Nitrogen (N) is an essential element required for all life on earth, composing proteins, DNA, and metabolic cofactors. As such, N cycling within the biosphere is a critical regulator of primary productivity, as N frequently acts as a limiting nutrient of tree growth in temperate forests . Proteases — a class of enzymes that depolymerize proteins into free amino acids and peptides — are the biotic workhorses of N cycling in forest soils, catalyzing the rate-limiting step of N mineralization. While the role that proteases play in N cycling is well established, drivers of spatial differences in protease activity across forest soils and how these spatial differences correlate with primary productivity remain largely unexplored. To better understand these relationships, protease activity was measured in soil samples collected from the Harvard Forest ForestGEO Plot, a 35 hectare forest plot that has been censused on a 5-year basis since 2014. Samples were collected at the center of 20 x 20 meter quadrats, and quadrats dominated by ectomycorrhizae (EcM) associated tree species, arbuscular mycorrhizae (AM) associated species, and a mix of EcM and AM species were selected for proteolytic analysis. We hypothesized that protease activity would be higher in EcM dominated tree stands than in AM dominated tree stands, as EcM fungi secrete proteases directly into the rhizosphere, while AM fungi rely on proteases secreted by saprotrophic fungi to degrade proteins. However, we found that protease activity was higher in AM dominated and mixed stands than in EcM dominated stands. In addition, we found that tree growth rate is positively correlated with protease activity. Together, these results suggest that enzymes secreted by saprotrophic fungi rather than EcM fungi are primarily responsible for protein degradation in soils, and that the proteases secreted by these fungi may play a critical role in promoting aboveground primary productivity.