Considerazioni biogeografiche sulla presenza di specie aliene nella flora vascolare del Mediterraneo

Relations between the occurrence of aliens and biogeographic features of some territories in theMediterranean are analysed.Mediterranean islands host a higher percentage of aliens in comparison with the mainland.The most important relations have been observed between aliens occurrence and human population density in small islands and between aliens occurrence and floristic density in large islands. Other territorial factors, such as the island area and altitudinal range or the distance of the island from the mainland show a little influence as regards aliens occurrence and contribute only to a low percentage of variation.