Using unmanned aerial vehicle data to assess the three-dimension green quantity of urban green space: A case study in Shanghai, China

Urban green space (UGS), which plays an important role in reducing the problems associated with urbanization, needs to be evaluated by metrics. Three-dimension green quantity (3DGQ), a quantitative index that measures the crown space occupied by a growing plant, is often used to evaluate the extent, and the environmental and climatic benefits of UGS. The objective of this study was to measure the 3DGQ of Paotaiwan Wetland Park (PWP) in Shanghai, China. Implementation of the 3DGQ index was supported by remote sensing (RS) images taken by an unmanned aerial vehicle (UAV). The 3DGQ calculations for 100 species of trees were used to calculate the 3DGQ of the UGS in PWP. The environmental and climatic benefits of UGS in PWP were also evaluated. The 3DGQ for the whole PWP was 668,624.13 m3. The mixed woods in the PWP annually absorbed 1,635.57 t CO2, 2.03 kg SO2, 735.48 t dust, and 2,254.49 t of O2. There was 367.74 t of diurnal transpiration. The lowered temperature of the PWP in the transpiration scope at 100 m altitude was 1.8 °C. The use of a UAV to assess UGS could help planners and policy makers to improve the environmental and climatic benefits of UGS.