Small-scale plant mobility in a species-rich grassland

Plant mobility was studied in a species-rich grassland in S. Moravia (Czech Republic) at scales from 0.0025 to 2.25 m(2). Cumulative species numbers, cumulative species frequencies and the distribution of distances between sites of occurrence in particular years were established using data collected from 1991 to 1997. The observed values were compared with null models of completely random and restricted random movement of the plants. Most plants persisted at a spot more frequently than expected from the completely random model and with a few exceptions they also spread to neighbouring subplots more often than expected. Cumulative species numbers were between the ranges predicted by the two random models and increased linearly during the 7-yr period at all scales, indicating a large species pool. The role of clonal spreading and of generative reproduction depended on the growth form of the species. I conclude that a high species richness is not necessarily linked with a high plant mobility, even if coexistence of plant species may be promoted by plant mobility.