A Report on the City of Radford s Existing and Possible Urban Tree Canopy

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1 A Report on the City of Radford s Existing and Possible Urban Tree Canopy Project Background Key Terms The analysis of Radford s urban tree canopy (UTC) was carried out at the request of the Virginia Department of Forestry in collaboration with the City of Radford with funding provided by the USFS Urban and Community Forest grant. The analysis was performed by the Virginia Geospatial Extension Program (VGEP) at Virginia Tech s Department of Forest Resources and Environmental Conservation in consultation with the Spatial Analysis Laboratory (SAL) of the University of Vermont. UTC: Urban tree canopy (UTC) is the layer of leaves, branches, and stems of trees that cover the ground when viewed from above. Land Cover: Physical features on the earth mapped from satellite or aerial imagery such as trees, or water. : The amount of UTC present within parcel boundaries. Possible UTC: The amount of land that is theoretically available for the establishment of tree canopy within parcel boundaries. Possible UTC excludes areas covered by tree canopy, roads, buildings, and water. It is the combination of Possible UTC - Vegetation and Possible UTC - Impervious. Possible UTC - Vegetation: The amount of land that is theoretically available for the establishment of tree canopy in nontree vegetation areas within parcel boundaries. This excludes areas covered by tree canopy, impervious surfaces, and water. Possible UTC - Impervious: The amount of land that is theoretically available for the establishment of tree canopy in impervious areas within parcel boundaries. This includes impervious areas (roads, parking lots, and sidewalks) except for buildings. The goal of the project was to apply the USDA Forest Service s UTC assessment protocols to the City of Radford. This analysis was conducted based on year 2008 data. Table 1: area and percentages for the City *% Total Land Area includes area covered by water. UTC Classes Acres % Total Land Area* % Land Area Tree Canopy % 53.1% Non-Tree Vegetation % 29.0% Non-Building Impervious % 13.6% Buildings Impervious % 4.2% Water % 0.0% Total Area % 100% Why is Tree Canopy Important? Urban tree canopy (UTC) is the layer of leaves, branches, and stems of trees that cover the ground when viewed from above. Urban tree canopy provides many benefits to communities including improving water quality, conserving energy, lowering city temperatures, reducing air pollution, enhancing property values, providing wildlife habitat, facilitating social and educational opportunities, and providing aesthetic benefits. How Much Tree Canopy Does Radford Have? Figure 1: Land cover for the City of Radford. Figure 1 shows the UTC analysis for Radford, which is derived from high resolution aerial imagery. 3,320 acres of Radford is covered by tree canopy (termed ). This corresponds to 51% of all land area within the City (Table 1). An additional 39% (2,110 acres) of the city could theoretically be improved to support urban tree canopy (termed Possible UTC), Table 2. 1

2 Using high-resolution (1 meter) National Agriculture Imagery Program (NAIP) imagery acquired in the summer of 2008 (Figure 2) in combination with remote sensing techniques, land cover data for the City was generated (Figure 2). A 96% accuracy rate was found after conducting an accuracy assessment. Single trees with canopies larger than 16 square meters were detected. Parcels Mapping Radford s Trees Who Owns Radford s Trees? The detailed land cover mapping conducted as part of this assessment allowed the percentage of Existing and Possible UTC to be calculated for each parcel of land (Figure 3). Using this data, ownership patterns for and Possible UTC (Figure 4) can be examined NAIP Imagery (1m) Possible UTC Land Cover Derived from 2008 NAIP Imagery (1m) Figure 2: Comparison of 2008 NAIP imagery to the resulting highresolution land cover. Figure 3: UTC metrics summarized at the property parcel level 2

3 Figure 4: UTC metrics summarized by property parcel. 3

4 Urban Tree Canopy Summarized by Property Parcels Using the parcel data provided by the City of Radford, Existing and Possible UTC were summarized by property parcels. This summary excludes any area outside of property parcel boundaries and areas covered by water. Radford has 57% (3,090 acres) and 39% (2,110 acres) Possible UTC. Possible UTC has two components, Possible UTC - Vegetation and Possible UTC - Impervious. 29% (1,576 acres) of parcel land area is associated with Possible UTC - Vegetation. 10% (534 acres) of parcel land area is associated with Possible UTC - Impervious (Figure 5). Figure 4 shows through out the City of Radford summarized by property parcels. Urban Tree Canopy Summarized by Zoning Using the zoning data provided by the City of Radford, Existing and Possible UTC were summarized by zoning category (pages 4-6). The zoning category Single-Family Residential District: R3 has the largest amount of land area with 1,599 acres (Table 3). Single-Family Residential District: R3 has the largest percentage of (25.4%). Conservation District: CD is 2nd (24.3%) in the amount of. Figure 6 compares zoning categories by the amount of land area within the categories. Figure 7 shows Possible UTC by zoning category for the City. 10% 9% Table 2: Acres and percent land area from UTC metrics summarized by property parcels. *Not Suitable for UTC includes all water areas some of which may lay outside of parcel boundaries. 29% Possible UTC - Impervious 57% Possible UTC - Vegetation Not Suitable for UTC UTC Parcel Metrics Acres % Parcel Land Area Parcel Land Area % % Possible UTC % Possible UTC - Vegetation % Possible UTC - Impervious % Not Suitable for UTC* % Figure 5: Pie chart showing Radford UTC distribution. Central Business District: B3 Conservation District: CD General Business District: B2 General Industrial/Commercial District: M2 Limited Business District: B1 Manufactured Home Residential District: RMH Medical Arts District: MED Possible UTC Area Possible UTC-Vegetation Possible UTC-Impervious Land Area Mixed Use Residential/Business District: MU Multifamily Residential District: R4 Planned Unit Development District: PUD Restricted Industrial/Commercial District: M1 Single-Family Residential District: R1 Single-Family Residential District: R2 Single-Family Residential District: R3 University Residential/Business District: UD Acres Figure 6: UTC metrics summarized by zoning categories. 4

5 Urban Tree Canopy Summarized by Zoning Table 3: UTC metrics by type, summarized by zoning categories. For each zone, category UTC metrics were computed as a percent of all zoned land in the City (% Land Area), as a percent of land area by zoning categories (% Zoning ) and as a percent of the area for the UTC type (% UTC Type). Zoning Land Area (Acres) % Land Area Possible UTC Vegetation Possible UTC Impervious % Zoning % UTC Type % Land Area % Zoning % UTC Type % Land Area % Zoning Central Business District: B % 10.4% 0.1% 0.1% 12.5% 0.3% 0.2% 31.3% 2.7% Conservation District: CD % 67.3% 24.3% 5.5% 28.5% 18.8% 0.5% 2.6% 5.8% General Business District: B % 40.7% 4.5% 1.3% 22.9% 4.6% 1.1% 18.2% 12.4% General Industrial/Commercial District: M % 31.0% 2.1% 1.0% 27.4% 3.3% 1.1% 32.2% 13.3% Limited Business District: B % 25.1% 0.2% 0.1% 27.8% 0.4% 0.1% 19.8% 0.9% Manufactured Home Residential District: RMH 5 0.0% 15.3% 0.0% 0.0% 43.9% 0.1% 0.0% 21.1% 0.2% Medical Arts District: MED % 21.8% 0.1% 0.1% 26.8% 0.2% 0.1% 20.9% 0.6% Mixed Use Residential/Business District: MU % 21.4% 0.1% 0.2% 49.8% 0.6% 0.0% 5.1% 0.2% Multifamily Residential District: R % 49.3% 8.5% 2.4% 25.9% 8.1% 0.9% 10.2% 10.9% Planned Unit Development District: PUD % 69.5% 13.2% 2.7% 26.6% 9.2% 0.2% 2.2% 2.6% Restricted Industrial/Commercial District: M % 33.7% 3.1% 1.3% 26.5% 4.5% 1.1% 22.5% 13.0% Single-Family Residential District: R % 70.6% 13.2% 1.9% 18.8% 6.4% 0.3% 3.1% 3.6% Single-Family Residential District: R % 34.2% 4.0% 2.9% 46.4% 10.0% 0.4% 5.9% 4.3% Single-Family Residential District: R % 52.8% 25.4% 8.3% 32.3% 28.4% 1.5% 5.7% 17.0% University Residential/Business District: UD % 16.0% 1.1% 1.4% 38.0% 4.9% 1.1% 28.1% 12.4% % UTC Type Area of UTC type for specified land use % Land = % = Area of all land Area of UTC type for specified land use Area of all land for specified land use Area of UTC type for specified land use % UTC Type = Area of all UTC type The % Land Use value of 0.6% indicates that 0.6% of University Residential/ Business District: UD land is covered by tree canopy. The % value of 16.0% indicates that 16.0% of Radford s land area is tree canopy in areas where the land use is University Residential/Business District: UD. The % UTC Type value of 1.1% indicates that 1.1% of all lies in areas of University Residential/Business District: UD land use. 5

6 Figure 7: Possible percentage increase of UTC mapped using zoning categories provided by the City of Radford. 6

7 Where to Plant Trees? Decision makers can use GIS to find out specific UTC metrics for a parcel or zoning category. This information can be used to estimate the amount of tree loss in a planned development or set UTC improvement goals for an area. GIS Database Figure 8: Parcel-based UTC metrics can be used to support targeted UTC. Conclusions Radford s urban tree canopy is a vital community asset, reducing stormwater runoff, improving air quality, reducing the City s carbon footprint, enhancing quality of life, contributing to savings on energy bills, and serving as habitat for wildlife. With 53%, Radford has similar canopy coverage as Charlottesville and Lynchburg. Figure 9 shows how Radford compares to other Virginia localities participating in Urban Tree Canopy Assessment Program. When summarized by property parcels, Radford has 57% with 49% of all parcels having less than 25% canopy coverage. 76% (2,526 acres) of the is located within the following zoning categories: Conservation District: CD, Planned Unit Development District: PUD, Single-Family Residential: R1, and Single-Family Residential: R3. 58% 60% 47% 50% 44% 41% 41% 53% 40% 30% 30% 33% 27% 27% 27% 20% 20% 10% 0% * Data provided by University of Vermont **Data provided by Fairfax County Figure 9: Comparison of of % land area (excludes water area) with other Virginia localities that have completed UTC assessments. Prepared by: Additional Information Jennifer McKee Geospatial Project Developer Virginia Geospatial Extension Program Department of Forest Resources and Environmental Conservation Virginia Tech , jmckee@vt.edu The study was conducted with funding from the Virginia Department of Forestry. More information on the UTC assessment project can be found at the following web site. utc/ 7