A source of shade and privacy. A streetscape brightener. A place for dogs to pee. How can anyone know the true value of a New York City sidewalk tree? Impossible, perhaps—but this being the Bloomberg era, someone had to come up with a number. “It’s New York, and we like to quantify things,” says Fiona Watt, the Parks Department’s chief of forestry and horticulture. And so over the last two summers, more than a thousand people volunteered to conduct a tree census of the five boroughs, the second in the city’s history (the other was in 1995)—and the first to put a price tag on each specimen.
City foot soldiers counted 592,130 non-park trees altogether. Each tree’s type, age, size, and location was fed into a computer program, developed by the U.S. Forest Service and the University of California, Davis, that quantified the plant’s annual value in saving energy costs (more shade means less air-conditioning), improving air quality, absorbing storm-water runoff, and prettifying the block. The study determined that street trees are collectively worth $122 million a year to the city, with an average of $50 to $300 apiece. Not surprisingly, the oldest and largest are worth the most.
Those figures may mean a lot to urban planners, but the average homeowner is more interested in how much money that ginkgo will put in his pocket someday. The standard formula says a dwelling with a tree in front is worth .88 percent more than a home without one; apartment buildings are more complicated. The city’s math allowed for a tree’s effect on property values, but with a limitation: The survey priced all houses equally, at $537,300, the median cost of a single-family home in 2005.
To account for real-world variations in home prices, we got rough appraisals from real-estate agents for each of the addresses at right and did the math ourselves. The result? Maybe Park Slopers shouldn’t let dogs whiz on that Callery pear.