Freeze-thaw cycles simultaneously decrease peatland photosynthetic carbon uptake and ecosystem respiration

International audience Decreasing snow cover in winter resulting from climate warming increases the incidence of freeze-thaw cycles (FTCs) in many ecosystems, including peatlands. As peatland ecosystems form a globally significant long-term carbon storage, understanding the effects of changing condi...

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Bibliographic Details
Main Authors: Küttim, Martin, Hofsommer, Maaike, Robroek, Bjorn, Jassey, Vincent, Laine, Anna, Lamentowicz, Mariusz, Buttler, Alexandre, Ilomets, Mati, Mills, Robert
Other Authors: University of Southampton, 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), Laboratory of Wetland Ecology and Monitoring, Faculty of Geographical and Geological Sciences, Adam Mickiewicz University, Laboratoire des systèmes écologiques (ECOS), Ecole Polytechnique Fédérale de Lausanne (EPFL), National Nuclear Laboratory
Format: Article in Journal/Newspaper
Language:English
Published: HAL CCSD 2017
Subjects:
[SDE.MCG]Environmental Sciences/Global Changes
Boreal Environment Research
Online Access:https://hal.archives-ouvertes.fr/hal-02466188
https://hal.archives-ouvertes.fr/hal-02466188/document
https://hal.archives-ouvertes.fr/hal-02466188/file/Kuttim2017_ber22-267-276.pdf
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Summary:International audience Decreasing snow cover in winter resulting from climate warming increases the incidence of freeze-thaw cycles (FTCs) in many ecosystems, including peatlands. As peatland ecosystems form a globally significant long-term carbon storage, understanding the effects of changing conditions in winter on carbon dynamics is essential. We studied how FTCs affect peatland carbon cycling by conducting mesocosm experiments with Sphagnum. Our results indicate an overall impeding effect of FTCs on Sphagnum photosynthesis, chlorophyll content, ecosystem respiration and enzymatic processes. A threefold reduction in photosynthesis in the FTC treatment was related to a decrease in chlorophyll content, showing that Sphagnum physiologically suffers from repeated FTCs. In the FTC treatment β-glucosidase and phosphatase enzymatic activities decreased by 50% and 30%, respectively , whilst alanine remained unaffected, indicating that in peat soils short-term FTCs affect the carbon and phosphorus cycles, but not the nitrogen cycle. Long-term effects of FTCs deserve further studies.

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