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

非本土物种的引入及其传播被认为是对生物多样性和生态系统功能的主要威胁之一。气候变化预计将通过改变地中海地区的资源可获得性(例如水)和荒漠化风险来提高生态系统的侵入性，但科学研究很少。该项目将评估一种特征入侵者对有限资源的竞争以及随之而来的地下水可获得性下降对社区功能的改变。我们选择了一个具有很高生态价值的受保护的地中海滨海沙丘系统，那里大规模的地下水开采为研究入侵物种和本地物种之间竞争平衡的变化提供了良好的实验条件。我们将在苗木层面分析影响，以评估植物建立的变化；ii)在植物层面，就水源的时空分配和选定物种的调节机制获得主要见解；以及iii)在群落层面，评估水流、竞争和促进(如水力提升)、群落功能和系统可入侵性的变化。其目的是确定控制入侵新植物和本地物种之间的竞争平衡以及半干旱系统的入侵性的关键过程，以帮助在全球变化情景下进行风险评估。

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.