Impacts of Invasive Plant Species on the Plant Community in the Northern Great Plains

Abstract

Invasive species are encroaching rangelands in the U.S. and altering community composition and plant diversity. In the Northern Great Plains, exotic cool-season perennial grasses (Kentucky bluegrass, Poa pratensis; crested wheatgrass, Agropyron cristatum; smooth brome, Bromus inermis) have invaded rangelands with their ecological impacts less understood. This study analyzed a long-term (13-year) and landscape-scale dataset to identify potential impacts on site richness, diversity, community composition shifts, and species tolerant of invasion by Kentucky bluegrass, crested wheatgrass, and smooth brome. We found these three invaders cumulatively are associated with decreased site richness, maximum richness, and site diversity, especially native forb diversity. Clayey and loamy sites had a shift in plant community composition when invaded with Kentucky bluegrass and smooth brome. Clayey, loamy and limy residual ecological sites were more likely to be invaded, while very shallow, shallow loamy, and thin loamy sites were least likely to be invaded by cool-season invasive perennials.