Even viewed conservatively, trees are worth far more than they cost to plant and maintain. The U.S. Forest Service's Center for Urban Forest Research found a ten-degree difference between the cool of a shaded park in Tucson and the open Sonoran desert. A tree planted in the right place, the center estimates, reduces the demand for air conditioning and can save 100 kilowatt hours in annual electrical use, about 2 to 8 percent of total use. Strategically planted trees can also shelter homes from wind, and in cold weather they can reduce heating fuel costs by 10 to 12 percent. A million strategically planted trees, the center figures, can save $10 million in energy costs. And trees increase property values, as much as 1 percent for each mature tree. These savings are offset somewhat by the cost of planting and maintaining trees, but on balance, if we had to pay for the services that trees provide, we couldn't afford them. Because trees offer their services in silence, and for free, we take them for granted.
