An Urbanization-Aware Remote Sensing Ecological Index for Urban Ecological Quality Assessment: A Case Study of Hangzhou, China

Rapid urban expansion has intensified interactions between human disturbance and urban ecological processes, creating an urgent need for robust and urban-sensitive assessment tools. To improve the applicability of conventional remote sensing ecological evaluation in cities, this study develops an Urban Remote Sensing Ecological Index (URSEI) by incorporating an Urbanization Index (UI) into the RSEI-based PCA framework. Multi-temporal Landsat observations acquired during the peak vegetation season were used to construct annual ecological indicators, thereby improving the temporal representativeness of ecological assessment. Taking Hangzhou, China, as a case study, URSEI was applied to examine ecological quality dynamics inside and outside the Ecological Conservation Redline (ECR) from 2010 to 2024, together with temporal trend characteristics, indicative persistence patterns, and meteorological associations. The results show that URSEI generally achieved higher first principal component contribution rates than RSEI, suggesting stronger integration of ecological information within the PCA framework. UI exhibited the strongest negative correlation with URSEI among the stress-related indicators, highlighting the importance of explicitly representing urbanization-related disturbance in urban ecological assessment. Citywide ecological quality displayed a fluctuating but weakly improving tendency over the study period, while the ECR consistently maintained higher URSEI values than the overall urban area. However, most detected temporal changes were statistically non-significant, indicating that ecological conditions remained broadly stable rather than showing pronounced improvement or degradation. Temperature-related thermal conditions were predominantly negatively associated with URSEI, whereas precipitation showed mainly positive relationships and a stronger association with URSEI among the climatic variables examined. Overall, URSEI provides an urbanization-aware framework for long-term ecological monitoring and offers a useful basis for ecological management and sustainable planning in rapidly urbanizing regions.