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ASSESSING ABUNDANCE DISTRIBUTIONS IN NATURAL COMMUNITIES OF ECTOMYCORRHIZAS ALONG AN ENVIRONMENTAL GRADIENT
Citation:
Martin, K. J., P T. Rygiewicz, AND A. R. Tuininga. ASSESSING ABUNDANCE DISTRIBUTIONS IN NATURAL COMMUNITIES OF ECTOMYCORRHIZAS ALONG AN ENVIRONMENTAL GRADIENT. Presented at American Society of Agronomy 2000 Annual Meeting, Minneapolis, MN, November 5-9, 2000.
Description:
Alpha diversity indices often fail to distinguish between natural populations that a more detailed investigation of the distribution of ramets among types would show are quite different. We studied the effectiveness of applying SHE analyses to morphotype classifications of ectomycorrhizal populations collected from soil cores. The SHE analysis uses the changes in the relationship between richness (S), diversity (H) and evenness (E) as sample size is increased to determine whether the abundance distribution is best described as Log Normal, Log Series or Broken Stick, etc. These distributions are associated with different modes of niche sharing within the communities being studied. Soil cores were collected in the fall of 1994 and 1995, at various elevations in the Oregon cascades and Willamette valley and from enclosed lysimeters in Corvallis. These lysimeters were maintained at ambient and elevated temperatures, in effect extending the trend from cooler, high-elevation climates to warmer climates. We compared various approaches to performing SHE analyses on these data: both treating the larger transect as a single data set and treating the multiple cores collected at each site as separate data sets. Although some ectomycorrhizal populations did not clearly segregate into specific abundance distribution types, there were indications that changes over time were more important than changes in elevation.