The oribatid community (Acari : Oribatida) on a dry cow pasture

The oribatid communities in the soil of two microhabitats of a dry cow past ure were observed The microhabitats differed by cow gazing. The vegetation cover of gazed plot was about 70% (dominated by a grass Poa pratensis and t he herbs Achillea milefolium. Veronica arvensis). The vegetation was trampl ed down and grazed by cows. The ditch plot was not grazed, but it was tramp led down, as well, with a vegetation cover of about 60% (the herbs Myosotis stricta and Thymus pulegioides prevailing). 12 samples were monthly picked from the grazed plot, 5 samples from the ditch plot, From July 1993 to Jun e 1994. Twenty species in 719 individuals were sampled. Only 4 species had stable populations, the others probably migrated from the surrounding bioto pes. Tectocepheus velatus occurred on both plots, its means of abundance we re I individual and 3 individuals per sample on the grazed and on the ditch plot, respectively. Trichoribates les trimaculatus occurred only on the gr azed plot (mean 0.5 ind. per sample). Oppositely, Zygoribatula frisiae occu rred only on the ditch plot (mean 5 ind. per sample). The seasonal fluctuat ions of the total oribatid population and the Tectocepheus velatus abundanc e differed between the studied plots. Zygoribatula frisiae and Tectocepheus velatus showed aggregation trends, these trends correlated with higher pop ulation densities. The oribatid communities of the observed plots showed gr eater similarity to the communities of disturbed biotopes like wastelands a nd fields than to other occasional pastures, meadows and grass stands in ur ban areas.