Predicting invasion outcomes of non-native plants using a traits-based framework

Background/Question/Methods

Identifying potentially invasive species and their impacts is of critical importance to the prevention and mitigation of biological invasions. However, the definition of invasiveness is incredibly complex, reflected by the diversity of traits and impacts associated with currently known invasive species. For that reason, invasiveness should be analyzed in terms of success along the different axes of invasion 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 functional and life history traits of 1,050 invasive plant species and their distributions in the conterminal United States. We then used data on these traits as proxies of different mechanisms, such as niche breadth, aggressiveness, and capacity for adaptation, to test their effects on the number of U.S. counties where the species is currently established. We tested these effects while taking into account each species’ minimum residence time in the United States.

Results/Conclusions

Our results suggest that niche breadth may be the leading mechanism in determining the size of an invasive plant species’ invasive range. Specifically, it appears that a species’ elevation range and hardiness determine how widespread it may become 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 this specific aspect of invasion success. Ultimately, a comprehensive understanding of these processes could facilitate the forecast of impacts of potentially invasive species.