ORIGINAL PAPER Are there habitats that contribute best to plant species diversity in coastal dunes? A. Acosta Æ M. L. Carranza Æ C. F. Izzi Received: 15 February 2008 / Accepted: 28 August 2008 Ó Springer Science+Business Media B.V. 2008 Abstract The following paper describes patterns of diversity across major habitat types in a relatively well preserved coastal dune system in central Italy. The research addresses the following questions: (a) whether different habitats defined on the base of a land cover map support similar levels of biodiversity in terms of vascular flora richness and number of rare and endangered species, and (b) how each habitat contributes to the total species diversity of the coastal environment. A random stratified sampling approach based on a detailed land cover map was applied to construct rarefaction curves for each habitat type and to estimate total species richness. In addition, the number of exclusive, rare and endangered species was calculated for each habitat type. Results highlight the importance of the coastal dune zonation (embryo-dune, main dune, transition and stabilized dune) in species conservation because they harbour progressively higher species richness. However, differences among these habitats were not significant, so no particular species rich ‘‘hot- spots’’ could be evidenced. On the contrary, rarefaction curves show that the upper beach (strand) habitat sustains significantly smaller number of species, but surprisingly, it shows the highest rarity values and highest proportion of endangered species. Therefore, for the establishment of successful biodiversity conservation programs in these coastal environ- ments, it is imperative not only to conserve biologically rich hotspots but also to include species poor habitats containing endangered or unique elements. Thus, the complete coastal vegetation mosaic including all coastal habitats is important to adequately char- acterize the plant species diversity of coastal dune ecosystems. A. Acosta (&)  C. F. Izzi Dipartimento di Biologia, Universita ` di Roma Tre, V.le Marconi 446, 00146 Rome, Italy e-mail: acosta@uniroma3.it C. F. Izzi e-mail: c.izzi@uniroma3.it M. L. Carranza Dipartimento di Scienze e Tecnologie per l’Ambiente e il Territorio, Universita ` degli Studi del Molise, Contrada Fonte Lappone, 86170 Isernia, Italy e-mail: carranza@unimol.it 123 Biodivers Conserv DOI 10.1007/s10531-008-9454-9