A Geographical Information Systems (GIS) vineyard mapping project, A Spatially Explicit Vineyard Expansion Model: Addressing Crop Production, Public Policy, and Environmental Concerns, (Merenlender 1996-2000), is evaluating the conversion of open hardwood oak rangelands to vineyards in Sonoma County. Vineyard expansion can increase habitat fragmentation which can negatively affect the natural resources the land currently supports. The GIS model predicts where undeveloped, potentially productive grape-growing land is located and addresses the habitat and watershed consequences of vineyard expansion. Results will be shared with community land use planners, farmers and others concerned about long-term land use decisions. Full Project Report.