An investigation into the driving mechanisms of wetland evolution under the influence of Daihai Lake's shrinkage.

The Daihai Basin, situated on the central Inner Mongolia Plateau, China, represents a typical endorheic lake system within a semi-arid ecological transition zone. This region is currently characterized by pronounced water shrinkage and ecosystem degradation. The driving mechanisms of wetland evolution and carbon stock dynamics from 1984 to 2023 were investigated. Wetland boundaries were delineated using multi-source remote sensing indices and quantitatively validated via the shape context algorithm. An optimized Geodetector model was employed to identify stage-specific driving factors, while regional carbon stocks were estimated using a soil organic carbon density-depth model derived from in-situ sampling. Results indicate an "expansion-rapid contraction" trajectory, culminating in a net wetland loss of 9.12 km2. Dominant drivers demonstrated a distinct regime shift: topographic factors prevailed initially, anthropogenic activities intensified during the mid-period, and multi-factor coupling characterized the later stage. Crucially, the reconstructed SOC stock showed a non-linear, wetland-area-mediated two-stage pattern. Lake area and wetland SOC stock exhibited divergent trends before 2001. Over the full study period, the estimated wetland SOC stock decreased by approximately 1.63 × 105 t between 1984 and 2023. This indicates a wetland-area-mediated weakening of regional SOC storage capacity under sustained lake shrinkage.