A Report on Virginia Beach s Existing and Possible Urban Tree Canopy

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1 A Report on Virginia Beach s Existing and Possible Urban Tree Canopy Project Background The analysis of Virginia Beach s urban tree canopy (UTC) was carried out by the Spatial Analysis Laboratory of the U of Vermont s Rubenstein School of the Environment and Natural Resources, in collaboration with the City of Virginia Beach Dept of Parks and Recreation. This report was developed by the VA Dept of Forestry as part of the Virginia UTC Project. The goal of the project was to apply the USDA Forest Service s UTC assessment protocols to Virginia Beach. Federal lands have been removed from the analysis, so that all of the land area included may possibly be affected by Virginia Beach. 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. Establishing a UTC goal is crucial for communities seeking to improve their green infrastructure. Key Terms 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 the city boundary.. Possible UTC: The amount of land that is theoretically available for the establishment of tree canopy within the city boundary. 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 non-tree vegetation areas within the city boundary. 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. This excludes areas covered by tree canopy, non-tree vegetation, roads, buildings, and water. How Much Tree Canopy Does Virginia Beach Have? Figure 1 shows the urban tree canopy (UTC) analysis for Virginia Beach, which is derived from 2008 high resolution aerial imagery acres of Virginia Beach is covered by tree canopy (termed ). This corresponds to 35.8% of all land area within the city (Table 1). An additional acres of the city could theoretically be improved to support urban tree canopy (termed Possible UTC), Table 2. UTC Classes Acres % Total Area % Land Area Tree Canopy % 35.8% Grass/Shrub % 30.4% Bare Soil % 0.8% Water % 11.0% Buildings % 9.0% Roads/Railroads % 7.6% Other Impervious % 16.3% Total Area % 100.0% Figure 1: Land cover for Virginia Beach. Table 1: area and percentages for the City *% Total Area includes area covered by water. 4/29/2010 1

2 Mapping Virginia Beach s Trees Using high-resolution (1 meter) National Agriculture Imagery Program (NAIP) imagery acquired in the summer of 2008 (Figure 2a) in combination with remote sensing techniques, land cover data for the city was generated (Figure 2b). An accuracy assessment was conducted. Single trees (tree canopies larger than 16 square meters) were detected with a 93% accuracy. Who Owns Virginia Beach 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. Parcels 2008 NAIP Imagery (1m) Land Cover Derived from 2008 NAIP Imagery (1m) Possible UTC Figure 2a, 2b: Comparison of 2008 NAIP imagery to the resulting highresolution land cover. Figure 3: UTC metrics summarized at the property parcel level 4/29/2010 2

3 Figure 4: UTC metrics summarized by property parcel. 4/29/2010 3

4 Urban Tree Canopy Summarized by Property Parcels Using the parcel data provided by Virginia Beach, Existing and Possible UTC were summarized by property parcels. This summary excludes any area outside of property parcel boundaries and areas covered by water. Virginia Beach has 39.0% (26974 acres) Existing UTC and 49.9% (34497 acres) Possible UTC. Possible UTC has two components, Possible UTC - Vegetation and Possible UTC - Impervious. 32.6% (22544 acres) of parcel land area is associated with Possible UTC - Vegetation. 17.3% (11953 acres) of parcel land area is associated with Possible UTC - Impervious (Figure 5). Figure 4 shows throughout Virginia Beach. Urban Tree Canopy Summarized by Class Using the Class data provided by Virginia Beach, Existing and Possible UTC were summarized by Class Description (page 5). The Residence Class has the largest amount of land area with acres (Table 3). The Residence Class also contains 46.3% of the Existing UTC in the city. The Vacant Land and Local Government Classes are 2nd (15.7%) and 3rd (10.0%) in respectively. Figure 6 compares Classes with greater than 250 acres by the amount of land area within the categories. Figure 7 shows the spatial distribution of Possible UTC by Class for the City. UTC Parcel Metrics Acres % Parcel Land Area Parcel Land Area % % 17% 11% Possible UTC % Possible UTC - Vegetation % Possible UTC - Impervious % Not Suitable for UTC % 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. 33% Possible UTC - Impervious Possible UTC - Vegetation Not Suitable for UTC 39% Figure 5: Pie chart showing Virginia Beach UTC distribution. UTC by Class Description Land Area Possible UTC Vegetation Possible UTC Impervious Possible UTC Area Class Description Apartment Complex Charitable - Other Common Elements - Common Elements - Residential Condos Duplex Educational Federal Government General Commercial Homeowners Association Homesite Included Industrial Building Local Government Local Government - Park Areas Local Government - Schools Markets/Retail NULL Office Building Office Building/Owner Occupied Outbuildings Only Regional Government Religious - Churches Residence Shopping Center Townhouse Vacant Land Acres Figure 6: UTC metrics for zoning categories with more than 250 acres of land area (not including water). 4/29/2010 4

5 Class Description Urban Tree Canopy Summarized by Class Description Land Area (Acres) Possible UTC Vegetation Possible UTC Impervious % Land % Class % UTC % Land % Class % UTC % Land % Class % UTC Apartment Complex % 21.8% 1.4% 0.6% 24.5% 1.8% 0.8% 33.8% 4.7% Charitable - Other % 36.2% 0.4% 0.1% 31.0% 0.4% 0.1% 23.0% 0.6% Common Elements - Commercial/Industrial Condos % 17.1% 0.3% 0.2% 31.0% 0.8% 0.2% 30.2% 1.4% Common Elements - Residential Condos % 18.3% 1.0% 0.5% 21.9% 1.4% 0.6% 30.9% 3.7% Duplex % 46.0% 0.5% 0.1% 24.9% 0.3% 0.1% 13.2% 0.3% Educational % 32.5% 0.7% 0.3% 38.3% 1.0% 0.2% 21.0% 1.0% Federal Government % 58.1% 1.0% 0.1% 20.7% 0.4% 0.1% 14.2% 0.5% General Commercial % 31.2% 3.2% 1.9% 48.7% 5.9% 0.6% 16.0% 3.7% Homeowners Association % 37.3% 1.5% 0.8% 51.4% 2.4% 0.1% 9.0% 0.8% Homesite Included % 45.7% 2.3% 1.0% 51.3% 3.1% 0.0% 2.1% 0.2% Industrial Building % 12.8% 0.5% 0.3% 20.9% 1.0% 0.7% 41.5% 3.9% Local Government % 53.5% 10.0% 2.3% 32.1% 7.2% 0.9% 12.6% 5.3% Local Government - Park Areas % 56.1% 5.3% 1.3% 35.5% 4.0% 0.3% 7.3% 1.6% Local Government - Schools % 12.9% 0.8% 1.1% 43.1% 3.4% 0.8% 31.4% 4.7% Markets/Retail % 10.3% 0.1% 0.1% 12.8% 0.2% 0.2% 53.0% 1.4% NULL % 31.7% 2.1% 1.0% 38.8% 3.1% 0.6% 22.2% 3.3% Office Building % 27.5% 0.7% 0.2% 15.8% 0.5% 0.4% 43.1% 2.6% Office Building/Owner Occupied % 18.5% 0.2% 0.1% 18.8% 0.2% 0.2% 49.9% 1.1% Outbuildings Only % 29.0% 0.5% 0.4% 60.8% 1.2% 0.1% 8.9% 0.3% Regional Government % 29.7% 0.7% 0.5% 47.5% 1.4% 0.2% 19.1% 1.1% Religious - Churches % 25.4% 0.8% 0.4% 34.4% 1.3% 0.4% 29.8% 2.2% Residence % 43.2% 46.3% 12.3% 29.4% 37.6% 5.5% 13.1% 31.8% Shopping Center % 5.1% 0.2% 0.1% 6.1% 0.3% 1.1% 62.6% 6.6% Townhouse % 19.4% 1.0% 0.5% 25.9% 1.5% 0.5% 25.5% 2.9% Vacant Land % 49.1% 15.7% 5.5% 44.1% 16.9% 0.8% 6.0% 4.4% Area of UTC type for specified land use % Land = Area of all land Area of UTC type for specified land use % Category = % UTC Type = Area of all land for specified land use Area of UTC type for specified land use Area of all UTC type The % Land Use value of 6.1% indicates that 6.1% of Vacant Land is covered by tree canopy. The % Category value of 49.1% indicates that 49.1% of Virginia Beach s land area is tree canopy in areas where the Class Desc is Vacant Land. The % UTC Type value of 15.7% indicates that 15.7% of all lies in areas of Vacant Land. Table 3: UTC metrics by type, summarized by Class Description, for classes with greater than 250 acres land area. For each 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 (% Class Description) and as a percent of the area for the UTC type (% UTC Type). 4/29/2010 5

6 Figure 7: Possible percentage increase of UTC mapped using Class Descriptions provided by Virginia Beach. 4/29/2010 6

7 Decision makers can use GIS to find out specific UTC metrics for a parcel or set of parcels. This information can be used to estimate the amount of tree loss in a planned development or set UTC improvement goals for an individual property. Where to Plant Trees? GIS Database Figure 8: Parcel-based UTC metrics can be used to support targeted UTC. Conclusions Virginia Beach s urban tree canopy is a vital community asset, reducing storm water 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 36% tree canopy cover, Virginia Beach has similar coverage to Norfolk (33%) and Vinton (39%) Figure 9 shows how Virginia Beach compares to other Virginia localities participating in Urban Tree Canopy Assessments. When summarized by parcels, Virginia Beach has 39%. 70% 60% 50% 40% 30% 20% 41% 30% 47% 44% 27% 44% 58% 27% 33% 20% 53% 48% 40% 36% 39% 27% 10% 0% Arlington, VA Blacksburg, VA Charlottesville, VA Fredericksburg, VA Leesburg, VA Lexington, VA Lynchburg, VA Manassas, VA Norfolk, VA Purcellville, VA Radford, VA Roanoke, VA Salem, VA Virginia Beach, VA Vinton, VA Winchester, VA Prepared by: Additional Information Jim Pugh GIS/Remote Sensing Technician Virginia Department of Forestry 900 Natural Resources Drive, Suite 800 Charlottesville, VA (434) jim.pugh@dof.virginia.gov The study was conducted with funding from the City of Virginia Beach Department of Parks and Recreation, Virginia Department of Forestry and Dept. of Conservation and Recreation and the USDA Forest Service. More information on the UTC assessment project can be found at the following web sites. 4/29/