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

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 121; no. 28; p. e2402689121
• Main Authors: Trejos-Espeleta, Juan Carlos, Marin-Jaramillo, Juan P, Schmidt, Steven K, Sommers, Pacifica, Bradley, James A, Orsi, William D
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 09.07.2024
• Subjects: Agricultural sciences; Amino Acids - metabolism; Arctic Regions; Bioclimatology; Biodiversity and Ecology; Carbon - metabolism; Ecology, environment; Ecosystem; Environmental Sciences; Fungi - metabolism; Global Warming; Ice Cover - microbiology; Life Sciences; Microbiology and Parasitology; Mycology; Soil - chemistry; Soil Microbiology; Soil study; Arctic Regions; Arctic soil; carbon cycle; fungal ecology; climate change; polar ecology; stable isotope probing; Arctic soils; soil development; organic carbon
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.2402689121

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.