Invasive species represent one of the most serious threats to vegetation community composition and ecosystem function worldwide. However, science-driven techniques needed to restore these invaded communities are lacking. One specific hypothesis is that community resistance to invasion can be strengthened by selecting native species that are similar to invasive species in resource use, thus increasing competition. This is based on the theory of limiting similarity, which posits that there is a finite limit to the similarity between the resource-use of co-existing species. The first step in elucidating the utility of limiting similarity approach to restoration is quantifying differences in resource use between native and invasive species across a variety of invaded systems. Through this project, functional trait data will be collected from native and invasive plant species in two vegetation communities in Spain. The data will be combined with existing data from three other mediterranean-climate ecosystems (MCEs) to test how one ecological theory ? limiting similarity ? can be used to restore invaded vegetation communities. Results from the present Catalyzing research will be incorporated into a subsequent proposal that will use these trait data to select native species that are functionally similar to invaders and to monitor community composition in these restored systems over time.
Results from this research will contribute to an understanding of conservation issues in MCEs, which are highly diverse and increasingly threatened by human activity. The work will directly contribute to the practice of restoration by exploring how easy-to-measure plant traits can be used to select native plants that will increase invasion resistance of restored communities. In addition, this project will promote a new collaboration between an early career, female U.S. scientist at an undergraduate institution and an internationally renowned plant ecologist in Spain. An undergraduate student will participate in the activities in Spain, benefitting from close faculty-student mentoring and the opportunity to engage in international research at the early stage of an academic career.
Mediterranean-climate ecosystems (MCEs) are biodiversity hotspots and are highly vulnerable to degradation by a number of anthropogenic activities, including land use change, nitrogen deposition, climate change, and invasive species. This project examined how native and invasive plant species occurring in five MCEs use resources (light, water, nutrients) with the goal of identifying a common suite of traits that characterize invasive species in these systems. In restoring invaded plant communities, resistance to invasion may be strengthened by selecting native species that are similar to invasive species in resource use, thus increasing competition. Thus, our results will have implications for restoring native plant diversity in MCEs. We sampled eight plant communities in all five MCEs (California, USA; Perth, Australia; Santiago, Chile; Bolonia, Spain; Cape Town, South Africa). Our results are still being analyzed and we have no results to report at this time. This project had several broader impacts. First, the project advanced the research program of an early-career female scientist by providing funds to initiate collaborations with two renowned international plant ecologists. Second, the project supported faculty-student mentorship: two female undergraduates (one from an underrepresented group in the sciences) assisted with data collection and analysis. Lastly, this work also directly contributed to the practice of ecological restoration by exploring how easy-to-measure plant traits can be used to select native plants that will increase invasion resistance of restored communities. Identifying science-driven restoration techniques for MCEs is essential to their conservation.