Influence of environmental factors on Mediterranean coastal dune vegetation: a case study in central Italy (Tuscany)

Coastal dune habitats are undeniably important ecosystems in Europe, as they contain a high ecological diversity in terms of environmental heterogeneity and variability of species composition. They are characterized by a close interaction between abiotic and biotic components along a complex coast-to-inland environmental gradient, which determines a characteristic vegetation zonation. The aim of the present work is to define which are the abiotic factors that mostly affect distribution and composition of Mediterranean plant dune communities in regard to dune morphology, sedimentological and geopedological features. The study was carried out within two protected areas of the Tuscan coast (central Italy): Migliarino – San Rossore – Massaciuccoli Regional Park and Maremma Regional Park, which are characterized by the presence of the most well-preserved dune systems of Tuscany. Topographic surveys along eleven randomly positioned transects perpendicular to the shoreline were performed on coastal systems, starting from the beach face up to the plant communities of the back dunes. Along all transects 75 plots were positioned, and then floristic and geomorphological data (such as distance to the coastline, plot altitude, slope, grain-size, sorting, pH, conductivity) were collected. The analyses revealed differences at the morpho-sedimentological and geopedological levels. Relationships between vegetation composition and geomorphological characteristics were investigated through Canonical Correspondence Analysis (CCA). In particular, three factors - distance from the sea, grain size and pH - were found to be closely correlated with the floristic composition of plant communities along the environmental gradient. These results may be useful for management and conservation actions