response of plant community diversity to alien invasion: evidence from a sand dune time series

• Published in: Biodiversity and conservation Vol. 24; no. 2; pp. 371 - 392
• Main Authors: Vecchio, Silvia Del, Pizzo, Leonardo, Buffa, Gabriella
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer-Verlag 01.02.2015; Springer Netherlands; Springer; Springer Nature B.V
• Subjects: Analysis; Anthropogenic factors; Biodiversity; Biological diversity; Biomedical and Life Sciences; Climate Change/Climate Change Impacts; Coasts; Community ecology; Conservation biology; Conservation Biology/Ecology; Dunes; Ecology; Ecosystems; Environmental changes; Habitats; homogenization; humans; Introduced species; Italy; Life Sciences; Nonnative species; Original Paper; Plant communities; Plant diversity; Plant populations; plant response; population dynamics; Sand dunes; Species diversity; Species richness; Time series; time series analysis; vegetation; Vegetation changes; Italy; MED, Italy; Alien species; Coastal sand dune; Biotic homogenization; Habitat properties; Anthropogenic pressure; Time series
• ISSN: 0960-3115; 1572-9710
• DOI: 10.1007/s10531-014-0814-3

This study examines the process of invasion of coastal dunes in north-eastern Italy along a 60-year time series considering alien attributes (origin, residence time, invasive status, and growth form strategy) and habitat properties (species richness, diversity and evenness, proportion of aliens, and proportion of focal species). Vegetation changes through time were investigated in four sandy coastal habitats, using a fine-scale diachronic approach that compared vegetation data collected by use of the same procedure, in four time periods, from the 1950s to 2011. Our analysis revealed an overall significant decline of species richness over the last six decades. Further, both the average number of species per plot and the mean focal species proportion were proved to be negatively affected by the increasing proportion of alien species at plot level. The severity of the impact, however, was found to be determined by a combination of species attributes, habitat properties, and human disturbance suggesting that alien species should be referred to as “passengers” and not as “drivers” of ecosystem change. Passenger alien species are those which take advantage of disturbances or other changes to which they are adapted but that lead to a decline in native biodiversity. Their spread is facilitated by widespread anthropogenic environmental alterations, which create new, suitable habitats, and ensure human-assisted dispersal, reducing the distinctiveness of plant communities and inducing a process of biotic homogenization.