The Habitat Suitability Model (HSM) project was conducted in central Connecticut in The study site (8.5 km 2 ) surrounded a golf course that uses creeping bentgrass in putting greens and fairways (Figure 1A). Other criteria used in selecting the study site were the presence of natural areas, roads, utility right-of- ways, old agricultural fields, and recreation areas. These diverse land uses were of interest because they are managed ecosystems that could have herbicide applications to remove weeds or invasive plants. The research team visited 290 random plots (10 m 2 ) in the study site to collect botanical and ecological information (Figure 1A). Environmental variables were recorded at each plot including percent tree canopy cover (sun/shade), percent area covered by leaf litter, wetlands status, invasive plants present, bentgrass species present and other features. The HSM is built upon survey data and remotely-sensed GIS layers. This task can be couched as a statistical problem using multivariate logistic regression (MLR): given an observed dichotomous outcome (the presence or absence of bentgrass species) and a set of observations of explanatory variable factor, the model will estimate the probability of finding bentgrass in an unobserved location subject to the same explanatory factors. This poster presents the first efforts to generate a statistical model using the survey data collected in Future efforts will improve and validate the model. Characterizing Bentgrass Distribution with Spatial and Biological Data To Support Ecological Risk Assessment in Connecticut Ahrens, C 1, J. Chung 2, T. Meyer 2, and C. Auer 1 1 Department of Plant Science, University of Connecticut 2 Department of Natural Resources and the Environment, University of Connecticut The survey of 290 randomly-chosen plots in the HSM study site showed that 77% of bentgrass populations were associated with little to no tree canopy (Table 1). This is consistent with the requirement that most grass species have for high light conditions. Over 92% of the non-native species (A. stolonifera, A. gigantea and A. capillaris) were found in areas covered predominantly by herbaceous plants (Table 1). The survey suggests that there is positive correlation between non-native bentgrasses and invasive plant species (Table 1). More importantly, some bentgrass populations lie within areas of critical habitat for state-listed animal and plant species, including species that are endangered in Connecticut (Figure 1, B-C.). These observations are important because species at both ends of the spectrum (invasive species and endangered species) may need management regimes that could include herbicide. If HR creeping bentgrass escapes from the golf course, these management practices could be compromised. A Habitat Suitability Model ( Multivariate Logistic Regression using three environmental variables) was generated to examine the ability of specific environmental features to predict the presence/absence of bentgrass populations. The most complex model had the lowest AIC number and explained the most variability (Table 2). Based on that model, locations with little or no forest litter, the absence of wetlands, and little or no tree canopy (high light conditions) have the highest probability of supporting native and/or non-native bentgrass species. Observations by the research team (Table 1) support this conclusion. In future, efforts will be made to test other environmental variables and validate the model. If a HSM for bentgrass is validated, it suggests that simple environmental variables can be useful for land managers and government agencies tasked with predicting bentgrass gene flow or monitoring transgene movement. These models could help predict the degree of risk to critical habitats that need herbicide management to help preserve state-listed species. This work is supported by grants from the USDA Biotechnology Risk Assessment Grant Program and the University of Connecticut. ABC All new technologies carry both benefits and risks. For example, medical research tests the effects of new drugs before they are approved for sale. Likewise, genetically- modified (GM) crops must be assessed before they are released into the environment. Our research examines the potential for gene flow and negative ecological impacts from the release of GM plants. Gene flow can produce hybrid offspring with transgenes and novel traits that could change the ability of the plant to survive and spread. If hybrid offspring have an advantage in the environment, they could become invasive and/or affect other components of our ecosystems. Creeping bentgrass (Agrostis stolonifera) is a common, non-native turfgrass that is a weed and could hybridize with other Agrostis species. At present, United States Department of Agriculture (USDA) is considering an application to allow commercialization of genetically-modified herbicide-resistant (HR) creeping bentgrass. If approved, there is a probability that the transgenic HR trait would move into feral bentgrass populations and could create environmental hazards over various temporal and spatial scales. Connecticut has three native bentgrasses and four non- native bentgrasses that form a hybridizing complex. The non-native bentgrasses (A. stolonifera, A. gigantea, A. canina and A. capillaris) are highly adaptable, weedy species that are widely distributed in wet meadows, agricultural fields, lawns, and roadside areas. The escape of HR creeping bentgrass could lead to risks that are difficult to accurately predict such as more harmful weed management practices, genetic pollution, increased ‘weediness’, and loss of community and ecological diversity (see photographs). This project aims to predict potential ecological risk by modeling bentgrass distribution in New England, and the probability that gene flow and seed dispersal will move the HR trait into feral and cultivated bentgrass populations. This poster reports on the development of a Habitat Suitability Model using site visits, ecological variables and GIS data for a golf course study site in central Connecticut. INTRODUCTION METHODS RESULTS and discussion Figure 1. The Habitat Suitability Model involved surveys of 290 plots. A) Occurrence of bentgrass species. Yellow dots = no bentgrasses, red dots = bentgrasses present. B) Study site with overlay of Connecticut Natural Diversity Database. The pale circles represent areas where state-listed species are found. C) Co- occurrence of critical habitat for state-listed species and bentgrass populations found during the surveys. Photographs: Habitats that could be impacted by release of herbicide-resistant bentgrasses. The freshwater marsh (left) has invasive purple loosestrife and non-native bentgrasses. Spraying glyphosate to control purple loosestrife could allow spread of HR bentgrass populations. Roadside plant communities (right) could be altered by weed control with glyphosate, a herbicide commonly used by homeowners. In Connecticut, many sunny roadside areas have one or more bentgrass species in the plant community. Table 2. Models produced using bentgrass survey data and STATA software. Three parameters were run in the model (Column 1): litter cover, tree canopy cover, and wetlands status. The interaction effects used in the model are represented by letters (l, t and w). Log likelihood (ll), number of parameters (k), and Akaike Information Criteria (AIC) are shown. Models are ranked by the AIC values, a measure of the goodness of fit of an estimated model. The lowest AIC value represents the model with the best explanatory value, but models within 2 units provide the same explanatory value. B AC Table 1. The first column lists all bentgrass species found in the study. “Unclassified” means that plants could be identified to the genus Agrostis but not a specific species. The “unclassified” plants were mostly found in sites where mowing prevented the development of flower panicles which are helpful for species identification. Column two shows the number of plots containing each species. The four other columns show the percentage of the bentgrass species (n) found in association with: open sunny habitat, invasive plant species, area with active management practices, or area with predominantly herbaceous plants.