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

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.