Disentangling the effect of coastal erosion and accretion on plant communities of Mediterranean dune ecosystems

Coastal erosion, in combination with sea-level rise and extreme meteorological events, is globally threatening the biodiversity and functioning of dune ecosystems, along with the essential ecosystem services they provide. In this study, by quantifying the intensity of erosion and accretion processes occurred over two decades in a wide Mediterranean dune system, we explore the influence of sand processes on dune plant communities focusing on a large portion of the sea-inland gradient. In particular, using different regression techniques, we assess how erosion and accretion processes affect richness, cover and diversity of Mediterranean coastal dune plant communities. Results show that the influence of coastal erosion and accretion varies along the sea-inland gradient, with foreseeable consequences on the integrity of dune systems. The negative effect of erosion seems to be particularly marked on foredunes, which play a key role in dune formation, while decreasing in landward communities. On the other hand, accretion features an opposite trend, unexpectedly influencing only Mediterranean shrubs. We highlight the importance of monitoring the effects of erosion and accretion processes on coastal vegetation in order to support the conservation of dune habitats and preserve the associated ecosystem services, especially in the context of climate and human-induced changes.