Ecological Risk Assessment of Agrostis stolonifera and Its Relatives

The introduction of genetically engineered plants into agricultural and cultural landscapes in the U.S. continues to be a discussed with regard to their risks and benefits. Agrostis stolonifera (creeping bentgrass) is a wind-pollinated grass used on golf courses throughout the U.S., and biotechnology has been used to create glyphosate-resistant (GR) creeping bentgrass (GRCB). However, there are concerns that future release of GRCB will lead to gene flow and negative environmental impacts. The goals of this research were to: (1) assess the current distribution of Agrostis (bentgrasses) in the Northeastern U.S., (2) identify plant communities and habitats with Agrostis species, (3) quantify changes in Agrostis growth when plant competition was removed by glyphosate, and (4) assess past dispersal of creeping bentgrass from a golf course. The first project studied an area around a golf course using botanical surveys, multivariate logistic regression, and spatial analysis. A habitat suitability map showed that 36% of the cultural landscape around the golf course provided highly suitable habitat for bentgrasses, and bentgrasses co-existed in critical habitat with species of special concern. The second project involved botanical surveys in nine habitat types across two ecoregions. This study showed that non-native Agrostis species are ubiquitious, co-occurrence patterns could facilitate hybridization (gene flow), and feral creeping bentgrass was commonly found in managed areas that could be maintained with herbicides. The third project studied the effects of removing plant competition on the vegetative growth and reproductive potential of creeping bentgrass and A. gigantea (redtop). Glyphosate application greatly increased survivorship of bentgrass plants, and bentgrasses with less competition produced more flowers and vegetative growth. The fourth project used genetic markers to study the relationship between cultivated creeping bentgrass and nearby feral populations; preliminary results suggest that genes were shared between feral and cultivated populations. These four projects produced five lines of evidence suggesting that ecological risk assessment for GRCB is complex and must consider impacts to natural and cultural landscapes over time.