Changing ground water levels: the impact on an invasive species and native plant communities in a Mediterranean dune ecosystem

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The introduction of non-native species and its spread are recognized to be one of the major threats to biodiversity and ecosystem functioning. Climate change is expected to enhance ecosystem invasibility through changes in resource availability (e.g. water) and the risks of desertification in Mediterranean areas, however scientific studies are rare. This project will evaluate specific traits of a characteristic invader towards competition for limited resources and the consequent alteration of community functioning under decreasing ground water availability. We selected a protected Mediterranean costal dune system of high ecological value, where large-scale extraction of ground water provides excellent experimental conditions to study changes in the competitive balances among invasive and native species. We will analyse the effects i) at the seedling level to evaluate changes in plant establishment; ii) at the plant level to gain major insights on the spatial and temporal partitioning of water sources and regulating mechanisms of selected species and iii) at the community level to evaluate changes in water flow, competition and facilitation (e.g. hydraulic lift), community functioning, and changes in invasibility of the system. The aim is the identification of key processes controlling the competitive balances between invasive neophytes and native species and invasibility of semi-arid systems to contribute to a risk assessment under global change scenarios.