The Qinghai-Tibetan Plateau is the highest natural geographical unit over the world and called "the third pole of thr earth" because of its high relief and cold climate. It is the source of numerous rivers in south and south East Asia and nursed the civilizations in the Yellow River area, Yangtze River area and river are in India. It plays the critical role in the survival and development of China, south and south East Asia. The rangeland could be grouped into alpine steppe,alpine meadow,desert steppe,alpine shrubland,in which,the alpine steppe and alpine steppe take the largest area. The zonal distrbution pattern is forest-meadow-steppe-desert. A small area of forest distributes in the south and northeast parts of the plateau. The animal production is characterized by "pursuing after water and grass" according to the natural rules, which is a typical pattern to graze livestock and meanwhile protect grasslands. The livestock population the Tibetan people raise is always kept to only meet their essential living and not to expand the flock size for more profit. They usually take three ways to control the livestock number, I. E,"free animal", "eliminate weak animals" and "keep the lowest demand". In terms of the control of livestock structure,they keep the ratio of sheep and yak as 1 ! 1 to 3 : l,and mostly 1. 5: 1 to adapt the alpine environment. So,the Tibetan people can be called "the people on the back of yak".%青藏高原是全球海拔最高的自然地域单元,由于地势高耸、气候寒冷而被称之为“地球第三极”.它是南亚、东南亚众水发源地,哺育了中华黄河、长江流域文明和印度河流域文明.至当代,它仍然对中华民族乃至南亚、东南亚人民的生存和发展有着决定性影响.草原分为高寒草原、高寒草甸、荒漠草原、高寒灌丛等.在各类草地类型中,以高寒草原与草甸草地面积为最大.草原呈现东湿西干由森林-草甸-草原-荒漠的地带性更替.在青藏高原东南部与东北部边缘地带分布有小面积的森林.藏区牧民畜牧活动的特点按自然变化而行的行为“逐水草而居”.循自然规律所动,是一种较典型的既饲养家畜又保护草原的方式.藏族牧民饲养家畜的数量仅维持在满足其生存的基本需求之内,不靠养畜来推动经济增长和积累更多财富.在控制家畜数量上采用“放生”、“淘汰瘦弱体保护整体”和“维持最低需求”3大类型.在畜种结构的控制方面,将绵羊与牦牛的比例保持在1:1～3:1,大部分为1.5:1.0.这种选择,乃是对高寒自然生态环境的适应.因而,藏族牧民可看成是“牦牛背上的人.
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