Using Geospatial Tools to Assess the Urban Tree Canopy: Decision Support for Local Governments

Urban forests provide many benefits, but many localities continue to experience a slow, steady decline in urban tree canopy (UTC). UTC assessment is essential for managing urban forests. However, quantifying UTC is difficult because ground-based assessments are (1) expensive, (2) hampered by difficulties accessing private property, and (3) conducted less frequently than the pace of canopy change. Remote sensing provides a viable alternative for UTC assessment, but many communities lack human or financial resources to perform frequent, accurate UTC assessments using remotely sensed data. Virginia's UTC program provides a model for canopy assessment in such communities by providing baseline data at 90% accuracy using publicly available, four-band, 1-m spatial-resolution imagery. With these baseline UTC data, communities can accurately determine (1) the distribution of current canopy cover, (2) whether canopy goals are being met, and (3) areas where canopy could be increased or better managed to support ecosystem services such as storm water mitigation and energy savings. A case study of UT assessment in Winchester, Virginia, is presented.