A Threshold-Driven Method to Urban Ecological Security Zoning Management: The Case of Green Infrastructure Planning in Harbin, China

Ecological vulnerabilities in cold-region legacy industrial cities remain poorly addressed by conventional management, which frequently lack the quantitative threshold guidance necessary for effective intervention. To bridge this critical gap, this research uses Harbin as a case study to develop a comprehensive “assessment-identification-zoning-application” framework, operationalizing a threshold-driven approach to ecological security. The investigation integrates the Pressure-State-Response model to evaluate the Urban Ecological Security Index (UESI), employing Geo-Detectors for driver screening and generalized additive models to pinpoint precise ecological security thresholds. Analysis reveals that Harbin’s ecological integrity is primarily dictated by climatic variables ‒ specifically winter ground surface temperature (GST win) and annual precipitation (PRE ann) ‒ which function through significant nonlinear synergies. These natural drivers markedly amplify the stress caused by anthropogenic disturbances such as building density and air quality degradation. By applying a two-dimensional state-stability coupling matrix, the study delineates Harbin into six distinct functional zones, ranging from ideal safety to extreme danger. This spatial differentiation directly informs a tailored green infrastructure planning strategy for each zone. Ultimately, this work converts abstract threshold theory into a pragmatic spatial instrument, providing rigorous quantitative benchmarks for territorial planning and nature-based resilience restoration in cold-region urban contexts.