Spatiotemporal evolution of ecological quality and its driving mechanisms in Shenzhen, China

Ecological quality is an important indicator of urban development. Understanding the spatiotemporal evolution of urban ecological conditions and their driving mechanism is essential for urban ecological construction and sustainable development. In this study, Landsat imagery was used to construct a remote sensing ecological index (RSEI) by integrating four indicators—greenness, wetness, heat and dryness—through principal component analysis (PCA). Based on the RSEI, the ecological quality of Shenzhen during 1990—2020 and its spatiotemporal variations were systematically analyzed. Furthermore, the geographical detector model was employed to quantify the effects of nine driving factors including natural environmental conditions and human activities, on ecological quality changes. The results show that: ① Ecological quality in Shenzhen exhibits significant spatial heterogeneity, with relatively high ecological quality mainly distributed in the southeastern and western urban fringes, whereas lower ecological quality is concentrated in the western and central built-up areas. ② Over the past 30 years, ecological quality in Shenzhen has shown an overall improvement trend, with 33.0% of the area experiencing ecological improvement and 23.9% showing degradation, indicating that the ecological improvement dominates overall. ③ Temperature, slope, elevation and land use type are the key factors influencing ecological quality changes, while the influence of precipitation factor is relatively weak. Interactions among driving factors mainly exhibit two patterns: bivariate enhancement and nonlinear enhancement, with bivariate enhancement being the dominant interaction type. Overall, the spatial differentiation of ecological quality in Shenzhen results from the joint action of natural factors and anthropogenic factors. Natural factors currently play a dominant role, but the influence of human activities is gradually increasing. This study reveals the spatiotemporal evolution patterns and driving mechanisms of ecological quality in Shenzhen and provides a scientific basis for urban ecological protection and sustainable development.