Abstract: Cheng-Yu Economic Zone is an ecological barrier of the upper reaches of Yangtze River, but its eco-environment is fragile. It is of significance to maintain and improve the ecosystem services of the Zone. Based on the satellite images taken in 2000 and 2007, and with the help of RS and GIS techniques, this paper quantitatively analyzed the spatiotemporal variations of land use in the Zone, and by using modified ecosystem services value coefficient, evaluated the dynamic changes of land ecosystem services, aimed to understand the responses of the ecosystem services to land use change and to provide useful information for policy maker concerned with the sustainable development of the Zone. In 2000-2007, the constructive land showed the fastest increase (1044.5 km²), with an annual increasing rate 5.3%, forestland had the largest increase (2908.7 km²), with an annual increasing rate 0.5%, grassland, water body, and unused land decreased with an annual rate of -2.0%, -0.7%, and -2.9%, respectively, while cropland shrank largest (2388.9 km²), with an annual rate -0.3%. Owing to the land use change, the total land ecosystem services value had somewhat increase, with the total value increased from 318.84 billion Yuan in 2000 to 321.15 billion Yuan in 2007. The increase of the total value was mainly contributed to the conversion from other land use types to forestland and from cropland and grassland to other land use types, while the decrease of the ecosystem services function was mainly due to the conversion from forestland to other land use types. To maintain the land ecosystem services function and sustainable development of the Zone, it would be necessary to protect the land use types with high ecosystem services value (e.g, forestland and wetland).

Key words: CO₂ concentration, high temperature, drought, grain yield, photosynthesis, water.