摘要

Since the implementation of the government initiative-the Development of Western Regions for 2000-2019, a series of major ecological construction projects have been launched, leading to great changes in the ecological conditions and ecological services of western China. This study calculated the amount of total ecosystem services in the western region from 2000 to 2019, and analyzed ecological changes and the characteristics of spatio-temporal variations in ecological services. And a relevant analysis method was applied to explore the trade-offs and synergy of service. It was found that the area of settlements and wetland ecosystems in the study area increased significantly from 2000 to 2015, whereas grassland showed a downward trend year by year. The vegetation fraction showed a decreasing zonal distribution from south to north. A fluctuating increase was observed during 2000-2019, with inter-annual and large spatial differences. The water conservation service had a slight downward trend from 2000 to 2019, and the main decreasing areas were distributed in southeastern Tibet, the western part of the Three Rivers Source Region, and the karst rocky desertification area. The soil conservation service showed an increasing but fluctuating trend, with the greatest increases observed in the Loess Plateau, western Sichuan and Yunnan provinces, northwest Tibet, and southeast Tibet. The windbreak and sand fixation showed a downward trend, and the sharp decline was mainly found in the central and western parts of Inner Mongolia, Tibet and parts of northern Xinjiang. Ecosystem supply, water conservation, and soil conservation were synergistically connected, they were observed north of the Huaihe River-Qinling Mountains, especially in Ningxia and Inner Mongolia. Ecosystem supply was mainly trade-offs with windbreak and sand fixation, and it was observed in the farming-pastoral transitional zone. The synergistic degree of ecosystem services in areas subjected to ecological engineering policy was greater than that in non-engineering areas. Quantitative assessment of ecosystem service changes and their trade-offs is helpful for scientific ecological management and maximizing ecological benefits.