THE IMPACT OF GRAZING ON COMMUNITIES OF GROUND-DWELLING SPIDERS (ARANEAE) IN UPLAND VEGETATION TYPES

Adult spider communities were sampled by pitfall trapping over a 24-mo nth period in plots subjected to a range of grazing regimes on five ve getation types on a hill farm in County Antrim, north-east Ireland. Sp ider community composition was influenced by vegetation type and grazi ng regime. Variation in the number of individuals and species diversit y was also apparent between vegetation types and grazing regime. Plots grazed by all herbivores were characterised by the predominance of sp ecies characteristic of disturbed land. Inbye land and areas where gra zing had ceased had characteristic coloniser species. The spiders Erig one dentipalpis, Allomengea scopigera and Centromerita bicolor were tr apped with greater success in vegetation types where grass species dom inated.