EVALUATION OF DRY GRASSLAND MANAGEMENT ON THE SWISS OCCIDENTAL PLATEAU USING SPIDER COMMUNITIES (ARACHNIDA, ARANEAE)

Dry grassland is a seriously endangered habitat in Switzerland. Within the framework of the Swiss Dry Grassland Inventory, the question of w hether current management techniques meet the protection requirements was asked. The current research, using spiders as representatives of m any epigeic groups, was expected to show what influence the management has on the small animal fauna. For that reason, a valuation method wa s developed which is based on the assessment of all the captured speci es at any given site, and does not only consider a few indicator speci es. It takes into account habitat fidelity and the rarity of individua l species. The study showed that very extensive use (mowing in autumn, if possible not in every year) is required for the conservation of th e most valuable dry grass land possible. Grazing, either by sheep or c attle, was discovered to be less favourable. Rotation of used and fall ow sections of a site is recommended. In areas with different uses in consecutive years, it has been shown that spiders react quickly to cha nges in use and are therefore good bioindicators. Spiders should there fore be used in the future in case studies for the description of the actual condition or development of specific habitat types, together wi th other parameters such as vegetation.