Microbial communities associated with ectomycorrhizal mat soils were investigated as part of the HJ Andrews LTER Microbial Observatory II project. Amplicon pyrosequencing of Fungal ITS and Bacterial 16S was used to quantify the microbial communities from two ectomycorrhizal mat forming genera (Piloderma and Ramaria) as well as non-mat soils. Samples were split into organic and mineral soil horizons prior to sequencing. <p> The project was designed to explore the chemical and biological properties of mat-forming ectomycorrhizal fungi in the HJ Andrews forest.