COS 150-1 - Predicting macroscale success of non-native plants in the United States using a traits-based framework

Abstract: Identifying potentially invasive species and their impacts is of critical importance to the prevention and mitigation of biological invasions. Functional traits may serve as potential proxies for ecological mechanisms that drive invasion success, and therefore are a promising framework for predicting future outcomes of species that have been recently introduced. However, invasion success is a concept that is hard to define, reflected by the diversity of traits and impacts associated with currently known invasive species. For that reason, invasiveness should be analyzed in terms of specific outcomes. In this study, we focus on understanding the mechanisms that influence the distribution of invasive plants, specifically the size of their invasive ranges. We collected data on the distribution of all non-native plant species in the conterminal United States as documented by the Early Detection and Distribution Mapping System (EDDMapS). We also collected data on functional and life history traits of these species from various traits databases. These traits data were then summarized as proxies of different mechanisms, such as niche breadth, aggressiveness, and capacity for adaptation, to test the relationships between these ecological mechanisms and the size of each species’ invasive range (i.e., the number of U.S. counties where the species is deemed to be present). We tested these effects while taking into account each species’ minimum residence time in the United States.

We present a preliminary watchlist of recently introduced non-native plant species that could potentially become widespread invasive threats across the conterminous United States. Our results suggest that climate matching may be the leading mechanism in determining the size of an invasive plant species’ invasive range. Specifically, it appears that species whose native continents share similar climates to the United States and species with broad elevational and hardiness tolerances are more likely to be more widespread in the conterminal United States. Preliminary results also suggest that phylogenetic relatedness to plant species native to North America may play another role in invasive distribution. The findings from this study provide important insights into the mechanisms underlying invasion success at the macroscale. Ultimately, a comprehensive understanding of these processes could facilitate the forecast of impacts of potentially invasive species.