9726404 Parker This study will use a combination of field and molecular genetic techniques to directly measure effects of artificial defoliation and litter manipulation on ectomycorrhizal (EM) community structure and specificity patterns in a successional context. EM specificity is thought to be an important factor controlling plant community dynamics, however, because it is often impossible to definitively identify fungal species forming EM on given roots, EM community structure and factors controlling specificity patterns are poorly understood. Recent molecular developments have largely solved this problem, and in previous work, these methods were used to perform the first field test of conflicting hypotheses regarding specificity in a field setting in Yellowstone National Park. This project will extend these results to study factors that change during forest succession and are thought to influence EM community dynamics. Specifically, these investigators will determine the roles of soil surface litter and chemistry, and carbon allocation to roots in controlling EM specificity. This project will be the first test of litter and chemistry effects on specificity using molecular methods, and the first assessment of species-specific responses by EM fungi in mutualistic relationships with plants to above-ground manipulations. Furthermore, results from this study will provide information critical to understanding connections between EM and plant community succession in a geographically dominant mixed conifer ecosystem.
