Carbon and nitrogen cycling in Yedoma permafrost controlled by microbial functional limitations

• Published in: Nature Geoscience
• Main Authors: Monteux, Sylvain, Keuper, Frida, Fontaine, Sébastien, Gavazov, Konstantin, Hallin, Sara, Juhanson, Jaanis, Krab, Eveline, Revaillot, Sandrine, Verbruggen, Erik, Walz, Josefine, Weedon, James, Dorrepaal, Ellen
• Other Authors: Swedish University of Agricultural Sciences (SLU), Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Unité Mixte de Recherche sur l'Ecosystème Prairial - UMR (UREP), VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Universiteit Antwerpen = University of Antwerpen Antwerpen, Vrije Universiteit Amsterdam Amsterdam (VU)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2020
• Subjects: soil organic-matter; thawing permafrost; fatty-acids; r package; communities; biomass; temperature; sensitivity; diversity; reveals; [SDE.MCG]Environmental Sciences/Global Changes; permafrost
• Online Access: https://hal.inrae.fr/hal-03121697; https://doi.org/10.1038/s41561-020-00662-4

International audience Warming-induced microbial decomposition of organic matter in permafrost soils constitutes a climate-change feedback of uncertain magnitude. While physicochemical constraints on soil functioning are relatively well understood, the constraints attributable to microbial community composition remain unclear. Here we show that biogeochemical processes in permafrost can be impaired by missing functions in the microbial community-functional limitations-probably due to environmental filtering of the microbial community over millennia-long freezing. We inoculated Yedoma permafrost with a functionally diverse exogenous microbial community to test this mechanism by introducing potentially missing microbial functions. This initiated nitrification activity and increased CO2 production by 38% over 161 days. The changes in soil functioning were strongly associated with an altered microbial community composition, rather than with changes in soil chemistry or microbial biomass. The present permafrost microbial community composition thus constrains carbon and nitrogen biogeochemical processes, but microbial colonization, likely to occur upon permafrost thaw in situ, can alleviate such functional limitations. Accounting for functional limitations and their alleviation could strongly increase our estimate of the vulnerability of permafrost soil organic matter to decomposition and the resulting global climate feedback.