Local and regional species richness in communities of surface‐dwelling grassland Collembola: indication of species saturation

The relationship of local (LSR) versus regional species richness (RSR) provides an insight into patterns of species diversity. We examined communities of surface‐dwelling Collembola in ten differently sized, temperate dry grasslands. To register genuine manifestations of saturation or proportional sampling, accurate determination of species pools is essential. Therefore. we applied the first‐order jackknife as a species‐richness estimator for LSR and introduce here a method for defining a range within which the real RSR probably lies. Our data exhibited similar levels of local Collembolan species richness across all regions, largely independent of regional richness. This curvilinear relationship between LSR and RSR indicates that a limit is present for the number of species that can locally coexist, suggesting local interactions and community saturation. We discuss several conditions that may cause pseudo‐proportionality or pseudosaturation, i.e. artificial relationships between LSR and RSR, Furthermore, we test the LSR‐RSR relationship for possible effects of autocorrelation.