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    延安市退耕还林前后土壤保持功能价值评估

    Valuation of ecological service on soil conservation function before and after Grain for Green Project in Yan'an City, northwestern China.

    • 摘要: 为研究陕西省延安市退耕还林工程的实施效果,选取退耕还林前的1995 年、退耕还林初期的2000 年以及退 耕还林后期的2007 年作为研究时点,采用USLE 模型测算退耕还林前后延安市的土壤侵蚀量变化,并运用生态系 统服务功能价值评估方法从不同时点、不同土地利用类型2 个方面对土壤保持服务功能价值进行对比分析。主要 结论如下:1)从1995—2007 年,延安市的土壤保持总量呈先减少后增加的态势;2)1995、2000、2007 年延安市农林 牧业土壤保持功能价值总量分别为1 076.84 亿、911.04 亿、1 341.59 亿元,在此3 期的价值量评估中,土壤肥力保 持的价值量占总价值量的98%以上;3)1995—2007 年的10 余年中,延安市耕地和草地的土壤保持功能价值量互为 消长,疏林地(包括灌木林地)的土壤保持功能价值较平缓,而有林地的土壤保持功能价值在1995—2000 年较为平 缓,2000—2007 年则大幅提高;4)有林地单位面积的土壤保持功能价值量最大,其次是疏林地、草地,最小的是耕 地。上述结果表明,退耕还林工程带来的土地利用变化对增强研究区土壤保持功能起到了明显作用,促进了研究 区环境的改善。

       

      Abstract: The Grain for Green Project (GFGP) of ecological restoration has been implemented in China for more than ten years. To evaluate the effects and benefits of GFGP up to now, we have carried out a comparative study in Yan'an City, the central area of the Loess Plateau in northwestern China and one of the main initiation areas of the GFGP, through choosing three special time points, i. e. the years of 1995, 2000 and 2007 (dynamically representing the before, the early and the later stages of the project, respectively). The USLE model and the method for evaluating ecological services on soil conservation function were used in the study from the aspects of land use type and time change. The results showed that: 1) From 1995 to 2007, the quantity of soil conservation benefit by the project reduced slightly first and then increased very much later on. 2) The estimated total economic benefits of soil conservation in the study area was valued at 107.684 billion CNY in 1995, 91.104 billion CNY in 2000, and 134.159 billion CNY in 2007, in which the value from protection of soil fertility accounted for more than 98%. 3) From 1995 to 2007, the benefits of soil conservation from the farmland and the grassland accounted by money value were mutually interrelated, showing a trade-off in between. Meanwhile, the benefits of the same aspect from the open forest (shrub) land did not change very much; whereas that from the forestland changed slightly from 1995 to 2000, and sharply increased from 2000 to 2007. 4) The highest benefit of soil conservation per unit area, counted by economic value, was from the forestland, followed by the open forest (shrub) land and then the grassland, while the lowest one came from the farmland. The results of the research imply that the land use change initialized by GFGP has greatly enhanced the local ecosystems'function, especially in soil conservation aspect, and thus contributed to the better-off on local environment.

       

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