Untersuchungen zur Spinnenfauna (Araneae) an Mittelgebirgsbächen und zur Besiedlung neu entstandener Uferstrukturen
The spider community (Araneae) of low mountains streams and investigations on the colonization of newly-developed gravel bars
In 2000 and 2001 the spider communities along ten low mountainous streams in Thuringia, Hesse and Lower Saxony were studied. Pitfall traps were set along a perpendicular transect extending from close to the water's edge to a distance of about 10-30 m away. Additonally, hand collectionwithin defined areas and time-frames was carried out. In order to investigate colonization patterns experimentally, coarse substrate was exposed simultating newly-developed bars. In total 164 species were detected. 138 species were caught only in the pitfall traps of which 75 (54%) species were caught not only in grassland but also in other floodplain habitats. 19 speciese were restricted to unvegetated banks or open stream bars. 12 species had a significantly higher abundance along restored sections compared to sections which are still regulated, and therefore would be positively influenced by increased fluvial dynamics whereas no species showed a significantly reduced abundance in response to restoration. Oedothorax agrestis, Pirata knorri and Pirata latitans are regarded as typical for the riparian spider community of low mountainous streams.
Araneae; stream restoration; gravel bars; floodplain density; colonization