Wei Zhen-hai

Land use and land cover change and its driving forces in the source region of the Yangtze River during 1990–2005

Land use and cover change (LUCC) is an important field in studying the global change or global warming. The source region of the Yangtze River locates in the northeast of Qinghai-Tibetan Plateau. The ecosystem there is extremely vulnerable and sensitive to global climate change and human activities, which have brought in significant change of eco-environment in this region in recent years. Therefore it is essential to investigate the land use and land cover change, and to explore its driving forces in the source of the Yangtze River. In this study, we used Landsat images obtained in 1990 and 2005 to establish databases of land use and cover. Then we derived LUCC information by overlaying these layers using GIS software. To examine the processes responsible for LUCC, we discussed its driving forces including climatic change, human activities, animal and insect damage. During the past 15 years, the forest, grassland experienced the most significant decrease. The forest and grassland decreased by 2509 hm2, 41847.1 hm2, respectively. However, unused land and water area showed the opposite trend, increased by 33903.8 hm2, 10480.1 hm2 respectively. The farmland and build-up land changed no obvious in past 15 years. These results suggested that the degradation of the eco-environment is obvious, showing a decrease in the forest, grassland, and an increase in the area of unused land. The major factors responsible for LUCC include increasing temperature, decreasing precipitation in summer and autumn, variation in the frozen soil environment, human activity (seasonal overgrazing) and rodent damage.