Soil protozoa - An intensive study of population dynamics and community structure in an upland grassland

We focus on the key results from a 3-year intensive investigation of soil protozoan diversity sponsored by the Natural Environment Research Council (UK). The investigation enabled us to study simultaneously all major protozoan groups at a single site-the I ha area of upland grassland at the Macaulay Land Use Research Institute's Sourhope Research Station in Southern Scotland. A total of 365 protozoan species were recorded, in four broad taxonomic groups-ciliates, testate amoebae, naked amoebae and flagellates. We explored the natural history of these groups, recording species richness, growth rates, and absolute abundance, as well as community structures within the context of the fractal character of the soil. We developed methods for estimating the abundance and growth potential of the soil protozoan community, plus seasonal variation in protozoan abundance within taxonomic groups. We isolated new species, re-described others, and produced a guide to the identification of testate amoebae in soil. We produced evidence for the ubiquitous random dispersal of soil protozoa, and we found no evidence for geographically restricted distributions at spatial scales ranging from 4 m 2 to global. Roughly one quarter of global free-living protozoan diversity was recorded from this I ha site. Local and global abundances were correlated-i.e. species that are locally rare tend to be globally rare, and those that are locally abundant tend to be globally abundant. (c) 2006 Elsevier B.V. All rights reserved.