Ectomycorrhizal communities of Quercus garryana are similar on serpentine and nonserpentine soils

Serpentine soils, rich in iron, magnesium, and heavy metals, select for unique plant communities and for endemic species. Because mycorrhizal fungi mediate the interaction between plants and soil, we hypothesized that distinct ectomycorrhizal fungi would colonize Quercus garryana roots on serpentine and nonserpentine soils. We sampled roots of Q. garryana on serpentine soils at two locations in the Klamath-Siskiyou Mountains of southwestern Oregon and identified ectomycorrhizas by morphological and molecular methods. The same six most abundant and most frequent mycorrhizal species, Cenococcum geophilum, Tuber candidum, Genea harknessii, Tomentella sp., Sebacina sp., and Inocybe sp., were found on serpentine and nonserpentine soils. Based on similarities calculated using the Sørensen index in Non-metric Multidimensional Scaling, mycorrhizal communities on serpentine and nonserpentine soils were not significantly different. This study showed that ectomycorrhizal species associated with Q. garryana exhibit edaphic tolerance and were neither reduced nor excluded by serpentinite or peridotite parent materials.