8Snyman H A, du Preez C C. Rangeland degradation in a semiarid South Africa-Ⅱ: Influence on soil quality. Journal of Arid Environments, 2005, 60(3): 483-507.
9Wang Genxu, Qian J, Cheng Guodong, et al. Soil organic carbon pool of grassland soils on the Qinghai - Tibetan Plateau and its global implication. Science of the Total Environment, 2002, 29 (1-3): 207-217.
10Liu Jiyuan, Zhuang Dafang, Luo Di, Xiao Xiangming. Land - cover classification of China: Integrated analysis of AVHRR imagery and geo - physical data. International Journal of Remote Sensing, 2003, 24(12) : 2485 -2500.
