Balancing ecosystem services for environmental sustainability: An integrated assessment method in region 4 of Iran's spatial plan

Human activities and overpopulation have disrupted the balance of ecosystem services (ESs), leading to environmental instability. This study introduces an integrated assessment method for assessing ecosystem functions by identifying ecological functional zones based on supply-demand ratios for key services, including water yield, soil retention, food production, and carbon storage. Additionally, we assess regional carrying capacity using these ratios. By integrating land suitability with carrying capacity, we identified areas suitable for agricultural, urban, and industrial development within Region 4 of Iran's spatial plan. The findings reveal considerable spatial variability, with over 90 % of the region experiencing water yield deficits. Notably, strong synergies exist among carbon storage, soil retention, and water yield, with statistically significant explanation coefficients of 0.85 and 0.61, respectively (p < 0.01). Based on ecosystem functionality, we classified the landscape into four zones: reconstruction (61 %), restoration (21 %), protection (6 %), and developable areas (12 %). The 6 % protection zone primarily within the Central Zagros—a critical water-supplying region—encompasses forested and mountainous areas such as Lordegan, Koohrang, and parts of Farsan, Izeh, Andika, and Borujen counties. These counties exhibit high water yield and carbon storage with minimal soil erosion. We recommend designating this zone as a protected area and implementing integrated watershed management strategies to enhance environmental sustainability. Alarmingly, only 0.2 % of the region is deemed suitable for future agricultural, industrial, and urban development, underscores the urgent need to prevent excessive agricultural expansion in Khuzestan and Isfahan provinces to protect regional sustainability. This approach highlights the necessity of integrating ecosystem science into spatial planning to support—an adaptable framework, for other Middle Eastern regions facing similar environmental challenges. • Integrated method assesses ecosystem functionality (CESDR). • Spatial analysis guides future development in region 4 of Iran. • Ecological zones classified: reconstruction, restoration, conservation, developable. • Highlights significant spatial heterogeneity in ecosystem services. • Emphasizes the importance of mainstreaming ecosystem science for environmental sustainability.