Percent of land covered by tree canopy
Geographic Unit of Analysis:
|Percent of land covered by tree canopy (2013)|
|Financial District/South Beach||10.4%|
|Golden Gate Park||48.0%|
|South of Market||3.4%|
|West of Twin Peaks||17.3%|
Trees provide natural cooling through the shading of streets and buildings, reducing exposure to UV radiation and the risk of skin cancer, as well as energy demand and consumption. Trees also capture air pollution, reduce carbon dioxide, increase oxygen, and help capture storm-water runoff, reducing the amount of mercury, oil, and lead going into the Bay. Trees can also serve as buffers to traffic, reducing pedestrian injuries. Several studies show that the presence of forests, trees and other vegetation improves adult recovery from mental fatigue, leading to a reduction in socially unacceptable behavior and crime, as well as increased concentration and fewer behavior problems among children.a,b
A city’s tree canopy is measured by the amount of land covered by trees when viewed from above. San Francisco’s tree canopy (13.7%) is smaller than Chicago (17%), Los Angeles(21%), and New York City (24%). This translates to very few trees. Even worse, the city’s tree canopy is actually shrinking. New tree plantings arenot keeping pace with deaths and removals. As many as 100,000 potential streettree planting spaces remain empty. Thousands of additional planting spaces existin parks and on private property. The city’s trees are also not evenly distributed, and neighborhoods with more disadvantaged populations generally having less tree canopy. The neighborhoods with the lowest rates of tree canopy coverage include: Mission Bay, South of Market, and Tenderloin which all have less than 5% canopy coverage. In contrast, Seacliff, Presidio Heights, and Inner Sunset all have greater than 25% canopy coverage.
The poor state of San Francisco's urban forest was the inpetus for the 2014 Urban Forest Plan: http://sf-planning.org/urban-forest-plan. The Plan outlines 4 priority recommendations: 1) maximize the benefit of the urban forest through strategic species selection, 2) increase the street tree population with 50,000 new trees by 2035, 3) establish & fund a citywide street tree maintenance program and 4) manage street trees throughout their entire life-cycle by creating an interdependent urban forestry operation.
A city’s tree canopyis measured by the amount of land covered by trees when viewed from above.San Francisco’s tree canopy (13.7%) 1 is smaller than Chicago (17%), Los Angeles(21%), and New York City (24%). This translates to very few trees.Even worse, the city’s tree canopy is actually shrinking. New tree plantings arenot keeping pace with deaths and removals. As many as 100,000 potential streettree planting spaces remain empty. Thousands of additional planting spaces existin parks and on private property. The city’s trees are also not evenly distributed,
In preparation for the San Francisco Urban ForestPlan (2013), the Planning Department performed anUrban Tree Canopy (UTC) Analysis using aerial imagery and additional data sets to determine a canopy estimate for the City & County of San Francisco. Detailed explaination of the analysis process can be found in Appendix A of the Urban Forest Plan: http://default.sfplanning.org/plans-and-programs/planning-for-the-city/urban-forest-plan/Urban_Forest_Plan_Final-092314WEB.pdf
Because of limited funding for this analysis, low-cost multispectralimagery from the NAIP program was used in conjunction with LiDAR data purchased under current City contracts and licensing with PictometryCorp. There is no guarantee that NAIP will have 2015 imagery available or that the City will have purchased the required LiDAR data needed to perform this analysis exactly the same as described here in the future.
Urban Tree Canopy data from the San Francisco Planning Department, 2013
Maco SE, McPherson EG, Simpson JR, Peper PJ, Xiao Q. City of San Francisco, California Street Tree Resource Analysis. Center for Urban Forest Research, Pacific Southwest Research Station, USDA Forest Service. December 2003.