[Analysis of Spatiotemporal Evolution and Driving Factors of Ecological Environment Quality in the Min Delta Urban...

Investigating the spatiotemporal evolution patterns of ecological environment quality and its driving factors in the Min Delta Urban Agglomeration is essential for ensuring regional ecological security and promoting high-quality development. Utilizing Landsat remote sensing datasets from 2000 to 2024 on the Google Earth Engine platform， this study calculated the remote sensing ecological index （RSEI） through principal component analysis. The spatiotemporal evolution patterns of RSEI in the Min Delta Urban Agglomeration were analyzed in conjunction with the coefficient of variation. Furthermore， the interpretable Extreme Gradient Boosting （XGBoost-SHAP） model was employed to identify key drivers， nonlinear effects， and interaction effects of both natural and human activity factors on ecological environment quality. The results showed that： ① Temporally， the RSEI of the Min Delta Urban Agglomeration exhibited an initial decline followed by an upward trend. The multi-year average RSEI was 0.62， with the lowest and highest values occurring in 2010 （0.53） and 2024 （0.68）， respectively， indicating generally good ecological quality overall. ② Spatially， the RSEI in the study area showed a distribution pattern of "higher in the northwest and lower in the southeast". The area with improved ecological quality was larger than that with degraded quality， with a difference of 4.51% in their respective proportions. ③ The coefficient of variation of RSEI in the study area ranged from 0.58% to 84.63%， with a mean value of 11.97%. The overall ecological environment was stable， but significant spatial heterogeneity existed. Specifically， 54.86% of the area exhibited low RSEI volatility， indicating stability， primarily distributed in the western and northern regions with high vegetation coverage. In contrast， 9.10% of the area was shown to be unstable， mainly located in the eastern coastal regions. ④ The dominant factors driving changes in ecological environment quality demonstrated temporal heterogeneity： From 2000 to 2010， changes were primarily driven by natural factors such as fractional vegetation coverage （FVC）， annual average temperature （AT）， and annual precipitation. In contrast， from 2015 to 2024， changes shifted to being co-driven by both natural factors （FVC） and human activity factors （nighttime light intensity （NTL）， population distribution）. Moreover， the interactions between natural and human activity factors were highly complex， exhibiting distinct threshold dependency and reversibility of effect directions. For instance， the most pronounced interaction was observed between FVC and AT in 2000. Specifically， when FVC was below 50%， an increase in AT had a positive interactive effect； however， beyond this threshold， the influence of FVC on RSEI changes gradually shifted to a negative effect as AT increased. By contrast， in 2024， the most significant interaction occurred between FVC and NTL. When FVC was less than 45%， increasing NTL transitioned from a negative to a positive effect on RSEI dynamics； conversely， when FVC exceeded 45%， the interactive effect shifted from positive to negative. These findings provide a scientific reference for ecological civilization construction and sustainable development in the Min Delta Urban Agglomeration.