Shifting Controls on Erosion‐Induced Soil Carbon Loss in the Yellow River Basin

Abstract Soil erosion is a major but often overlooked pathway of soil organic carbon (SOC) loss in large basins. Check dam networks and vegetation recovery have reconfigured SOC transport, yet long‐term spatiotemporal dynamics of eroded SOC yield and shifting contributions of check dams, vegetation and rainfall remain poorly understood. We developed an integrated model that couples soil erosion, sediment and SOC yield and trapping by cascading check dams, and applied it to reconstruct grid‐scale sediment and eroded SOC yield across the Middle Yellow River Basin (MYRB) (1970–2020). Including check dam trapping improved simulation performance by ∼20% (NSE = 0.72) versus a no‐trapping scenario, and simulated sediment and SOC storage matched field‐survey results (NSE = 0.65 and 0.64, respectively). Mean eroded SOC yield was 125.15 ± 28.73 kgC ha −1 yr −1 and declined significantly across 50.0% of the basin; it showed no significant trend before 2005 but declined rapidly afterward ( P < 0.001). Over the five decades, check dams trapped 3.84 × 10 9 t of sediment and 20.8 TgC of SOC (accounting for 11.1% of total eroded SOC yield). Check dams dominated the SOC yield reduction before 2005 with basin‐wide contribution of 53.5% and up to 99.1% within dam‐controlled watersheds. After 2005, rapid vegetation recovery weakened sediment connectivity and erosion, with contributing 90.9% to basin‐wide SOC yield reduction and 75.8% in dam‐controlled watersheds. These findings highlight a shift from engineering‐dominated interception to vegetation‐dominated suppression in controlling SOC yield, with important implications to guide soil conservation and carbon management under global change.