ENVIRONMENT : Campaign Seeks to Plant Billion More Trees a Year : The nationwide reforestation effort aims to restore woodlands and shade city streets. It could help stabilize global climate.

In the months ahead, volunteers with shovels, spades and seedlings will fan out across the country as part of an ambitious effort to boost the number of trees planted in America by at least a billion each year.

The National Tree Initiative, a $175-million campaign, is intended to reverse--or at least slow--the rapid deforestation of America. So far, the Bush Administration seems pleased with the results.

“Since March, when the President introduced the America the Beautiful program, there has been a tremendous amount of volunteer effort going forward,” said Fred Deneke, assistant director of urban and community forestry at the Agriculture Department.

Since it was begun in earnest in November, Deneke said, tree-planting activity has been particularly strong in California, Utah, New Mexico, Arizona, Texas and South Carolina, and federal officials are confident that the idea will catch on throughout the nation.

BACKGROUND: In the early 17th Century, forests covered an estimated 1 billion acres of the area that is now the United States. By 1987, with the building of cities and towns and clearing of land for agriculture, the forest lands had dwindled to 730 million acres.

Although the rate of deforestation appears to be slowing in rural areas, it is proceeding rapidly in cities and towns. According to government statistics, only one tree is planted for every four that die or are removed.

Under the National Tree Initiative, part of a broader environmental improvement program called America the Beautiful, the Administration has challenged individuals and businesses to join forces with the government in planting trees and improving forests.

The U.S. Forest Service is working to mobilize the public, corporate and civic sectors to participate in the tree-planting campaign. The agency hopes to expand efforts that got started under the Conservation Reserve Program, which expired last October.

The initiative calls for the planting of 30 million trees in nearly 40,000 communities. The American Forestry Assn. estimates that at least 100 million planting spaces are available for trees in cities and smaller communities.

The program provides also for tree planting, maintenance and improvement in rural areas, including croplands, highway rights-of-way and industrial sites. Most of the new trees come from forest nurseries, although some come from private nurseries.

IMPACT: Roots keep soil from eroding, and trees provide shelter for birds and animals. Expanding the forests may also help reduce global climate changes caused by the buildup of carbon dioxide in the atmosphere. Because trees and other plants consume carbon dioxide in photosynthesis, reforestation may counteract the greenhouse effect.

The taxpayers also benefit, at least indirectly. Government expenditures to promote planting will “buy” decades worth of conservation, advocates say. In addition, the government will no longer need to subsidize crops produced on farmland that has been converted to forest.

Supporters of the National Tree Initiative hope they can persuade more Americans to take part in the program, even though it will be years before its results are fully visible.

“We are a now generation; we tend to live very much in the present,” John Bethea, former state forester of Florida, noted. “But when we are dealing with environmental matters as serious as loss of soil productivity, the degradation of our waters and possible changes in our climate, we need to find ways to think not only about here and now, but about what is down the road.

“When we plant trees, we are doing both.”