title: Protozoan community structure in a fractal soil environment.
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.
authors.affiliation: CEH-Windermere, The Ferry House, Ambleside, Cumbria, UK. bjf@ceh.ac.uk
authors.forename: B J
authors.initials: BJ
authors.lastname: Finlay
authors.forename: T
authors.initials: T
authors.lastname: Fenchel
mesh_terms: D000818:Animals; D004777:Environment; D056890:Eukaryota / Q000145:classification / Q000302:isolation & purification; D011156:Population Density; D012987:Soil / Q000469:parasitology*
chemical_list: D012987:Soil