A Study on the Ecological Services Value of Oasis Ecosystem - Take the Middle Reaches of Heihe River, China as an Example

Studying the services value of oasis ecosystems in arid middle reaches of the Heihe Oasis is significant for understanding the development and evolution, revealing the maintaining mechanism of oasis security, and promoting the resources and environment sustainable development of this area. Based on the data of landsat TM image in the middle of Heihe River Basin acquired in 2000 and 2006, land use and land cover data were obtained first and also the changes were analyzed. On this basis, the service value per unit area of each type ecosystem was calculated, and the economic value of food production per hectare was calculated by production and area of crops in 2000, 2006. According to the result of calculation of the ecological services value per unit area, ecosystem service value and dynamic changes were analyzed. In addition, the sensitivity index was used to test rationality of ecological value coefficients. The result showed that firstly the land use types of farmland, grassland, water area and unused land decreased from 2000 to 2006 with a change rate of 4.50%, 1.62%, 2.42%, 0.96%, respectively, whereas, types of forest land, construction land and sandy land increased with a change rate of 16.64%, 4.96%, 2.38%, respectively. Secondly, the total services value of oasis ecosystem was increasing from 249.31 billion RMB Yuan in 2000 to 280.43 billion RMB Yuan in 2006, there were 12.48% net increment of 31.12 billion RMB Yuan, this was mainly due to the increasing forest land area and grassland ecosystem had the higher ecological service value per unit area. Thirdly, the services value of farmland, forest land, grassland, water area and sandy land ecosystem keep increasing, the service value of forest land, grassland and water area ecosystem accounted for above 80% of the total value, and forest ecosystem gave the greatest contribution to the total ecosystem service value, reaching 19.49 billion RMB Yuan. Fourthly, the sensitivity analysis suggested that these estimates were relatively reasonable. The ecological value coefficients adopted were suitable for application in the study area. So, it is important to protect oasis ecological environment and improve the service function of oasis ecosystem.