Comparison of the invasive alien flora in continental islands: Sardinia (Italy) and Balearic Islands (Spain)

This article provides a comparison of the invasive vascular flora of Sardinia and that of the Balearic Islands. The study has recorded 53 invasive taxa in Sardinia (12% of the alien flora) while 48 (14%) in the Balearic Islands, 19 of them common for both territories. The invasive flora of Sardinia is included in 18 families; Asteraceae is the richest in taxa, followed by Amaranthaceae, while in the Balearic Islands in 19 families, with a predominance of Poaceae and Asteraceae. The comparison of the biological spectrum reveals that in Sardinia therophytes and phanerophytes are the most represented, as well as therophytes and hemicryptophytes are in the Balearic Islands. Neophytes are clearly dominant comparing to archaeophytes. A study of the geographical origin shows supremacy of the American element. The majority of invasive taxa is a result of intentional human introductions, mainly for ornamental use. The most occupied habitats in both territories are the semi-natural, agricultural and synanthropic for both territories, followed by natural habitats as coastal ones in Sardinia and wetlands in the Balearic Islands. An important part of the work deals with the environmental, economic and human-health impact