TY - JOUR

T1 - Reduced methane emissions in former permafrost soils driven by vegetation and microbial changes following drainage

AU - Keuschnig, Christoph

AU - Larose, Catherine

AU - Rudner, Mario

AU - Pesqueda, Argus

AU - Doleac, Stéphane

AU - Elberling, Bo

AU - Björk, Robert G.

AU - Klemedtsson, Leif

AU - Björkman, Mats P.

N1 - Funding Information: European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska‐Curie grant agreement No: 657627 (M.P.B.), the Research and development projects to future research leaders at FORMAS – Swedish Research Council for Sustainable Development grant agreement 2016‐01187 (M.P.B.), Danish National Research Foundation, Center for Permafrost, CENPERM DNRF100 (B.E). The strategic research environment BECC ‐ Biodiversity and Ecosystem services in a Changing Climate, SITES ‐ Swedish Infrastructure for Ecosystem Science, and the foundations of H. Ax:son Johnson, Wilhelm & Martina Lundgren, Knut & Alice Wallenberg, and Carl Tryggers. Funding Information: European Union?s Horizon 2020 research and innovation programme under the Marie Sk?odowska-Curie grant agreement No: 657627 (M.P.B.), the Research and development projects to future research leaders at FORMAS ? Swedish Research Council for Sustainable Development grant agreement 2016-01187 (M.P.B.), Danish National Research Foundation, Center for Permafrost, CENPERM DNRF100 (B.E). The strategic research environment BECC - Biodiversity and Ecosystem services in a Changing Climate, SITES - Swedish Infrastructure for Ecosystem Science, and the foundations of H. Ax:son Johnson, Wilhelm & Martina Lundgren, Knut & Alice Wallenberg, and Carl Tryggers. We would like to thank the following people for their contribution during planning, field and laboratory work: Haldor Lorimer-Olsson, Stina Johlander, Andrea Jaeschke, Janet Rethenmeyer, and Saskia Bergmann. We would also like to acknowledge: Graeme Nicol and Pascal Simonet for suggestions on the manuscript text, Timothy M. Vogel for valuable inputs on the analysis, and Bart?omiej Luks for the map. We would also like to thank the personnel at Abisko Scientific Research Station as part of the Swedish Polar Research Secretariat and all the dedicated field personnel that throughout the years have been part of the Latnjajaure research crew. This work was granted access to the HPC resources of the PMCS2I-?cole Centrale de Lyon, member of the FLMSN, "F?d?ration Lyonnaise de Mod?lisation et Sciences Num?riques". Publisher Copyright: © 2022 The Authors. Global Change Biology published by John Wiley & Sons Ltd.

PY - 2022/5

Y1 - 2022/5

N2 - In Arctic regions, thawing permafrost soils are projected to release 50 to 250 Gt of carbon by 2100. This data is mostly derived from carbon-rich wetlands, although 71% of this carbon pool is stored in faster-thawing mineral soils, where ecosystems close to the outer boundaries of permafrost regions are especially vulnerable. Although extensive data exists from currently thawing sites and short-term thawing experiments, investigations of the long-term changes following final thaw and co-occurring drainage are scarce. Here we show ecosystem changes at two comparable tussock tundra sites with distinct permafrost thaw histories, representing 15 and 25 years of natural drainage, that resulted in a 10-fold decrease in CH4 emissions (3.2 ± 2.2 vs. 0.3 ± 0.4 mg C-CH4 m−2 day−1), while CO2 emissions were comparable. These data extend the time perspective from earlier studies based on short-term experimental drainage. The overall microbial community structures did not differ significantly between sites, although the drier top soils at the most advanced site led to a loss of methanogens and their syntrophic partners in surface layers while the abundance of methanotrophs remained unchanged. The resulting deeper aeration zones likely increased CH4 oxidation due to the longer residence time of CH4 in the oxidation zone, while the observed loss of aerenchyma plants reduced CH4 diffusion from deeper soil layers directly to the atmosphere. Our findings highlight the importance of including hydrological, vegetation and microbial specific responses when studying long-term effects of climate change on CH4 emissions and underscores the need for data from different soil types and thaw histories.

AB - In Arctic regions, thawing permafrost soils are projected to release 50 to 250 Gt of carbon by 2100. This data is mostly derived from carbon-rich wetlands, although 71% of this carbon pool is stored in faster-thawing mineral soils, where ecosystems close to the outer boundaries of permafrost regions are especially vulnerable. Although extensive data exists from currently thawing sites and short-term thawing experiments, investigations of the long-term changes following final thaw and co-occurring drainage are scarce. Here we show ecosystem changes at two comparable tussock tundra sites with distinct permafrost thaw histories, representing 15 and 25 years of natural drainage, that resulted in a 10-fold decrease in CH4 emissions (3.2 ± 2.2 vs. 0.3 ± 0.4 mg C-CH4 m−2 day−1), while CO2 emissions were comparable. These data extend the time perspective from earlier studies based on short-term experimental drainage. The overall microbial community structures did not differ significantly between sites, although the drier top soils at the most advanced site led to a loss of methanogens and their syntrophic partners in surface layers while the abundance of methanotrophs remained unchanged. The resulting deeper aeration zones likely increased CH4 oxidation due to the longer residence time of CH4 in the oxidation zone, while the observed loss of aerenchyma plants reduced CH4 diffusion from deeper soil layers directly to the atmosphere. Our findings highlight the importance of including hydrological, vegetation and microbial specific responses when studying long-term effects of climate change on CH4 emissions and underscores the need for data from different soil types and thaw histories.

KW - Arctic

KW - climate change

KW - methane

KW - post-permafrost soil

KW - Tundra ecosystems

U2 - 10.1111/gcb.16137

DO - 10.1111/gcb.16137

M3 - Journal article

C2 - 35285570

AN - SCOPUS:85126235681

VL - 28

SP - 3411

EP - 3425

JO - Global Change Biology

JF - Global Change Biology

SN - 1354-1013

IS - 10

ER -