Plant invasions in Mediterranean island ecosystems. Impacts to biodiversity and risk of invasion in the Tuscan Archipelago: from ecology to management.

The researches within this PhD thesis focus on the problem of non-native plants in the Tuscan Archipelago, particularly investigating distributions, invasiveness, impacts on diversity of alien plants and management options for the invasive alien plants. The PhD thesis is here presented as a collection of the resulting contributions, including poster presented at international conferences and papers published or in preparation. The investigations on the distributions and invasive status of alien species in the Tuscan Archipelago led to the preparation of a checklist of the alien flora of the Tuscan Archipelago. The ecological traits of plant invasions in the Tuscan Archipelago were explored towards the research on potential impacts due to invasive species on the Island of Elba. These studies allowed us to detect the impacts on plant richness and diversity, soil chemical properties and soil microbial communities of Acacia dealbata and impacts on plant communities of Acacia pycnantha. Finally, regarding management aspects, the work dealt with the evaluation of the risk of invasion through two different approaches. The invasiveness of alien species in the Tuscan Archipelago was assessed by use of risk assessment procedures. We assessed the risk of invasion related to 212 alien plants in Tuscan Archipelago testing two different procedures of Weed Risk Assessment. The risk of invasion by alien species on habitats worthy of conservation was investigated adopting Species Distribution Models. The potential distributions of six harmful invasive plants in Mediterranean Ecosystems were merged with the density of habitat win the Island of Elba to obtain a MAP of Risk of invasion. Thanks to the exploration of these topics we highlighted different aspects of the biology of invasions in this representative Mediterranean island ecosystem. We provided both theoretical contributions to the issues on the impacts of invasive species and technical tools for conservation, such as monitoring of the current distributions and evaluation and prioritization of risk of invasion.