Soil carbon storage is an important function of terrestrial ecosystems. Soil contains more carbon than plants and the atmosphere combined.[1] Understanding what maintains the soil carbon pool is important to understand the current distribution of carbon on Earth, and how it will respond to environmental change. While much research has been done on how plants, free-living microbial decomposers, and soil minerals affect this pool of carbon, it is recently coming to light that mycorrhizal fungi—symbiotic fungi that associate with roots of almost all living plants—may play an important role in maintaining this pool as well.[2] Measurements of plant carbon allocation to mycorrhizal fungi have been estimated to be 5 to 20% of total plant carbon uptake,[3][4] and in some ecosystems the biomass of mycorrhizal fungi can be comparable to the biomass of fine roots.[5] Recent research has shown that mycorrhizal fungi hold 50 to 70 percent of the total carbon stored in leaf litter and soil on forested islands in Sweden.[6] Turnover of mycorrhizal biomass into the soil carbon pool is thought to be rapid[7] and has been shown in some ecosystems to be the dominant pathway by which living carbon enters the soil carbon pool.[8]
Outlined below are the leading lines of evidence for how different aspects of mycorrhizal fungi may alter soil carbon decomposition and storage. Evidence is presented for arbuscular and ectomycorrhizal fungi separately as they are phylogenetically distinct and often function in very different ways.
- ^ Tarnocai et al. 2009. Soil organic carbon pools in the northern circumpolar permafrost region. Global Biogeochemical Cycles, 23(2) doi: 10.1029/2008GB003327
- ^ Hawkins, Heidi-Jayne; Cargill, Rachael I.M.; Van Nuland, Michael E.; Hagen, Stephen C.; Field, Katie J.; Sheldrake, Merlin; Soudzilovskaia, Nadejda A.; Kiers, E. Toby (June 2023). "Mycorrhizal mycelium as a global carbon pool". Current Biology. 33 (11): R560–R573. doi:10.1016/j.cub.2023.02.027. hdl:1942/40689.
- ^ Pearson JN and Jakobsen I. 1993. The relative contribution of hyphae and roots to phosphorus uptake by arbuscular mycorrhizal plants, measured by dual labeling with 32P and 33P. New Phytologist, 124: 489-494.
- ^ Hobbie JE and Hobbie EA. 2006. 15N in symbiotic fungi and plants estimates nitrogen and carbon flux rates in arctic tundra. Ecology, 87: 816-822
- ^ Wallander H, Goransson H and Rosengren U. Production, standing biomass and natural abundance of 15N and 13C in ectomycorrhizal mycelia collected at different soil depths in two forest types. Oecologia, 139: 89-97.
- ^ K.E. Clemmensen et al. 2013. Roots and associated fungi drive long-term carbon sequestration in boreal forest. Science, 339: 1615-1618.
- ^ Staddon et al. 2003. Rapid turnover of hyphae of mycorrhizal fungi determined by AMS microanalysis of 14C. Science, 300: 1138-1140.
- ^ Godbold DL et al. 2006. Mycorrhizal hyphal turnover as a dominant process for carbon input into soil organic matter. Plant and Soil, 281: 15-24.