Just how valuable are trees to a city?
Quite valuable. Nate Berg writes up a new study (pdf) for the U.S. Department of Agriculture estimating that urban trees in Tennessee alone provide $638 million in net benefits each year. That's $2.25 per tree:
The biggest savings are attributed to carbon storage, which the authors of the report value at an estimated $350 million. Collectively, the state’s urban trees store about 16.9 million tons, with each ton stored worth about $20.70 to the state every year. Air and water filtration is also one of the functional benefits of urban trees, and the report estimates the value of this work at $204 million per year. The trees are credited with removing 27,100 tons of pollutants each year, including ozone, particulate matter, and sulfur dioxide. And because of the shading they provide, these urban trees are credited with saving about $66 million in energy costs annually.
Mind you, that’s not even counting the aesthetic value of the trees (or, in the case of Washington D.C.’s gingkos, all the wonderful, er, aromatic benefits). In a somewhat different vein, Susan Wachter of Wharton recently did a study looking at the values of trees to urban home values. One striking conclusion: “Planting a tree within 50 feet of a house can increase its value by about 9%.”