Native and alien plant species distribution on coastal dunes in Central Italy

Mediterranean coastal dunes are affected by high levels of human disturbance, particularly in the last years. Disturbance not only promotes a physical alteration that increase the invasibility of coastal dunes, but also allows the arrival of new alien plant propagules. This study examined the current distribution of the native and alien species growing on coastal dunes in central Italy, considering alien origin, invasive status and growth form strategies. The floristic sampling was carried out following the European Cartographic Project protocol. Major trends in wild plant distribution in coastal dunes were identified through Principal Coordinates Analysis (PCoA). High floristic diversity was found with consistent numbers of non-native species and clear differences between the Tyrrhenian and the Adriatic coast. There was also a negative relationship between the total number of alien species and the species richness of the plot, probably related to disturbance. America represents the continent which provides the highest number of aliens species. Most alien species were casuals while the number of invasive aliens was relatively much lower. Finally, the success of invasive aliens appeared to be related to both annual or perennial evergreen strategies.