, Shao J, Liu H, Du Z, Zhou L, Liu R, Bernhofer C, Grünwald T, Dušek J, Montagnani L, Tagesson T, Black TA, Jassal R, Woodgate W, Biraud S, Varlagin A, Mammarella I, Gharun M, Shekhar A, Buchmann N, Manco A, Magliulo E, Billesbach D, Silberstein RP, Ohta T, Yu G, Chen Z, Zhang Y and Zhou X (2021), "Relative importance of climatic variables, soil properties and plant traits to spatial variability in net CO2 exchange across global forests and grasslands", Agricultural and Forest Meteorology. Vol. 307, pp. 108506.
Abstract: Compared to the well-known drivers of spatial variability in gross primary productivity (GPP), the relative importance of climatic variables, soil properties and plant traits to the spatial variability in net ecosystem exchange of CO2 between terrestrial ecosystem and atmosphere (NEE) is poorly understood. We used principal component regression to analyze data from 147 eddy flux sites to disentangle effects of climatic variables, soil properties and plant traits on the spatial variation in annual NEE and its components (GPP and ecosystem respiration (RE)) across global forests and grasslands. Our results showed that the largest unique contribution (proportion of variance only explained by one class of variables) to NEE variance came from climatic variables for forests (24%-30%) and soil properties for grasslands (41%-54%). Specifically, mean annual precipitation and potential evapotranspiration were the most important climatic variables driving forest NEE, whereas available soil water capacity, clay content and cation exchange capacity mainly influenced grassland NEE. Plant traits showed a small unique contribution to NEE in both forests and grasslands. However, leaf phosphorus content strongly interacted with soil total nitrogen density and clay content, and these combined factors represented a major contribution for grassland NEE. For GPP and RE, the majority of spatial variance was attributed to the common contribution of climate, soil and plant traits (50% - 62%, proportion of variance explained by more than one class of variables), rather than their unique contributions. Interestingly, those factors with only minor influences on GPP and RE variability (e.g., soil properties) have significant contributions to the spatial variability in NEE. Such emerging factors and the interactions between climatic variables, soil properties and plant traits are not well represented in current terrestrial biosphere models, which should be considered in future model improvement to accurately predict the spatial pattern of carbon cycling across forests and grasslands globally.
BibTeX:
@article{Zhou2021,
  author = {Zhou, Huimin and Shao, Junjiong and Liu, Huiying and Du, Zhenggang and Zhou, Lingyan and Liu, Ruiqiang and Bernhofer, Christian and Grünwald, Thomas and Dušek, Jiří and Montagnani, Leonardo and Tagesson, Torbern and Black, Thomas Andrew and Jassal, Rachhpal and Woodgate, William and Biraud, Sébastien and Varlagin, Andrej and Mammarella, Ivan and Gharun, Mana and Shekhar, Ankit and Buchmann, Nina and Manco, Antonio and Magliulo, Enzo and Billesbach, Dave and Silberstein, Richard P and Ohta, Takeshi and Yu, Guirui and Chen, Zhi and Zhang, Yiping and Zhou, Xuhui},
  title = {Relative importance of climatic variables, soil properties and plant traits to spatial variability in net CO2 exchange across global forests and grasslands},
  journal = {Agricultural and Forest Meteorology},
  year = {2021},
  volume = {307},
  pages = {108506},
  url = {https://www.sciencedirect.com/science/article/pii/S0168192321001908},
  doi = {10.1016/j.agrformet.2021.108506}
}
Zinke LA, Evans PN, Santos-Medellín C, Schroeder AL, Parks DH, Varner RK, Rich VI, Tyson GW and Emerson JB (2021), "Evidence for non-methanogenic metabolisms in globally distributed archaeal clades basal to the Methanomassiliicoccales.", Environmental microbiology., jan, 2021. Vol. 23(1), pp. 340-357.
Abstract: Recent discoveries of mcr and mcr-like genes in genomes from diverse archaeal lineages suggest that methane metabolism is an ancient pathway with a complicated evolutionary history. One conventional view is that methanogenesis is an ancestral metabolism of the class Thermoplasmata. Through comparative genomic analysis of 12 Thermoplasmata metagenome-assembled genomes (MAGs) basal to the Methanomassiliicoccales, we show that these microorganisms do not encode the genes required for methanogenesis. Further analysis of 770 Ca. Thermoplasmatota genomes/MAGs found no evidence of mcrA homologues outside of the Methanomassiliicoccales. Together, these results suggest that methanogenesis was laterally acquired by an ancestor of the Methanomassiliicoccales. The 12 analysed MAGs include representatives from four orders basal to the Methanomassiliicoccales, including a high-quality MAG that likely represents a new order, Ca. Lunaplasma lacustris ord. nov. sp. nov. These MAGs are predicted to use diverse energy conservation pathways, including heterotrophy, sulfur and hydrogen metabolism, denitrification, and fermentation. Two lineages are widespread among anoxic, sedimentary environments, whereas Ca. Lunaplasma lacustris has thus far only been detected in alpine caves and subarctic lake sediments. These findings advance our understanding of the metabolic potential, ecology, and global distribution of the Thermoplasmata and provide insight into the evolutionary history of methanogenesis within the Ca. Thermoplasmatota.
BibTeX:
@article{Zinke2021,
  author = {Zinke, Laura A and Evans, Paul N and Santos-Medellín, Christian and Schroeder, Alena L and Parks, Donovan H and Varner, Ruth K and Rich, Virginia I and Tyson, Gene W and Emerson, Joanne B},
  title = {Evidence for non-methanogenic metabolisms in globally distributed archaeal clades basal to the Methanomassiliicoccales.},
  journal = {Environmental microbiology},
  year = {2021},
  volume = {23},
  number = {1},
  pages = {340--357},
  doi = {10.1111/1462-2920.15316}
}
Zweifel R, Etzold S, Basler D, Bischoff R, Braun S, Buchmann N, Conedera M, Fonti P, Gessler A, Haeni M, Hoch G, Kahmen A, Köchli R, Maeder M, Nievergelt D, Peter M, Peters RL, Schaub M, Trotsiuk V, Walthert L, Wilhelm M and Eugster W (2021), "TreeNet–The Biological Drought and Growth Indicator Network", Frontiers in Forests and Global Change. Vol. 4
Abstract: The TreeNet research and monitoring network has been continuously collecting data from point dendrometers and air and soil microclimate using an automated system since 2011. The goal of TreeNet is to generate high temporal resolution datasets of tree growth and tree water dynamics for research and to provide near real-time indicators of forest growth performance and drought stress to a wide audience. This paper explains the key working steps from the installation of sensors in the field to data acquisition, data transmission, data processing, and online visualization. Moreover, we discuss the underlying premises to convert dynamic stem size changes into relevant biological information. Every 10 min, the stem radii of about 420 trees from 13 species at 61 sites in Switzerland are measured electronically with micrometer precision, in parallel with the environmental conditions above and below ground. The data are automatically transmitted, processed and stored on a central server. Automated data processing (R-based functions) includes screening of outliers, interpolation of data gaps, and extraction of radial stem growth and water deficit for each tree. These long-term data are used for scientific investigations as well as to calculate and display daily indicators of growth trends and drought levels in Switzerland based on historical and current data. The current collection of over 100 million data points forms the basis for identifying dynamics of tree-, site- and species-specific processes along environmental gradients. TreeNet is one of the few forest networks capable of tracking the diurnal and seasonal cycles of tree physiology in near real-time, covering a wide range of temperate forest species and their respective environmental conditions.
BibTeX:
@article{Zweifel2021a,
  author = {Zweifel, Roman and Etzold, Sophia and Basler, David and Bischoff, Reinhard and Braun, Sabine and Buchmann, Nina and Conedera, Marco and Fonti, Patrick and Gessler, Arthur and Haeni, Matthias and Hoch, Günter and Kahmen, Ansgar and Köchli, Roger and Maeder, Marcus and Nievergelt, Daniel and Peter, Martina and Peters, Richard L and Schaub, Marcus and Trotsiuk, Volodymyr and Walthert, Lorenz and Wilhelm, Micah and Eugster, Werner},
  title = {TreeNet–The Biological Drought and Growth Indicator Network},
  journal = {Frontiers in Forests and Global Change},
  year = {2021},
  volume = {4},
  url = {https://www.frontiersin.org/article/10.3389/ffgc.2021.776905},
  doi = {10.3389/ffgc.2021.776905}
}
Zweifel R, Sterck F, Braun S, Buchmann N, Eugster W, Gessler A, Häni M, Peters RL, Walthert L, Wilhelm M, Ziemiʼnska K and Etzold S (2021), "Why trees grow at night", New Phytologist., sep, 2021. Vol. 231(6), pp. 2174-2185. John Wiley & Sons, Ltd.
Abstract: Summary The timing of diel stem growth of mature forest trees is still largely unknown, as empirical data with high temporal resolution have not been available so far. Consequently, the effects of day?night conditions on tree growth remained uncertain. Here we present the first comprehensive field study of hourly-resolved radial stem growth of seven temperate tree species, based on 57 million underlying data points over a period of up to 8?yr. We show that trees grow mainly at night, with a peak after midnight, when the vapour pressure deficit (VPD) is among the lowest. A high VPD strictly limits radial stem growth and allows little growth during daylight hours, except in the early morning. Surprisingly, trees also grow in moderately dry soil when the VPD is low. Species-specific differences in diel growth dynamics show that species able to grow earlier during the night are associated with the highest number of hours with growth per year and the largest annual growth increment. We conclude that species with the ability to overcome daily water deficits faster have greater growth potential. Furthermore, we conclude that growth is more sensitive than carbon uptake to dry air, as growth stops before stomata are known to close.
BibTeX:
@article{Zweifel2021,
  author = {Zweifel, Roman and Sterck, Frank and Braun, Sabine and Buchmann, Nina and Eugster, Werner and Gessler, Arthur and Häni, Matthias and Peters, Richard L and Walthert, Lorenz and Wilhelm, Micah and Ziemiʼnska, Kasia and Etzold, Sophia},
  title = {Why trees grow at night},
  journal = {New Phytologist},
  publisher = {John Wiley & Sons, Ltd},
  year = {2021},
  volume = {231},
  number = {6},
  pages = {2174--2185},
  url = {https://doi.org/10.1111/nph.17552},
  doi = {10.1111/nph.17552}
}
Łakomiec P, Holst J, Friborg T, Crill P, Rakos N, Kljun N, Olsson P-O, Eklundh L, Persson A and Rinne J (2021), "Field-scale CH_4 emission at a subarctic mire with heterogeneous permafrost thaw status", Biogeosciences. Vol. 18(20), pp. 5811-5830.
BibTeX:
@article{Lakomiec2021,
  author = {Łakomiec, P and Holst, J and Friborg, T and Crill, P and Rakos, N and Kljun, N and Olsson, P.-O. and Eklundh, L and Persson, A and Rinne, J},
  title = {Field-scale CH_4 emission at a subarctic mire with heterogeneous permafrost thaw status},
  journal = {Biogeosciences},
  year = {2021},
  volume = {18},
  number = {20},
  pages = {5811--5830},
  url = {https://bg.copernicus.org/articles/18/5811/2021/},
  doi = {10.5194/bg-18-5811-2021}
}
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&apos;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&thinsp;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&thinsp;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&thinsp;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$$textless/spantextgreatergC-textlessspan classCombining double low line"inline-formula"textgreaterCO2textless/spantextgreater&thinsp;gdwtextlessspan classCombining double low line"inline-formula"textgreater-1textless/spantextgreater&thinsp;dtextlessspan classCombining double low line"inline-formula"textgreater-1textless/spantextgreater) and C content (%C of dry weight) in the samples, but we show that relationships are consistent when using textlessspan classCombining double low line"inline-formula"textgreaterC ĝ• Ntextless/spantextgreaterratios or different production units such as textlessspan classCombining double low line"inline-formula"textgreater$$textless/spantextgreatergC per gram soil C per day (textlessspan classCombining double low line"inline-formula"textgreater$$textless/spantextgreatergC-textlessspan classCombining double low line"inline-formula"textgreaterCO2textless/spantextgreater&thinsp;gCtextlessspan classCombining double low line"inline-formula"textgreater-1textless/spantextgreater&thinsp;dtextlessspan classCombining double low line"inline-formula"textgreater-1textless/spantextgreater) or per&thinsp;cmtextlessspan classCombining double low line"inline-formula"textgreater3textless/spantextgreaterof soil per day (textlessspan classCombining double low line"inline-formula"textgreater$$textless/spantextgreatergC-textlessspan classCombining double low line"inline-formula"textgreaterCO2textless/spantextgreater&thinsp;cmtextlessspan classCombining double low line"inline-formula"textgreater-3textless/spantextgreater&thinsp;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&thinsp;% 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&lt;sub&gt;2&lt;/sub&gt; 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&lt;sub&gt;2&lt;/sub&gt; 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, futur