Evaluating urban park ecosystem services and modeling improvement scenarios

Three ecosystem services of the 25 public parks in Bangkok, including carbon sequestration, avoided runoff, four air pollutant removals (CO, NO₂, PM₁₀, and PM_2.5), and the relevant monetary values, were determined using i-Tree Eco software. Two modeling scenarios (MS) including MS1 (no greening improvement) and MS2 (improvement by increasing either green area or tree planting, or both in the parks) with tree annual mortality rates (AMR) of 1 and 3% were developed to forecast the parks' ecosystem services for 50 years after 2020 (2021-2071). The results revealed the synergistic interactions of the different tree planting specifications (MS1 and MS2) and tree mortality rates on the parks' ecosystem services. For MC2 with the assigned 1% AMR, the parks' optimal ecosystem services were obtained and the average annual monetary value (0.55 million USD) of the total ecosystem services of the 25 parks over the 50-year forecast was 150% higher than that (0.22 million USD) in 2020. Based on MS1 and MS2, tree rotations should be conducted in the parks after 2057 and 2065, respectively, for the low tree AMR (≤1%) but not later than 2041 and 2043, respectively, for the higher tree AMR.