Mycorrhizal fungi in Coast Live Oak: Diversity and scaling.
ALLEN, M.F.* 1, T.ZINK 2, L.EGERTON-WARBURTON 1 and O.KAREN 1
University of California, Riverside, CA 92521 USA 1
San Diego State University, CA USA 2
Coast Live Oak in southern California persists as small stands within a matrix of endomycorrhizal plants. Ectomycorrhizal fungi exist as clones stretching across individual trees. Over 10 years of observations, we have identified 90 species of ectomycorrhizal fungi symbiotic with coast live oak from fruiting structures. Over a 4 year period in 18,700 m2 plots, 51 species were observed. To initiate studies on connections, we planted seedlings associated with large trees. Morphotypes were determined per seedling. The highest richness associated with an individual seedling was 7. The highest richness on all seedlings per source tree was 10. Morphotypes increased both with increasing numbers of seedlings and numbers of source trees. Based on species area curves, 4,000 trees in patches would need to be surveyed for at least 4 years to find most of the sporocarps. Although morphotypes cannot be equated with species, only 10-15 trees could be surveyed to find the majority of described morphotypes. However, over a million individual EM tips would need to be observed. Both grass competition and N fertilization reduced both sporulation and numbers of morphotypes. These observations suggest that most EM fungal taxa exist across many stands but a few are scattered across the region. Since differing EM fungi have varying physiological characteristics in response to the changing environment of southern California, evaluating mycorrhizal biodiversity may require both intensive and extensive study.
Keywords: mycorrhizae, diversity, oaks
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