Terrain-sensitive carbon management for SDG11: A spatial-explicit assessment of mountainous cities under climate and...

Understanding the driving effect of terrain gradient and land use change on carbon stock in mountain cities(MCS) can provide effective support for the terrain-sensitive carbon management in mountain cities. In this study, a spatially explicit assessment framework is established to explore the spatial and temporal evolution of carbon stocks based on land use changes between 2000 and 2040 and the "topography‑carbon storage" index. The results show that MCS exhibit significant topography-driven heterogeneity, with steep slopes (slopes >25°) retaining more than 50 % of baseline MCS under ecological red line policies, while gently sloping slopes (slopes <15°) lose 1.4 % per year due to urban sprawl, which would require three-dimensional green infrastructures (e.g., vertical forests). Scenario simulations show that the synergistic effect of policy intervention and topographic constraints is significant, and the ecological red line effectively inhibits the development of steep-slope zones (SDCLE = 0 for slope zones with slope > 25° under SSP2), but weak control of the mid-slope zones leads to them becoming a hotspot of carbon loss. Therefore, local governments should prioritize the absolute protection of steep slopes, the dynamic threshold of transition zones, and the compact green development of lowlands through gradient-based zoning, so as to achieve the sustainable development of low-carbon resilience in mountain cities. This study has important implications for urban planning, environmental sustainability in mountainous areas.