Abstract: Based on the long-term site-specific observed data and AnnAGNPS model, this paper valuated the changes of ecosystem services in Heigou forested watershed in Three Gorges Reservoir area under the scenarios A-J of Converting Cropland to Forestland Project (CCFP). It was found that the quality of the ecosystem services in the watershed varied with the scenarios. The annual outputs of runoff, sediment yield, total nitrogen, total phosphorus, and total organic carbon from Heigou watershed were the highest under scenario B, being 455 mm, 56.8 t·hm^-2, 132 kg·hm^-2, 33 kg·hm^-2, and 678 kg·hm^-2, and the lowest under scenario J, being 303 mm, 4.8 t·hm^-2, 75 kg·hm^-2, 18 kg·hm^-2, and 383 kg·hm^-2, with a reduce of 33.4%, 91.5%, 43.1%, 45.4%, and 43.5%, respectively. The ecosystem services value in the watershed also varied with CCTP implementation stages, which was the lowest (225×10⁴yuan) under scenario B and the highest (291×10⁴ yuan) under scenario J, and increased by 29.3% under scenario J at the stages before and after CCTP. The method of using observed data and AnnAGNPS model was relatively objective, which reduced the uncertainty of the quantity of ecosystem services. However, this method not only needs a large amount of data, but also has a very complicated process, which might limit its application in assessing the ecosystem services value in some other places.

Key words: Multiangle remote sensing, Multicomponent bidirectional reflectance distribution model, Leaf area index, Rice