Southworth, Darlene , Gladish, Sandra , Frank, Jonathan .
The serpentine syndrome belowground: hypogeous fungi and ectomycorrhizas.
Serpentine soils, rich in iron, magnesium, and heavy metals, select for unique plant communities, with sparse vegetation. Mycorrhizal fungi mediate the interaction between plants and soils. Although virtually all pine and oak root tips are ectomycorrhizal, covered with a mantle of fungal cells, little is known about mycorrhizal asemblages of serpentine-tolerant trees. Ectomycorrhizas and hypogeous fungal sporocarps were sampled on paired serpentine and nonserpentine soils on the Josephine ophiolite in the Klamath-Siskiyou bioregion of southwestern Oregon. We hypothesized that trees on serpentine soils would have fewer species of mycorrhizas, a distinct assemblage of ectomycorrhizal fungi, and fewer hypogeous sporocarps with less species richness. Sporocarps were sampled and soil cores collected around pines and oaks on serpentine and nonserpentine soils. Mycorrhizas were sorted by morphology and identified using DNA sequences of the ITS region. The most abundant and most frequent mycorrhizal taxa, Cenococcum, Tuber, Genea, Tomentella, Sebacina, and Inocybe, were found on serpentine and nonserpentine soils. Communities of ectomycorrhizal fungi associated with conifers on serpentine and nonserpentine soils diverged slightly as characterized by non-metric multidimensional scaling, but those of oaks were similar on the two soil types. We collected 44 hypogeous sporocarps in 21 species, 11 from serpentine and 17 from nonserpentine soils. Serpentine soils supported fewer hypogeous sporocarps with less taxonomic richness than nonserpentine soils. Mycorrhizal species richness was less than that of sporocarps. The lack of indicator species on serpentine or nonserpentine soils and greater variability among samples on serpentine soils suggest that it is not soil composition that controls the mycorrhizal community; but sparseness of host vegetation, a consequence of the serpentine syndrome, reduces the ability of fungi to grow from tree to tree and increases reliance on spore dispersal, thus creating a more varied pattern of mycorrhizal communities.
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1 - Southern Oregon University, Department of Biology, 1250 Siskiyou Blvd, Ashland, Oregon, 97520-5010, USA
2 - Southern Oregon University, Biology, Ashland, OR, 97520, USA
Presentation Type: Oral Paper:Papers for BSA Sections
Location: Wasatch A/Cliff Lodge - Level C
Date: Wednesday, July 29th, 2009
Time: 3:45 PM