The Biogeography of Invasive Plants in the Continental United States

University Of Massachusetts Amherst, Amherst MA

Investigators

Abstract

Invasive plants are species introduced by humans to new parts of the world where they not only survive but thrive in novel habitats. Although many individual invasive plants have been studied extensively, basic understanding of the biogeography of invasive plants as a broader group remains limited. This research project will analyze and project the geographies of invasive plants in their non-native ranges within the continental U.S. The investigators will compare the geographic traits of invasive species to those of non-native species that are established but are not known to be spreading or negatively affecting natural systems. Project results will enhance fundamental knowledge of unique biogeographical patterns of invasive plants in their non-native range; knowledge that is critical for forecasting invasion risk. The project will provide new insights regarding how geography influences the factors affecting the spread of new species into ecosystems in the invaded range, including identifying "hot spots" of future invasion risk. The investigators will create spatially explicit invasion risk models for the nation to guide policy and management, and they will produce state-level "watch lists" of invasive plants likely to become problematic under potential future climate conditions. The project also will contribute to improved education in science, technology, engineering, and mathematics (STEM) fields through graduate training and expansion of undergraduate participation in research. Invasive species have been identified as one of five prominent threats to global ecosystems by the Millennium Ecosystem Assessment. Despite the prominence of the problem, there is a paucity of basic scientific understanding regarding what sets these species apart, especially why invasive species are invasive. Considerable effort has gone into addressing this question through ecological studies, but relatively few researchers have focused on understanding the geography of invasive species. Invasive plant research tends to be biased towards a handful of very well-studied species, which inhibits understand of invasion patterns more generally. Furthermore, lumping invasive and established species together conflates the influence of human introduction with the influence of biology on the geographic distributions of invasions, thereby hindering identification of patterns characteristic of invasives. This project will focus on evaluating the validity of answers to two core sets of questions: (1) For non-native plants in the continental U.S., how does non-native range geography differ for plants that are established vs. those that are invasive? (2) What is the current geography of establishment and invasion risk across the U.S., and how might they shift with changing climatic conditions? The investigators will use occurrence records for invasive plants compiled from museum and management records to model potential distribution for all 1,000 invasive plants under current and projected future climate conditions. This analysis will enable creation of a spatially explicit model of "hot spots" of future invasion risk across the continental U.S.