Trees Modify Metropolitan Climate and Noise    (View PDF)

Gordon M. Heisler

Abstract: Human comfort in urban areas is altered by trees primarily through their influence on the exchange of radiant energy - both solar and long-wave. Although urban trees probably use large amounts of heat for transpiration, this process does not result in significantly cooler air in the vicinity of single or small groups of trees. Even low winds quickly disperse the cooled air. Outdoor spaces that receive heavy pedestrian use should be made as versatile as possible by providing both sunny and shady sites for sitting and walking. Windbreaks may reduce energy requirements for heating buildings by 10 to 25 percent. Although shade ob­ viously is a benefit in summer; winter shade is a disad­ vantage, and even deciduous-tree shade is significant in win­ ter. Trees are useful for noise control primarily because they scatter sound waves, which are then absorbed by the ground. Dense forests or plantings of trees can reduce transmission of traffic noise, but if highways carrying high-speed truck traf­ fic pass through residential areas, tree barriers alone cannot reduce sound levels to an acceptable maximum within about 350 feet of the highway.

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https://doi.org/10.48044/jauf.1977.054