Coastal salt-marsh zonation in Tyrrhenian 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 establishing the plant-community distribution in the Orbetello Lagoon and then carrying out a comparative analysis with other halophytic wetlands belonging to the western Mediterranean district. Floristic sampling was performed in the Orbetello Lagoon through belt transects. Cluster analyses revealed two main vegetation groups centred around Sarcocornia fruticosa and Atriplex portulacoides , and seven plant communities belonging to Sarcocornietea fruticosae and Juncetea maritimi phytosociological classes. The analysis of spatial pattern confirmed the classification results showing a typical plant 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 plant zonations located in the Iberian Peninsula showed a strong correspondence between the Italian Tyrrhenian district and the south-eastern Spanish coast, explained not only by floristic but also by ecological affinities.