A group of ectomycorrhizal fungi restricts organic matter accumulation in boreal forest. (2nd May 2021) - Lindahl, Björn D.
Abstract: Boreal forest soils are important global carbon sinks, with significant storage in the organic topsoil. Decomposition of these stocks requires oxidative enzymes, uniquely produced by fungi. Across Swedish boreal forests, we found that local carbon storage in the organic topsoil was 33% lower in the presence of a group of closely related species of ectomycorrhizal fungi – Cortinarius acutus s.l.. This observation challenges the prevailing view that ectomycorrhizal fungi generally act to increase carbon storage in soils but supports the idea that certain ectomycorrhizal fungi can complement free‐living decomposers, maintaining organic matter turnover, nutrient cycling and tree productivity under nutrient‐poor conditions. The indication that a narrow group of fungi may exert a major influence on carbon cycling questions the prevailing dogma of functional redundancy among microbial decomposers. Cortinarius acutus s.l. responds negatively to stand‐replacing disturbance, and associated population declines are likely to increase soil carbon sequestration while impeding long‐term nutrient cycling. Abstract : Across Swedish boreal forests, carbon storage in the organic topsoil was significantly lower in the presence of the ectomycorrhizal fungus Cortinarius acutus . The correlation suggests that this fungus capitalize on its symbiotic relationship with trees to maintain decomposition under nutrient poor conditions. This link between ecosystem properties and a specific group of soil fungi questions the idea of large functional redundancy among microbial decomposers. Artwork: Liza Johansson (painted with Cortinarius pigments).