Land‐Use Intensity Reversed the Role of Cropland in Ecological Restoration Over the World's Most Severe Soil Erosion Region.

Long‐term extending cultivation activities resulted in the world's worst soil erosion on the Chinese Loess Plateau (LP). By converting cropland into vegetated land, the Grain for Green Project (GfGP)—the world's largest investment revegetation project—effectively alleviates the soil erosion on the LP. However, during the GfGP implementation, the positive effect of cropland to the revegetation and soil erosion control has been underestimated to date, hindering a comprehensive evaluation to the effect of cropland on ecological restoration. Here, we evaluated the effect of the GfGP on soil erosion control across the LP, analyzed the dominant driver of the LP vegetation greening, and further identified the contributions of croplands to this world's largest revegetation project. We found that the vegetation of the LP was significantly improved and its leaf area increased by 1.23 × 105 km2 after the implementation of the GfGP, which contributed 42% to the decrease of the LP soil loss. Among them, our results show that cropland contributed 39.3% to the increased leaf areas of the LP, higher than grassland (36.3%) and forestland (14.3%). With the reduction of agricultural area, the contribution of cropland to the increased leaf areas in the LP was still the largest, which was mainly due to the increase in cropland utilization intensity. This study highlights the significance of the GfGP in soil erosion control and revises our understanding of the role of cropland in ecological restoration and society development. Plain Language Summary: Long‐term extending cultivation activities resulted in the world's worst soil erosion on the Chinese Loess Plateau (LP). For controlling this soil erosion, the Grain for Green Project (GfGP)—the world's largest investment revegetation project—was carried out. This was followed by the conversion of large amounts of cropland to vegetated land. However, this manuscript offers evidence indicating that cropland, rather than grassland and forestland, contributed the most to the vegetation improvement of the LP during the implementation of GfGP. We find that vegetation improvement after the GfGP could explain 42% of the reduction in the LP soil loss. The contribution of cropland to the LP greening was 39.3%, higher than that of grassland (36.3%) and forestland (14.3%). Although the area of cropland was greatly reduced after the implementation of GfGP, the contribution of cropland to the LP vegetation greening was still dominant, which was mainly due to the intensive cropland utilization. The positive effect of cropland on ecological restoration indicates its significant potential for future human land‐use management and revegetation management. Key Points: Vegetation greening reduces the sediment yield of the Loess Plateau by 42%Cropland contributes 39.3% to the Loess Plateau vegetation greening, higher than grassland (36.3%) and forestland (14.3%)Cropland dominates the Loess Plateau greening, mainly due to the improvement of cropping intensity [ABSTRACT FROM AUTHOR]