Diverse Climatic and Anthropogenic Impacts on Desertification in the Middle Reaches of Yarlung Zangbo River Catchment on the Tibetan Plateau

The unique desertification processes occurring under the Alpine climate and ecosystem on the Tibetan Plateau could provide critical clues to the natural and anthropogenic impacts on desertification. This study used the Landsat data to investigate the spatial and temporal distribution of desertification from 1990 to 2020 in two areas(Shannan and Mainling), within the Yarlung Zangbo River Basin. The results show not only distinct spatial patterns but also various temporal changes of desertification. In Shannan, aeolian sand was distributed over wide areas from valley floor to mountain slope,while in Mainling, it is distributed sporadically at the footslope. The aeolian sandy land initially expanded before undergoing long-term shrinkage in Shannan. While in Mainling, it steadily expanded followed by a rapid decrease. These changes are attributed to both climate change and human activites.The increase in temperature causes desertification expansion in Shannan, while favorable climate conditions coupled with decreasing human activity promoted desertification reversal. However, both the expansion and shrinkage of desertification were sensitive to human activity in Mainling. This highlights the diverse responses of desertification to natural and anthropogenic impacts on different backgrounds of climatic and vegetation coverage. A threshold of climatic conditions may control the dominance factors in desertification, shifting from natural to anthropogenic elements.