Distribution of zoosporic fungi in forest soils of the Blue Ridge and Appalachian Mountains of Virginia

Abstract

Although uniflagellate zoosporic fungi and protists (here defined as Chytridiomycota and Hyphochytriomycota) are common in soil, little is known about the spatial scale and factors which correlate with distributional differences. We focused our study on soil uniflagellate zoosporic fungi and protists or their parasites, which were epibiotic degraders of pollen. To determine if similar, but separate forest habitats varied in species composition and frequency, we inventoried four sites, two in the Blue Ridge Mountains and two in the Appalachian Mountains of Virginia. We devised a reliable sampling protocol, identifying numbers of samples and duration of sampling as parameters required to detect the maximum species diversity. Because we were seeking to recognize distributional patterns, we sampled species composition and frequency at all four sites over a 6-mo period to detect site specific differences. To find if more extensive sampling would reveal additional species diversity and potential annual frequency patterns, we sampled species composition over a 12-mo period at the site with the greatest species diversity. In these mountainous habitats, similar species composition was found in all four sites, even though the sites were separated by distance and/or a valley. A total of 15 epibiotic, monocentric zoosporic fungi and protists were isolated, of which 11 were present at all 4 sites. Based on their frequency at individual sites, 5–7 species were ubiquitous, while the rest were common to rare. Mycographs based on species frequency from collections (pooled samples) portrayed general site similarity. Mycographs based on species frequency from individual samples best showed heterogeneity among the sites, and suggested differences in the pattern of distribution of species on a microscale. Sampling over 12-mo indicated that the common species were present regardless of seasonal changes. Our study demonstrated that the study sites were rich in species diversity. In addition, multiple samples from a site and repeated sampling through a 6-mo period were necessary to detect the maximum number of species. This study provides baseline data for future comparative studies of zoosporic fungal distribution from forest habitats.