Analysis of Spatial-Temporal Variation of Grassland Landscape Pattern Based on Terrain Factors in Qinghai Yushu Tibetan Autonomous Prefecture, China

Yushu Tibetan Autonomous Prefecture (Yushu Prefecture), located in the Qinghai-Tibet Plateau area, is one of the areas sensitive to global climate change. Due to impacts from climate change and human disturbance, the vegetation of grassland in the study area has been degrading dramatically, and the desertification of land has been expanding rapidly. Based on remote sensing images and statistical data, this paper focused on analyzing the distribution characteristics of grassland landscape pattern in Yushu Tibetan Autonomous Prefecture from 1995 to 2015, and the spatial-temporal differentiation characteristics of grassland landscape under the influence of elevation and slope topographic factors. Also, we combined GIS and GeoDa software to analyze spatial autocorrelation relationship of grassland landscape distribution in the source region of the Yangtze River. The results indicated that: (1) Both the slope and altitude gradient factors can affect the distribution type of grassland. (2) Three kinds of grassland change revealed different spatial-temporal variations. From the vertical perspective of time passing on, human activities would control the grassland distribution pattern based on original terrain factors. From the vertical perspective of altitude or slope, climate conditions would decide the grassland distribution. Terrain factors have direct effect on local climate conditions. (3) Grassland distribution and terrain conditions have significant spatial autocorrelation. Altitude and slope have absolutely different spatial relationship.