Seasonal dynamics of ectomycorrhizal fungus assemblages on oak seedlings in the southeastern Appalachian Mountains
Abstract
The potential for seasonal dynamics in ectomycorrhizal (EM) fungal assemblages has important implications for the ecology of both the host trees and the fungal associates. We compared EM fungus distributions on root systems of out-planted oak seedlings at two sites in mixed southeastern Appalachian Mountain forests at the Coweeta Hydrologic Laboratory in North Carolina, from samples taken in mid-July and early September. Species level EM fungus type specificity, and identification in some cases, was enabled by direct sequencing of the mycobionts from the seedling roots. Seventy-four EM fungal ITS types were documented, most of which occurred only in the midsummer or early-fall samples, respectively. Cenococcum geophilum(morphotyped) was ubiquitously present and accounted for the majority of root tips sampled. Abundance and relative frequency of types other than C. geophilum were significantly higher in the July samples, while C. geophilum was significantly more frequent and abundant in September. Several generalistic dominants were found fairly equally at both sites and on both sample dates.