From the press release:
"Urban street trees have myriad proven benefits for communities including providing shade, improving air quality, assisting with stormwater runoff, raising property values, decreasing utility bills, and enhancing the look and feel of communities. While tree inventories ensure that municipalities have data to consult when managing the urban forest, creating a complete inventory is a time consuming and resource intensive process. PhillyTreeMap provides an easy-to-use public inventorying platform that encourages the public to contribute to an interactive and dynamic map of the city's tree population."
170,000 trees have been pre-loaded into the system, but the developers are counting on the public to add the rest. The site was commissioned by the City of Philadelphia Parks & Recreation, the Pennsylvania Horticultural Society (PHS), and the Delaware Valley Regional Planning Commission.