Evaluation of ecological measures: spiders and butterflies

To evaluate the impact of set aside land (ecological compensation areas) on biodiversity, spiders and butterflies were used as indicators in two regions in 1997 and 1998. The first results show that the impact of ecological compensation areas depend on the indicator and the type of area. In a typical region of arable crops, wildflower strips offer a food source for adult butterflies, but spiders do not particularly react to their presence. In an intensively cultivated grassland region, extensively managed meadows are more visited by butterflies than intensively managed meadows, but species with particular life-cycles and feeding requirements were not observed. Spider species richness is not higher in extensively managed meadows in comparaison to intensively managed ones but the extensively managed meadows have particular groups of species.