San Antonio Forest
Evapotranspiration
Trees have great potential to cool cities by shading and through "evapotranspiration."
Evapotranspiration occurs when plants secrete or "transpire" water through pores in their leaves--in a way, plants sweat like people do. The water draws heat as it evaporates, cooling the air in the process.
A mature, properly watered tree with a crown of 30 feet can "evapotranspire" up to 40 gallons of water in a day. This is like removing all the heat produced in four hours by a small electric space heater.
The area under a tree is cooler and the plants require less water than in unshaded areas. Another way to conserve water.
Because of evapotranspiration, the air in and around the shade of a tree is cooler. This has a positive impact on the microclimate caused by the tree.
Trees also mute the sound of traffic and other neighborhood noise. This calms any area with a good planting of trees.
HOME