Objective Against the background of intensifying global climate change and the advancement of carbon neutrality goals, extreme weather events impact the the Earth’s natural environment, human survival, and socioeconomic development. The Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report states that the world must implement deep, rapid, and sustained emission reductions to address climate risks in the future. As major centers of energy consumption and carbon emissions, cities have become key units in achieving low-carbon transition goals. How to achieve the coordinated development of urban low-carbon transition and ecological security has emerged as a hot topic in current research. As Beijing’s only purely mountainous district and a typical mountainous, resource-based transition area, Mentougou District faces highly distinctive climate risks and land-use pressures. Changes in its land use and dynamics of carbon stocks hold significant implications for the regional ecological security landscape and urban sustainable development.

Methods This study focuses on Mentougou District in Beijing and constructs an SD-PLUS-InVEST multi-model coupling framework to conduct a systematic analysis covering the entire process of “land use-scenario simulation-carbon stock assessment.” Specifically, based on land use data from 2000, 2010, and 2020, a System Dynamics (SD) model was developed and coupled. Scenario simulation parameters were set according to climate change projections and socioeconomic data under different Shared Socioeconomic Pathways and Representative Concentration Pathways (SSP-RCPs) scenarios to simulate land use demands under various scenarios. Second, the PLUS model was used to explicitly simulate future land-use spatial patterns. By establishing a land-use transition matrix and a development probability map, the model allocates macro-level demands to spatial units, thereby ensuring consistency between quantitative and spatial constraints. Finally, the InVEST model was used to calculate the total carbon stock and its spatial distribution for different scenarios. This study aims to elucidate the mechanisms underlying land use evolution during the transition period of mountainous cities and to provide decision-making references for low-carbon development in ecological conservation areas.

Results The results indicate that: 1) Simulations based on the PLUS model reveal that under different SSP-RCP scenarios, the area of ecologically sensitive farmland decreases significantly, water bodies are obviously regulated by policies, and the expansion pattern of construction land shows substantial spatial heterogeneity.. This phenomenon of spatial displacement reflects the dynamic interplay between economic development needs and ecological conservation within the framework of the “farmland reclamation and compensation” policy. 2) Comparative scenario analysis indicates that the SSP2-4.5 scenario, characterized by moderate development intensity, is most conducive to the coordinated eco-economic development of Mentougou District. Under this scenario, carbon stocks steadily increase from 26.59 Tg in 2020 to 27.05 Tg in 2060, achieving enhanced carbon sequestration under conditions of moderate economic growth and mild climate warming. In contrast, regional carbon stocks under the SSP1-2.6 scenario are lower than those under SSP2-4.5, primarily due to the conversion of some forested land into grasslands with lower carbon density. This highlights the risk of internal functional degradation that mountainous ecological conservation areas may face under strict regulatory frameworks. Under the SSP5-8.5 scenario, urban land expands in a concentrated manner in the eastern Mentougou New Town, with both cropland and urban land encroaching upon high-carbon-density forested areas, leading to a significant decline in carbon stocks. 3) Analysis of land use optimization indicates that maintaining the synergistic effects of forest, grassland, and water bodies is key to increasing carbon stocks. The scale of construction land expansion must be controlled to prevent encroachment on high-carbon-sink forest areas; simultaneously, the layout of cropland should be optimized to avoid the conversion of marginal forest land into low-efficiency cropland. Such adjustments to the land use structure can enhance carbon stocks; 4) Analysis of the transformation and development pathway suggests a three-phase strategy: First, prioritize the ecological restoration of abandoned mining areas such as the Wangping Mine to increase carbon density in the restored zones, while simultaneously developing green industries such as eco-tourism and specialty agriculture; second, establish a spatial system comprising “new cities, characteristic towns, and ecological villages,” leveraging rail transit to achieve intensive development and focusing on the exploitation of abundant natural and rich cultural resources; finally, develop green industries such as eco-tourism to establish a mountainous economic development pathway that integrates high-quality green development in old industrial and mining areas with eco-tourism-driven prosperity for local residents, thereby laying a solid foundation for building a low-carbon city.

Conclusion This study focuses on Mentougou District in Beijing, a mountainous urban area, and constructs a relatively accurate, comprehensive, and dynamic land-use simulation model. It simulates future land demand quantitatively from a macro, top-down perspective and simulates the spatial patterns of future land use from a micro, bottom-up perspective. The aim is to provide scenario simulations to support the development of future regional spatial planning in the district. It also offers a reference framework and scenario pathways for other mountainous and resource-based cities undergoing transformation to optimize land use and manage carbon sequestration in the context of climate change.