Photosynthetic basis of temperate plant invasions: a pan-hemisphere comparison of leaf function

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Invasive plants cost millions of dollars annually in control and eradication efforts and are among the most pervasive threats to biological conservation and natural area management. However, only a small percentage of introduced plants actually become problems, and one of the biggest challenges in invasive species management is to identify whether some species are 'pre-adapted' to invade - that is, have attributes in their home range that may identify them as potential threats before they are introduced. This project compares the performance of over 40 species of invasive plants in their home and invaded ranges across fields and forests in the Northeast U.S. and in similar climates of Europe and Asia. Combined with laboratory tests of leaf chemistry and structure, the investigators will determine whether invasive plants change in their invaded range in ways that make them better able to compete with native vegetation, or whether they already possessed these competitive attributes in their home range. The combination of field and laboratory measurements across a large range of species in multiple habitats will provide a unique set of data to identify the main constraints on leaf function. The project fosters international knowledge transfer and research partnerships through exchanges of senior personnel, graduate students, and postdoctoral associates between research labs. Results will contribute to land management practices through a better understanding of mechanisms behind successful invasions of non-native plants. The project enhances STEM education by increasing resource development and outreach activities for the "Syracuse Global Change Garden", an education-based arboretum on the Syracuse campus.This project addresses the mechanism of ecological advantage of invasive plant species from two complementary angles. First, researchers will determine how plants of different photosynthetic capacity allocate a key limiting resource (nitrogen) to different leaf functions (light harvesting, carbon fixation, cell wall structure, defensive compounds) to test whether nitrogen allocation drives assimilation rate, and whether invaders have higher allocation to assimilation than co-occurring native species. Second, researchers will determine whether invasive species have altered their allocation to assimilation rate in their invaded range in response to reduced natural enemies, or whether photosynthetic advantages were already present in their native range due to different regional evolutionary histories. Finally, the investigators will test experimentally whether photosynthetic performance is the principal driver of competitive dominance in invaders. This project will be among the first to test invasion and leaf allocation theory empirically across a large number of species and habitats (forest and field environments), and to test the 'pre-adaptation' theory of species invasions at a physiological level. The project will also advance our understanding of invasion processes by determining whether shifts in leaf function commonly occur in the invaded range, and whether such processes are sufficient to alter interactions with native species.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.