Every tree in urban Tennessee provides an estimated $2.25 worth of measurable economic benefits every year. Might not seem like a lot, but with 284 million urban trees in the state, the payoff's pretty big.
Through energy savings, air and water filtering and carbon storage, the urban trees of Tennessee account for more than $638 million in benefits, according to a report [PDF] conducted by the Forest Service of the U.S. Department of Agriculture and released earlier this year.
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.
And these valuations don't even consider the aesthetic value of having streets and parks lined with red maples and yellow poplars. Those benefits are a little more difficult to quantify, which is why this study, a pilot, focused on the more measurable benefits urban trees can provide. The method used for estimating tree values is commonly used and was developed by the Council of Tree and Landscape Appraisers.
Similar pilot studies have been or are being conducted in Indiana, Wisconsin, New Jersey, and Colorado. Indiana's street trees, for example, have been found [PDF] to provide about $38 million in tangible benefits every year, including stormwater treatment, energy use reduction, air quality improvement and carbon sequestration. They were also estimated to provide about $41 million in aesthetic values and impacts on property values. (That study counted about 52 million trees in the state, but it's unclear how many are "urban.")
The authors behind the Tennessee report also note that the state's trees are under threat from a variety of invasive species and diseases. They argue that more work needs to be done to prevent these threats from reducing the urban tree canopy and the benefits it provides. If every urban tree in the state were to die, the cost of replacing them is estimated at $79.5 billion. While that's an unlikely event, the high cost underlines the economic value that trees provide, whether in functional and utilitarian ways or in those less tangible.
Photo credit: Lucas Jackson / Reuters