Nitrogen availability alters macrofungal basidiomycete community structure in optimally fertilized loblolly pine forests.

•  We investigated the effect of an optimal nutrition strategy designed to maximize loblolly pine (Pinus taeda) growth on the rank abundance structure and diversity of associated basidiomycete communities. •  We conducted both small- and large-scale below-ground surveys 10 years after the initiation of optimal nutrition, and used TRFLP of selectively PCR-amplified nrDNA ITS to determine the distribution and abundance of macrofungal basidiomycete species in c. 200 soil samples collected from optimally fertilized and unfertilized treatments at the SETRES loblolly pine experimental site, North Carolina, USA. •  Our results indicated an increased relative abundance of Tylopilus and Thelephora spp. on optimally fertilized stands. Our results also suggested improved mycelial growth of several species, possibly caused by increased connectivity in the forest floor as a result of increased plant growth. •  In addition, our results suggest a trend towards reduced basidiomycete diversity, and that large-scale application of optimal nutrition may need to be sensitive to increased nitrate availability.