Spatial-temporal changes and driving forces of aeolian desertification of grassland in the Sanjiangyuan region from 1975 to 2015 based on the analysis of Landsat images.

The Sanjiangyuan region is the source of the Yangtze, Yellow, and Lantsang rivers and is an important water conservation area in China. Due to the high altitude and cold climate in the region, the vegetation ecosystem has become very sensitive to environmental changes. In recent decades, due to the impact of climate change and human activities, the grassland degradation and desertification in this region have become very serious. In order to study the changes in aeolian desertification of grassland (ADG) in Sanjiangyuan, the Landsat images and GIS technology were used to monitor the dynamics of ADG from 1975 to 2015, and the driving factors behind this were analyzed. The results revealed that from 1975 to 2000, the area of ADG increased by 2855.8 km2, and the growth rate was 114.23 km2 a-1. In contrast, the ADG was restored from 2000 to 2015, with a decrease of 1286.54 km2 and a rate of 85.77 km2 a-1. The main reasons for the expansion of ADG in the early stage were the rising temperature, the fluctuation of precipitation and wind speed, and the increase in intensified human activities. The main reasons for the reversal of ADG in the later stage were the warming and humidification of the climate, the reduction in wind speed, and the reduction in human activities and restoration of grassland caused by the ecological protection project.