Bridging the key components of urban ecosystem services assessment: links and feedbacks between “typology-multifunctionality-supply and demand”

Current research on urban ecosystem services faces three major challenges: scale gap, disciplinary barriers, and knowledge fragmentation, necessitating a systematic assessment framework to support precise governance decisions. This study proposes a cascading "Typology-multifunctionality-supply and demand" framework to establish a full-chain research paradigm, enhancing information flow and feedback mechanisms from fundamental understanding to management implementation. A practical case study in Changchun, Northeast China, applied multisource data and interdisciplinary tools to map urban green space (UGS) typologies, assess multifunctionality, and identify supply–demand mismatches. UGS ecological functions exhibit higher values at the edges and lower values in the center, contrasting with the spatial distribution of social functions. Significant synergies exist among ecological functions, while weak trade-offs are observed between ecological and social functions, with most UGS being ecology-dominant. The mismatches of supply–demand gradually transition from social to ecological aspects from the inner ring to the outer ring of the city. The multifunctional performance characteristics of different UGS types vary significantly. The "Three-Question Decision Toolkit" (Where-What-Which) enables the optimization of UGS management by tracing decision-making processes back to typological adjustments, integrating spatial prioritization, functional enhancement, and targeted type-specific interventions. The cascading framework’s bidirectional coupling mechanism (forward analysis and feedback optimization) provide theoretical and practical tools for precision governance of high-density cities.