Trees Offer Significant Benefits as Northwest Arkansas Population Grows

American Forests
Wednesday, 22 January 2003

According to a new study by conservation organization AMERICAN FORESTS, the Northwest Arkansas's urban forest has not declined significantly over the last 15 years, however, local growth hotspots, like in the City of Fayetteville, indicate patterns of decline in air and water quality which communities can avoid by managing tree cover. AMERICAN FORESTS' conducted an Urban Ecosystem Analysis (UEA) of 1.4 million acres of Northwest Arkansas including Benton and Washington Counties, and 30 miles surrounding the Northwest Regional Airport, including fast growing Fayetteville and Bentonville. The analysis shows changes in tree cover between 1985-2000 as well as measures the value of the area's tree cover for stormwater management, air quality, and energy conservation. A press conference at 3:30PM in Springdale City Hall will be held to announce the results of the study.

The study not only calculated the functional value of trees, but also identified hotspots of development patterns in areas around the new airport, in Bentonville, and along the I-540 corridor and it's corresponding reduction in air and water quality benefits. The City of Fayetteville experienced an 18 percent decline of heavy tree canopy over the last 15 years. "The region is on the brink of major development", explained Patti Erwin, with the Arkansas Forestry Commission. We need this information so that local communities can coordinate future planning to maintain the region's natural resources including the green connections along the region's watersheds, trail systems, and wildlife corridors."

The Urban Ecosystem Analysis technique conducted in Fayetteville used satellite and aerial imagery, Geographic Information System technology, and scientific research to calculate the benefits trees provide to the urban environment. AMERICAN FORESTS' CITYgreen® computer software was used to analyze the environmental benefits of Fayetteville. The analysis also serves as an introduction for the city leaders to learn about ways to use tree cover as an asset—building a "green" infrastructure for future city management decisions. The findings show that in the City of Fayetteville's the existing tree cover currently reduces stormwater runoff by 50 million cubic feet during a storm event. The costs associated with containing stormwater are valued at $92 million (using $2 per cubic foot construction cost).

Trees help reduce stormwater runoff by intercepting rainwater on its leaves, branches and trunk, where it evaporates, or slowly soaks into the ground, reducing peak flow after a storm. Trees also reduce the volume of runoff. Municipalities must spend millions of dollars for flood control systems and sewer infrastructure to handle stormwater runoff. If the tree canopy were increased from 27 to 40 percent in Fayetteville, the environmental benefits would be significant. Stormwater benefits alone would be $135 million—a 47 percent increase and air quality would also increase by 52 percent at $2.5 million annually.

Besides reducing stormwater runoff, the City of Fayetteville's tree canopy provides other benefits including the removal of 731, 000 pounds of pollutants a year a value estimated at $1.64 million annually. The city's urban forest currently stores an estimated 330,000 tons of carbon and sequesters nearly 2,568 tons of carbon each year. These benefits become more important with the realization that tree canopy has been lost over the last 15 years. The analysis compared
classified Landsat TM satellite images between 1985 and 2000 and revealed a 18 percent loss in heavy tree canopy cover (50 percent or greater tree cover) over this time period. Fortunately, the area still retains a 27 percent canopy cover. However, if the current patterns of development continue, estimates show that the 18% heavy tree loss will reduce stormwater benefits to $83 million by the year 2030.

The report makes a number of recommendations for these and other decision-makers. The study suggests the city develop public policies that increase tree cover and promote green infrastructure. Second, the community should include trees and the values associated with trees when making land-use decisions. Lastly, the analysis recommends that the community should set tree cover goals and institutionalize a system to maintain this goal. The communities of Fayetteville can use the green data layer collected by American Forests and one-meter, color infrared imagery to conduct additional local analyses. "The study shows that the region's trees are a vital community asset," said Gary Moll, Vice President of AMERICAN FORESTS' Urban Forest Center. "The real strength of this project is in the data it provides to regional and local communities who use it for future planning."

AMERICAN FORESTS is a national leader in the urban forestry movement. The organization combines education, action, and research into programs that improve the trees, forests, and overall environmental health of our communities. In addition to conducting Urban Ecosystem Analyses (UEA) in regions around the US, AMERICAN FORESTS developed CITYgreen software for communities to use in calculating the value of urban forests in their local areas. Every two years, AMERICAN FORESTS organizes the National Urban Forest Conference, which brings together practitioners, researchers, citizen groups, legislators, and others interested in improving the urban environment. The 2003 National Urban Forest Conference, Engineering Green, will be held in San Antonio, Texas, September 17-20.

For more information, or to contact American Forests, see their website at: www.americanforests.org