榆林市还林还草后土壤保持功能和经济价值评价

Assessment of Soil Conservation Function and Economic Value in Yulin City after Implementing the Project of “Grain for Green”

为了定量评估退耕还林还草工程在黄土高原核心区的土壤保持能力和经济价值,以榆林市12个县市为研究对象,利用USLE土壤侵蚀模型结合RS、GIS技术,估算了2000—2013年榆林市土壤侵蚀模数,在此基础上评估了土壤保持能力的变化,利用市场价值法、机会成本法和影子工程法估算了其经济价值。结果表明:14 a来榆林市土壤侵蚀强度呈现降低趋势,2013年比2002年平均侵蚀模数减少784.82 t·km-2·a-1,土壤流失总量减少4.20×107t。土壤保持能力明显提高,但空间差异明显,南部丘陵沟壑区较西北部风沙区土壤保持能力明显提高。2013年土壤保持能力从大到小依次是林地41 540.00 t·km-2·a-1、草地34 852.71 t·km-2·a-1、耕地29 679.39t·km-2·a-1、未利用土地7 973.03 t·km-2·a-1。2013年土壤保持能力为33 685.89 t·km-2·a-1、潜在侵蚀总量为1.61×109t,土壤保持总量约为1.43×109t。为了消除年际降雨侵蚀力不同对土壤侵蚀造成的影响,利用模拟降雨法,模拟了2013年在2002年降雨条件下的土壤保持能力为37 303.64 t·km-2·a-1,比2002年增加1 423.54 t·km-2·a-1。土壤总保持量为1.58×109t,比2002年多出7.20×107t,N、P、K元素共增加了8.24×104t。2013年和2002年土壤保持总价值分别为1.49×1010元和1.51×1010元,增加了5.90×108元。退耕还林还草工程在榆林市取得了显著的生态经济价值,该研究结果可以为该地区土壤保持能力与生态管理提供一定的参考。

In order to assess the soil conservation function and economic value of the core area in the Loss Plateau,12 counties and cities in Yulin were selected as the study area. The USLE model,Remote Sensing（RS） and Geographic Information Systems（GIS） were used to assess the soil erosion modulus during the period from 2000 to2013. The soil conservation capability was evaluated based on the result of soil loss,and the market evaluation method,opportunity cost method and shadow engineering method were applied to calculate the economic values of soil conservation. The results showed that the intensity of soil erosion was significantly reduced after 2000. Compared with 2002,the annual soil erosion modulus in 2013 was decreased by 784. 82 t·km-2,and the total annual soil loss was reduced by 4. 2 × 107 t. The soil conservation capability in Yulin was significantly improved,and it was significantly higher in the hilly-gully area than in the windy desert area. In 2013,the annual soil conservation functions of forest,grassland,cropland and bared land were 7 973. 03 t·km-2,34 852. 71 t·km-2,29 679. 39 t·km-2 and7 973. 03 t·km-2 respectively. The annual soil erosion modulus was 33 685. 89 t ·km-2,the total potential soil loss and soil conservation were 1. 61 and 1. 43 billion tons respectively in Yulin. The simulation rainfall method was accepted to eliminate soil loss effects caused by unequal rainfall in different years. Rainfall erosivity in 2002 was taken as the rainfall erosivity in 2013,the simulated results revealed that the annual soil conservation modulus was37 303. 64 t·km-2,and the total annual soil conservation was 1. 58 billion tons in 2013. Compared with 2002,they were increased by 1 423. 54 t·km-2 and 73 million tons respectively. The total value of TN,AN,AP and AK was increased by 8. 24 × 104 t. The simulated total soil conservation values in 2002 and 2013 were 14. 85 billion yuan and 15. 14 billion yuan respectively,and they were increased by 590 million yuan. So the prominent ecological economic value was obtained after implementing the project of ＂grain for green＂in the Loss Plateau.