Greener San Antonio. (Clippings).

Greater San Antonio is saving more than $70 million annually from its urban tree canopy, according to a new study by AMERICAN FORESTS.

AMERICAN FORESTS' Urban Ecosystem Analysis (UEA) analyzed tree cover in terms of its benefits to stormwater management, air quality, and energy conservation for 22 sites in the San Antonio area, including Bexar County and portions of Wilson, Guadalupe, and Comal counties. The analysis used Geographic Information System (GIS) technology along with scientific research to calculate the effects of trees on the urban environment. The change in tree cover over time was figured by comparing Landsat TM satellite images from 1985 and 2001.

Despite the hefty savings provided by its trees, the city itself is experiencing a loss of "heavy" tree cover (areas with more than 50 percent tree cover), from more than 50 percent in 1985 to 39 percent in 2001. During the same period, canopy coverage in surrounding counties dropped from 26 percent to 20 percent.

In the report, AMERICAN FORESTS suggests San Antonio develop public policies to increase tree cover, promote green infrastructure, and include trees and the values associated with them when making land-use decisions. It also recommended the city set canopy cover goals and institutionalize a system to maintain that goal.

"Too often city planners and officials think of trees in aesthetic terms. This report illustrates the financial savings and positive health effects trees can have on an urban community and how these benefits increase as tree cover increases," AMERICAN FORESTS vice president Gary Moll said in releasing the findings. Those findings are particularly significant given the growing problem of urban sprawl and the fact that San Antonio is the nation's ninth largest city. The population there has grown nearly 25 percent in the last decade.

The report found tree cover in the Study area's residential, commercial, and vacant areas reduces stormwater runoff by 678 million cubic feet during major storms. Building retention facilities to deal with this runoff could cost $1.35 billion. The study areas tree cover also removes 17 million pounds of pollutants a year, a value estimated at $42.1 million annually.

The urban forest stores an estimated 7 million tons of carbon and sequesters nearly 56,000 tons of carbon yearly.

San Antonio's long, hot summers cost residents about $555 annually in air conditioning costs. That figure could be worse; residential shade trees were shown to save each home an average of $76 annually.

Urban forest practitioners will get a first-hand look at San Antonio's canopy efforts as well as innovative ideas for making their cities more liveable when the city hosts AMERICAN FORESTS' biennial National Urban Forest Conference in 2003. For information about the conference, visit www.americanforests.org