SRP126330 PRJNA421474 Cedar Creek Soil Organic Matter Manipulation We manipulated the amount and composition of soil organic matter in a field experiment at the Cedar Creek Ecosystem Science Reserve. If ECM fungi mobilize organic N stores via OM depolymerization, then ECM fungi will be more abundant when organic N is in polymeric forms that require enzymatic liberation, relative to monomeric organic N pools. Alternatively, if mycorrhizal are able to persist in nutrient-poor conditions, due to plant host supply of photosynthates, then we expect that ECM fungi will be most abundant in low C and low N conditions. To test these hypotheses, we buried three soil treatments (low ON, high ON, high labile ON) in in-growth bags and characterized microbial biomass and fungal community following four months of colonization in pine and oak stands.