Main Driving Factors for Seacoast Vegetation in the Southern and Eastern Baltic

This study aimed to determine the role of environmental factors in the pattern of vegetation related to marsh soils, which are rare in the Baltic coastal zone. It was assumed that the pattern of vegetation directly affected by seawater depends on seawater salinity, and in general reflects the decreasing salinity gradient of the Baltic Sea. The research of vegetation and soils (0-25 cm) has been undertaken on 11 selected sites along the Baltic seacoast in Germany, Poland and Estonia. According to TWINSPAN classification, five plant communities were distinguished: the Puccinellia maritima-Spergularia marina community, Juncus gerardi community, Agrostis stolonifera-Phragmites australis-Scirpus lacustris ssp. tabernaemontani community, Phragmites australis - Calystegia sepium community and Elymus repens community. A canonical correspondence analysis showed that the most important environmental factors influencing vegetation differentiation were: electrical conductivity of the saturation paste extract, hay/pasture management, redox potential, soil moisture and actual pH. In conclusion, the spatial distribution of the investigated vegetation and soil properties along the Baltic Sea shore were inconsistent with the spatial salinity gradient of the open surface seawater, but was significantly dependent on local conditions. This was confirmed by the highest soil salinity and most abundant occurrence of Salicornia europaea in Estonia.