City Trees is a premier publication focused on urban + community forestry. In each issue, you’ll learn how to best manage the trees in your community and more!
Issue link: https://read.dmtmag.com/i/75614
Figure 2b. Enhanced 3D LiDAR visualization in which the LiDAR data has been processed to highlight points in the data (yellow and red) that likely correspond to tree canopy. Funding from the National Urban and Community Forestry Advisory Council (NUCFAC) enabled a team from the University of Vermont, in collaboration with the City of New York, Department of Parks and Recreation and Columbia University, to map tree canopy with greater accuracy and precision than any previous effort. To help answer the third question of prioritizing tree planting locations, a team from the Forest Service, University of Vermont, and City of New York Department of Parks and Recreation conducted an Urban Tree Canopy Prioritization analysis. The goal was to match the places where the benefits of trees are lacking with appropriate organizations—those best suited to plant on those particular site types. For example, because trees intercept the sun's rays and evapotranspirate water, which cools the air, satel- lite data showing the City's hottest neighborhoods in the summer were incorporated. Replacing impervious surfaces with soil and planting trees, similarly, can help reduce and mitigate the damage that floods inflict. It was beyond the scope of the project to do detailed flood modeling, but the team was able to leverage existing data from 311, NYC's hotline for citizen reporting of non-emergency service requests. A GIS layer derived from flood reports was also added into the prioritization, further targeting where trees may improve stormwater concerns. Trees do more than keep our cities cooler and drier, they can be part of making urban areas more beau- tiful and healthier places to live. The prioritization analysis incorporated variables related to social and environmental justice, like low median income, poor public health measures, and high crime. The prioriti- zation framework allows organizations, such as gov- ernment agencies and non-profits, to pick and choose www.urban-forestry.com Figure 3a. High-resolution aerial image for a portion of Manhattan. Figure 3b. Results from the first tree canopy mapping project done for New York City in which only imagery was used. The pink areas correspond to tree canopy. Figure 3c. Revised tree canopy map in which a combination of LiDAR and imagery were used. LiDAR made it possible to accu- rately map tree canopy in areas with complex shadows. For this particular area the LiDAR approach detected more than double the amount of tree canopy when compared to using imagery alone. 31