Use of vegetation classification and plant indicators to assess grazing abandonment in Estonian coastal wetlands

Question: What are the effects of grazing abandonment on the vegetation composition of Estonian coastal wetlands? Location: Vormsi Island and Silma Nature Reserve in western Estonia, Europe. Methods: Local knowledge and field reconnaissance were used to identify current and historical management levels of wetland sites within the west Estonian study area. Nine study sites, with varying management histories, were selected comprising an area of 287 ha. A total of 198 quadrats were taken from 43 distinct vegetation patches in. ve of the sites. TWINSPAN analysis was used to identify community type, and a phytosociological key was constructed for character taxa. This vegetation classification was then applied within a GIS-based context to classify all the study sites, using a ground survey technique and 1:2000 scale air photos. Results: We identified 11 different brackish coastal wetland community types. Indicator species were defined with community characteristics for the seven main vegetation types readily recognisable in the field. Coastal wet grasslands were most extensive in grazed sites, or sites that had been more intensively grazed, while abandoned sites were largely composed of Phragmites australis stands, tall grassland, and scrub. Site variations based on vegetation composition were significantly correlated with past grazing intensity. Plant community types showed significant edaphic differences, with particularly low soil moisture and high conductivity and pH for open pioneer patches compared to other vegetation types. Conclusion: Abandonment of traditionally grazed coastal grasslands threatens their characteristic biodiversity. This study found that grazing abandonment reduced the extent of coastal wetland grasslands of particular conservation value. Nevertheless, plant species of conservation interest were found across the sequence of community types described. The study shows that grazing is an important factor influencing coastal wetland plant communities but suggests that vegetation distribution is affected by environmental variables, such as topography.