Sand dune species distribution and size variations in two areas inside a natural protected area subjected to different human disturbance

Sand dune species were analyzed across two areas included in the “Roman Coastal State Nature Reserve” (Italy): Ostia (O) and Marina di Palidoro (P). Significant variations in species distribution, dry mass and size over the gradient from the water-edge toward the inland between O and P were observed. Species colonize O, on an average, at 79 m from the water-edge extended along the gradient toward the inland over a length of 26 m. PD is 40.8 ± 9.9 plants·m−2. Ononis variegata and Elymus farctus have the highest PD (15.4 ± 1.3 plants·m−2), followed by Silene colorata and Sporobulus pungens (4.3 ± 3.9 plants·m−2), by Cakile maritima, Echinophora spinosa, Eryngium maritimum, Ammophila arenaria, Anthemis maritima, Cyperus capitatus, Medicago marina and Calystegia soldanella (<0.5 plants·m−2), with C. soldanella having the lowest PD (0.02 plants·m−2). On an average, in P, the species colonize the dune at 17 m from the water-edge for a length of 46 m toward the inland, PD is on an average 21.5 ± 16.1 plants·m−2. S. pungens, E. farctus and O. variegata have the highest PD (6.0 ± 2.4 plants·m−2), followed by C. capitatus (2.1 ± 4.7 plants·m−2), by S. col-orata and A. maritima (0.4 ± 0.1 plants·m−2) and by E. spinosa, E. maritimum, M. marina, Pancratium maritimum and C. soldanella (0.2 plants·m−2). The results underline a larger species presence along the gradient from the water-edge to- ward the inland in P site compared to O site where, on the contrary, plants exclusively colonize the inner dune area due to the strong human disturbance which causes the foredune to become flat. Nevertheless, the presence of the most im- portant autoctonous sand dune species (on an average, 15.3 ± 0.5 species) can provide information for restoring the perturbed dune areas when preparing management strategies considering that the maintenance of coastal areas depends on the maintenance of native species.