Developing a composite index for urban ecosystem services (Hyrcanian forests—Gorgan).

This article focuses on assessing the changes in urban ecosystem services (ESs) in Gorgan, Iran, over 35 years, using an integrated approach that includes a composite total ecosystem services (TES) index. The study quantifies six key ESs—water yield, flood risk mitigation, net primary production (NPP), soil retention, carbon sequestration, and air pollution removal—modeled and mapped via remote sensing, InVEST, and i-Tree Eco software, uniquely employing a hexagonal spatial unit for analysis. Results show a significant decline in TES from 0.427 in 1985 to 0.192 in 2020, primarily due to urban expansion and land use change that reduced forest and green spaces, leading to increased flood risk, soil erosion, decreased air quality, and ecological imbalance. The Hyrcanian forests were identified as the main contributors to ES supply, while urban areas exhibited the lowest levels. The study highlights the importance of integrating ESs into urban land use planning to promote sustainable development and ecological resilience.