Mapping Georgia’s Urban Forests

Georgia Tech’s Center for Urban Resilience and Analytics (CURA) has released a high-resolution canopy assessment for the City of Atlanta, continuing more than 15 years of work to track and understand the city’s urban forest. Led by Anthony Giarrusso and funded by the city’s Tree Recompense Fund, the study uses advanced tools such as WorldView-2 satellite imagery, field validation, and a random forest classification model to categorize land into tree canopy, non-tree vegetation, and non-vegetation. The research aims to provide neutral, science-based data that equips policymakers, planners, and community leaders to make informed decisions about urban growth, conservation, and climate resilience.

Beyond mapping existing canopy, the Georgia Tech team developed a Potential Planting Index (PPI) to identify locations where tree planting is physically possible. The study also warns of misleading “loss-gain-loss” canopy cycles, in which temporary regrowth occurs on cleared land—often stalled development sites—only for the vegetation to be cleared again later. Giarrusso stresses that without understanding land use patterns, short-term canopy gains can create a false sense of progress, especially when the regrowth is low-quality and lacks permanence.

The city is incorporating these tools into zoning reform and updates to its tree ordinance, including recommendations to limit full lot clearing in certain zones and adjust setback and lot coverage requirements to protect existing trees. Giarrusso emphasizes the importance of prioritizing intact, high-quality forest tracts, warning that once they are cleared, they are rarely restored to their original ecological value. “If you can see it from space and it’s still forest — save it,” he said.