An ecological investigation of spiders in coastal meadows : in Uppland and Sörmland

Abstract: Coastal meadows are important habitats for many animals, but the habitats are threatened by changes in land use such as abandonment of grazing. On the Swedish East coast, many coastal meadows can be found and they are highly influenced by the brackish marine environment which supports large populations of spiders. Spiders are the most abundant carnivorous arthropods on coasts of Uppland, and it is known that spider communities are closely associated with the vegetation. This study aims to investigate the spider communities in coastal meadows in Uppland and Sörmland, Sweden, and spiders were collected with pitfall traps and vacuum suction sampling. The meadows are under varying management either grazed by cattle, abandoned or has never been managed, and this is expected to influence the vegetation structure. The vegetation was on average higher in the abandoned sites, but the coefficient of variation in height was similar. The Lycosid community was not influenced by the vegetation structure, but was extremely abundant. Mean height of the vegetation had a positive influence on species richness, and a higher number of species were found in the abandoned and grazed meadows compared to the non-managed meadows, in the analysis of the vacuum sampled community. The communities were distinctly different in meadows under different management, and this was influenced by the height of the vegetation. Management of costal meadows is therefore also important for conserving diverse communities of spiders, but clearly some spiders prefer the less species rich un-managed habitats, so consideration should be taken to this.