Alien Plant Diversity in Mediterranean Wetlands: A Comparative Study within Valencian, Balearic and Sardinian Floras

Although wetlands provide an important range of environmental, social and economic services, they are increasingly subjected to anthropogenic erturbations, amongst which invasion by alien plants is particularly alarming. This paper focuses on the alien flora of wetlands from three territories belonging to the western Mediterranean area: one continental (Valencian Community) and two insular (Balearic Islands and Sardinia), providing a complete checklist for the three territories and a general comparison. In total, 380 alien taxa from 89 families have been reported, being the Valencian Community the area richer in taxa (312), followed by the Balearic Islands (151) and Sardinia (134). The invasive component includes 77 taxa, of which nine are common to the three territories - and have been recognised as the most invasive ones in Mediterranean islands -and six are considered invasive worldwide (Ailanthus altissima, Arundo donax, Cortaderia selloana, Oxalis pes-caprae, Ricinus communis and Eichhornia crassipes). Multiple Correspondence Analysis (MCA) revealed that the three territories do not show statistically relevant differences in relation to the alien species present in wetlands and their characteristics. The information on the characteristics of plants in similar habitats of the same biogeographic region provides a portrait of the current dimensions of the phenomenon in Western Mediterranean wetlands and is especially useful from the management perspective: its predictive value can be applied in establishing a prioritization of control measures of those most invasive species and will help screening new introductions with invasive potential. Keywords: continent; environmental impact; invasions; islands