A thousand points of shade? President Bush recently asked Congress for $175 million to start a national foundation to plant 1 billion trees in the United States each year. Conservations say they hope the 1 billion will be in addition to, rather than included in, the estimated 2.3 billion trees now planted each year in the US. Many also say that where the trees are planted can make an enormous difference.
Planting even one-tenth of them in urban environments would probably be several times more effective in reducing carbon emissions than planting the total in rural forest areas, says Hashem Akbari, a scientist and energy analyst at the Lawrence Berkeley Laboratory in Berkeley, Calif. Such an investment in city planting, he says, could also save US consumers $3 billion to $4 billion each year in energy costs.
In addition to the shade they provide, trees, which draw water up their trunks and into their leaves, transpire the moisture back into the air, cooling it.
Yet urban trees face a particularly tough challenge. The American Forestry Association (AFA) says the average urban street tree lasts seven years compared with the 32 years it would last in a rural forest. Poor city soils are a key culprit, says Gary Moll, AFA vice president for urban forestry.
Selecting street-tough trees that can tolerate harsh conditions is one possible solution. Also, new scientific evidence shows that the method of planting can substantially extend the life of a tree, says Mr. Moll. A particularly wide hole for planting - five times the size of the root ball - is helpful.
For more information write: Global ReLeaf, AFA, P.O. Box 2000 Washington, D.C. 20013; or call 1-900-420-4545