Researchers take tree census in Seattle using iTree; Seattle, WA

Study's goal: Finding out how much Seattle's trees are worth: "Standing on a steep incline surrounded by tall alders, cottonwoods and maple trees, the two men in orange vests stretch out a measuring tape.
Troy Beady lays one end on the forest floor at the higher elevation, then Jack Simonson stretches the other end straight ahead to a point where it meets the tree, about 5 feet above the descending ground. Then Beady tilts a hand-held meter until he can see the top of the mature alder they're surveying. He calls out the calculated figure, then Simonson adds on the length of the trunk below the tape and announces the tree's estimated height, in meters: 'Thirty-five-point seven-five,' he said. That's more than 117 feet tall.
Slowly, for the rest of this summer and maybe into next spring, the crew is circulating through Seattle, assessing city trees one plot at a time trying to answer a fundamental question: What is Seattle's urban forest worth?
The study is being undertaken with the U.S. Forest Service, the University of Washington, Cascade Land Conservancy, King County and Seattle. It will ultimately estimate the trees' economic worth to the city: how much pollution they absorb, how much summer cooling they provide and how much storm water they absorb in winter, showing how much they might save in energy and drainage costs."