Philadelphia used OpenTreeMap's code to create, a GIS-based map of assets like this Japanese raisin tree. Photo: Bob Gutowski

Open-source code is enabling governments and tree-huggers to work together to manage urban forests.

Available for free, OpenTreeMap provides all the information necessary to inventory public trees. Developed by GIS software developer Azavea, Urban Forest Map, and Urban Ecos, the wiki-inspired application enabled Philadelphia Parks and Recreation, the Pennsylvania Horticulture Society, and forestry enthusiasts to map the three-state, 13-county Philadelphia region.

With the help of the U.S. Forest Service's iTree software, OpenTreeMap uses yearly ecosystem impact metrics to paint a clear picture of the benefits of trees to a community.