The small-scale species mobility in calcareous grasslands - example from southern Poland

Abstract

In this paper I use the different measures of species mobility to describe the fine small-scale dynamics of calcareous grassland built mainly by perennial species and developed in the highly heterogeneous habitat of calcareous rocks. The community showed the low dynamics on a plot-scale (100 m²) and a high one on the scale of 1 m². However, the studied species differed greatly in calculated indices: turnover rate, (T; 6-64), residence time (RT; 0.5-21.8 y) and carousel time (CT; 4-420 y) as well as the observed tendency to persistence on the spots (PERSIST) and their re-colonisation (AGAIN). This allowed to distinguish the three groups of species: (1) "core species" characterized by high frequency and low T and high CT and RT values, which determine the low dynamics of a community on the plot scale, (2) species with intermediate mobility rate and (3) the group with high mobility rate. The observed cumulative frequencies of all the studied species (CFobs) were much lower than expected under the random re-assignation model (CFRR). Moreover, they were also lower than those predicted by random immigration model (CFRI). The results showed that the "complex carousel" model rather than "single carousel" one explained better the small-scale dynamics of calcareous grasslands.