Impact of Land-Use Change on Carbon Storage in the Loess Plateau Based on the PLUS–InVEST Model: A Case Study of Huangling County, China

Land-use change is a key driver of carbon cycling and carbon stock changes in regional ecosystems. Taking Huangling County as a case study, this study combined land-use data from 1990 to 2020 with the InVEST model, the Patch-generating Land-Use Simulation (PLUS) model, and GeoDetector to examine the spatiotemporal evolution of land-use change and carbon stocks, identify the drivers of carbon stock spatial heterogeneity, and project land-use patterns and carbon stock changes under alternative development scenarios for 2030. The results showed the following: (1) The land-use structure of Huangling County remained relatively stable during 1990–2020, with forestland and grassland accounting for more than 80% of the total area. Built-up land expanded from 12.58 km2 to 30.12 km2, while cropland decreased overall, indicating the coexistence of ecological land reconfiguration and urban expansion. (2) Total carbon stocks showed a fluctuating decline during 1990–2020, decreasing by 2.57% from 5517 × 104 t to 5375 × 104 t. Forestland constituted the dominant carbon pool, and its change was the primary driver of carbon stock dynamics. (3) Precipitation, NDVI, and elevation were the leading factors associated with carbon stock spatial heterogeneity, with mean q-values of 0.722, 0.669, and 0.588, respectively. Interaction detection revealed the strongest interaction for precipitation–GDP in 2010 (q = 0.829) and NDVI–GDP in 2020 (q = 0.799), highlighting the joint associations of natural and socioeconomic factors with carbon stock patterns. (4) Carbon stocks varied markedly among the 2030 scenarios. The Natural Development Scenario produced the highest carbon stock (5409.98 × 104 t), an increase of 35.36 × 104 t relative to 2020. The Economic Development Priority Scenario exhibited the largest built-up land area (34.18 km2), while the Sustainable Development Scenario maintained a more coordinated land-use structure by balancing ecological protection and socioeconomic development. These findings provide valuable scientific support for land-use optimization and carbon sink enhancement in the hilly–gully region of the Loess Plateau.