Influence of Ecological Defarming Scenarios on Agriculture in Ansai County, Loess Plateau, China

At present, the return of farmland to forests is the key ecological conservation policy in use to control soil erosion and restore the eco-environment of the Loess Plateau, China. In order to explore policy-driven ecological defarming scenarios, Ansei County is taken as a case study. The land use map in 2000 and the topographic and slope map (taking the defarmed slopes with 15 degrees, 20 degrees, and 25 degrees as the do farming thresholds) were used, supported by spatial analysis techniques in geographic information systems (GIS). This paper simulates and analyzes the scale and spatial difference of ecological defaming of Ansai County, the subsidy demand for deforming, and the influences of deforming on agricultural development. The results show: (1) The area of do farmed land with slopes greater than 25 degrees in Ansai amounts to 3451.05 ha, which accounts for 2.84% of total area with slopes over 25 degrees, and the defarming index will be 3.14%. The total subsidy demand for deforming land will be 6884.84 x 10(4) yuan (RMB) or US$ 1008.03 x 10(4). The loss of agricultural food products that results from defarming will be 955.17 t in the average year, or 1.66% of total average annual production. (2) The area of defamed land with slopes over 20 degrees in Ansai will increase to 36,281.61 ha, which accounts for 19.74% of total area with slopes over 20 degrees, and the defarming index will be 32.96%. The total subsidy demand for do farming land will be 72,381.81 x 10(4) yuan or US$ 10,597.63 x 10(4). The loss of agricultural food products due to deforming will be 10,041.9 t in the average year, or 17.50% of total average annual production. (3) The area of do farmed land with slopes over 15 degrees in Ansai increases to 101,807.99 ha, which accounts for 37.23% of total area with slopes over 15 degrees, and the defarming index will be 92.49%. The total subsidy demand for deforming land will be 203,106.94 x 10(4) yuan or US$ 29,737.47 x 10(4). The loss of agricultural food products owing to defarming will be 28,178.06 t in the average year, or 49.10% of total average annual production.