Ecological flow-driven multifunctionality: A Nature-based Solutions framework for urban ecological corridor planning in high-density cities

• A flow-led framework reshapes ecological corridor design in high-density cities. • Corridor extent and zoning directly tied to ecological flows and management. • Dual indicators link species migration with human non-motorized movement. • Shanghai case study demonstrates framework feasibility and transferability. This study develops an ecological flow driven framework, grounded in Nature-based Solutions (NbS), that upgrades the canonical source, resistance, and path paradigm for urban ecological corridors to the realities of high-density cities. We refine each stage with process explicit, scale aware, and context sensitive criteria, and extend the paradigm in two directions: (i) delineating corridor extents compatible with dynamic ecological processes and management zoning; and (ii) diagnosing intra-corridor multifunctional coupling by mapping trade-offs and synergies across supporting, regulating, provisioning, and cultural functions. Connectivity assessment is consolidated into structural, potential, and actual categories and aligned with data and models, including least-cost paths, circuit or omnidirectional flow simulation, graph metrics, and movement or genetic evidence. We propose a dual indicator scheme that couples understory birds and small to medium sized mammals with human non-motorized movement to capture proactive ecological and social flows across strata and scales. Mechanisms and critical transitions are operationalized with a quantitative toolkit that includes bivariate spatial autocorrelation, constraint line analysis, response curves, structural equation modeling, interpretable machine learning, and threshold detection. The principal result is an implementable methodology that links ecological flows to corridor extent and internal zoning, producing reproducible steps, indicators, and decision ready maps. The major conclusion is that the framework reframes corridor planning from static structure toward dynamic flow governance, providing actionable guidance for evidence based planning and adaptive management in high-density urban contexts, and a transparent path to integrate monitoring innovations and scenario testing into NbS.