The organic soil carbon (C) amount is very large and, therefore, small changes in its size could have large effects on atmospheric CO2 concentration. Evidence of fungi closely associated with roots (called mycorrhizal fungi) directly utilizing soil carbon and respiring it to the atmosphere has recently come from several laboratories around the world, but the significance of this has yet to be established through broad-scale surveys. This research will document variation in the degree to which these fungi can utilize (and respire C from) soil litter in four contrasting ecosystems, among soil horizons within ecosystems, and among species within ecosystems.
Most scientists currently assume that mycorrhizal fungi obtain C for growth and maintenance solely from a living host plant. However, even a small ability to directly utilize litter as a carbon source could have large effects on global C cycles because mycorrhizal roots contribute up to 65% of total soil respiration and, in some forest ecosystems, mycorrhizal fungi constitute about one-third of total soil microbial biomass. This research will enhance the infrastructure for research and education by initiating a collaboration among a group of domestic and foreign scientists working in contrasting ecosystems across the globe (USA, Japan and Sweden).
