Trade-off analyses between food provision and soil conservation service of Grain for Green Program in Mountainous Area

The Grain for Green Program and soil and water conservation engineering initiatives are crucial for controlling erosion in steep-slope agriculture. However, it is still unclear how these two management methods should be carried out in respect to the situation in mountainous areas. Therefore, taking a typical mountainous area in southwest China as an example, we simulated six scenarios in order to compare the food provisioning service (FPS) and soil conservation service of the Grain for Green Program (converting to grassland) and Construction Measures (converting to sloping terrace) under different slopes. Results showed that when farmland with a >25° slope was converted into grassland, the amount of soil erosion (M) decreased by 21.0%, while FPS decreased by only 0.7%. However, when farmland with a >25° slope was converted into sloping terrace, M decreased by 31.3% while FPS increased by 18.7%. With the increases of farmland slope ranges in the Construction Measures scenario, M gradually decreased and FPS gradually increased. Particularly when farmland >15° was converted into sloping terrace, M decreased by 63.9% and FPS increased by 52.7%. Furthermore, the trade-offs of Construction Measures are lower than that of Grain for Green on different slope ranges. Therefore, we conclude that Construction Measures are a more suitable method in mountainous areas than the Grain for Green, and we suggest that further research be conducted to consider the ecological risks of construction engineering measures.