EFFECTS OF HABITAT TYPE AND GRASSLAND MANAGEMENT-PRACTICES ON THE BODY-SIZE DISTRIBUTION OF CARABID BEETLES

The carabid faunas of fifty grassland, nine moorland and thirty-nine w oodland sites were assessed using pitfall traps. For each site, the av erage carabid body size was expressed as the Weight Median Length, or WML, being the median point of the carabid biomass distribution. The v ariation in WML among and within the ninety-eight sites was examined i n relation to measured environmental variables. Generalised Linear Int eractive Modelling was used to generate equations describing these rel ationships. Overall, the maximum median body sizes were achieved in mo orland, woodland and less intensively managed grassland. Within grassl and, the level of management had the greatest effect on carabid size, and all other environmental variables except soil organic matter could be neglected when considering the effect of intensification of manage ment. It is concluded that disturbed habitats support a carabid fauna of smaller average body size. Some possible reasons for this are discu ssed.