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.

In this thesis, I examine the variation in plant species richness along gradients of productivity and disturbance in grasslands and forest habitats in southern Sweden, and I compare the documented patterns with theoretical predictions. Moreover, I evaluate the relative importance of habitat quality and habitat configuration for the occurrence of field layer species in deciduous forests. Finally, I present a new method for the determination of the regional species pool. To examine regional and local variation in plant species richness, I gathered data on species composition in plots of different size (0.001 - 1000 m2) in three vegetation types (deciduous forests, dry grasslands and coastal meadows) in four regions of southern Sweden (Öland, Gotland, Småland and Uppland). As predicted by the species pool hypothesis, differences in small-scale species richness of deciduous forests and dry grasslands were correlated with differences in the size of the regional species pool. Moreover, among plots large-scale diversity was predictive of small-scale diversity. Species diversity showed a hump-shaped relationship with productivity in forests, and was related to environmental heterogeneity and the size of the 'habitat-specific' species pool. In the two types of grassland examined, grazed sites were richer in species than abandoned sites. Moreover, both species composition and the representation of plants with different life-history characteristics differed between grazed and abandoned sites. As predicted by the intermediate disturbance hypothesis, species richness was highest at intermediate levels of grazing in coastal meadows. However, all the above patterns were scale-dependent, and not observed at all plot sizes. The occurrence of field layer species in deciduous forests was more strongly related to habitat quality (mainly soil factors) than to habitat configuration (forest area and isolation). Across species, low seed production, clonal reproduction and habitat specificity were negatively associated with isolation.

Havsstrandängar av EU-kod 1330 har en utbredning från atlantkusten till Öresund. Längs med Hallands kust finns salta strandängar utspridda. Habitatet är hem för många hotade och ohotade arter och har krav på finkorniga jordarter samt topografi med låg höjd och sluttning. Genom bete eller slåtter hålls strandängarna öppna. Klimatförändringar påverkar den globala havsnivån och kommer påverka strandängarna negativt. Genom en GIS-analys går det att beräkna strandsförluster samt ta fram potentiella marker för nyetablering. Resultatet visar att stora areella försluter drabbar Hallands strandängar. 87,9% av befintliga strandängar kommer gå förlorade vid en havsnivåhöjning på 1m. Resultatet visar också att det finns möjligheter för nyetablering av salta strandängar. Arealen för potentiell nyetablering är större än den strandängsareal som finns idag vilket ses som ett positivt resultat. GIS-analysen ger en indikation om vad som kommer att ske med Hallands salta strandängar men för att nya marker ska kunna fungera som strandängar måste aktiva åtgärder vidtas. Både omföring av befintliga markslag och åtgärdsprogram som kan underlätta för strandängarna att återetablera sig vid eventuella havsnivåhöjningar. / Coastal meadows of the EU-code 1330 have a range reaching from the Atlantic coast to the Öresund including all along the coastline of Halland. The habitat is home to many species, including many that are threatened and have requirements for fine-grained soils with low height and slope. Grazing and haymaking keep these species rich meadows open. Climate change, however, affects global sea level and is projected to negatively affect on the salt meadows. Through a GIS analysis, meadow losses due to sea level rise are calculated. The result shows large losses of meadows in Halland, a full 87.9% of the existing meadows are projected to be lost in a sea level rise of 1m. In addition to these concerns, the result also shows that there are opportunities for establishment of new salt meadows. In fact, the area for potential new meadows is greater than what’s available today, which is considered as a positive result. In conclusion, GIS analysis provides an indication of what may happen with salt meadows in Halland due to climate change, losses and potential compensation. However, if new areas are to serve as meadows, active measures must be taken. Necessary actions include both change of existing land types and effort that can help the meadows to re-establish themselves in the event of sea level rises.