中文摘要：

根据1992～2005年西藏藏族自治区森林火灾统计，分析了森林火灾发生的时间和空间规律。森林火灾的年际间波动较大，2001以来火灾次数呈明显的上升趋势，但主要是火警次数增多。西藏的森林火灾主要发生在春季和冬季，特别是12月～翌年5月，2月和3月份的森林火灾最为严重。从森林火灾的空间分布来看，森林火灾主要发生在藏东南地区，特别是芒康、察隅、林芝和米林等县的森林火灾较多。引起森林火灾的火源主要是由生产用火和生活用火引起的。文中还对西藏森林火灾发生的火环境进行了分析，气候特点和可燃物分布特征决定了西藏的森林防火期为冬春季，火灾多发生在海拔2800m～3600m的阳坡针叶林和阔叶林中，以地表火最多，大多火场面积少于10hm^2。根据西藏森林火灾的发生特点，建议今后在防火基础建设、火源管理、可燃物管理、林火预防和扑救等方面加强工作，提高森林防火的能力。

英文摘要：

The law of forest fires distribution on temporal and spatial scale is analyzed based on forest fire statistics from 1992 to 2005. In yearly scale,forest fires have a significant variance. It is obviously that the forest fires increased since 2001 ,and most of them are fire alarm. Forest fires are mainly occurred in spring and winter in Tibet, especially from December to next May. February and March are the peak fire season. Most forest fires lie in southeastern Tibet,especially in Mangkang,Chayu, Linzhi and Milin counties. The main fire sources are caused by productive and living activities. The paper also analyses the fire environment in Tibet, which indicate the climate and fuel distribution have a decisive influence on the fire season. Most forest fires occurred in deciduous and broadleaf forests at altitude rang from 2,800 m to 3,600 m. Average fire is surface fire and average burned area is less than 10 hm^2. It suggests strengthening the infrastructure,fire resources and fueling management and improving fire prevention and fire attack.