Analyzing spatiotemporal changes in urban green spaces’ ecosystem service value and resilience

BACKGROUND AND OBJECTIVES: Urban ecosystem services are provided by a multitude of habitats, including green and water spaces. Such services are commonly under the control of heavy demand raised by the large number of beneficiaries. In this context, urban green spaces viz. parks and gardens supply these services for city residents. From this perspective, this study is to analyze the spatiotemporal changes in the ecosystem servicevalue of urban green spaces in Districts 1 and 14 (out of 22) of Tehran Municipality, Tehran, Iran. The level of resilience (namely, capacity and adaptability) of these districts, once confronted with climate change and environmental degradation, particularly carbon sequestration, is then investigated. As an innovation, the current study ultimately assesses the ecosystem services value of urban green spaces with higher accuracy to exert more actions to improve these spaces.METHODS: This library-based documentation study utilized spatiotemporal modeling with reference to software packages and field visits. In the first step, remote sensing was applied to create land-use maps using ENVI 5.3 software package and its formulas, algorithms, and extensions. In the second step, the InVEST software and model were used to model carbon sequestration in selected districts. To assess carbon sequestration and its changes over time, land-cover maps were generated for three 10-year periods (2003, 2013, and 2023) with 30 m accuracy via Landsat satellite-based program. The maps were classified in ENVI 5.3, and the net carbon sequestration in land, along with the market size of carbon sequestration, was estimated using the InVEST model, incorporating land-use maps, land-cover types, and carbon sequestration in reservoirs. Organic carbon content was determined based on other carbon reservoirs, previous surveys, and available data. Each carbon reservoir unit was valued in dollars, and discount rates and annual changes in carbon value were calculated based on global and local conditions surveys.RESULTS: The study results obtained from land-cover/use maps produced during 2003, 2013, and 2023 in the selected districts, demonstrated a diminishing trend of green spaces and barren lands, while the area of ​​built land has increased over time. The numerous changes in land use in the company of construction in green spaces and barren lands in District 1 from 2003 to 2013 had further led to 191401608 tons of emission, including 179114669 tons of carbon, valued 49056267 and 4636422 million Dollars, respectively. In District 14, the emission during 2003-2023 was also equal to 18.3644 tons of carbon, and that was 3444.14 tons of carbon for the period of 2013-2023, worth 1873871 and 1749769 thousand Dollars, in that order.CONCLUSION: Indiscriminate construction and development of built-up areas in Tehran have undermined green spaces and barren lands, negating the benefits of green infrastructure efforts. This has resulted in a reduction in urban green spaces, hampering their capacity for carbon absorption and sequestration. Consequently, reduced carbon deposition will contribute to higher temperatures, diminishing the resilience of these urban areas.