Comparing the impacts of two alien species (Carpobrotus, Opuntia stricta) on plant and invertebrate communities in small Mediterranean islands.

Our study aims to assess the impacts of these IAPs on native plant and invertebrate communities in Giglio and Capraia, two small islands of the Tuscan Archipelago (Italy). Preliminary results show a decrease in plant species richness in the invaded areas compared to the uninvaded ones in both cases. We detected a greater loss of plant species in the case of Carpobrotus spp. invasion than in the case of Opuntia stricta invasion, given the ability of the former to build suffocating monospecific mats. As regards the impacts on the pedofauna, Opuntia stricta does not seem to change completely soil structure and invertebrate communities, while Carpobrotus spp. consistently with the literature, significantly modify edaphic properties and invertebrate communities.