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Several regulatory and management tools are commonly used to prevent negative effects of human trampling on sand dune habitats, but few studies have attempted to evaluate the effects of boardwalks on dune vegetation. We aimed to evaluate changes of species richness and cover, floristic composition and ecological functional guilds among different dune habitats 2 years after the boardwalks had been established, highlighting those habitats mainly affected by these changes. In a Special Protection Area of Molise region (Italy), we sampled 53 square plots before the installation of five wooden boardwalks (control plots) and 57 plots after the boardwalks had been set up (testing plot), across the whole dune system ranging from the upper beach to the pine forest. We compared species richness through rarefaction curves, considering two plant functional groups: focal species (characteristic and diagnostic) and ruderal/exotic species. We finally compared florist composition and cover changes between time intervals, dune habitats and functional groups. In all habitats the total plant richness of testing plots was higher than in the control plots. In beach and mobile dunes habitat focal species drive the increase in both species’ richness and cover. Dune grasslands proved to be the most affected by the presence of ruderal and exotic species, while the more stable fixed dunes habitat was less affected by species changes. Only 2 years after the boardwalks having been set up, we have found a rapid recovery since human trampling was limited. The use of boardwalks could be an effective tool for reducing negative impact of bathing tourism on coastal dunes and requires little and inexpensive maintenance.

Multi-year temporal studies are invaluable tools for monitoring changes in biodiversity through time. However, their applications in coastal ecosystems are still scarce. We investigated temporal trends in coastal dunes analyzing a set of 858 randomly-sampled georeferenced relevés performed between 2002 and 2015 along Central Italy’s sandy coastlines. Specifically, we explored changes in species richness and cover of targeted sandy habitats, we investigated trends in the cover of selected psammophilous native species and we assessed patterns of invasion by means of regression techniques. We observed a significant decrease in species richness and cover of the dune grasslands habitat. The species-level analysis confirmed a negative trend for two characteristic species of dune grasslands, Cutandia maritima and Medicago littoralis, while revealing a similar decline for Crucianella maritima and for Ammophila arenaria subsp. australis, key species of mobile dunes. The most striking trends emerged analyzing patterns in the cover of an invasive alien species, Carpobrotus sp., which showed a concerning increase in shifting dunes. In conclusion, our analyses reveal concerning changes involving dune grasslands, and at the same time hint at “early warnings” of degradation processes traceable in shifting dunes.