藏北高寒草地生态系统现状及发展态势

以藏北那曲地区为例，分析了1955－2005年高寒草地、人口、家畜和社会经济现状与发展态势。结果表明，50年来，藏北那曲地区的年均气温上升了0.8～2.0 ℃，年均降水量增加了100～240 mm，牧业人口增加了5倍左右，家畜存栏数增加了2.9倍，牧民人均纯收入增长了94.1%，人均消费支出增长了93.1%，高寒草地退化面积占总草地面积的64.3%。以上结果说明，藏北那曲地区的气候向湿润暖温方向变化，对减缓草地退化趋势具有促进作用，而牧业人口的增加和过度放牧利用成为高寒草地退化的主要原因。因此，正确处理草地畜牧业经济发展与生态屏障保护的关系，合理利用草地资源，是目前藏北高寒草地生态系统可持续发展亟待解决的问题。

Current situation and development trend of the alpine rangeland ecosystem in northern Tibet, China

As a case of the Naqu region in northern Tibet, this study analyzed the current situation and development trend of alpine rangeland ecosystem from alpine rangeland, population, livestock and social economy of Naqu region in northern Tibet from 1955 to 2005. During the 50 years, the annual average temperature increased 0.8-2.0 ℃, with an average annual precipitation increased by 100-240 mm. Animal husbandry population increased by 5 times or so, and livestock numbers increased by 2.9 times. Per capita net income of the herds increased by 94.1%, and the per capita consumption expenditure increased by 93.1%. The degradation area of alpine rangeland accounted for 64.3% of the total rangeland area in the Naqu region in northern Tibet. These results showed that main reasons of alpine rangeland degradation were increasing in population of herdsman and overgrazing, but not climatic change due to development of weather varied from dry to moist from 1955 to 2005. These reasons make positive contribution to slow down trend of rangeland degradation. Therefore, rational using rangeland resources through correctly managing relation between ecological safety shelter zone and animal husbandry economy is an issue that needs to be resolved to maintain the alpine rangeland ecosystem in northern Tibet.