Soil temperatures under urban trees and asphalt

Abstract

Summer temperatures under trees planted in holes cut through an asphalt cover in a parking lot and in soil beneath the surrounding asphalt were higher than soil temperatures under trees at a control site. Winter minimums were not different, but maximum summer temperature exceeded the control by 3ºC beneath the parking lot trees and up to 10ºC beneath the asphalt cover at a depth of 15 cm below the surface. Horizontal and vertical soil temperatures varied little at a given time within each type of site. Asphalt covering the soil not only increased maximum temperatures through a 60-cm profile, but apparently increased the rate of heat exchange since temperatures in the covered soil rose and fell more rapidly than control soil temperatures. The soil, even when covered, could be a sink or source of excess heat exchange in the urban energy balance.

Citation

Halverson, Howard G.; Heisler, Gordon M. 1981. Soil temperatures under urban trees and asphalt. Res. Pap. NE-481. Broomall, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station. 6p.