What is a tree worth?

“The best time to plant a tree is twenty years ago. The second best time is now.”
Chinese Proverb

Trees perform a lot of functions. They beautify a landscape. They provide shade. They convert carbon dioxide to oxygen. The absorb stormwater runoff. They reduce energy costs. In springtime, many bloom and are highly fragrant. In the fall they can provide incredible color. In wintertime they can be a windbreak. Street trees can make an urban street more hospitable and enjoyable, and can reduce the heat island effect. Trees have even been put to use to symbolize a great many ideas, such as the “Tree of Liberty,” and can be even be used as a compliment (or epithet) in phrases like “tree-hugger.” But what is a tree worth, monetarily?

A recent article in the Wilson Quarterly tries to quantify the value of a tree, and discusses the history of urban forests in America. From the article:

“In 2006… the New York Parks Department asked them to value all of New York City’s 592,000 street trees. With the advances made over the preceding dozen years, McPherson could deliver a far more sophisticated report than he had for Chicago. Energy savings: New York City’s trees annually saved roughly $28 million, or $47.63 per tree. Air pollution: Each street tree removed an average of 1.73 pounds of air pollutants per year (a benefit of $9.02 per tree), for a total of more than $5 million. The report also calculated that street trees reduced stormwater runoff by nearly 900 million gallons each year, saving the city $35.6 million it would have had to spend to improve its stormwater systems. The average street tree intercepted 1,432 gallons, a service worth $61, a figure large enough to impress cost-conscious city managers.

McPherson and his colleagues were also able to tally various benefits associated with aesthetics, increased property values and economic activity, reduced human stress, and improved public health, which were estimated at $52.5 million, or $90 a tree. These drew on straight-up economic studies of real estate prices as well as social science research, which showed, for example, that hospital patients who could see a tree out the window of their room were discharged a day earlier than those without such a view. Other studies showed that shopping destinations with trees had more customers than those that didn’t, and leafy public-housing projects experienced less violence than barren ones.”

The conclusion of New Yorks’ study was that for each and every tree in the city the city was recieving $209 in benefit,  per year.

Salt Lake County’s local branch of the iTree program can be found here: http://www.milliontrees.slco.org/

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