A Report on the City of Newport News Existing and Possible Urban Tree Canopy

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1 A Report on the City of Newport News Existing and Possible Urban Tree Canopy 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 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 non-tree 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. Project Background The analysis of Newport News urban tree canopy (UTC) was carried out at the request of the Virginia Department of Forestry (VDOF) in collaboration with the City of Newport News and the Virginia Department of Conservation and Recreation (VDCR). 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. This project was funded by the Virginia Coastal Zone Management Program at the Department of Environmental Quality through a grant from the National Oceanic and Atmospheric Administration, Office of Ocean and Coastal Resources Management, under the Coastal Zone Management Act of This project was conducted as part of the Coastal Nonpoint Source Pollution Control Program as administered by VDCR and the VDOF. The goal of the project was to apply the USDA Forest Service s UTC assessment protocols to the City of Newport News. This analysis was conducted based on year 2008 data. 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 Newport News Have? Figure 1 shows the UTC analysis for the Newport News assessment area (82% of the City s entire area), which is derived from high resolution aerial imagery. 16,018 acres of Newport News is covered by tree canopy. This corresponds to 36% of the total area within the City (Table 1). An additional 14,748 acres of the City could theoretically be improved to support urban tree canopy (termed Possible UTC), Table 2. Figure 1: Land cover for the City of Newport News. Land Classes % Land Acres % Total Area* Area Tree Canopy 16, % 37.7% Non-Tree Vegetation 11, % 27.4% Non-Building Impervious 10, % 25.3% Buildings Impervious 4, % 9.6% Water 1, % 0.0% Total Area 44, % 100.0% Table 1: Land class areas and percentages for the City. *% Total Area includes area covered by water. 3/29/2011 1

2 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). A 93.6% accuracy rate was found after conducting an accuracy assessment. Single trees with canopies larger than 9 square meters were detected. 3a Parcels Mapping Newport News Trees Who Owns Newport News 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) 3b 2b Land Cover Derived from 2008 NAIP Imagery (1m) 3c Possible UTC 2a Figures 2a, 2b: Comparison of 2008 NAIP imagery to the resulting highresolution land cover. 3/29/2011 Figures 3a, 3b, 3c: UTC metrics summarized at the property parcel level. 2

3 Figure 4: mapped using property parcels provided by the City of Newport News. 3/29/2011 3

4 Urban Tree Canopy Summarized by Property Parcels Using the parcel data provided by the City of Newport News, Existing and Possible UTC were summarized by property parcels. This summary excludes any area outside of the assessment area, property parcel boundaries and areas covered by water. Figure 4 shows throughout the City of Newport News summarized by property parcels. Newport News has 41% (12,410 acres) and 48% (14,748 acres) Possible UTC, table 2. Possible UTC has two components, Possible UTC - Vegetation and Possible UTC - Impervious. 28% (8,660 acres) of parcel land area is associated with Possible UTC - Vegetation. 20% (6,088 acres) of parcel land area is associated with Possible UTC - Impervious (Figure 5). 20% 28% 19% Possible UTC - Impervious 41% Possible UTC - Vegetation Not Suitable for UTC Figure 5: Pie chart showing Newport News UTC distribution within parcels. Urban Tree Canopy Summarized by Zoning Categories Using the zoning data provided by the City of Newport News, Existing and Possible UTC were summarized by zoning category (pages 4-7). This summary excludes any area outside the assessment area and areas covered by water. The zoning category R3 has the largest amount of land area with 5,892 acres with the 2nd highest amount of 18.4% (Table 3). The zoning category P1 has the largest amount of 23.4%. R4 and R2 are 3rd (13.9%) and 4th (9.6%) in respectively. Figure 6a compares zoning categories by the amount of land area for all zones with more than 2,000 acres. Figure 6b compares zoning categories by the amount of land area for all zones with less than 2,000 acres. Figure 7 shows theoretical Possible UTC increases by zoning category for the City. Table 2: Acres and percent land area from UTC metrics summarized by property parcels. *Not Suitable for UTC includes all Building Impervious areas within the parcel boundaries. UTC Parcel Metrics Acres % Parcel Land Area Parcel Land Area 30, % 12, % Possible UTC 14, % Possible UTC - Vegetation 8, % Possible UTC - Impervious 6, % Not Suitable for UTC* 5, % C1 M1 Possible UTC Area Possible UTC-Vegetation Possible UTC-Impervious Land Area P1 R2 R3 R Acres Figure 6a: UTC metrics summarized by zoning categories for all zones with more than 2,000 acres, which comprises 70% (24,843 acres) of all zoning areas. 3/29/2011 4

5 C2 C3 C4 C5 M2 O1 O2 O3 R1 R5 R6 R7 R8 R9 Possible UTC Area Possible UTC-Vegetation Possible UTC-Impervious Land Area Acres Urban Tree Canopy Summarized by Zoning Categories Urban Tree Canopy Summarized by Zoning Categories Figure 6b: UTC metrics summarized by zoning categories for all zones with less than 2,000 acres, which comprises 10,693 acres (30%) of all zoning areas. 3/29/2011 5

6 Zoning Category Land Area (Acres) % Land Area Urban Tree Canopy Summarized by Zoning Categories Urban Tree Canopy Summarized by Zoning Categories Possible UTC Vegetation Possible UTC Impervious % Zoning Category % UTC Type % Land Area % Zoning Category % UTC Type % Land Area 3/29/ % Zoning Category % UTC Type C1 2, % 18.5% 3.8% 1.6% 20.7% 5.8% 2.6% 33.3% 15.0% C % 14.1% 0.8% 0.3% 16.8% 1.2% 0.8% 39.8% 4.7% C % 3.7% 0.1% 0.1% 21.6% 0.5% 0.2% 31.6% 1.2% C % 27.0% 0.9% 0.3% 22.7% 1.1% 0.3% 25.9% 2.0% C % 24.5% 0.4% 0.1% 18.1% 0.4% 0.2% 30.6% 1.1% M1 3, % 25.7% 5.9% 2.8% 32.8% 10.4% 2.6% 29.5% 14.9% M2 1, % 26.3% 3.6% 0.5% 10.7% 2.0% 2.4% 47.6% 14.2% O % 26.3% 0.3% 0.1% 18.1% 0.3% 0.1% 31.4% 0.8% O % 36.1% 0.4% 0.1% 17.8% 0.3% 0.1% 31.3% 0.7% O % 49.2% 1.4% 0.3% 25.3% 1.0% 0.2% 17.9% 1.1% P1 5, % 60.2% 23.4% 3.7% 25.1% 13.4% 1.3% 8.7% 7.5% R1 1, % 47.6% 4.6% 1.6% 42.4% 5.7% 0.2% 4.7% 1.0% R2 2, % 49.8% 9.6% 2.1% 29.2% 7.8% 0.5% 6.4% 2.7% R3 5, % 41.8% 18.4% 4.6% 27.7% 16.8% 1.4% 8.7% 8.4% R4 5, % 34.8% 13.9% 4.8% 32.2% 17.6% 1.3% 8.6% 7.6% R5 1, % 30.8% 3.9% 1.4% 30.4% 5.3% 0.8% 15.8% 4.4% R % 20.1% 0.2% 0.1% 25.9% 0.3% 0.1% 38.6% 0.8% R7 1, % 30.2% 3.7% 1.1% 24.8% 4.2% 1.1% 24.3% 6.5% R % 24.5% 1.6% 0.7% 30.3% 2.6% 0.6% 23.7% 3.3% R % 45.8% 3.3% 0.9% 34.4% 3.4% 0.4% 13.2% 2.1% % Land = Area of UTC type for specified land use Area of all land The % Category value of 1.2% indicates that 1.2% of Newport News land area is tree canopy in areas where the land use is R9. % Category = Area of UTC type for specified land use Area of all land for specified land use The % Land Use value of 45.8% indicates that 45.8% of R9 land is covered by tree canopy. % UTC Type = Area of UTC type for specified land use Area of all UTC type The % UTC Type value of 3.3% indicates that 3.3% of all lies in areas of R9 land use. 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 Category) and as a percent of the area for the UTC type (% UTC Type).

7 Figure 7: Possible percentage increase of UTC mapped using zoning categories provided by the City of Newport News. 3/29/2011 7

8 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 Newport News 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 38% canopy coverage of all land area within the City, Newport News has similar percentages of coverage as Chesapeake, Fairfax County, Front Royal, Salem, Vinton, and Virginia Beach. Figure 9 shows how Newport News compares to other Virginia localities participating in Urban Tree Canopy Assessments. When summarized by property parcels, Newport News has 41% with 47% of all parcels having less than 25% canopy coverage. 70% (24,843 acres) of the is located within the following zoning categories: C1, M1, P1, R2, R3, and R4. 58% 60% 53% 52% 50% 39% 40% 30% 30% 48% 47% 44% 26% 41% 44% 44% 41% 42% 38% 33% 27% 27% 40% 39% 36% 27% 20% 22% 20% 10% 0% * Data provided by University of Vermont **Data provided by Fairfax County ^Subset (urban/suburban areas) of locality 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 VA_UTC.html 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 sites. utc/ 3/29/2011 8