Multiscale evolution of the coupling relationship between ecosystem service value and human activity intensity in the southwest Guangxi Karst-Beibu Gulf

Assessing ecosystem service values (ESV) and human activity intensity (HAI) is essential for ecosystem management and human well-being. Focusing on the southwest Guangxi Karst–Beibu Gulf (SWG–KBG), this study adopts a human–land coupling perspective to analyze the spatiotemporal dynamics of ESV and HAI from 2000 to 2020 at regional, county, and grid scales. Spatial heterogeneity and key natural and anthropogenic drivers of ESV were quantified using the geographic detector method, while a four-quadrant model was applied to evaluate ecological quality based on ESV–HAI interactions. The results showed that: ESV exhibited an overall increasing trend, characterized by lower values in the central and southern regions and higher values in the northwestern Karst–Beibu Gulf. Spatial autocorrelation analysis showed that ESV hot spots were spatially clustered, whereas cold spots were fragmented and dispersed. GDP density and population density were identified as the primary drivers of ESV variation. Meanwhile, HAI demonstrated pronounced spatiotemporal heterogeneity, with ecosystem disturbance increasing over time and generally declining from the central and southern regions toward the northwest. Overall, the coupling between HAI and ESV remained largely coordinated, indicating relatively good ecological conditions across the region. Grid-level analysis uncovered localized degradation and conflicts masked at the county scale, highlighting the necessity of multi-scale assessments to capture spatial heterogeneity and support targeted ecosystem management. By examining ESV–HAI coupling across scales, this study elucidates their joint influence on ecological quality and provides a scientific basis for scale-sensitive management in complex human–nature systems.