USDA Forest Service Gen. Tech. Rep.
2002: PSW-GTR-183: 83-89.

Current Investigations of Fungal Ectomycorrhizal Communities in the Sierra National Forest

Thomas D. Bruns2, Annette M. Kretzer3, Thomas R. Horton4, Eric A-D. Stendell5, Martin I. Bidartondo6 and Timothy M. Szaro7

2 Professor, Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720.
3 Adjunct Professor, Department of Environmental and Forest Biology, SUNY-ESF, Syracuse, NY 13210.
4 Assistant Professor, Department of Environmental and Forest Biology, SUNY-ESF, Syracuse, NY 13210.
5 Student, Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720.
6 Graduate Student, Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720.
7 Technician, Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720.


Abstract
Progress on two main studies on fungal ectomycorrhizal communities in the Sierra National Forest is discussed. One study examined the short-term effects of ground fire on the ectomycorrhizal community and the other examined the ectomycorrhizal associates of snow plant (Sarcodes sanguinea). In the ground-fire study we found that a large initial reduction in ectomycorrhizal biomass is caused primarily by combustion of the upper organic layers; prefire dominants in the Russulaceae and Thelephoraceae are dramatically reduced; and species at greater depths appear to survive the fire. We speculate that fire causes a short-term increase in species evenness. In the field portion of the Sarcodes study, we found that Sarcodes is specialized on a single mycorrhizal associate, Rhizopogon ellenae; the presence of Sarcodes is associated with dense islands of R. ellenae; R. ellenae appears to be a minor below-ground component of the red fir (Abies magnifica) community in locations near but not immediately adjacent to Sarcodes plants; and the Abies magnifica ectomycorrhizal community is dominated by members of the Russulaceae and Thelephoraceae. From studies of Sarcodes-R. ellenae interactions under laboratory conditions, we report that seed germination is stimulated by isolates of R. ellenae, isolates of R. ellenae derived from Sarcodes and Abies roots are capable of forming mycorrhizae on pine (Pinus) roots, and we have achieved initial success in establishing a tripartite Sarcodes-Rhizopogon-Pinus association under laboratory conditions.

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