Principal role of fungi in soil carbon stabilization during early pedogenesis in the high Arctic

• Published in: Proceedings of the National Academy of Sciences
• Main Authors: Trejos-Espeleta, Juan Carlos, Marin-Jaramillo, Juan, Schmidt, Steven, Sommers, Pacifica, Bradley, James, Orsi, William
• Other Authors: Ludwig Maximilian University Munich = Ludwig Maximilians Universität München (LMU), University of Colorado Boulder, Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Queen Mary University of London (QMUL)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2024
• Subjects: fungal ecology; stable isotope probing; Arctic soils; soil development; organic carbon; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; [SDV.EE.BIO]Life Sciences [q-bio]/Ecology; environment/Bioclimatology; [SDV.MP.MYC]Life Sciences [q-bio]/Microbiology and Parasitology/Mycology; [SDV.SA.SDS]Life Sciences [q-bio]/Agricultural sciences/Soil study; Global warming
• Online Access: https://hal.science/hal-04663492; https://hal.science/hal-04663492/document; https://hal.science/hal-04663492/file/Svalbard_manuscript_2nd_REVISion_cleancopy.pdf; https://doi.org/10.1073/pnas.2402689121

International audience Climate warming is causing widespread deglaciation and pioneer soil formation over glacial deposits. Melting glaciers expose rocky terrain and glacial till sediment that is relatively low in biomass, oligotrophic, and depleted in nutrients. Following initial colonization by microorganisms, glacial till sediments accumulate organic carbon and nutrients over time. However, the mechanisms driving soil nutrient stabilization during early pedogenesis after glacial retreat remain unclear. Here, we traced amino acid uptake by microorganisms in recently deglaciated high-Arctic soils and show that fungi play a critical role in the initial stabilization of the assimilated carbon. Pioneer basidiomycete yeasts were among the predominant taxa responsible for carbon assimilation, which were associated with overall high amino acid use efficiency and reduced respiration. In intermediate- and late-stage soils, lichenized ascomycete fungi were prevalent, but bacteria increasingly dominated amino acid assimilation, with substantially decreased fungal:bacterial amino acid assimilation ratios and increased respiration. Together, these findings demonstrate that fungi are important drivers of pedogenesis in high-Arctic ecosystems that are currently subject to widespread deglaciation from global warming.