CITYgreen Software

Using CITYgreen Software to Quantify Tree Values

The Roanoke urban forestry staff can use CITYgreen software to determine the value of trees on specific parcels of land. With this software, the effect of removing trees or planting new trees is quantified. The analysis of each parcel of land indicates the tons of carbon sequestered by the trees, the pounds of air pollutants removed annually, and the effect on stormwater quantity and quality. The findings are site-specific because each site's slope, land cover, and other characteristics are entered into the model.

As an example, the benefit of reforesting land can be measured with this analysis. One Roanoke park currently has 21 acres of trees, providing an annual stormwater management value of $20,800 and removing 860 pounds of ozone from the air per year. If the tree canopy in that park increased by 25%, the park would have 26.2 acres of trees providing an annual stormwater management value of $27,965 and removing 1,075 pounds of ozone from the air annually.

The "stormwater management value" reflects the deferred cost of dealing with increased stormwater runoff that would accompany tree removal. Trees stabilize the soil, slow down runoff from storms, and thereby reduce the need for construction of stormwater facilities.

Roanoke's site-specific use of CITYgreen was preceded by a 2002 report by American Forests that quantified the value of Roanoke's total tree canopy. The Urban Ecosystem Analysis: Roanoke, Virginia revealed that Roanoke's trees provide $2.3 million in air quality benefits each year. Furthermore, if Roanoke did not have its trees, the cost of building the infrastructure to handle the increase in stormwater runoff would be $128 million.

Assistance with this project was received from the Urban and Community Forestry Program of the USDA Forest Service and Virginia Department of Forestry