Abstract: It is a challenging task to conserve soil and water at the ecological aspects in the Ili River Valley.The potential impact of soil erosion should be paid great attention to in both ecological governance and further development.Distribution of soil erosion should be grasped so as to further clarify the development direction.A unified standard for estimating the ecological service value is not formed yet.Different valuation methods may produce an enormous difference in the results.The lack of comparability between the different assessment results has seriously hampered the widespread application of ecological service value in solving the practical social problems.In this paper,the main sources of various satellite remote sensing data in the Ii Valley during the period from 2001 to 2013 were analyzed.Options for assessing the value of ecological services in this paper included two approaches,i.e.the “index construction” and “equivalence factor”.During the assessment process,a number of empirical models were used,and their corrections were made based on the actual data of the study area.On which the assessed results of ecological service value were obtained based on soil and water conservation in the Ili Valley.The commons and differences of the conclusions obtained by the two methods were discussed.The results of this study showed that,during the study period,the annual soil and water conservation in the natural ecology in the Ili Valley was 2.64×10⁸ t.The value of soil-related ecological services assessed by the “Indicator Construction method” was 2.38×10⁸ to 4.72×10⁸ yuan.The value of soil-related ecological services assessed by the “Equivalent Factor method” was 182.99×10⁸ to 201.81×10⁸ yuan,of which the highest value occurred in Zhaosu County where the ecological conditions are fine,and the lowest one occurred in Yining City.The difference between the two methods in the calculation was nearly a hundredfold.The geometric mean method was used to balance the results of the extreme differences.Combining the two results,the final average soil-related ecological service value in the Ili Valley was 23.95×10⁸ yuan.The results from the two methods were similar.Maximum and minimum values of ecosystem services occurred in 2007 and 2012 respectively.The highest (29.73×10⁸ yuan) and the lowest (20.93×10⁸ yuan) ecological service values occurred in 2007 and 2012 respectively.The average annual ecological service value was high in Zhaosu County and Turks County but low in Yining County and Yining City.

Key words: soil and water conservation, indicator construction method, equivalent factor method, ecological service value, Ili Valley