ALTITUDINAL EFFECTS ON HABITAT SELECTION OF DUNG BEETLES (SCARABAEOIDEA, APHODIIDAE) IN THE NORTHERN IBERIAN PENINSULA

The effects of vegetation cover on the abundance and species richness of dung beetles (Aphodiidae) were examined in three altitudinal zones: lowland (520-600 m), mid-altitude (950-963 m) and highland (1230-1275 In). Pitfall traps baited with Fresh cattle dung were placed in three vegetation types at each altitudinal zone: forest, heathland and past ure. Species richness was lower in forests than in the other vegetatio n types. The total abundance of beetles also varied with vegetation ty pe, but the effect was dependent on altitude. Number of individuals wa s higher in pasture at highlands and in heathland and forest at mid-al titude and lowlands. An altitudinal dependence of distribution of indi viduals between vegetation types was also found for the more abundant species in the study area. These results could be explained if the loc al distribution of individuals between vegetation types was determined by microclimatic factors, mainly temperature. Differences in altitude between sites are associated with temperature changes, determining th e habitat selection of species at each altitude.