Beaches under pressure - effects of human access on vegetation at Baltic Sea beaches

Questions: How do cover, richness and composition of plant species vary according to different levels of beach access? What shifts in plant traits occur along gradients of tourism intensity? What recommendations regarding the sustainable management of Baltic Sea beaches can be proposed? Location: Southern Baltic Sea beaches in Germany. Methods: In this study, the species composition of vascular plants on beaches with differing accessibility to tourists was analysed at the southwest Baltic Sea coast. In total, 894 vegetation plots were evaluated in order to determine vegetation changes along the sea-inland gradient due to different levels of human accessibility at beaches. Releves were conducted as repeated transects from the beach ridge to the shore. Shifts in vegetation characteristics due to different levels of tourism access were analysed at the level of plant communities and plant species traits. Results: Species richness did not differ significantly between the levels of accessibility. Vegetation cover significantly increased with distance to the shore and was highest in the upper shore area of closed beaches (52.0 +/- 2.7%). Corresponding to the increase in beach access, we observed an increase in ruderal species and a decrease in typical beach species of the vegetation class Honckenyo-Elymetea. Tourism access and distance to the shoreline had a decisive influence on the distribution of plants with selected plant traits. In particular, at accessible sites, a loss of plants with leaves having high scleromorphy was recorded. Conclusions: Increased beach access results in a loss of typical beach plant species. Changes in vegetation characteristics are considered to alter the function of the beach ecosystem. Based on these results, we derived spatially differentiated management measures for excluding the most sensitive beach areas from tourism.