Assessment of the impacts of Opuntia stricta on vegetation and invertebrates in a small Mediterranean island.

The extensive use of the Opuntia genus as food and ornamental plant has made it one of the most widespread in the Mediterranean basin. Especially, in the small Mediterranean island, Capraia (Tuscany Archipelago, Italy) the invasive alien species, Opuntia stricta, is the most pervasive one. In order to have a more comprehensive view of the impacts of this species at various levels in Capraia Island, our study aims to assess the impacts of this lAP not only on plant communities, but also on native microinvertebrates, and soil chemistry. For what concern the preliminary vegetation results, they show significant impacts on the composition of plant species but not as regards the diversity indices. Instead, preliminary results on soil physico-chemical properties and microbial activities show that there is a greater difference at the spatial level rather than between invaded and uninvaded areas. Hence, the invasion of O. stricta seems not to significantly change the soil characteristics, and probably also the soil fauna.