Comparative analysis of the alien vascular flora of Sardinia and Corsica

This article provides a comparison of the vascular alien flora of Sardinia (Italy) and that of Corsica (France), both territories belonging to the Western Mediterranean biogeographic subregion. The study has recorded 598 (90 doubtful) alien taxa in Sardinia (18% of the total flora) while 553 (87 doubtful) in Corsica (17%); six are new report to Sardinia and 27 to Corsica. A total of 234 taxa are common to both islands. Neophytes are 344 taxa (68% of the total) in Sardinia and 399 taxa (73%) in Corsica. The invasive component includes 64 taxa in Sardinia (13% of the alien flora) and 99 taxa (21%) in Corsica, 33 of them common to both territories. The total 740 alien taxa of Sardinia and Corsica are included in 93 families; being Fabaceae the richest. The comparison of the biological spectrum reveals that phanerophytes (202 taxa, 40%) are the most represented in Sardinia and therophytes (149 taxa, 32%) in Corsica. A study of the geographical origin shows supremacy of the American element in Sardinia (170 taxa, 34%) and in Corsica (136 taxa, 29%). The majority of taxa arrived as a result of intentional human introductions, mainly for ornamental use (247 taxa, 49% in Sardinia; 208 taxa, 45% in Corsica). Seminatural, agricultural and synanthropic are the most occupied habitats. These data show the need for joint action to stem the increasingly worrying phenomenon of the alien flora in order to reduce the negative effects on natural habitats and native flora.