Alien versus native species on coastal dunes in Central Italy. Plant distribution and traits.

This study is part of a project searching for general mechanistic patterns of plant invasions in Mediterranean coastal sand dunes ecosystems. In this work we propose a vascular flora census and a comparative study of plant traits (for alien and native species) between the Italian Thyrrenian and Adriatic coast. We test the hypothesis that alien invasive species from Mediterranean sand dunes share common biological traits across different environmental conditions. In each site the vascular flora sampling was carried out using the approach of European Cartographic Project. List of vascular plants, information about life forms, chorotypes, physical environment and disturbance were stored in a data-bank. Most common native and alien species (among them naturalized and actual and potential invaders) were selected. In order to perform a functional classification, we focused on the characterization of plant traits based both on measured and on published information. Morphological traits (plant height, plant growth form, leaf surface and leaf consistency) and regeneration traits (seed mass, dispersal mode, phenology (onset of flowering) and clonality or resprouting ability) were considered. Functional groups were determined using multivariate analyses. At present, more than 650 species of vascular plants were registered on sand dunes of Central Italy, with 86 taxonomic families. Among these species, 50 were considered aliens. The comparative analyses of plant traits showed different functional groups among aliens species and also different distribution patterns between the Tyrrhenian and the Adriatic coast.