Historical atmospheric nitrogen deposition has reduced ectomycorrhizal diversity in endangered spruce-fir ecosystem

The spruce-fir ecosystem in the Southern Appalachian Mountains is considered one of the most endangered in North America. Fraser fir (Abies fraseri) is only found in this region and has experienced massive decline due to a variety of biotic and abiotic factors, including atmospheric nitrogen (N) deposition. Spruce-fir forests improve watershed quality and provide important habitat for endemic species, some of which are poorly understood and may be at risk of extinction. Soil fungi play a dynamic role in the spruce-fir ecosystem and many mutualistic fungi are specifically tied to tree survival. Two important ecological guilds of fungi, ectomycorrhizal (ECM) and saprotrophic (SAP), respond differently to the changing edaphic conditions caused by N deposition. The goal of this work is to understand how N deposition and other edaphic factors vary across the spruce-fir ecosystem and how these affect fungal diversity.