Multi-Scenario Land Use Change Dynamic Simulation and Carbon Stock Assessment of Man–Nature in Border Mountainous Areas

As an important gateway for China’s foreign exchanges, the border areas of Guangxi face irrational land use issues that impact local ecology, the economy, national security, and international relations. With global attention on climate change, “carbon peaking”, “carbon neutrality”, and ecosystem carbon storage, this study focuses on the border area, using natural resource, socio-economic, and transportation factors. Through the PLUS and In VEST models, it predicts carbon storage under multiple scenarios. (1) The results show that from 2000 to 2020, forest land, water bodies, and other land types decreased, while construction land and cropland increased. Land use changes accelerated over time, with significant urban expansion into cropland and forest areas, reflecting rapid socio-economic development. (2) For 2030, the following projections were made: Under natural development, construction land expands significantly, forest land declines, and urbanization spreads outward. Under urban development, construction land grows fastest, forest and grassland decline sharply, and infrastructure reduces other land types. Under sustainable development, reductions in forest and grassland are mitigated, construction land grows moderately, and water bodies remain stable, achieving a balance between humans and nature. (3) Compared to 2020, ecosystem carbon storage declines across scenarios. Annual decreases are 513,223.13 tons (natural), 5,469,327.95 tons (urban), and 500,214.24 tons (sustainable). Sustainable development is crucial for achieving “dual carbon” goals. This study emphasizes ecological priority, strict cropland protection, and controlled construction land, offering sustainable land management strategies to ensure rational land use and border security.