Technical Abstract: The goal of the pasture ecology and management research project at University Park is to provide science-based information for establishing, maintaining, and managing diverse forage and grazing lands of the northeastern U.S. to support multiple ecosystem services. The concept of multifunctionality in grassland agriculture recognizes ecosystem services beyond the traditional forage, food, and fiber production to include emerging services such as carbon sequestration, greenhouse gas mitigation, and bioenergy production. Managing multiple plant species in grassland systems is an ecological approach to providing these multiple services. Our objectives are to: 1) develop tools to aid the selection of forage mixtures for pastures and their distribution across a farm; 2) identify new management and supplementation strategies that complement grazing preferences of dairy cattle on mixed-species pastures; 3) identify management practices that minimize net greenhouse gas emissions in forage and energy crop systems; and 4) provide improved management practices that enhance the environment and increase the economic viability of bioenergy cropping systems. This research will generate new tools for pasture management and guidelines for supplementing grazing dairy cows that account for forage selection and preference; new information on grassland systems that minimize net greenhouse gas emissions; and new management practices for bioenergy crops.