Spatiotemporal associations between ecosystem service value and human activity intensity: a case study of the Chengdu metropolitan area, China

Understanding the spatiotemporal association between ecosystem service value (ESV) and human activity intensity (HAI) is essential for coordinating regional ecological protection with sustainable socioeconomic development. Using geospatial data for the Chengdu Metropolitan Area from 2000 to 2020, this study estimated ESV and HAI with an ESV accounting model and an HAI assessment model, and examined their spatiotemporal patterns and associations using bivariate spatial autocorrelation and coupling coordination degree models. The results showed that: (1) Temporally, total ESV initially increased and subsequently decreased, with an overall decline of CNY 37 million. Spatially, ESV decreased outward from the Longmen Mountains in the west and Longquan Mountains in the central area, with high-value zones occurring mainly along the Tuojiang and Minjiang rivers. (2) HAI increased continuously. Low values were concentrated in the western Longmen Mountains and eastern hilly areas, whereas high values were centered in Chengdu’s main urban area and expanded into surrounding areas. (3) HAI and ESV exhibited a significant and increasingly strong negative spatial correlation. High-low clusters were concentrated in Chengdu’s main urban area and adjacent built-up areas, low-high clusters remained stable in the densely vegetated western Longmen Mountains, and low-low clusters were widespread across the eastern hilly agricultural areas. (4) Overall coupling coordination remained low and was dominated by low coordination. Areas of severe and moderate imbalance continued to expand, forming a contiguous, outward-expanding pattern in the central region. By revealing the spatiotemporal association between ESV and HAI at the metropolitan-area scale, this study provides a theoretical basis for constructing ecological security patterns and sustainable planning in similarly urbanizing regions.