Protozoan community structure in a fractal soil environment. |
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Authors: | B J Finlay T Fenchel |
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Affiliation: | CEH-Windermere, The Ferry House, Ambleside, Cumbria, UK. bjf@ceh.ac.uk |
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Abstract: | Protozoan abundance was quantified, and 365 protozoan species were recorded, in 150 soil samples from an upland grassland in Scotland. Across the entire size range (2-200 pm) protozoan species richness varied by a factor of two, whereas abundance increased by a factor of 20 with decreasing body size. As the soil had fractal structure, the relatively flat species curve can be explained if spatial heterogeneity determines species number--for in a fractal environment, heterogeneity will be the same at all spatial scales. Community structure appeared to approach a temporary steady-state about six days after re-hydration of dried soil. A simple model based on combining the fractal character of increasing habitat area at smaller spatial scales, with the weight-specific energy requirements of protozoa, provided theoretical curves of abundance and biovolume on body size which provide a reasonable fit to real data. We suggest two possibilities--that the apparent competence of the theoretical model is fortuitous and the product of poorly understood dynamic elements of the trophic structure in the community; or that key elements of protozoan community structure in a fractal soil environment may be largely explained in terms of habitat space and energy requirements. |
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Keywords: | Corresponding author fax 44 15394 46914 |
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