OOS 18-7
Assessing urban vacant land forest structure and ecosystem services in the city of Roanoke, Virginia
The purpose of this study is to identify and demonstrate the value of urban vacant land as a form of green infrastructure that provides ecosystem services, such as: air pollution removal, carbon sequestration and storage, oxygen production, reducing rainfall runoff, energy saving, and structural value for city residents. A typology of urban vacant land was developed using the city of Roanoke as a study site. Aerial photo interpretation and ground-truthing were used to identify and catalog vacant parcels. The results were mapped using i-Tree Canopy. i-Tree Canopy randomly laid 1000 points onto Google Earth imagery within the city of Roanoke boundary, and then classified different types of urban vacant land by an aerial photo interpretation process. The Urban Forest Effects (UFORE) model was used to quantify urban vacant land forest structure and calculate various ecosystem services based on standard inputs of field, meteorological, and pollution data. In the city of Roanoke, 114 one-tenth-acre plots were sampled using a stratified random sampling based on five different types of urban vacant land. i-Tree Canopy results for the plots were assigned proportionate to land area of each vacant land type. All field data was collected during the 2013 leaf-on season (June ~ July).
Results/Conclusions
An analysis of urban forest in Roanoke’s vacant land reveals that there are about 210 thousand trees, covering of 30.6 percent vacant land. Trees on Roanoke’s vacant land store about 107,000 tons (97,049 metric tons) of carbon, valued at $7.65 million. In addition, these trees remove about 2,300 tons (2,086 metric tons) of carbon per year ($a reduction valued at $164 thousand per year). These trees also remove about 91 tons (82 metric tons) of air pollution per year ($valued at $916 thousand per year), which is high, relative to other land uses in Roanoke. The trees on Roanoke vacant land are estimated to reduce annual residential energy costs by $211 thousand per year. The structural value of the trees on vacant land is estimated at $169 million. Information on the structure and functions of the urban vacant land can be used to inform urban forest management programs to improve environmental quality. This study has implications for both policy and practice in better understanding the value of urban vacant land and in improving the design of green spaces.