Coastal salt-marsh zonation in the Thyrrenian central Italy and its relationship with other Mediterranean wetlands

The spatial patterns of salt-marsh vegetation in the central Mediterranean district (Tyrrhenian central Italy) were analysed by identifying the plant-communities distribution in the Orbetello Lagoon and then carrying out a comparative analyses with other halophytic wetlands belonging to western Mediterranean district. Floristic sampling was performed in the Orbetello Lagoon through belt transects. Cluster analyses revealed 2 main vegetation groups centred around Sarcocornia fruticosa and Atriplex portulacoides respectively and 7 plant-communities belonging to Sarcocornietea fruticosae and Juncetea maritimi phytosociological classes. The analyses of spatial pattern confirmed the classification results showing a typical vegetation zonation ranging from Sarcocornia communities in the lower areas of the lagoon to rushes dominated by Juncus acutus in more elevated areas. Alterations to this pattern may indicate the presence of disturbance (Aetheorhiza bulbosa community) or a geomorphological discontinuity (Limonium narbonense and Carex extensa communities). A comparative approach with other vegetation zonations located in the Iberian Peninsula showed a strong correspondence between the Italian Tyrrhenian district with the south-eastern Spanish coast, explained not only by floristical but also by ecological affinities