Spatial patterns and floristic composition of plant communities in coastal salt marshes of southeastern Sicily (Italy)

Abstract The results of a study on the spatial patterns, composition and structure of coastal salt marsh plant communities of a central Mediterranean area are presented. Eleven transects perpendicular to the salt marsh shore were selected in southeastern Sicily. For each transect, the floristic composition and cover were determined using standard relevé methods, collecting 220 plots. The plot data were analysed using classification (Unweighted Pair Group Method with Arithmetic Mean, similarity ratio) and ordination methods (Detrended Correspondence Analysis). A total of 15 plant communities with specific floristic compositions were recognized, mainly distributed in two different habitats: a regularly flooded lower zone and an irregularly flooded upper zone. According to detrended correspondence analysis, the spatial patterns of plots follow an ecological gradient that can be related to flooding time, the main ecological factor affecting the distribution of communities in the salt marshes. Moreover, floristic richness and diversity index increased from the lower zone towards the upper zone. The regularly flooded soils contain the lowest shrub abundance and the lowest diversity, whereas the irregularly flooded soils have the highest shrub abundance and the highest diversity.