Jie Chen, Pengxiang Gao, Yi Hou
Abstract Against the backdrop of China’s “Dual Carbon” (carbon peak and carbon neutrality) strategic initiative, terrestrial ecosystem carbon sequestration has become a core pillar of climate mitigation and ecological governance. This study systematically quantifies the spatiotemporal distribution of carbon storage and and projects long-term carbon sink trajectories under divergent socioecological development pathways across the Fen River Basin—a representative ecologically fragile tributary catchment of the Yellow River. Four scenarios based on the basin’s ecological landscape planning were established: Natural Development, Economic Priority, Cropland Protection, and Ecological Protection. By coupling the PLUS and InVEST models, an analytical framework linking land use change with ecosystem carbon storage was constructed to simulate and predict the spatial distribution and dynamics of carbon storage under different scenarios. The Geodetector was used to identify the key driving factors. The results indicate that: (1) From 2005 to 2020, cropland remained the dominant land use type but showed a continuous decreasing trend alongside grassland degradation. Forest land area initially decreased before recovering slightly, while built-land expanded consistently. (2) The total carbon storage in the basin showed a declining trend, decreasing from 700.32 Tg in 2005 to 683.48 Tg in 2020, with a cumulative loss of 16.84 Tg. Soil organic carbon was the major carbon pool. Spatially, areas with high carbon storage were primarily distributed in the eastern and western parts of the basin, while the central-southern regions generally had lower carbon storage. Carbon storage exhibited significant positive spatial autocorrelation, with High-High clusters (hot spots) being more extensive than Low-Low clusters (cold spots). The area experiencing carbon loss was substantially larger than the area with carbon gain. (3) Multi-scenario simulations revealed that different development pathways significantly impact carbon storage. The Ecological Protection scenario yielded the highest carbon storage (683.57 Tg), highlighting the effectiveness of ecological protection in enhancing regional carbon sink capacity. (4) NDVI was the dominant factor influencing the spatial heterogeneity of carbon storage, possessing strong independent explanatory power. Its interactive effects with other factors further enhanced the ability to explain variations in carbon storage. This study elucidates the coupling mechanism between land use change and carbon storage, providing a scientific reference for ecological protection, land structure optimization, and carbon sink enhancement in the Fen River Basin.