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1. Plant traits and associated data from a warming experiment, a seabird colony, and along elevation in Svalbard

Author: Vigdis Vandvik, Aud H. Halbritter, Inge H. J. Althuizen, Casper T. Christiansen, Jonathan J. Henn, Ingibjörg Svala Jónsdóttir, Kari Klanderud, Marc Macias-Fauria, Yadvinder Malhi, Brian Salvin Maitner, Sean Michaletz, Ruben E. Roos, Richard J. Telford, Polly Bass, Katrín Björnsdóttir, Lucely Lucero Vilca Bustamante, Adam Chmurzynski, Shuli Chen, Siri Vatsø Haugum, Julia Kemppinen, Kai Lepley, Yaoqi Li, Mary Linabury, Ilaíne Silveira Matos, Barbara M. Neto-Bradley, Molly Ng, Pekka Niittynen, Silje Östman, Karolína Pánková, Nina Roth, Matiss Castorena, Marcus Spiegel, Eleanor Thomson, Alexander Sæle Vågenes, and Brian J. Enquist
Subjects: Science
Abstract: Abstract The Arctic is warming at a rate four times the global average, while also being exposed to other global environmental changes, resulting in widespread vegetation and ecosystem change. Integrating functional trait-based approaches with multi-level vegetation, ecosystem, and landscape data enables a holistic understanding of the drivers and consequences of these changes. In two High Arctic study systems near Longyearbyen, Svalbard, a 20-year ITEX warming experiment and elevational gradients with and without nutrient input from nesting seabirds, we collected data on vegetation composition and structure, plant functional traits, ecosystem fluxes, multispectral remote sensing, and microclimate. The dataset contains 1,962 plant records and 16,160 trait measurements from 34 vascular plant taxa, for 9 of which these are the first published trait data. By integrating these comprehensive data, we bridge knowledge gaps and expand trait data coverage, including on intraspecific trait variation. These data can offer insights into ecosystem functioning and provide baselines to assess climate and environmental change impacts. Such knowledge is crucial for effective conservation and management in these vulnerable regions.
Published: 2023
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2. Disaggregating the Carbon Exchange of Degrading Permafrost Peatlands Using Bayesian Deep Learning

Author: Norbert Pirk, Kristoffer Aalstad, Erik Schytt Mannerfelt, François Clayer, Heleen deWit, Casper T. Christiansen, Inge Althuizen, Hanna Lee, and Sebastian Westermann
Subjects: carbon fluxes, permafrost degradation, Bayesian neural networks, Geophysics. Cosmic physics, QC801-809
Abstract: Abstract Extensive regions in the permafrost zone are projected to become climatically unsuitable to sustain permafrost peatlands over the next century, suggesting transformations in these landscapes that can leave large amounts of permafrost carbon vulnerable to post‐thaw decomposition. We present 3 years of eddy covariance measurements of CH4 and CO2 fluxes from the degrading permafrost peatland Iškoras in Northern Norway, which we disaggregate into separate fluxes of palsa, pond, and fen areas using information provided by the dynamic flux footprint in a novel ensemble‐based Bayesian deep neural network framework. The 3‐year mean CO2‐equivalent flux is estimated to be 106 gCO2 m−2 yr−1 for palsas, 1,780 gCO2 m−2 yr−1 for ponds, and −31 gCO2 m−2 yr−1 for fens, indicating that possible palsa degradation to thermokarst ponds would strengthen the local greenhouse gas forcing by a factor of about 17, while transformation into fens would slightly reduce the current local greenhouse gas forcing.
Published: 2024
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3. Winters are changing: snow effects on Arctic and alpine tundra ecosystems1

Author: Christian Rixen, Toke Thomas Høye, Petr Macek, Rien Aerts, Juha M. Alatalo, Jill T. Anderson, Pieter A. Arnold, Isabel C Barrio, Jarle W. Bjerke, Mats P. Björkman, Daan Blok, Gesche Blume-Werry, Julia Boike, Stef Bokhorst, Michele Carbognani, Casper T. Christiansen, Peter Convey, Elisabeth J. Cooper, J. Hans C. Cornelissen, Stephen J. Coulson, Ellen Dorrepaal, Bo Elberling, Sarah C. Elmendorf, Cassandra Elphinstone, T’ai G.W. Forte, Esther R. Frei, Sonya R. Geange, Friederike Gehrmann, Casey Gibson, Paul Grogan, Aud Helen Halbritter, John Harte, Gregory H.R. Henry, David W. Inouye, Rebecca E. Irwin, Gus Jespersen, Ingibjörg Svala Jónsdóttir, Ji Young Jung, David H. Klinges, Gaku Kudo, Juho Lämsä, Hanna Lee, Jonas J. Lembrechts, Signe Lett, Joshua Scott Lynn, Hjalte M.R. Mann, Mikhail Mastepanov, Jennifer Morse, Isla H. Myers-Smith, Johan Olofsson, Riku Paavola, Alessandro Petraglia, Gareth K. Phoenix, Philipp Semenchuk, Matthias B. Siewert, Rachel Slatyer, Marko J. Spasojevic, Katharine Suding, Patrick Sullivan, Kimberly L. Thompson, Maria Väisänen, Vigdis Vandvik, Susanna Venn, Josefine Walz, Robert Way, Jeffrey M. Welker, Sonja Wipf, and Shengwei Zong
Subjects: review, tundra, ground temperatures, snow experiments, ITEX, synthèse, Environmental sciences, GE1-350, Environmental engineering, TA170-171
Abstract: Snow is an important driver of ecosystem processes in cold biomes. Snow accumulation determines ground temperature, light conditions, and moisture availability during winter. It also affects the growing season’s start and end, and plant access to moisture and nutrients. Here, we review the current knowledge of the snow cover’s role for vegetation, plant-animal interactions, permafrost conditions, microbial processes, and biogeochemical cycling. We also compare studies of natural snow gradients with snow experimental manipulation studies to assess time scale difference of these approaches. The number of tundra snow studies has increased considerably in recent years, yet we still lack a comprehensive overview of how altered snow conditions will affect these ecosystems. Specifically, we found a mismatch in the timing of snowmelt when comparing studies of natural snow gradients with snow manipulations. We found that snowmelt timing achieved by snow addition and snow removal manipulations (average 7.9 days advance and 5.5 days delay, respectively) were substantially lower than the temporal variation over natural spatial gradients within a given year (mean range 56 days) or among years (mean range 32 days). Differences between snow study approaches need to be accounted for when projecting snow dynamics and their impact on ecosystems in future climates.
Published: 2022
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4. Can bryophyte groups increase functional resolution in tundra ecosystems?1

Author: Signe Lett, Ingibjörg S. Jónsdóttir, Antoine Becker-Scarpitta, Casper T. Christiansen, Heinjo During, Flemming Ekelund, Gregory H.R. Henry, Simone I. Lang, Anders Michelsen, Kathrin Rousk, Juha M. Alatalo, Katlyn R. Betway, Sara B. Rui, Terry Callaghan, Michele Carbognani, Elisabeth J. Cooper, J. Hans C. Cornelissen, Ellen Dorrepaal, Dagmar Egelkraut, Tatiana G. Elumeeva, Siri V. Haugum, Robert D. Hollister, Annika K. Jägerbrand, Frida Keuper, Kari Klanderud, Esther Lévesque, Xin Liu, Jeremy May, Pascale Michel, Martin Mörsdorf, Alessandro Petraglia, Christian Rixen, Bjorn J.M. Robroek, Agnieszka M. Rzepczynska, Nadejda A. Soudzilovskaia, Anne Tolvanen, Vigdis Vandvik, Igor Volkov, Irina Volkova, and Kristel van Zuijlen
Subjects: mosses, Arctic–Alpine, environmental change, functional traits, water holding capacity, mousses, Environmental sciences, GE1-350, Environmental engineering, TA170-171
Abstract: The relative contribution of bryophytes to plant diversity, primary productivity, and ecosystem functioning increases towards colder climates. Bryophytes respond to environmental changes at the species level, but because bryophyte species are relatively difficult to identify, they are often lumped into one functional group. Consequently, bryophyte function remains poorly resolved. Here, we explore how higher resolution of bryophyte functional diversity can be encouraged and implemented in tundra ecological studies. We briefly review previous bryophyte functional classifications and the roles of bryophytes in tundra ecosystems and their susceptibility to environmental change. Based on shoot morphology and colony organization, we then propose twelve easily distinguishable bryophyte functional groups. To illustrate how bryophyte functional groups can help elucidate variation in bryophyte effects and responses, we compiled existing data on water holding capacity, a key bryophyte trait. Although plant functional groups can mask potentially high interspecific and intraspecific variability, we found better separation of bryophyte functional group means compared with previous grouping systems regarding water holding capacity. This suggests that our bryophyte functional groups truly represent variation in the functional roles of bryophytes in tundra ecosystems. Lastly, we provide recommendations to improve the monitoring of bryophyte community changes in tundra study sites.
Published: 2022
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5. Effects of Climate and Atmospheric Nitrogen Deposition on Early to Mid-Term Stage Litter Decomposition Across Biomes

Author: TaeOh Kwon, Hideaki Shibata, Sebastian Kepfer-Rojas, Inger K. Schmidt, Klaus S. Larsen, Claus Beier, Björn Berg, Kris Verheyen, Jean-Francois Lamarque, Frank Hagedorn, Nico Eisenhauer, Ika Djukic, TeaComposition Network, Inger Kappel Schmidt, Klaus Steenberg Larsen, Jean Francois Lamarque, Adriano Caliman, Alain Paquette, Alba Gutiérrez-Girón, Alessandro Petraglia, Algirdas Augustaitis, Amélie Saillard, Ana Carolina Ruiz-Fernández, Ana I. Sousa, Ana I. Lillebø, Anderson da Rocha Gripp, Andrea Lamprecht, Andreas Bohner, André-Jean Francez, Andrey Malyshev, Andrijana Andrić, Angela Stanisci, Anita Zolles, Anna Avila, Anna-Maria Virkkala, Anne Probst, Annie Ouin, Anzar A. Khuroo, Arne Verstraeten, Artur Stefanski, Aurora Gaxiola, Bart Muys, Beatriz Gozalo, Bernd Ahrends, Bo Yang, Brigitta Erschbamer, Carmen Eugenia Rodríguez Ortíz, Casper T. Christiansen, Céline Meredieu, Cendrine Mony, Charles Nock, Chiao-Ping Wang, Christel Baum, Christian Rixen, Christine Delire, Christophe Piscart, Christopher Andrews, Corinna Rebmann, Cristina Branquinho, Dick Jan, Dirk Wundram, Dušanka Vujanović, E. Carol Adair, Eduardo Ordóñez-Regil, Edward R. Crawford, Elena F. Tropina, Elisabeth Hornung, Elli Groner, Eric Lucot, Esperança Gacia, Esther Lévesque, Evanilde Benedito, Evgeny A. Davydov, Fábio Padilha Bolzan, Fernando T. Maestre, Florence Maunoury-Danger, Florian Kitz, Florian Hofhansl, Flurin Sutter, Francisco de Almeida Lobo, Franco Leadro Souza, Franz Zehetner, Fulgence Kouamé Koffi, Georg Wohlfahrt, Giacomo Certini, Gisele Daiane Pinha, Grizelle González, Guylaine Canut, Harald Pauli, Héctor A. Bahamonde, Heike Feldhaar, Heinke Jäger, Helena Cristina Serrano, Hélène Verheyden, Helge Bruelheide, Henning Meesenburg, Hermann Jungkunst, Hervé Jactel, Hiroko Kurokawa, Ian Yesilonis, Inara Melece, Inge van Halder, Inmaculada García Quirós, István Fekete, Ivika Ostonen, Jana Borovská, Javier Roales, Jawad Hasan Shoqeir, Jean-Christophe Lata, Jean-Luc Probst, Jeyanny Vijayanathan, Jiri Dolezal, Joan-Albert Sanchez-Cabeza, Joël Merlet, John Loehr, Jonathan von Oppen, Jörg Löffler, José Luis Benito Alonso, José-Gilberto Cardoso-Mohedano, Josep Peñuelas, Joseph C. Morina, Juan Darío Quinde, Juan J. Jiménez, Juha M. Alatalo, Julia Seeber, Julia Kemppinen, Jutta Stadler, Kaie Kriiska, Karel Van den Meersche, Karibu Fukuzawa, Katalin Szlavecz, Katalin Juhos, Katarína Gerhátová, Kate Lajtha, Katie Jennings, Katja Tielbörger, Kazuhiko Hoshizaki, Ken Green, Klaus Steinbauer, Laryssa Pazianoto, Laura Dienstbach, Laura Yahdjian, Laura J. Williams, Laurel Brigham, Lee Hanna, Liesbeth van den Brink, Lindsey Rustad, Lourdes Morillas, Luciana Silva Carneiro, Luciano Di Martino, Luis Villar, Luísa Alícida Fernandes Tavares, Madison Morley, Manuela Winkler, Marc Lebouvier, Marcello Tomaselli, Marcus Schaub, Maria Glushkova, Maria Guadalupe Almazan Torres, Marie-Anne de Graaff, Marie-Noëlle Pons, Marijn Bauters, Marina Mazón, Mark Frenzel, Markus Wagner, Markus Didion, Maroof Hamid, Marta Lopes, Martha Apple, Martin Weih, Matej Mojses, Matteo Gualmini, Matthew Vadeboncoeur, Michael Bierbaumer, Michael Danger, Michael Scherer-Lorenzen, Michal Růžek, Michel Isabellon, Michele Di Musciano, Michele Carbognani, Miglena Zhiyanski, Mihai Puşcaş, Milan Barna, Mioko Ataka, Miska Luoto, Mohammed H. Alsafaran, Nadia Barsoum, Naoko Tokuchi, Nathalie Korboulewsky, Nicolas Lecomte, Nina Filippova, Norbert Hölzel, Olga Ferlian, Oscar Romero, Osvaldo Pinto-Jr, Pablo Peri, Pavel Dan Turtureanu, Peter Haase, Peter Macreadie, Peter B. Reich, Petr Petřík, Philippe Choler, Pierre Marmonier, Quentin Ponette, Rafael Dettogni Guariento, Rafaella Canessa, Ralf Kiese, Rebecca Hewitt, Robert Weigel, Róbert Kanka, Roberto Cazzolla Gatti, Rodrigo Lemes Martins, Romà Ogaya, Romain Georges, Rosario G. Gavilán, Sally Wittlinger, Sara Puijalon, Satoshi Suzuki, Schädler Martin, Schmidt Anja, Sébastien Gogo, Silvio Schueler, Simon Drollinger, Simone Mereu, Sonja Wipf, Stacey Trevathan-Tackett, Stefan Stoll, Stefan Löfgren, Stefan Trogisch, Steffen Seitz, Stephan Glatzel, Susanna Venn, Sylvie Dousset, Taiki Mori, Takanori Sato, Takuo Hishi, Tatsuro Nakaji, Theurillat Jean-Paul, Thierry Camboulive, Thomas Spiegelberger, Thomas Scholten, Thomas J. Mozdzer, Till Kleinebecker, Tomáš Rusňák, Tshililo Ramaswiela, Tsutom Hiura, Tsutomu Enoki, Tudor-Mihai Ursu, Umberto Morra di Cella, Ute Hamer, Valentin Klaus, Valter Di Cecco, Vanessa Rego, Veronika Fontana, Veronika Piscová, Vincent Bretagnolle, Vincent Maire, Vinicius Farjalla, Vittoz Pascal, Wenjun Zhou, Wentao Luo, William Parker, Yasuhiro Utsumi, Yuji Kominami, Zsolt Kotroczó, and Zsolt Tóth
Subjects: tea bag, Green tea, Rooibos tea, litter decomposition, carbon turnover, nitrogen deposition, Forestry, SD1-669.5, Environmental sciences, GE1-350
Abstract: Litter decomposition is a key process for carbon and nutrient cycling in terrestrial ecosystems and is mainly controlled by environmental conditions, substrate quantity and quality as well as microbial community abundance and composition. In particular, the effects of climate and atmospheric nitrogen (N) deposition on litter decomposition and its temporal dynamics are of significant importance, since their effects might change over the course of the decomposition process. Within the TeaComposition initiative, we incubated Green and Rooibos teas at 524 sites across nine biomes. We assessed how macroclimate and atmospheric inorganic N deposition under current and predicted scenarios (RCP 2.6, RCP 8.5) might affect litter mass loss measured after 3 and 12 months. Our study shows that the early to mid-term mass loss at the global scale was affected predominantly by litter quality (explaining 73% and 62% of the total variance after 3 and 12 months, respectively) followed by climate and N deposition. The effects of climate were not litter-specific and became increasingly significant as decomposition progressed, with MAP explaining 2% and MAT 4% of the variation after 12 months of incubation. The effect of N deposition was litter-specific, and significant only for 12-month decomposition of Rooibos tea at the global scale. However, in the temperate biome where atmospheric N deposition rates are relatively high, the 12-month mass loss of Green and Rooibos teas decreased significantly with increasing N deposition, explaining 9.5% and 1.1% of the variance, respectively. The expected changes in macroclimate and N deposition at the global scale by the end of this century are estimated to increase the 12-month mass loss of easily decomposable litter by 1.1–3.5% and of the more stable substrates by 3.8–10.6%, relative to current mass loss. In contrast, expected changes in atmospheric N deposition will decrease the mid-term mass loss of high-quality litter by 1.4–2.2% and that of low-quality litter by 0.9–1.5% in the temperate biome. Our results suggest that projected increases in N deposition may have the capacity to dampen the climate-driven increases in litter decomposition depending on the biome and decomposition stage of substrate.
Published: 2021
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6. The Effect of Freeze-Thaw Conditions on Arctic Soil Bacterial Communities

Author: Virginia K. Walker, Casper T. Christiansen, Haiyan Chu, Niraj Kumar, and Paul Grogan
Subjects: climate change, arctic soils, freeze-thaw, phylogenetic composition, fatty acids, bacteria, chaos theory, Biology (General), QH301-705.5
Abstract: Climate change is already altering the landscape at high latitudes. Permafrost is thawing, the growing season is starting earlier, and, as a result, certain regions in the Arctic may be subjected to an increased incidence of freeze-thaw events. The potential release of carbon and nutrients from soil microbial cells that have been lysed by freeze-thaw transitions could have significant impacts on the overall carbon balance of arctic ecosystems, and therefore on atmospheric CO2 concentrations. However, the impact of repeated freezing and thawing with the consequent growth and recrystallization of ice on microbial communities is still not well understood. Soil samples from three distinct sites, representing Canadian geographical low arctic, mid-arctic and high arctic soils were collected from Daring Lake, Alexandra Fjord and Cambridge Bay sampling sites, respectively. Laboratory-based experiments subjected the soils to multiple freeze-thaw cycles for 14 days based on field observations (0 °C to −10 °C for 12 h and −10 °C to 0 °C for 12 h) and the impact on the communities was assessed by phospholipid fatty acid (PLFA) methyl ester analysis and 16S ribosomal RNA gene sequencing. Both data sets indicated differences in composition and relative abundance between the three sites, as expected. However, there was also a strong variation within the two high latitude sites in the effects of the freeze-thaw treatment on individual PLFA and 16S-based phylotypes. These site-based heterogeneities suggest that the impact of climate change on soil microbial communities may not be predictable a priori; minor differential susceptibilities to freeze-thaw stress could lead to a “butterfly effect” as described by chaos theory, resulting in subsequent substantive differences in microbial assemblages. This perspectives article suggests that this is an unwelcome finding since it will make future predictions for the impact of on-going climate change on soil microbial communities in arctic regions all but impossible.
Published: 2013
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7. Litter quality outweighs climate as a driver of decomposition across the tundra biome

Author: Haydn Thomas, Isla Myers-Smith, Toke Høye, Matteo Petit Bon, Jonas Lembrechts, Eleanor Walker, Katrin Björnsdóttir, Isabel Barrio, Ingibjörg Svala Jónsdóttir, Susanna Venn, Juha Alatalo, Jennifer Baltzer, Cory Wallace, Daniel Ackerman, Laura Gough, Janet Prevéy, Christian Rixen, Michele Carbognani, Alessandro Petraglia, Casper T. Christiansen, David Inouye, Jane Ogilvie, Mario Trouillier, Martin Wilmking, Rachel Treharne, Sandra Angers-Blondin, Christine Urbanowicz, Jonathan von Oppen, Sonja Wipf, Paul A. Smith, Satoshi N. Suzuki, Ryo Suzuki, Anna-Maria Virkkala, Miska Luoto, Svetlana Serikova, Anne Bjorkman, Daan Blok, Elise Gallois, and Judith Sarneel
Abstract: Considerable uncertainty exists regarding the strength, direction and relative importance of the drivers of decomposition in the tundra biome, partly due to a lack of coordinated decomposition field studies in this remote environment. Here, we analysed 3717 incubations of two uniform litter types, green and rooibos tea, buried at 330 circum-Arctic and alpine sites to quantify the effects of temperature, moisture and litter quality on decomposition. We found a surprisingly linear positive relationship between decomposition and soil temperature across all sites, counter to theory and previous model estimates. Litter mass loss was greater at wetter sites, even where soils reached almost full water saturation. However, litter quality was the strongest driver of litter mass loss across the tundra biome, explaining six times more variation in summer decomposition than soil temperature. Our results indicate that climate warming will directly increase decomposition across tundra environments. However, the indirect effects of climate change on vegetation communities, and thus plant litter inputs and quality, could have a more profound impact than direct effects on the balance of this globally important carbon store.
Published: 2023
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8. Intraspecific trait variability is a key feature underlying high Arctic plant community resistance to climate warming

Author: Ingibjörg S. Jónsdóttir, Aud H. Halbritter, Casper T. Christiansen, Inge H. J. Althuizen, Siri V. Haugum, Jonathan J. Henn, Katrín Björnsdóttir, Brian Salvin Maitner, Yadvinder Malhi, Sean T. Michaletz, Ruben E. Roos, Kari Klanderud, Hanna Lee, Brian J. Enquist, and Vigdis Vandvik
Subjects: plant community change, Svalbard, climate change, plant functional traits, community resilience, CO fluxes, intraspecific trait variation, community resistance, experimental warming, Ecology, Evolution, Behavior and Systematics
Abstract: In the high Arctic, plant community species composition generally responds slowly to climate warming, whereas less is known about the community functional trait responses and consequences for ecosystem functioning. Slow species turnover and large distribution ranges of many Arctic plant species suggest a significant role of intraspecific trait variability in functional responses to climate change. Here, we compare taxonomic and functional community compositional responses to a long-term (17 years) warming experiment in Svalbard, replicated across three major high Arctic habitats shaped by topography and contrasting snow regimes. We observed taxonomic compositional changes in all plant communities over time. Still, responses to experimental warming were minor and most pronounced in the drier habitats with relatively early snowmelt timing and long growing seasons (Cassiope and Dryas heaths). The habitats were clearly separated in functional trait space, defined by twelve size- and leaf economics-related traits, primarily due to interspecific trait variation. Functional traits also responded to experimental warming, most prominently in the Dryas heath and mostly due to intraspecific trait variation. Leaf area and leaf mass increased, and leaf δ15N decreased in response to the warming treatment. Intraspecific trait variability ranged between 30% and 71% of the total trait variation, reflecting functional resilience of those communities, dominated by long-lived plants, due to either phenotypic plasticity or genotypic variation that most likely underlies the observed resistance of high Arctic vegetation to climate warming. We further explored the consequences of trait variability for ecosystem functioning by measuring peak season CO2 fluxes. Together, environmental, taxonomic, and functional trait variables explained a large proportion of the variation in net ecosystem exchange (NEE), which increased when intraspecific trait variation was accounted for. In contrast, even though ecosystem respiration and gross ecosystem production both increased in response to warming across habitats, they were mainly driven by the direct kinetic impacts of temperature on plant physiology and biochemical processes. Our study shows that long-term experimental warming has a modest but significant effect on plant community functional trait composition and suggests that intraspecific trait variability is a key feature underlying high Arctic ecosystem resistance to climate warming.
Published: 2022
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9. Canadian permafrost stores large pools of ammonium and optically distinct dissolved organic matter

Author: Scott F. Lamoureux, Casper T. Christiansen, Julien Fouché, Melissa J. Lafrenière, Paul Grogan, Laboratoire d'étude des Interactions Sol - Agrosystème - Hydrosystème (UMR LISAH), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut de Recherche pour le Développement (IRD)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro), Queen's University [Kingston, Canada], Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management [Copenhagen] (IGN), Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU)-Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU), This research was funded by the Natural Sciences and Engineering Research Council (NSERC) Discovery Frontiers ADAPT program, the ArcticNet Network of Centres of Excellence, and NSERC Discovery grants to, Institut de Recherche pour le Développement (IRD)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut Agro - Montpellier SupAgro, Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH)-Faculty of Science [Copenhagen], and University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH)
Subjects: Cryospheric science, 010504 meteorology & atmospheric sciences, [SDV]Life Sciences [q-bio], Science, General Physics and Astronomy, 010501 environmental sciences, [SDV.SA.SDS]Life Sciences [q-bio]/Agricultural sciences/Soil study, Permafrost, 01 natural sciences, Article, General Biochemistry, Genetics and Molecular Biology, Carbon cycle, Dissolved organic carbon, chemical composition, Organic matter, lcsh:Science, 0105 earth and related environmental sciences, watershed, chemistry.chemical_classification, Multidisciplinary, Soil organic matter, General Chemistry, 15. Life on land, dissolved organic matter, dissolved organic carbon, Active layer, ammonium, chemistry, Arctic, 13. Climate action, Environmental chemistry, Soil water, Environmental science, lcsh:Q, permafrost
Abstract: Permafrost degradation may lead to mobilization of carbon and nutrients and enhance microbial processing rates of previously frozen organic matter. Although the pool size and chemical composition of dissolved organic matter (DOM) are fundamental determinants of the carbon cycle in Arctic watersheds, its source within the seasonally thawing active layer and the underlying permafrost remains largely uncharacterized. Here, we used 25 soil cores that extended down into the permafrost from nine sites across Arctic Canada to quantify dissolved organic carbon (DOC) and nitrogen stocks, and to characterize DOM optical properties. Organic permafrost stores 5–7 times more DOC and ammonium than the active layer and mineral permafrost. Furthermore, the permafrost layers contain substantial low molecular weight DOM with low aromaticity suggesting high biodegradability. We conclude that soil organic matter stoichiometry and cryogenic processes determine permafrost DOM chemistry, and that thawing will mobilize large amounts of labile DOC and ammonium into Arctic watersheds., Arctic warming leads to permafrost thaw and release of previously frozen organic matter and nutrients, but characterization of these pools is lacking. Here the authors use soil cores across Northern Canada to investigate dissolved organic matter and nitrogen stored in permafrost soils.
Published: 2020
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10. Author Correction: Large loss of CO2 in winter observed across the northern permafrost region

Author: Susan M. Natali, Jennifer D. Watts, Brendan M. Rogers, Stefano Potter, Sarah M. Ludwig, Anne-Katrin Selbmann, Patrick F. Sullivan, Benjamin W. Abbott, Kyle A. Arndt, Leah Birch, Mats P. Björkman, A. Anthony Bloom, Gerardo Celis, Torben R. Christensen, Casper T. Christiansen, Roisin Commane, Elisabeth J. Cooper, Patrick Crill, Claudia Czimczik, Sergey Davydov, Jinyang Du, Jocelyn E. Egan, Bo Elberling, Eugenie S. Euskirchen, Thomas Friborg, Hélène Genet, Mathias Göckede, Jordan P. Goodrich, Paul Grogan, Manuel Helbig, Elchin E. Jafarov, Julie D. Jastrow, Aram A. M. Kalhori, Yongwon Kim, John S. Kimball, Lars Kutzbach, Mark J. Lara, Klaus S. Larsen, Bang-Yong Lee, Zhihua Liu, Michael M. Loranty, Magnus Lund, Massimo Lupascu, Nima Madani, Avni Malhotra, Roser Matamala, Jack McFarland, A. David McGuire, Anders Michelsen, Christina Minions, Walter C. Oechel, David Olefeldt, Frans-Jan W. Parmentier, Norbert Pirk, Ben Poulter, William Quinton, Fereidoun Rezanezhad, David Risk, Torsten Sachs, Kevin Schaefer, Niels M. Schmidt, Edward A. G. Schuur, Philipp R. Semenchuk, Gaius Shaver, Oliver Sonnentag, Gregory Starr, Claire C. Treat, Mark P. Waldrop, Yihui Wang, Jeffrey Welker, Christian Wille, Xiaofeng Xu, Zhen Zhang, Qianlai Zhuang, and Donatella Zona
Published: 2019
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11. Volatile organic compound release across a permafrost-affected peatland

Author: Yi Jiao, Cleo L. Davie-Martin, Magnus Kramshøj, Casper T. Christiansen, Hanna Lee, Inge H.J. Althuizen, and Riikka Rinnan
Subjects: Arctic, Permafrost thaw, Palsa, Peatland, Climate change, VOCs, Soil Science
Abstract: As the permafrost region experiences unprecedented climate warming, accelerated decomposition rates are potentially switching these cold landscapes to a hotspot of carbon emissions. In addition to the more widely studied greenhouse gases, carbon dioxide and methane, permafrost-affected soils may also be a source of volatile organic compounds (VOCs), but these reactive trace gases have so far received little attention. Nevertheless, VOCs can i) prolong the lifetime of atmospheric methane, ii) contribute to hazardous ozone production, and iii) lead to the formation of secondary organic aerosols. Consequently, changing VOC emissions may exert significant impacts on climate forcing factors that can both exacerbate or mitigate future climate change. Here, we conducted in situ measurements of soil and pond VOC emissions across an actively degrading permafrost-affected peatland in subarctic Norway. We used a permafrost thaw gradient as a space-for-time substitute that covered bare soil and vegetated peat plateaus, underlain by intact permafrost, and increasingly degraded permafrost landscapes: thaw slumps, thaw ponds, and vegetated thaw ponds. Results showed that every peatland landscape type was an important source of atmospheric VOCs, emitting a large variety of compounds, such as methanol, acetone, monoterpenes, sesquiterpenes, isoprene, hydrocarbons, and oxygenated VOCs. VOC composition varied considerably across the measurement period and across the permafrost thaw gradient. We observed enhanced terpenoid emissions following thaw slump degradation, highlighting the potential atmospheric impacts of permafrost thaw, due to the high chemical reactivities of terpenoid compounds. Higher VOC emission rates were observed in summer (June, July and August) compared to early autumn (September). Overall, our study demonstrates that VOCs are being emitted in significant quantities and with largely similar compositions upon permafrost thawing, inundation, and subsequent vegetation development, despite major differences in microclimate, hydrological regime, vegetation, and permafrost occurrence. As the permafrost region experiences unprecedented climate warming, accelerated decomposition rates are potentially switching these cold landscapes to a hotspot of carbon emissions. In addition to the more widely studied greenhouse gases, carbon dioxide and methane, permafrost-affected soils may also be a source of volatile organic compounds (VOCs), but these reactive trace gases have so far received little attention. Nevertheless, VOCs can i) prolong the lifetime of atmospheric methane, ii) contribute to hazardous ozone production, and iii) lead to the formation of secondary organic aerosols. Consequently, changing VOC emissions may exert significant impacts on climate forcing factors that can both exacerbate or mitigate future climate change. Here, we conducted in situ measurements of soil and pond VOC emissions across an actively degrading permafrost-affected peatland in subarctic Norway. We used a permafrost thaw gradient as a space-for-time substitute that covered bare soil and vegetated peat plateaus, underlain by intact permafrost, and increasingly degraded permafrost landscapes: thaw slumps, thaw ponds, and vegetated thaw ponds. Results showed that every peatland landscape type was an important source of atmospheric VOCs, emitting a large variety of compounds, such as methanol, acetone, monoterpenes, sesquiterpenes, isoprene, hydrocarbons, and oxygenated VOCs. VOC composition varied considerably across the measurement period and across the permafrost thaw gradient. We observed enhanced terpenoid emissions following thaw slump degradation, highlighting the potential atmospheric impacts of permafrost thaw, due to the high chemical reactivities of terpenoid compounds. Higher VOC emission rates were observed in summer (June, July and August) compared to early autumn (September). Overall, our study demonstrates that VOCs are being emitted in significant quantities and with largely similar compositions upon permafrost thawing, inundation, and subsequent vegetation development, despite major differences in microclimate, hydrological regime, vegetation, and permafrost occurrence.
Published: 2023
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12. Explicitly modelling microtopography in permafrost landscapes in a land-surface model (JULES vn5.4_microtopography)

Author: Hanna Lee, Eleanor J. Burke, Casper T. Christiansen, Heather Rumbold, Noah Smith, Inge H. J. Althuizen, Kjetil Schanke Aas, Julia Boike, Sarah Chadburn, Bernd Etzelmüller, Thomas Friborg, Sebastian Westermann, and Rachael Turton
Subjects: Water flow, Mire, Snowmelt, Environmental science, Soil science, Palsa, Permafrost, Snow, Surface runoff, Water content
Abstract: Microtopography can be a key driver of heterogeneity in the ground thermal and hydrological regime of permafrost landscapes. In turn, this heterogeneity can influence plant communities, methane fluxes and the initiation of abrupt thaw processes. Here we have implemented a two-tile representation of microtopography in JULES (the Joint UK Land Environment Simulator), where tiles are representative of repeating patterns of elevation difference. We evaluate the model against available spatially resolved observations at four sites, gauge the importance of explicitly representing microtopography for modelling methane emissions and quantify the relative importance of model processes and the model’s sensitivity its parameters. Tiles are coupled by lateral flows of water, heat and redistribution of snow. A surface water store is added to represent ponding. The model is parametrised using characteristic dimensions of landscape features at sites. Simulations are performed of two Siberian polygon sites, Samoylov and Kytalyk, and two Scandinavian palsa sites, Stordalen and Iškoras. The model represents the observed differences between greater snow depth in hollows vs raised areas well. The model also improves soil moisture for hollows vs the non-tiled configuration (‘standard JULES’) though the raised tile remains drier than observed. For the two palsa sites, it is found that drainage needs to be impeded from the lower tile, representing the non-permafrost mire, to achieve the observed soil saturation. This demonstrates the need for the landscape-scale drainage to be correctly modelled. Causes of moisture heterogeneity between tiles are decreased runoff from the low tile, differences in snowmelt, and high to low-tile water flow. Unsaturated flows between tiles are negligible, suggesting the adequacy of simpler water-table based models of lateral flow in wetland environments. The modelled differences in snow depths and soil moistures between tiles result in the lower tile soil temperatures being warmer for palsa sites. When comparing the soil temperatures for July at 20 cm depth, the difference in temperature between tiles, or ‘temperature splitting’, is smaller than observed (3.2 vs 5.5 °C). The mean temperature of the two tiles remains approximately unchanged (+0.4 °C) vs standard JULES, and lower than observations. Polygons display small (0.2 °C) to zero temperature splitting, in agreement with observations. Consequently, methane fluxes are near identical (+0 to 9 %) to those for standard JULES for polygons, though can be greater than standard JULES for palsa sites (+10 to 49 %). Through a sensitivity analysis we identify the parameters resulting in the greatest uncertainty in modelled temperature. We find that at the sites tested, varying the parameters can result in the modelled July temperature splitting being at most 0.9 or 3 °C larger than observed for palsa or polygon sites respectively. Varying the palsa elevation between 0.5 and 3 m has little effect on modelled soil temperatures, showing that having only two tiles can still be a valid representation of sites with a large variability of palsa elevations. Lateral conductive fluxes, while small, reduce the temperature splitting by ~1 °C, and correspond to the order of observed lateral degradation rates in peat plateau regions, indicating possible application in an area-based thaw model.
Published: 2021
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13. Abrupt thaw enhances annual global warming potential of an actively degrading permafrost peatland

Author: Sigrid Trier Kjær, Sebastian Westermann, Casper T. Christiansen, Anders Michelsen, Peter Dörsch, Inge H. J. Althuizen, Hanna Lee, and David Risk
Subjects: Peat, Environmental science, Physical geography, Permafrost, Global-warming potential
Abstract: Global scale warming has led to permafrost thaw, which may release large amounts of carbon to the atmosphere as CO2 and CH4, potentially accelerating global warming (i.e. a positive feedback). However, uncertainty in the mechanisms controlling carbon mineralization is compounded by concurrent changes in soil hydrology associated with permafrost thaw. Thawing permafrost can lead to surface water accumulation in some areas and seasonal or permanent soil drying in areas where permafrost thaw opens up new channels of water to penetrate into the groundwater system. The complexity of the hydrologic response to permafrost thaw increases the challenge in generating reliable estimates of the permafrost carbon climate feedback. Furthermore, limited observational data exist to i) quantify the effects of permafrost thaw on net tundra carbon budgets, particularly on an annual basis, and ii) as well as constrain the underlying processes governing carbon release under aerobic and anaerobic conditions.Here, we investigated how changes in local hydrology affects CO2 and CH4 release from permafrost soils by establishing a field gradient study in northern Norway (69ᵒ N), where recent abrupt degradation of permafrost created thaw ponds in palsa-mire ecosystems. The site exhibits a natural gradient of permafrost thaw, which also corresponds to a strong hydrological gradient (i.e. dry palsas with intact permafrost, seasonally inundated thaw slumps, and thaw ponds). Since 2017, we have used a range of manual and automated techniques to measure changes in vegetation, soil and water microclimate, biogeochemistry, and soil CO2 and CH4 concentrations and efflux across the permafrost thaw gradient.Our preliminary results show that abrupt permafrost thaw and landscape subsidence – both intermediate slumping and thaw pond formation – increase net annual carbon loss from this type of subarctic wetland. Permafrost thaw approximately doubles CO2 emissions from thaw slumps compared to vegetated or soil palsas. Furthermore, CH4 release greatly increased across the permafrost thaw gradient. While vegetated palsas were small sinks of atmospheric CH4 during the growing season, permafrost thaw slumping and pond formation led to a dramatic increase in CH4 efflux compared to bare palsas. In contrast, bare soil palsas on were the most important source of N2O. Soil profile CO2 and CH4 concentrations in thawed permafrost plots were overall highly enriched relative to palsa profiles, reflecting soil conditions with inundated pore space and low oxygen availability along the permafrost thaw gradient. We therefore conclude that abrupt thaw will increase annual carbon loss in subarctic palsa wetlands.
Published: 2021
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14. Shallow soils are warmer under trees and tall shrubs across Arctic and Boreal ecosystems

Author: Toke T. Høye, Benjamin M. Jones, Marguerite Mauritz, Kirsty Langley, Lydia J. S. Vaughn, Gesche Blume-Werry, Thomas A. Douglas, James A. Laundre, Gareth K. Phoenix, Anders Michelsen, Elyn Humphreys, Michael M. Loranty, Susan M. Natali, M. Torre Jorgenson, Alexander Kholodov, Sean M. P. Cahoon, Julia Boike, Gerald V. Frost, Laura Gough, Hiroki Iwata, Mathew Williams, E. Blanc-Betes, Eugénie S. Euskirchen, Benjamin W Abbot, Heather Kropp, Ken D. Tape, Jan Hjort, Jonathan A. O'Donnell, Jakob Abermann, Daan Blok, Masahito Ueyama, Oliver Sonnentag, Monique M. P. D. Heijmans, Bo Elberling, Inge Grünberg, Casper T. Christiansen, M. Goeckede, Amy L. Breen, Magnus Lund, V. G. Salmon, Bang-Yong Lee, Isla H. Myers-Smith, Howard E. Epstein, Adrian V. Rocha, A. Britta K. Sannel, Sharon L. Smith, Peter M. Lafleur, Yongwon Kim, Gabriela Schaepman-Strub, Steven D. Mamet, and David Olefeldt
Subjects: DYNAMICS, 010504 meteorology & atmospheric sciences, ACTIVE-LAYER, soil temperature, ved/biology.organism_classification_rank.species, Plant Ecology and Nature Conservation, HEAT, 010501 environmental sciences, Permafrost, Atmospheric sciences, 01 natural sciences, Shrub, NORTHERN ALASKA, Arctic, vegetation change, TEMPERATURES, boreal forest, Thaw depth, 0105 earth and related environmental sciences, General Environmental Science, CLIMATE-CHANGE, WIMEK, Renewable Energy, Sustainability and the Environment, ved/biology, Taiga, Public Health, Environmental and Occupational Health, Soil carbon, Vegetation, PERMAFROST THAW, EXPANSION, 15. Life on land, Tundra, 13. Climate action, SNOW, Environmental science, Plantenecologie en Natuurbeheer, VEGETATION, permafrost
Abstract: Soils are warming as air temperatures rise across the Arctic and Boreal region concurrent with the expansion of tall-statured shrubs and trees in the tundra. Changes in vegetation structure and function are expected to alter soil thermal regimes, thereby modifying climate feedbacks related to permafrost thaw and carbon cycling. However, current understanding of vegetation impacts on soil temperature is limited to local or regional scales and lacks the generality necessary to predict soil warming and permafrost stability on a pan-Arctic scale. Here we synthesize shallow soil and air temperature observations with broad spatial and temporal coverage collected across 106 sites representing nine different vegetation types in the permafrost region. We showed ecosystems with tall-statured shrubs and trees (>40 cm) have warmer shallow soils than those with short-statured tundra vegetation when normalized to a constant air temperature. In tree and tall shrub vegetation types, cooler temperatures in the warm season do not lead to cooler mean annual soil temperature indicating that ground thermal regimes in the cold-season rather than the warm-season are most critical for predicting soil warming in ecosystems underlain by permafrost. Our results suggest that the expansion of tall shrubs and trees into tundra regions can amplify shallow soil warming, and could increase the potential for increased seasonal thaw depth and increase soil carbon cycling rates and lead to increased carbon dioxide loss and further permafrost thaw.
Published: 2021
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15. Decomposition of Senesced Leaf Litter is Faster in Tall Compared to Low Birch Shrub Tundra

Author: Casper T. Christiansen, Michelle C. Mack, Jennie DeMarco, and Paul Grogan
Subjects: 010504 meteorology & atmospheric sciences, Ecology, biology, ved/biology, ved/biology.organism_classification_rank.species, 04 agricultural and veterinary sciences, Plant litter, Snow, biology.organism_classification, 01 natural sciences, Shrub, Groundcover, Tundra, Decomposer, Deciduous, Agronomy, 040103 agronomy & agriculture, 0401 agriculture, forestry, and fisheries, Environmental Chemistry, Environmental science, Betula neoalaskana, human activities, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences
Abstract: Many Low Arctic tundra regions are currently undergoing a vegetation shift towards increasing growth and groundcover of tall deciduous shrubs due to recent climate warming. Vegetation change directly affects ecosystem carbon balance, but it can also affect soil biogeochemical cycling through physical and biological feedback mechanisms. Recent studies indicate that enhanced snow accumulation around relatively tall shrubs has negligible physical effect on litter decomposition rates. However, these investigations were no more than 3 years, and therefore may be insufficient to detect differences in inherently slow biogeochemical processes. Here, we report a 5-year study near Daring Lake, Canada, comparing Betula neoalaskana foliar litter decay rates within unmanipulated and snowfenced low-stature birch (height: ~ 0.3 m) plots to test the physical effect of experimentally deepened snow, and within tall birch (height: ~ 0.8 m) plots to test the combined physical and biological effects, that is, deepened snow plus strong birch dominance. Having corrected for carbon gain by the colonizing decomposers, actual litter carbon loss increased by approximately 25% in the tall birch relative to both low birch sites. Decay of lignin-like acid unhydrolizable litter residues also accelerated in the tall birch site, and a similar but lower magnitude response in the snowfenced low birch site indicated that physical effects of deepened snow were at least partially responsible. In contrast, deepened snow alone did not affect litter carbon loss. Our findings suggest that a combination of greater litter inputs, altered soil microbial community, enhanced soil nutrient pools, and warmer winter soils together promote relatively fast decomposition of recalcitrant litter carbon in tall birch shrub environments.
Published: 2018
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16. Long-term deepened snow promotes tundra evergreen shrub growth and summertime ecosystem net CO2gain but reduces soil carbon and nutrient pools

Author: Paul Grogan, Gregory H. R. Henry, Casper T. Christiansen, and Melissa J. Lafrenière
Subjects: Global and Planetary Change, 010504 meteorology & atmospheric sciences, Ecology, ved/biology, Soil organic matter, ved/biology.organism_classification_rank.species, 04 agricultural and veterinary sciences, Soil carbon, 15. Life on land, Evergreen, Snow, 01 natural sciences, Shrub, Tundra, Agronomy, 13. Climate action, 040103 agronomy & agriculture, 0401 agriculture, forestry, and fisheries, Environmental Chemistry, Environmental science, Ecosystem respiration, Thaw depth, 0105 earth and related environmental sciences, General Environmental Science
Abstract: Arctic climate warming will be primarily during winter, resulting in increased snowfall in many regions. Previous tundra research on the impacts of deepened snow has generally been of short duration. Here, we report relatively long-term (7-9 years) effects of experimentally deepened snow on plant community structure, net ecosystem CO2 exchange (NEE), and soil biogeochemistry in Canadian Low Arctic mesic shrub tundra. The snowfence treatment enhanced snow depth from 0.3 to ~1 m, increasing winter soil temperatures by ~3°C, but with no effect on summer soil temperature, moisture, or thaw depth. Nevertheless, shoot biomass of the evergreen shrub Rhododendron subarcticum was near-doubled by the snowfences, leading to a 52% increase in aboveground vascular plant biomass. Additionally, summertime NEE rates, measured in collars containing similar plant biomass across treatments, were consistently reduced ~30% in the snowfenced plots due to decreased ecosystem respiration rather than increased gross photosynthesis. Phosphate in the organic soil layer (0-10 cm depth) and nitrate in the mineral soil layer (15-25 cm depth) were substantially reduced within the snowfences (47-70 and 43%-73% reductions, respectively, across sampling times). Finally, the snowfences tended (p = .08) to reduce mineral soil layer C% by 40%, but with considerable within- and among plot variation due to cryoturbation across the landscape. These results indicate that enhanced snow accumulation is likely to further increase dominance of R. subarcticum in its favored locations, and reduce summertime respiration and soil biogeochemical pools. Since evergreens are relatively slow growing and of low stature, their increased dominance may constrain vegetation-related feedbacks to climate change. We found no evidence that deepened snow promoted deciduous shrub growth in mesic tundra, and conclude that the relatively strong R. subarcticum response to snow accumulation may explain the extensive spatial variability in observed circumpolar patterns of evergreen and deciduous shrub growth over the past 30 years.
Published: 2018
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17. Examination of Soil Microbial Communities After Permafrost Thaw Subsequent to an Active Layer Detachment in the High Arctic

Author: Kristy Moniz, Casper T. Christiansen, Virginia K. Walker, Scott N. Montross, Daniel Lamhonwah, Cara N. Inglese, Scott F. Lamoureux, Paul Grogan, and Melissa J. Lafrenière
Subjects: 0301 basic medicine, Global and Planetary Change, Ecology, Permafrost, Active layer, 03 medical and health sciences, 030104 developmental biology, Microbial population biology, Arctic, Environmental chemistry, Dissolved organic carbon, Soil water, Environmental science, Ecosystem, Ecology, Evolution, Behavior and Systematics, Temperature gradient gel electrophoresis, Earth-Surface Processes
Abstract: Active layer detachments (ALDs) are permafrost disturbances associated with climate change and increased seasonal warming. Such perturbations result from thawing of the upper permafrost and downslope movement of the overlying thawed material, including the active layer. ALDs have the potential to impact soil microbial community composition and function in arctic soil ecosystems. Here we report an initial investigation of an ALD located at Cape Bounty on Melville Island in the Canadian High Arctic. We examined soil nutrient content as well as microbial community structure using denaturing gradient gel electrophoresis and sequencing. Soil from the disturbed site showed changes in microbial communities with strikingly different fungal community composition compared to soils from an adjacent undisturbed site. These community changes were correlated with enhanced levels of dissolved organic carbon, microbial carbon, total dissolved nitrogen, and microbial nitrogen. The Nitrososphaerales—an order of am...
Published: 2017
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18. Large loss of CO2 in winter observed across the northern permafrost region

Author: Gerardo Celis, Jack W. McFarland, David Olefeldt, Mathias Göckede, Jennifer D. Watts, Christian Wille, Torben R. Christensen, Gregory Starr, Casper T. Christiansen, S. Potter, Kevin Schaefer, Jordan P. Goodrich, N. Pirk, Benjamin W. Abbott, Patrick M. Crill, Elisabeth J. Cooper, Edward A. G. Schuur, Qianlai Zhuang, Zhihua Liu, Bang Yong Lee, Massimo Lupascu, Xiaofeng Xu, Kyle A. Arndt, Torsten Sachs, Walter C. Oechel, Donatella Zona, S. Ludwig, Jinyang Du, Brendan M. Rogers, Michael M. Loranty, Mark J. Lara, Yongwon Kim, Oliver Sonnentag, Zhen Zhang, Susan M. Natali, David Risk, Gaius R. Shaver, Aram Kalhori, A. David McGuire, Bo Elberling, Mats P. Björkman, Leah Birch, Roser Matamala, Philipp R. Semenchuk, Klaus Steenberg Larsen, Manuel Helbig, M. P. Waldrop, Frans-Jan W. Parmentier, Thomas Friborg, Yihui Wang, Julie D. Jastrow, Anders Michelsen, Hélène Genet, Roisin Commane, Fereidoun Rezanezhad, Claudia I. Czimczik, Elchin Jafarov, Lars Kutzbach, A. Anthony Bloom, Christina Minions, Jeffrey M. Welker, Claire C. Treat, Eugénie S. Euskirchen, Patrick F. Sullivan, Nima Madani, Magnus Lund, Jocelyn Egan, William L. Quinton, Paul Grogan, Niels Martin Schmidt, Avni Malhotra, Ben Poulter, S. P. Davydov, A. K. Selbmann, and John S. Kimball
Subjects: 010504 meteorology & atmospheric sciences, Environmental Science and Management, Growing season, Environmental Science (miscellaneous), Atmospheric sciences, Permafrost, 01 natural sciences, Physical Geography and Environmental Geoscience, Atmospheric Sciences, 03 medical and health sciences, chemistry.chemical_compound, VDP::Mathematics and natural science: 400::Zoology and botany: 480, Ecosystem, 030304 developmental biology, 0105 earth and related environmental sciences, 0303 health sciences, Soil organic matter, 15. Life on land, Climate Action, chemistry, Arctic, Boreal, 13. Climate action, Carbon dioxide, Soil water, Environmental science, Social Sciences (miscellaneous), VDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480
Abstract: Recent warming in the Arctic, which has been amplified during the winter1–3, greatly enhances microbial decomposition of soil organic matter and subsequent release of carbon dioxide (CO2)4. However, the amount of CO2 released in winter is not known and has not been well represented by ecosystem models or empirically based estimates5,6. Here we synthesize regional in situ observations of CO2 flux from Arctic and boreal soils to assess current and future winter carbon losses from the northern permafrost domain. We estimate a contemporary loss of 1,662 TgC per year from the permafrost region during the winter season (October–April). This loss is greater than the average growing season carbon uptake for this region estimated from process models (−1,032 TgC per year). Extending model predictions to warmer conditions up to 2100 indicates that winter CO2 emissions will increase 17% under a moderate mitigation scenario—Representative Concentration Pathway 4.5—and 41% under business-as-usual emissions scenario—Representative Concentration Pathway 8.5. Our results provide a baseline for winter CO2 emissions from northern terrestrial regions and indicate that enhanced soil CO2 loss due to winter warming may offset growing season carbon uptake under future climatic conditions. Winter warming in the Arctic will increase the CO2 flux from soils. A pan-Arctic analysis shows a current loss of 1,662 TgC per year over the winter, exceeding estimated carbon uptake in the growing season; projections suggest a 17% increase under RCP 4.5 and a 41% increase under RCP 8.5 by 2100.
Published: 2019
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19. Long-term experimentally deepened snow decreases growing-season respiration in a low- and high-arctic tundra ecosystem

Author: Paul Grogan, Philipp R. Semenchuk, Bo Elberling, Elisabeth J. Cooper, and Casper T. Christiansen
Subjects: 0106 biological sciences, Atmospheric Science, 010504 meteorology & atmospheric sciences, Ecology, Global warming, Paleontology, Soil Science, Growing season, Forestry, 15. Life on land, Aquatic Science, Snow, Atmospheric sciences, 010603 evolutionary biology, 01 natural sciences, Tundra, 13. Climate action, Climatology, Soil water, Environmental science, Ecosystem, Ecosystem respiration, 0105 earth and related environmental sciences, Water Science and Technology, Snow fence
Abstract: Tundra soils store large amounts of carbon (C) that could be released through enhanced ecosystem respiration (ER) as the arctic warms. Over time, this may change the quantity and quality of available soil C pools, which in-turn may feedback and regulate ER responses to climate warming. Therefore, short-term increases in ER rates due to experimental warming may not be sustained over longer periods, as observed in other studies. One important aspect, which is often overlooked, is how climatic changes affecting ER in one season may carry-over and determine ER in following seasons. Using snow fences, we increased snow depth and thereby winter soil temperatures in a high-arctic site in Svalbard (78°N) and a low-arctic site in the Northwest Territories, Canada (64°N), for 5 and 9 years, respectively. Deepened snow enhanced winter ER while having negligible effect on growing-season soil temperatures and soil moisture. Growing-season ER at the high-arctic site was not affected by the snow treatment after 2 years. However, surprisingly, the deepened snow treatments significantly reduced growing-season ER rates after 5 years at the high-arctic site and after 8–9 years at the low-arctic site. We speculate that the reduction in ER rates, that became apparent only after several years of experimental manipulation, may, at least in part, be due to prolonged depletion of labile C substrate as a result of warmer soils over multiple cold seasons. Long-term changes in winter climate may therefore significantly influence annual net C balance not just because of increased wintertime C loss but also because of “legacy” effects on ER rates during the following growing seasons.
Published: 2016
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20. Complexity revealed in the greening of the Arctic

Author: Frode Stordal, Rogier de Jong, Rachael Treharne, Marc Macias-Fauria, Gabriela Schaepman-Strub, Gareth K. Phoenix, Pieter S. A. Beck, Bruce C. Forbes, Sarah C. Elmendorf, Anders Bryn, Patrick F. Sullivan, Jarle W. Bjerke, Signe Normand, J. Hans C. Cornelissen, Jeffrey T. Kerby, Sonja Wipf, Laia Andreu-Hayles, Kadmiel Maseyk, Haydn J.D. Thomas, Michael M. Loranty, Logan T. Berner, Anne D. Bjorkman, Sandra Angers-Blondin, Frans-Jan W. Parmentier, Martin Wilmking, Casper T. Christiansen, Christian John, Uma S. Bhatt, Thomas C. Parker, Hans Tømmervik, Jakob J. Assmann, Robert D. Hollister, Eric Post, Johan Olofsson, Andrew M. Cunliffe, Howard E. Epstein, Scott J. Goetz, Craig E. Tweedie, Isla H. Myers-Smith, Daan Blok, and Donald A. Walker
Subjects: bepress|Physical Sciences and Mathematics, 010504 meteorology & atmospheric sciences, Ecology (disciplines), Zoology and botany: 480 [VDP], VDP::Zoologiske og botaniske fag: 480, Environmental Science (miscellaneous), 01 natural sciences, bepress|Life Sciences|Ecology and Evolutionary Biology, 03 medical and health sciences, Greening, bepress|Life Sciences, VDP::Mathematics and natural scienses: 400::Zoology and botany: 480, SDG 13 - Climate Action, Arctic vegetation, bepress|Life Sciences|Other Life Sciences, Zoologiske og botaniske fag: 480 [VDP], 030304 developmental biology, 0105 earth and related environmental sciences, VDP::Mathematics and natural science: 400, 0303 health sciences, business.industry, Global warming, Environmental resource management, Vegetation, VDP::Matematikk og Naturvitenskap: 400, bepress|Physical Sciences and Mathematics|Other Physical Sciences and Mathematics, The arctic, Geography, Arctic, VDP::Matematikk og naturvitenskap: 400::Zoologiske og botaniske fag: 480, VDP::Zoology and botany: 480, business, Social Sciences (miscellaneous)
Abstract: As the Arctic warms, vegetation is responding, and satellite measures indicate widespread greening at high latitudes. This ‘greening of the Arctic’ is among the world’s most important large-scale ecological responses to global climate change. However, a consensus is emerging that the underlying causes and future dynamics of so-called Arctic greening and browning trends are more complex, variable and inherently scale-dependent than previously thought. Here we summarize the complexities of observing and interpreting high-latitude greening to identify priorities for future research. Incorporating satellite and proximal remote sensing with in-situ data, while accounting for uncertainties and scale issues, will advance the study of past, present and future Arctic vegetation change. acceptedVersion
Published: 2019
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21. The handbook for standardized field and laboratory measurements in terrestrial climate change experiments and observational studies (ClimEx)

Author: Lawren Sack, Simon M. Smart, Martine van der Ploeg, Petr Holub, Robert Weigel, Arezoo Taghizadeh-Toosi, Stuart W. Smith, Kamal Zurba, Ina C. Meier, Inger Kappel Schmidt, Lena Muffler, Fletcher W. Halliday, Benjamin Blonder, Karel Klem, Thomas Wohlgemuth, Arne Ven, Niki I. W. Leblans, Claus Beier, Peter A. Wilfahrt, Leandro Van Langenhove, Unni Vik, Casper T. Christiansen, Joan Llusià, Vigdis Vandvik, Marc Macias-Fauria, Katja Tielbörger, Iolanda Filella, Jan Jacob Keizer, Tone Birkemoe, Sabine Reinsch, Markus A. K. Sydenham, Mariska te Beest, Heidi Sjursen Konestabo, Inge H. J. Althuizen, Frederick C. Meinzer, Isabel C. Barrio, Megan L. Miller, Sara Vicca, Nelson Abrantes, Lee T. Dickman, Marc Estiarte, Richard J. Telford, Otmar Urban, Sean T. Michaletz, Catherine Preece, Stein Joar Hegland, Joachim Töpper, Ivika Ostonen, Paul Kardol, Albert Gargallo-Garriga, Sune Linder, Virve Ravolainen, Julie C. Zinnert, Michal Oravec, Miles R. Marshall, Gil Bohrer, Andreas Schindlbacher, Jarle W. Bjerke, Josep Peñuelas, Mark A. K. Gillespie, Pille Mänd, Lucas S. Cernusak, Daniel M. Johnson, Lucia Fuchslueger, Z. Carter Berry, Bjarni D. Sigurdsson, Ika Djukic, Jürgen Kreyling, Isabel Campos, Andrey V. Malyshev, Anke Jentsch, Ashley M. Matheny, James D. M. Speed, Hanna Lee, Jonas J. Lembrechts, Jan C. Ruppert, Christine Scoffoni, György Kröel-Dulay, Albert Porcar-Castell, Lauren K. Wood, Gesche Blume-Werry, Armando Lenz, Bogdan H. Chojnicki, Christopher M. Gough, Nate G. McDowell, Kristýna Večeřová, Günter Hoch, Iilka Beil, José M. Grünzweig, Iain Colin Prentice, Amy E. Eycott, Anja Linstädter, Erik Verbruggen, Inma Lebron, Dajana Radujković, Anne Sverdrup-Thygeson, David A. Robinson, Francesca Jaroszynska, Ellen Stuart-Haëntjens, Ragnhild Gya, Jordi Sardans, Hans J. De Boeck, Aud Helen Halbritter Rechsteiner, Bernhard J. Cosby, Gregory R. Goldsmith, Klaus Steenberg Larsen, John D. Marshall, María Almagro, Bernd Josef Berauer, Simon M. Landhäusser, Fiona M. Soper, Relena R. Ribbons, Karin Hansen, Scott B. Jones, Marco M. Lehmann, ClimMani Working Group, AXA Research Fund, Commission of the European Communities, Geology (-2014), Viikki Plant Science Centre (ViPS), Department of Forest Sciences, Ecosystem processes (INAR Forest Sciences), Forest Ecology and Management, and Institute for Atmospheric and Earth System Research (INAR)
Subjects: 0106 biological sciences, Open science, coordinated experiments, Computer science, Matematikk og naturvitenskap: 400::Basale biofag: 470 [VDP], Data management, DISTRIBUTED EXPERIMENTS, Hydrology and Quantitative Water Management, 01 natural sciences, Mathematics and natural scienses: 400::Basic biosciences: 470 [VDP], CARBON, Basic biosciences: 470 [VDP], open science, PRECIPITATION MANIPULATION EXPERIMENTS, 0502 Environmental Science and Management, Scientific disciplines, Ecology, Ecological Modeling, methodology, Basale biofag: 470 [VDP], Data availability, VDP::Basic biosciences: 470, experimental macroecology, data management and documentation, Chemistry, Life Sciences & Biomedicine, Hydrologie en Kwantitatief Waterbeheer, 119 Other natural sciences, Best practice, best practice, Climate change, Environmental Sciences & Ecology, 010603 evolutionary biology, Ecosystem structure, LITTER DECOMPOSITION, Meteorology and Climatology, 0603 Evolutionary Biology, vegetation, PLANT, Environmental planning, Biology, Ecology, Evolution, Behavior and Systematics, METAANALYSIS, ecosystem, WIMEK, Science & Technology, 0602 Ecology, business.industry, 010604 marine biology & hydrobiology, 15. Life on land, NITROGEN, MODEL, VDP::Basale biofag: 470, 13. Climate action, Observational study, business, RESPONSES
Abstract: 1. Climate change is a world-wide threat to biodiversity and ecosystem structure, functioning and services. To understand the underlying drivers and mechanisms, and to predict the consequences for nature and people, we urgently need better understanding of the direction and magnitude of climate change impacts across the soil–plant–atmosphere continuum. An increasing number of climate change studies are creating new opportunities for meaningful and high-quality generalizations and improved process understanding. However, significant challenges exist related to data availability and/or compatibility across studies, compromising opportunities for data re-use, synthesis and upscaling. Many of these challenges relate to a lack of an established ‘best practice’ for measuring key impacts and responses. This restrains our current understanding of complex processes and mechanisms in terrestrial ecosystems related to climate change. 2. To overcome these challenges, we collected best-practice methods emerging from major ecological research networks and experiments, as synthesized by 115 experts from across a wide range of scientific disciplines. Our handbook contains guidance on the selection of response variables for different purposes, protocols for standardized measurements of 66 such response variables and advice on data management. Specifically, we recommend a minimum subset of variables that should be collected in all climate change studies to allow data re-use and synthesis, and give guidance on additional variables critical for different types of synthesis and upscaling. The goal of this community effort is to facilitate awareness of the importance and broader application of standardized methods to promote data re-use, availability, compatibility and transparency. We envision improved research practices that will increase returns on investments in individual research projects, facilitate second-order research outputs and create opportunities for collaboration across scientific communities. Ultimately, this should significantly improve the quality and impact of the science, which is required to fulfil society's best practice, coordinated experiments, data management and documentation, ecosystem, experimental macroecology, methodology, open science, vegetation This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. © 2019 The Authors. Methods in Ecology and Evolution published by John Wiley & Sons Ltd on behalf of British Ecological Society.
Published: 2019
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22. Early stage litter decomposition across biomes

Author: Umberto Morra di Cella, Sean P. Charles, Matteo Gualmini, Naoko Tokuchi, Michael Mirtl, Marta Lobão Lopes, Takeshi Ise, Inmaculada García Quirós, Geovana Carreño-Rocabado, Arne Verstraeten, Joan-Albert Sanchez-Cabeza, Thomas Zechmeister, Jill Thompson, Norbert Hölzel, Maroof Hamid, Rodrigo Lemes Martins, Taiki Mori, José Marcelo Domingues Torezan, Dana Polyanskaya, Peter Haase, Björn Berg, Angela Stanisci, Issaka Senou, Inger Kappel Schmidt, Markus Wagner, Adriano Caliman, Laurel M. Brigham, Alejandro Valdecantos, Céline Meredieu, Kalifa Coulibaly, Margarida Santos-Reis, Georg Wohlfahrt, Regin Rønn, Marcello Tomaselli, Martin Weih, Bernd Ahrends, Kaie Kriiska, Anja Schmidt, Luciana S. Carneiro, Ana I. Lillebø, Alessandro Petraglia, Algirdas Augustaitis, Ana I. Sousa, Sonja Wipf, Chi-Ling Chen, Hassan Bismarck Nacro, Sue J. Milton, Ivan Mihal, Ika Djukic, Florence Maunoury-Danger, Peter Fleischer, Tatsuro Nakaji, Cendrine Mony, Sara Puijalon, Rafael D. Guariento, Rosa Isela Meneses, Mihai Pușcaș, Pablo Luis Peri, Flurin Sutter, Kate Lajtha, Peter B. Reich, Lindsey E. Rustad, María Guadalupe Almazán Torres, Laura Williams, George L. Vourlitis, Evanilde Benedito, Arely N. Palabral-Aguilera, Luis Villar, Stefanie Hoeber, Juan J. Jiménez, Esperança Gacia, Alba Gutiérrez-Girón, Kazuhiko Hoshizaki, Takanori Sato, Eric Lucot, Osvaldo Borges Pinto, Artur Stefanski, Andrew R. Smith, Takuo Hishi, Rosario G. Gavilán, Till Kleinebecker, Julia Seeber, Gina Arena, Marcelo Sternberg, Mo Jiangming, Tsutom Hiura, Satoshi N. Suzuki, Jeyanny Vijayanathan, Christine Delire, Francisco Cuesta, Bill Parker, Mark Frenzel, Franz Zehetner, Vincent Maire, Edward Crawford, Heinke Jäger, Nicolas Lecomte, Tanaka Kenta, Yuji Kominami, Joseph C. Morina, Paige E. Weber, Pavel Dan Turtureanu, Marc Lebouvier, Pascal Vittoz, Jónína Sigríður Þorláksdóttir, Anne Probst, David Fuentes Delgado, Laura Yahdjian, Johan Neirynck, Isaac Ahanamungu Makelele, Bernard Bosman, Fábio Padilha Bolzan, Yury Rozhkov, Ute Hamer, Henning Meesenburg, Vinicius F. Farjalla, Steffen Seitz, Marie-Noëlle Pons, Jess K. Zimmerman, Hans Verbeeck, Thomas Scholten, Elena Preda, Thomas Spiegelberger, Romain Georges, Stefan Löfgren, Ferdinand Kristöfel, Pierre Marmonier, Juha M. Alatalo, Katalin Szlavecz, Ana Carolina Ruiz Fernández, Johannes M. H. Knops, Rita Adrian, Vanessa Mendes Rêgo, Jean-Christophe Lata, Rafaella Canessa, Kathrin Käppeler, Andrea Fischer, Michael Bierbaumer, Jiří Doležal, Hideaki Shibata, Marcus Schaub, Zsolt Toth, Diyaa Radeideh, Matthew A. Vadeboncoeur, Robert Kanka, William H. McDowell, Birgit Sattler, Jean-Luc Probst, Mioko Ataka, Katarína Gerhátová, Jawad Shoqeir, Stefan Stoll, Michael Danger, Sébastien Gogo, Katja Tielbörger, Laryssa Helena Ribeiro Pazianoto, Bo Yang, Franco L. Souza, John Loehr, Francisco de Almeida Lobo, Michael J. Liddell, Sylvie Dousset, Dirk Wundram, Ralf Kiese, Yalin Hu, Miglena Zhiyanski, José-Luis Benito-Alonso, Katie A. Jennings, Tsutomu Enoki, Helena Cristina Serrano, Quentin Ponette, Helge Bruelheide, Simon Drollinger, Vincent Bretagnolle, Ivika Ostonen, Lambiénou Yé, Javier Roales, Philippe Choler, Madison Morley, Charles A. Nock, Grizelle González, Tudor-Mihai Ursu, Maaike Y. Bader, Cristina Branquinho, Hugo López Rosas, Nina V. Filippova, Erzsébet Hornung, Anzar A. Khuroo, Lourdes Morillas, Harald Auge, Andreas Bohner, Florian Kitz, Stephan Glatzel, Aurora Gaxiola, Marijn Bauters, Stefan Trogisch, Guylaine Canut, Oscar Romero, Hélène Verheyden, Yulia Zaika, Veronika Piscová, Michael Scherer-Lorenzen, Valentin H. Klaus, Elena Tropina, Michele Di Musciano, Marie-Andrée Giroux, Florian Hofhansl, Wenjun Zhou, Corinna Rebmann, Thomas J. Mozdzer, Zsolt Kotroczó, Evy Ampoorter, Michal Růžek, Jana Borovská, Jianwu Tang, Petr Petřík, Juan Dario Quinde, Simone Mereu, Esther Lévesque, Olga Ferlian, Veronika Fontana, Joël Merlet, Stacey M. Trevathan-Tackett, André-Jean Francez, Wentao Luo, Héctor Alejandro Bahamonde, Roberto Cazzolla Gatti, Brigitta Erschbamer, Christopher Andrews, Marie-Anne de Graaff, Martin Schädler, Luciano Di Martino, Verena Busch, Elli Groner, Victoria Carbonell, Michinari Matsushita, Maria Glushkova, Sarah Freda, Alain Paquette, Annie Ouin, Robert Weigel, Monique Carnol, Bohdan Juráni, Ian D. Yesilonis, Jean-Paul Theurillat, Hugo L. Rojas Villalobos, Alberto Humber, Martha Apple, Nico Eisenhauer, Claus Beier, Hermann F. Jungkunst, Hiroko Kurokawa, Nadia Barsoum, Thierry Camboulive, Klaus Steenberg Larsen, Frank Berninger, Laura Dienstbach, Yasuhiro Utsumi, Inara Melece, Felipe Varela, Sally Wittlinger, Christian Rixen, Valter Di Cecco, Anderson da Rocha Gripp, Marina Mazón, E. Carol Adair, Hanna Lee, István Fekete, Liesbeth van den Brink, José-Gilberto Cardoso-Mohedano, Ken Green, Heike Feldhaar, Jonathan von Oppen, Michele Carbognani, Lu Xiankai, Christophe Piscart, Fernando T. Maestre, Karibu Fukuzawa, Chiao-Ping Wang, Bart Muys, Lipeng Zhang, Harald Pauli, Inge van Halder, Carmen Eugenia Rodríguez Ortíz, Eduardo Ordóñez-Regil, Priscilla Muriel, Heather D. Alexander, Sebastian Kepfer-Rojas, Victoria Ochoa, Casper T. Christiansen, Mohammed Alsafran, Thaisa Sala Michelan, Christel Baum, Amélie Saillard, Hervé Jactel, Markus Didion, Evgeny A. Davydov, Sabyasachi Dasgupta, Anna Avila, Andrijana Andrić, Kris Verheyen, Jörg Löffler, Gisele Daiane Pinha, Anikó Seres, Jutta Stadler, Milan Barna, Andrey V. Malyshev, Rebecca E. Hewitt, Joh R. Henschel, Peter I. Macreadie, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Norwegian Institute for Water Research (NIVA), Swedish University of Agricultural Sciences (SLU), Dept Forest & Water Management, Lab Forestry, Universiteit Gent = Ghent University [Belgium] (UGENT), Centre for Forest Research (CFR), Université du Québec à Montréal = University of Québec in Montréal (UQAM), Laboratoire d'Ecologie Alpine (LECA ), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria = National Institute for Agricultural and Food Research and Technology (INIA), Ecosystèmes, biodiversité, évolution [Rennes] (ECOBIO), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Institute for Climate and Atmospheric Science [Leeds] (ICAS), School of Earth and Environment [Leeds] (SEE), University of Leeds-University of Leeds, Laboratoire Ecologie Fonctionnelle et Environnement (ECOLAB), Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées, Dynamiques Forestières dans l'Espace Rural (DYNAFOR), Institut National de la Recherche Agronomique (INRA)-École nationale supérieure agronomique de Toulouse [ENSAT]-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées, European Forest Institute = Institut Européen de la Forêt = Euroopan metsäinstituutti (EFI), Institute of Information Engineering [Beijing] (IIE), Chinese Academy of Sciences [Beijing] (CAS), Biodiversité, Gènes & Communautés (BioGeCo), Institut National de la Recherche Agronomique (INRA)-Université de Bordeaux (UB), University of Rostock, WSL Institute for Snow and Avalanche Research SLF, Institut des Sciences de l'Evolution de Montpellier (UMR ISEM), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Institut de recherche pour le développement [IRD] : UR226-Centre National de la Recherche Scientifique (CNRS), Department Computational Hydrosystems [UFZ Leipzig], Helmholtz Zentrum für Umweltforschung = Helmholtz Centre for Environmental Research (UFZ), Laboratoire Chrono-environnement - CNRS - UBFC (UMR 6249) (LCE), Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Département de chimie-biologie & Centre d’études nordiques [CANADA], Université du Québec à Trois-Rivières (UQTR), Area de Biodiversidad y Conservaciín, Universidad Rey Juan Carlos [Madrid] (URJC), Laboratoire Interdisciplinaire des Environnements Continentaux (LIEC), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Terre et Environnement de Lorraine (OTELo), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Helsingin yliopisto = Helsingfors universitet = University of Helsinki, Institute of Soil Research, Universität für Bodenkultur Wien = University of Natural Resources and Life [Vienne, Autriche] (BOKU), Institute of Ecology, University of Innsbruck, Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Computational & Applied Vegetation Ecology (CAVElab), Department Community Ecology [UFZ Leipzig], University of Vienna [Vienna], Institut du Développement rural (IDR), Université Polytechnique Nazi Boni Bobo-Dioulasso (UNB), Unité de recherche Comportement et Ecologie de la Faune Sauvage (CEFS), Institut National de la Recherche Agronomique (INRA), Institute of Biology/Geobotany and Botanical Garden, Martin-Luther-Universität Halle Wittenberg (MLU), Tohoku University [Sendai], Institute of Ecology and Earth Sciences [Tartu], University of Tartu, Institut d'écologie et des sciences de l'environnement de Paris (iEES), Institut National de la Recherche Agronomique (INRA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Centre alpien de Phytogéographie (CAP), Fondation Jean-Marcel Aubert, Inst Trop Ecosyst Studies, University of Puerto Rico (UPR), Universidad de Valladolid [Valladolid] (UVa), Mountain Agriculture Research Unit, Centre international de recherche-développement sur l'élevage en zone sub-humide (CIRDES), Centre Universitaire Polytechnique de Dédougou (CUP-D), Université Joseph Ki-Zerbo [Ouagadougou] (UJZK), USDA Forest Service, Instituto Pirenaico de Ecologia = Pyrenean Institute of Ecology (IPE), Station Biologique de Paimpont CNRS UMR 6653 (OSUR), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Institute of Pharmacology and Toxicology [Zurich], Universität Zürich [Zürich] = University of Zurich (UZH), Centre for Ecology - Evolution and Environmental Changes (cE3c) - Faculdade de Ciências, Universidade de Lisboa = University of Lisbon (ULISBOA), Canada Research in Northern Biodiversity, Université du Québec à Rimouski (UQAR), Laboratoire Réactions et Génie des Procédés (LRGP), Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Zone Atelier du Bassin de la Moselle [LTSER France] (ZAM), Department of Crop Production Ecology, University of Freiburg, Forest Research Institute- BAS, Bulgarian Academy of Sciences (BAS), Lab Plant & Microbial Ecol, Inst Bot B22, Université de Liège, Laboratoire Dynamique de la Biodiversité (LADYBIO), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Leipzig University, Westfälische Wilhelms-Universität Münster = University of Münster (WWU), Universitat Politècnica de Catalunya [Barcelona] (UPC), Université de Lausanne = University of Lausanne (UNIL), Department of Limnology and Conservation, Senckenberg Research Institutes and Natural History Museums, Department of Forest Resources, University of Minnesota [Twin Cities] (UMN), University of Minnesota System-University of Minnesota System, Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés (LEHNA), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Centre National de la Recherche Scientifique (CNRS), Université Catholique de Louvain = Catholic University of Louvain (UCL), Institut für Meteorologie und Klimaforschung - Atmosphärische Umweltforschung (IMK-IFU), Karlsruher Institut für Technologie (KIT), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Biogéosystèmes Continentaux - UMR7327, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Department of Science for Nature and Natural Resources, Università degli Studi di Sassari = University of Sassari [Sassari] (UNISS), Biogéosciences [UMR 6282] (BGS), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), Ecole Polytechnique Fédérale de Lausanne (EPFL), Tomakomai Research Station, Field Science Center for Northern Biosphere, Hokkaido University [Sapporo, Japan], Bangor University, Technische Universität Dresden = Dresden University of Technology (TU Dresden), Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), LTSER «Zone Atelier Plaine & Val de Sevre» [France], Institut National de la Recherche Agronomique (INRA)-La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA)-La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Condensed Matter Theory Laboratory RIKEN (RIKEN), RIKEN - Institute of Physical and Chemical Research [Japon] (RIKEN), 730938, Biological Interactions Doctoral Programme, Secretaría de Educación Superior, Ciencia, Tecnología e Innovación, 2/0101/18, Scientific Grant Agency VEGA, 2190, Fundación Charles Darwin, UID/AMB/50017, Centro de Estudos Ambientais e Marinhos, Universidade de Aveiro, ILTER Initiative Grant, ClimMani Short-Term Scientific Missions Grant, ES1308-231015-068365, Austrian Environment Agency, SFRH/BPD/107823/2015, Portuguese Foundation, DEB-1557009, NSF, UID/BIA/00329/2013, Fundação para a Ciência e Tecnologia, Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes 1 (UR1), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), University of Helsinki, Universität für Bodenkultur Wien [Vienne, Autriche] (BOKU), Groupe d'étude de l'atmosphère météorologique (CNRM-GAME), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Recherche Agronomique (INRA), Centre alpien de Phytogéographie, Fondation J.-M. Aubert, Centre international de recherche-développement sur l'élevage en zone Subhumide (CIRDES), Centre international de recherche-développement sur l'élevage en zone Subhumide, Instituto Pirenaico de Ecologia (IPE), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), University of Lisbon, Université de Leipzig, Westfälische Wilhelms-Universität Münster (WWU), Université de Lausanne (UNIL), University of Sassari, Biogéosciences [UMR 6282] [Dijon] (BGS), Université de Bourgogne (UB)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Centre National de la Recherche Scientifique (CNRS), Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Institut National de la Recherche Agronomique (INRA)-Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA)-Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS), Universiteit Gent = Ghent University (UGENT), Université de Rennes (UR)-Institut Ecologie et Environnement (INEE), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Ecologie Fonctionnelle et Environnement (LEFE), Université de Toulouse (UT)-Université de Toulouse (UT)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Institut National de la Recherche Agronomique (INRA)-École nationale supérieure agronomique de Toulouse (ENSAT), Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Université de Toulouse (UT), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-École Pratique des Hautes Études (EPHE), Laboratoire Chrono-environnement (UMR 6249) (LCE), Leopold Franzens Universität Innsbruck - University of Innsbruck, Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Instituto Pirenaico de Ecologìa = Pyrenean Institute of Ecology [Zaragoza] (IPE - CSIC), Université de Rennes (UR), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Institut National de la Recherche Agronomique (INRA)-La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique - CNRS (FRANCE), Institut National Polytechnique de Toulouse - INPT (FRANCE), Institut National de la Recherche Agronomique - INRA (FRANCE), Université Toulouse III - Paul Sabatier - UT3 (FRANCE), Météo France (FRANCE), UCL - SST/ELI/ELIE - Environmental Sciences, Swiss Federal Institute for Forest, Snow and Avalanche Research WSL, Swedish University of Agricultural Sciences - Department of Forest Soils, Ghent University [Belgium] (UGENT), Université du Québec à Montréal (UQAM), Laboratoire d'Ecologie Alpine (LECA), Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Université Joseph Fourier - Grenoble 1 (UJF)-Université Grenoble Alpes (UGA), Spanish National Institute for Agriculture and Food Research and Technology (INIA), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Centre National de la Recherche Scientifique (CNRS), Science Politique Relations Internationales Territoire (SPIRIT), Université Montesquieu - Bordeaux 4-Institut d'Études Politiques [IEP] - Bordeaux-Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Institut National de la Recherche Agronomique (INRA)-Ecole Nationale Supérieure Agronomique de Toulouse-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Bordeaux (UB)-Institut National de la Recherche Agronomique (INRA), University of Rostock [Germany], Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-École pratique des hautes études (EPHE)-Université de Montpellier (UM)-Institut de recherche pour le développement [IRD] : UR226-Centre National de la Recherche Scientifique (CNRS), Helmholtz Centre for Environmental Research (UFZ), Universiteit Gent [Ghent], Laboratoire de Comportement et d'Ecologie de la Faune Sauvage, INRA, 31326 Castanet-Tolosan cedex, France, Institut d'écologie et des sciences de l'environnement de Paris (IEES), Universidad de Puerto Rico, Centre Universitaire Polytechnique de Dédougou, Université de Ouagadougou, Instituto Pirenaico de Ecología, IPE-CSIC, University of Zürich [Zürich] (UZH), LTSER Zone Atelier du Bassin de la Moselle, Helmholtz Zentrum für Umweltforschung (UFZ), Institute of Terrestrial Ecosystems, University of Minnesota [Twin Cities], Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE), Université Catholique de Louvain (UCL), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Centre National de la Recherche Scientifique (CNRS)-Université de Bourgogne (UB)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement, Hokkaido University, Technische Universität Dresden (TUD), Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA)-Université de La Rochelle (ULR), LTSER Zone Atelier Plaine & Val de Sèvre, Djukic I., Kepfer-Rojas S., Schmidt I.K., Larsen K.S., Beier C., Berg B., Verheyen K., Caliman A., Paquette A., Gutierrez-Giron A., Humber A., Valdecantos A., Petraglia A., Alexander H., Augustaitis A., Saillard A., Fernandez A.C.R., Sousa A.I., Lillebo A.I., da Rocha Gripp A., Francez A.-J., Fischer A., Bohner A., Malyshev A., Andric A., Smith A., Stanisci A., Seres A., Schmidt A., Avila A., Probst A., Ouin A., Khuroo A.A., Verstraeten A., Palabral-Aguilera A.N., Stefanski A., Gaxiola A., Muys B., Bosman B., Ahrends B., Parker B., Sattler B., Yang B., Jurani B., Erschbamer B., Ortiz C.E.R., Christiansen C.T., Carol Adair E., Meredieu C., Mony C., Nock C.A., Chen C.-L., Wang C.-P., Baum C., Rixen C., Delire C., Piscart C., Andrews C., Rebmann C., Branquinho C., Polyanskaya D., Delgado D.F., Wundram D., Radeideh D., Ordonez-Regil E., Crawford E., Preda E., Tropina E., Groner E., Lucot E., Hornung E., Gacia E., Levesque E., Benedito E., Davydov E.A., Ampoorter E., Bolzan F.P., Varela F., Kristofel F., Maestre F.T., Maunoury-Danger F., Hofhansl F., Kitz F., Sutter F., Cuesta F., de Almeida Lobo F., de Souza F.L., Berninger F., Zehetner F., Wohlfahrt G., Vourlitis G., Carreno-Rocabado G., Arena G., Pinha G.D., Gonzalez G., Canut G., Lee H., Verbeeck H., Auge H., Pauli H., Nacro H.B., Bahamonde H.A., Feldhaar H., Jager H., Serrano H.C., Verheyden H., Bruelheide H., Meesenburg H., Jungkunst H., Jactel H., Shibata H., Kurokawa H., Rosas H.L., Rojas Villalobos H.L., Yesilonis I., Melece I., Van Halder I., Quiros I.G., Makelele I., Senou I., Fekete I., Mihal I., Ostonen I., Borovska J., Roales J., Shoqeir J., Lata J.-C., Theurillat J.-P., Probst J.-L., Zimmerman J., Vijayanathan J., Tang J., Thompson J., Dolezal J., Sanchez-Cabeza J.-A., Merlet J., Henschel J., Neirynck J., Knops J., Loehr J., von Oppen J., Thorlaksdottir J.S., Loffler J., Cardoso-Mohedano J.-G., Benito-Alonso J.-L., Torezan J.M., Morina J.C., Jimenez J.J., Quinde J.D., Alatalo J., Seeber J., Stadler J., Kriiska K., Coulibaly K., Fukuzawa K., Szlavecz K., Gerhatova K., Lajtha K., Kappeler K., Jennings K.A., Tielborger K., Hoshizaki K., Green K., Ye L., Pazianoto L.H.R., Dienstbach L., Williams L., Yahdjian L., Brigham L.M., van den Brink L., Rustad L., Zhang L., Morillas L., Xiankai L., Carneiro L.S., Di Martino L., Villar L., Bader M.Y., Morley M., Lebouvier M., Tomaselli M., Sternberg M., Schaub M., Santos-Reis M., Glushkova M., Torres M.G.A., Giroux M.-A., de Graaff M.-A., Pons M.-N., Bauters M., Mazon M., Frenzel M., Didion M., Wagner M., Hamid M., Lopes M.L., Apple M., Schadler M., Weih M., Gualmini M., Vadeboncoeur M.A., Bierbaumer M., Danger M., Liddell M., Mirtl M., Scherer-Lorenzen M., Ruzek M., Carbognani M., Di Musciano M., Matsushita M., Zhiyanski M., Puscas M., Barna M., Ataka M., Jiangming M., Alsafran M., Carnol M., Barsoum N., Tokuchi N., Eisenhauer N., Lecomte N., Filippova N., Holzel N., Ferlian O., Romero O., Pinto O.B., Peri P., Weber P., Vittoz P., Turtureanu P.D., Fleischer P., Macreadie P., Haase P., Reich P., Petrik P., Choler P., Marmonier P., Muriel P., Ponette Q., Guariento R.D., Canessa R., Kiese R., Hewitt R., Ronn R., Adrian R., Kanka R., Weigel R., Gatti R.C., Martins R.L., Georges R., Meneses R.I., Gavilan R.G., Dasgupta S., Wittlinger S., Puijalon S., Freda S., Suzuki S., Charles S., Gogo S., Drollinger S., Mereu S., Wipf S., Trevathan-Tackett S., Lofgren S., Stoll S., Trogisch S., Hoeber S., Seitz S., Glatzel S., Milton S.J., Dousset S., Mori T., Sato T., Ise T., Hishi T., Kenta T., Nakaji T., Michelan T.S., Camboulive T., Mozdzer T.J., Scholten T., Spiegelberger T., Zechmeister T., Kleinebecker T., Hiura T., Enoki T., Ursu T.-M., di Cella U.M., Hamer U., Klaus V.H., Rego V.M., Di Cecco V., Busch V., Fontana V., Piscova V., Carbonell V., Ochoa V., Bretagnolle V., Maire V., Farjalla V., Zhou W., Luo W., McDowell W.H., Hu Y., Utsumi Y., Kominami Y., Zaika Y., Rozhkov Y., Kotroczo Z., Toth Z., and Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
Subjects: DYNAMICS, 010504 meteorology & atmospheric sciences, Biome, Biochimie, Biologie Moléculaire, Carbon turnover, 01 natural sciences, CARBON, Waste Management and Disposal, ComputingMilieux_MISCELLANEOUS, CLIMATE-CHANGE, биомы, Tea bag, Green tea, Rooibos tea, Carbon turnover, TeaComposition initiative, 04 agricultural and veterinary sciences, Pollution, Environmental chemistry, [SDE]Environmental Sciences, Terrestrial ecosystem, Life Sciences & Biomedicine, Biologie, TRAITS, Rooibos tea, IMPACTS, Environmental Engineering, почвенные процессы, chemistry.chemical_element, Climate change, Environmental Sciences & Ecology, Ingénierie de l'environnement, Green tea, Tea bag, TeaComposition initiative, Ecology and Environment, Atmosphere, подстилки, Environmental Chemistry, Ecosystem, RATES, 0105 earth and related environmental sciences, оборот углерода, Science & Technology, Tea composition initiative, FEEDBACK, 15. Life on land, Decomposition, влияние климата, TERRESTRIAL ECOSYSTEMS, MODEL, экосистемы, chemistry, 13. Climate action, PATTERNS, 040103 agronomy & agriculture, Litter, 0401 agriculture, forestry, and fisheries, Environmental science, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, 500 Naturwissenschaften und Mathematik::570 Biowissenschaften, Biologie::577 Ökologie, Carbon, Environmental Sciences
Abstract: Through litter decomposition enormous amounts of carbon is emitted to the atmosphere. Numerous large-scale decomposition experiments have been conducted focusing on this fundamental soil process in order to understand the controls on the terrestrial carbon transfer to the atmosphere. However, previous studies were mostly based on site-specific litter and methodologies, adding major uncertainty to syntheses, comparisons and meta-analyses across different experiments and sites. In the TeaComposition initiative, the potential litter decomposition is investigated by using standardized substrates (Rooibos and Green tea) for comparison of litter mass loss at 336 sites (ranging from -9 to +26 °C MAT and from 60 to 3113 mm MAP) across different ecosystems. In this study we tested the effect of climate (temperature and moisture), litter type and land-use on early stage decomposition (3 months) across nine biomes. We show that litter quality was the predominant controlling factor in early stage litter decomposition, which explained about 65% of the variability in litter decomposition at a global scale. The effect of climate, on the other hand, was not litter specific and explained
Published: 2018
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23. Long-term deepened snow promotes tundra evergreen shrub growth and summertime ecosystem net CO

Author: Casper T, Christiansen, Melissa J, Lafreniére, Gregory H R, Henry, and Paul, Grogan
Subjects: Northwest Territories, Soil, Snow, Plant Development, Nutrients, Seasons, Carbon Dioxide, Tundra, Carbon
Abstract: Arctic climate warming will be primarily during winter, resulting in increased snowfall in many regions. Previous tundra research on the impacts of deepened snow has generally been of short duration. Here, we report relatively long-term (7-9 years) effects of experimentally deepened snow on plant community structure, net ecosystem CO
Published: 2017

24. Enhanced summer warming reduces fungal decomposer diversity and litter mass loss more strongly in dry than in wet tundra

Author: Casper T. Christiansen, Paul Grogan, Merian Skouw Haugwitz, Daan Blok, Bo Elberling, Anders Priemé, Cecilie Skov Nielsen, and Anders Michelsen
Subjects: 0106 biological sciences, Nutrient cycle, Greenland, 010603 evolutionary biology, 01 natural sciences, Decomposer, Environmental Chemistry, Ecosystem, Tundra, Betula, Soil Microbiology, General Environmental Science, Global and Planetary Change, Ecology, biology, Arctic Regions, Fungi, Temperature, 04 agricultural and veterinary sciences, 15. Life on land, Plant litter, Snow, biology.organism_classification, Betula glandulosa, Plant Leaves, Agronomy, 13. Climate action, 040103 agronomy & agriculture, Litter, 0401 agriculture, forestry, and fisheries, Seasons
Abstract: Many Arctic regions are currently experiencing substantial summer and winter climate changes. Litter decomposition is a fundamental component of ecosystem carbon and nutrient cycles, with fungi being among the primary decomposers. To assess the impacts of seasonal climatic changes on litter fungal communities and their functioning, Betula glandulosa leaf litter was surface-incubated in two adjacent low Arctic sites with contrasting soil moisture regimes: dry shrub heath and wet sedge tundra at Disko Island, Greenland. At both sites, we investigated the impacts of factorial combinations of enhanced summer warming (using open-top chambers; OTCs) and deepened snow (using snow fences) on surface litter mass loss, chemistry and fungal decomposer communities after approximately 1 year. Enhanced summer warming significantly restricted litter mass loss by 32% in the dry and 17% in the wet site. Litter moisture content was significantly reduced by summer warming in the dry, but not in the wet site. Likewise, fungal total abundance and diversity were reduced by OTC warming at the dry site, while comparatively modest warming effects were observed in the wet site. These results suggest that increased evapotranspiration in the OTC plots lowered litter moisture content to the point where fungal decomposition activities became inhibited. In contrast, snow addition enhanced fungal abundance in both sites but did not significantly affect litter mass loss rates. Across sites, control plots only shared 15% of their fungal phylotypes, suggesting strong local controls on fungal decomposer community composition. Nevertheless, fungal community functioning (litter decomposition) was negatively affected by warming in both sites. We conclude that although buried soil organic matter decomposition is widely expected to increase with future summer warming, surface litter decay and nutrient turnover rates in both xeric and relatively moist tundra are likely to be significantly restricted by the evaporative drying associated with warmer air temperatures.
Published: 2016

25. High arctic heath soil respiration and biogeochemical dynamics during summer and autumn freeze‐in – effects of long‐term enhanced water and nutrient supply

Author: Niels Martin Schmidt, Casper T. Christiansen, Sarah Hagel Svendsen, and Anders Michelsen
Subjects: Global and Planetary Change, Biogeochemical cycle, Ecology, Soil organic matter, Soil biology, Soil chemistry, Soil respiration, Nutrient, Agronomy, Soil water, Environmental Chemistry, Environmental science, Ecosystem, General Environmental Science
Abstract: In High Arctic NE Greenland, temperature and precipitation are predicted to increase during this century, however, relatively little information is available on the role of increased water supply on soil CO 2 efflux in dry, high arctic ecosystems. We measured soil respiration (Rsoil) in summer and autumn of 2009 in combination with microbial biomass and nutrient availability during autumn freeze-in at a dry, open heath in Zackenberg, NE Greenland. This tundra site has been subject to fully factorial manipulation consisting of increased soil water supply for 14 years, and occasional nitrogen (N) addition in pulses. Summer watering enhanced Rsoil during summer, but decreased Rsoil in the following autumn. We speculate that this is due to intensified depletion of recently fixed plant carbon by soil organisms. Hence, autumn soil microbial activity seems tightly linked to growing season plant production through plant-associated carbon pools. Nitrogen addition alone consistently increased Rsoil, but when water and nitrogen were added in combination, autumn Rsoil declined similarly to when water was added alone. Despite several freeze-thaw events, the microbial biomass carbon (C) remained constant until finally being reduced by ~60% in late September. In spite of significantly reduced microbial biomass C and phosphorus (P), microbial N did not change. This suggests N released from dead microbes was quickly assimilated by surviving microbes. We observed no change in soil organic matter content after 14 years of environmental manipulations, suggesting high ecosystem resistance to environmental changes.
Published: 2012
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26. Geographic, seasonal, and diurnal surface behavior of harbor porpoises

Author: Gösta Nachman, Casper T. Christiansen, Sanne Kjellerup, Jonas Teilmann, and Rune Dietz
Subjects: Correction factor, biology, Aerial survey, Satellite telemetry, Geographical differences, Ship surveys, Diving behavior, Phocoena, Diurnal surface pattern, Aquatic Science, biology.organism_classification, Aerial surveys, Surface pattern, Phocoena phocoena, Population estimate, Line transect surveys, Geography, Oceanography, Abundance (ecology), North sea, Transect, Ecology, Evolution, Behavior and Systematics, Surface time
Abstract: During ship surveys harbor porpoises are only visible when breaking the seasurface to breathe, while during aerial surveys they may be seen down to 2 mbelow the surface. The fractions of time spent at these two depths can be usedfor correcting visual surveys to actual population estimates, which are essentialinformation on the status and management of the species. Thirty-ﬁvefree-ranging harbor porpoises (Phocoena phocoena) were tracked in the regionbetween the Baltic and the North Sea for 25–349 d using Argos satellitetransmitters. No differences were found in surface behavior between geographi-cal areas or the size of the animals. Slight differences were found between thetwo sexes and time of day. Surface time peaked in April, where 6% was spentwith the transmitter above surface and 61.5% between 0 and 2 m depth,while the minimum values occurred in February (3.4% and 42.5%, respec-tively). The analyses reveal that individual variation among porpoises is themost important factor in explaining variation in surface rates. However, thelarge number of animals documented in the present study covering a widerange of age and sex groups justiﬁes the use of the seasonal average surfacetimes for correcting abundance surveys.Key words: Phocoena phocoena, diving behavior, surface time, satellite telemetry,ship surveys, aerial surveys, correction factor, diurnal surface pattern, geographi-cal differences, line transect surveys.
Published: 2013
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27. The effect of freeze-thaw conditions on arctic soil bacterial communities

Author: Virginia K. Walker, Paul Grogan, Haiyan Chu, Niraj Kumar, and Casper T. Christiansen
Subjects: Recrystallization (geology), phylogenetic composition, 010504 meteorology & atmospheric sciences, Climate change, Growing season, Fjord, Biology, Permafrost, 01 natural sciences, fatty acids, General Biochemistry, Genetics and Molecular Biology, Article, Nutrient, arctic soils, freeze-thaw, bacteria, lcsh:QH301-705.5, 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, General Immunology and Microbiology, Ecology, 04 agricultural and veterinary sciences, 15. Life on land, climate change, lcsh:Biology (General), Arctic, 13. Climate action, Soil water, 040103 agronomy & agriculture, 0401 agriculture, forestry, and fisheries, chaos theory, General Agricultural and Biological Sciences
Abstract: Climate change is already altering the landscape at high latitudes. Permafrost is thawing, the growing season is starting earlier, and, as a result, certain regions in the Arctic may be subjected to an increased incidence of freeze-thaw events. The potential release of carbon and nutrients from soil microbial cells that have been lysed by freeze-thaw transitions could have significant impacts on the overall carbon balance of arctic ecosystems, and therefore on atmospheric CO2 concentrations. However, the impact of repeated freezing and thawing with the consequent growth and recrystallization of ice on microbial communities is still not well understood. Soil samples from three distinct sites, representing Canadian geographical low arctic, mid-arctic and high arctic soils were collected from Daring Lake, Alexandra Fjord and Cambridge Bay sampling sites, respectively. Laboratory-based experiments subjected the soils to multiple freeze-thaw cycles for 14 days based on field observations (0 °C to −10 °C for 12 h and −10 °C to 0 °C for 12 h) and the impact on the communities was assessed by phospholipid fatty acid (PLFA) methyl ester analysis and 16S ribosomal RNA gene sequencing. Both data sets indicated differences in composition and relative abundance between the three sites, as expected. However, there was also a strong variation within the two high latitude sites in the effects of the freeze-thaw treatment on individual PLFA and 16S-based phylotypes. These site-based heterogeneities suggest that the impact of climate change on soil microbial communities may not be predictable a priori; minor differential susceptibilities to freeze-thaw stress could lead to a “butterfly effect” as described by chaos theory, resulting in subsequent substantive differences in microbial assemblages. This perspectives article suggests that this is an unwelcome finding since it will make future predictions for the impact of on-going climate change on soil microbial communities in arctic regions all but impossible.
Published: 2012

28. High Arctic dry heath CO2 exchange during the early cold season

Author: Anders Michelsen, Casper T. Christiansen, and Niels Martin Schmidt
Subjects: Ecology, Climate change, chemistry.chemical_element, Tundra, Nutrient, Agronomy, Arctic, chemistry, Environmental Chemistry, Environmental science, Terrestrial ecosystem, Ecosystem, Ecosystem respiration, Carbon, Ecology, Evolution, Behavior and Systematics
Abstract: Climate change may alter the terrestrial ecosystem carbon balance in the Arctic, and previous studies have emphasized the importance of cold season gas exchange when considering the annual carbon balance. Here, we examined gross ecosystem production (GEP), ecosystem respiration (R eco) and net ecosystem exchange (NEE) during autumn at a high arctic dry open heath, over a period where air temperatures decreased from +9.8 to −16.5°C. GEP declined by 95–100% during autumn but GEP significantly different from 0 was measured on October 8 despite sub-zero temperatures. R eco declined by 90% and dominated NEE throughout the study as the ecosystem on all measurement days was a source of atmospheric CO2. We estimated net September carbon losses (NEE) to be 17 g CO2 m−2, emphasizing the importance of autumn in relation to annual carbon budgets. The study site has been subjected to 14 summers of water addition, and occasional pulses of nitrogen (N) addition in a fully factorial design. N addition enhanced GEP up to 17-fold during September, although there was no effect in October when GEP was very low. Summer water addition decreased autumn R eco by up to 25%. Both N amendment and water addition decreased carbon loss, that is, increased NEE; N amendment increased NEE on all dates by 13–64% whereas water addition increased NEE by 20–54% late in September and onward, demonstrating the importance of nutrient and water availability on carbon balance in high arctic tundra, also during the autumn freeze-in.
Published: 2012
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28 results on '"Casper T. Christiansen"'

1. Plant traits and associated data from a warming experiment, a seabird colony, and along elevation in Svalbard

2. Disaggregating the Carbon Exchange of Degrading Permafrost Peatlands Using Bayesian Deep Learning

3. Winters are changing: snow effects on Arctic and alpine tundra ecosystems1

4. Can bryophyte groups increase functional resolution in tundra ecosystems?1

5. Effects of Climate and Atmospheric Nitrogen Deposition on Early to Mid-Term Stage Litter Decomposition Across Biomes

6. The Effect of Freeze-Thaw Conditions on Arctic Soil Bacterial Communities

7. Litter quality outweighs climate as a driver of decomposition across the tundra biome

8. Intraspecific trait variability is a key feature underlying high Arctic plant community resistance to climate warming

9. Canadian permafrost stores large pools of ammonium and optically distinct dissolved organic matter

10. Author Correction: Large loss of CO2 in winter observed across the northern permafrost region

11. Volatile organic compound release across a permafrost-affected peatland

12. Explicitly modelling microtopography in permafrost landscapes in a land-surface model (JULES vn5.4_microtopography)

13. Abrupt thaw enhances annual global warming potential of an actively degrading permafrost peatland

14. Shallow soils are warmer under trees and tall shrubs across Arctic and Boreal ecosystems

15. Decomposition of Senesced Leaf Litter is Faster in Tall Compared to Low Birch Shrub Tundra

16. Long-term deepened snow promotes tundra evergreen shrub growth and summertime ecosystem net CO2gain but reduces soil carbon and nutrient pools

17. Examination of Soil Microbial Communities After Permafrost Thaw Subsequent to an Active Layer Detachment in the High Arctic

18. Large loss of CO2 in winter observed across the northern permafrost region

19. Long-term experimentally deepened snow decreases growing-season respiration in a low- and high-arctic tundra ecosystem

20. Complexity revealed in the greening of the Arctic

21. The handbook for standardized field and laboratory measurements in terrestrial climate change experiments and observational studies (ClimEx)

22. Early stage litter decomposition across biomes

23. Long-term deepened snow promotes tundra evergreen shrub growth and summertime ecosystem net CO

24. Enhanced summer warming reduces fungal decomposer diversity and litter mass loss more strongly in dry than in wet tundra

25. High arctic heath soil respiration and biogeochemical dynamics during summer and autumn freeze‐in – effects of long‐term enhanced water and nutrient supply

26. Geographic, seasonal, and diurnal surface behavior of harbor porpoises

27. The effect of freeze-thaw conditions on arctic soil bacterial communities

28. High Arctic dry heath CO2 exchange during the early cold season

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28 results on '"Casper T. Christiansen"'

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