EU habitats of interest: an insight into Atlantic and Mediterranean beach and foredunes

We compared the Atlantic and Mediterranean beach and foredune habitats of European interest, focusing on floristic, structural and ecological features. We selected two representative sites of Atlantic (The Netherlands) and Mediterranean (Italy) coastal dunes. From a georeferenced vegetation database, samples of: (a) annual vegetation on drift lines (European Union habitat type 1210), (b) embryonic shifting dunes (2110), and (c) shifting dunes along the shoreline with Ammophila arenaria (2120), were selected. Floristic representativity and comparability of plot sizes were considered. For each habitat, the frequency and the fidelity of the species, the life form frequency spectra and Ellenberg ecological indicator values were assessed. We found a consistent floristic differentiation between the Atlantic and the Mediterranean coastal dune habitats and only a small set of shared species. The Italian and the Dutch annual vegetation of drift lines (1210) register a high structural similarity that strongly declines landwards. Floristic composition, life forms and Ellenberg indicator values show higher similarities among different foredune habitats of the same site than between homologous habitats of the Mediterranean and Atlantic coasts. The results confirm the current description and distribution of the habitat of European interest annual vegetation of drift lines (1210). On the other hand, the floristic, structural and ecological differences between the Atlantic and the Mediterranean embryonic shifting dunes (2110) and shifting dunes along the shoreline with Ammophila arenaria (2120) point at an inconsistency of the existing description of those habitats of European interest and highlight the need of adding in the Directive specific types that describe them in the Mediterranean basin. We suggest the introduction of two new habitat types named "Dunes along the Mediterranean shoreline with Ammophila arenaria" (new code 2280) and "Mediterranean embryonic dunes" (new code 2290) within the existing class "Sea dunes of the Mediterranean coast" (class 22 of the Annex I Habitats Directive 92/43/CEE).