Salt marsh vegetation on the Croatian coast: plant communities and ecological characteristics

There is a lack of a comprehensive study of eastern Adriatic salt marsh vegetation with special attention to plant–soil relationships that determine individual plant assemblages. We surveyed 41 sites of salt marshes on the Croatian coastline in order to classify their vegetation by numerical methods and to compare the resulting groups in terms of soil chemical properties. A clear zonation between plant communities along the hydro-sequence was identified and was well represented by the dominance of individual diagnostic species. Two large vegetation groups were detected, well distinguished by mean species richness and soil properties. The first group, assigned into the classes Thero-Salicornietea and Sarcocornietea fruticosae, contains three subgroups of succulent, sparse stands of species-poor vegetation on the mudflat zone flooded by sea water, characterised by high salinity, electric conductivity, exchangeable Mg and K, and low nutrient content (total nitrogen, organic carbon) of the substrate. In the second group, tall rush communities (class Juncetea maritimi), three subordinate clusters, were identified, occurring in the upper, brackish zone with infrequent tides. Their soils had low salinity and electric conductivity and increased total nitrogen, organic carbon and exchangeable Mg and Ca. Vegetation within the second group occurring in the uppermost tidal zone had the highest species-richness, nutrient content in the soil and the lowest salinity. It has not been previously identified. Here, we described it as the new association Limonio narbonensis–Caricetum divisae.