Abstract
Ectomycorrhizal fungi (EMF) provide the dominant pathway for nutrient fluxes from the soil to associated plants and represent a significant portion of belowground carbon (C). Within temperate forests, tree growth and productivity is nitrogen (N) limited and EMF are crucial for the ability of the trees to obtain N from the soil. However, information pertaining to the species of EMF that may be important to N cycling is lacking. I used a natural N gradient in order to assess the influence of N on fungal communities. I found that N availability was influential on the organization of fungal communities and their phylogenetic structure. Species within the genera Cortinarius and Piloderma were more abundant under low N availability while Amanita and Tomentella were more abundant under high N. I also demonstrate that species capable of producing large amounts of mycelium are more abundant under low N availability. I discuss the implications of these findings to the cycling of C and N under increased anthropogenic N deposition.