Abstract: Based on resource area data of Grain for Green Project in the provinces of the upper and middle reaches of Yangtze and Yellow River by the end of 2014, the continuous observation and periodical inventory of complete index system of forest ecosystem services (referred to as forest ecology continuous investigation) were applied to assess seven services, including water conservation, soil conservation, carbon fixation and oxygen release, trees’ nutrient accumulation, atmosphere purification, biodiversity conservation, forest protection, and their characteristics were analyzed by using data envelopment analysis model. The results showed that the total value of ecosystem services of Grain for Green Project in the study region was 10071.5×10⁸ yuan·a^-1, in which water conservation service had the highest value, accounting for 36.54% of the total value. Among the three vegetation restoration models of Grain for Green Project, ecosystem services of returning farmland to forests and closing hillsides to facilitate afforestation were better than those of afforestation on barren hills and wasteland. Among the three forest types, ecosystem services of ecological forests were better than those of economic forests and shrubs. Model of data envelopment analysis showed that water and soil conservation services (including water conservation and soil conservation) in the provinces of the upper and middle reaches of Yangtze and Yellow River played a leading role of ecosystem services. Carbon sequestration, atmosphere purification and biodiversity protection services were related to background environment, hydrothermal conditions and associated tree species of the returning farmland area, having certain regional characteristics. Accordingly, in the conversion mode and tree species selection and forest tending, the input/output efficiency of ecosystem services should be focused, to improve effectiveness of the engineering technology and scale, thus increasing the output of ecosystem services value of Grain for Green Project.

Key words: arsenite, aging, available As, combined As.