平原与山地超大城市生态环境质量差异性演进OACHSSCD

Rapid urbanization has profoundly altered the structure and function of urban ecosystems.Unveiling the evolutionary patterns and driving mechanisms of ecological environment quality in megacities with different geomorphic types is of great significance for optimizing urban spatial governance.This study selected Chongqing,a typical mountainous city,and Chengdu,a representative plain city,as case studies.Based on multi-source spatiotemporal data—including Landsat 5/8 imagery,Digital Elevation Model(DEM),Nighttime Light(NL),and OpenStreetMap(OSM)traffic networks—and leveraging the Google Earth Engine(GEE)cloud platform,we comprehensively applied the Remote Sensing Urban Ecological Index(RSUSEI),Landscape Pattern Index(LPI),and machine learning(ML)methods to systematically analyze the spatiotemporal evolution characteristics and driving mechanisms of ecological environmental quality in both cities.By integrating these datasets with robust computational approaches,the study provided a detailed,fine-scale,and multi-dimensional understanding of urban ecological dynamics.The results showed that:(1)From a temporal perspective,due to complex topographic barriers and ecological construction,Chongqing generally demonstrated an improving trend in habitat quality,while Chengdu,which is more weakly constrained by terrain and characterized by a rapidly expanding and fragmented urbanization model,exhibited an overall decline in habitat quality.(2)From a spatial pattern perspective,high-value ecological quality zones in Chongqing expanded from a"strip-like"to a"patch-like"distribution,indicating a gradual improvement and spatial stabilization of its overall ecological conditions.In contrast,Chengdu's high-value ecological zones evolved from"peripheral strip-like"to"ring-shaped patches,"yet showed a shrinking trend,while its low-value ecological zones expanded in a"radial wedge-shaped"pattern,suggesting an increasingly uneven spatial distribution of ecological quality.(3)From a structural perspective,high-value habitat areas in Chongqing maintained strong landscape connectivity and stability,whereas Chengdu exhibited increasing fragmentation,declining ecological quality,and weakened continuity of ecological corridors.(4)From a mechanistic perspective,Chengdu's driving mode shifted from a nature-society composite to one dominated by social factors,while natural factors continued to play the dominant role in Chongqing,reflecting the differing resilience and adaptability of their ecological systems.These findings reveal a distinct divergence in ecological driving mechanisms between plain and mountainous cities.In conclusion,significant differences were observed between mountainous and plain megacities in terms of ecological environmental quality evolution and driving mechanisms.This study provides an important reference for optimizing differentiated ecological patterns and formulating spatial governance strategies in megacities,offering deeper insights into sustainable urban development and contributing to the scientific basis for building resilient,ecologically harmonious,and livable urban environments.