Our research focuses on how human activities are impacting terrestrial ecosystems, with an emphasis on soil biota and nutrient cycling processes. We are specifically interested in how environmental changes affect the composition and diversity of soil microbial communities and microbial-mediated carbon and nitrogen cycles. For the past 12 years, we have been using several long-term experiments at the Harvard Forest LTER to examine if/how soil warming, simulated nitrogen deposition, and biotic invasion are altering microbial and nutrient cycling dynamics. We are conducting this work at the Soil Warming × Nitrogen Addition (SWaN) Study, the Chronic Nitrogen Amendment Study, the DIRT plots, and across a set of sites invaded by garlic mustard. Measurements include soil carbon and nitrogen stocks and fluxes (total soil C and N, inorganic N, soil respiration) and microbial biomass, activity and community structure. Our work has increasingly focused on the fungal component of the microbial community because fungi are the primary decomposers of plant litter in temperate forests and fungi are sensitive to environmental change. Key results from our decade plus of study include (1) environmental change fundamentally restructures the soil fungal community, (2) environmental change alters the relative abundance of key fungal functional groups, (3) fungi exposed to long-term environmental change have altered physiology, and (4) shifts in the fungal community are associated with changes in soil nutrient cycles.