大兴安岭森林火险季节动态特征及其气候条件分析

Seasonal dynamic characteristics and climatic condition analysis of forestry fire risk in Daxing'an Mountains

森林火险季节是火环境中的一个重要因子，对于森林防火实际工作具有十分重要的意义．本文利用内 蒙古大兴安岭林区近３０年的林火资料和临近火点的气象资料，对比分析了该地区森林火险季节的时空分布 特征及其与气候条件的关系．结果表明：该地区多年平均森林火险季节长度大于２００ｄ，且２０世纪８０年代以 来呈增长趋势；南北林区火险季节指标差异明显，南部林区比北部林区进入火险季节的时间早而结束晚；森 林火险季节长度与全年无雪日数有关，起止日期与春季和秋季的日平均气温－５℃的日期相符合．

Forestry fire risk season is an important factor in fire environment. It is very important to forestry fireproof. Using forestry fire data and climatic data about thirty years in Daxing'an Mountains forestry district of Nei Monggol, the author contrasts and analyzes temporal and spa- tial distribution characteristics of fire risk season and their relation to clirnatic condition. The results show:The annually average forestry fire risk season exceeds 200 days in the district. Moreover, the period increases since 1980s. The indices of fire season show great difference in north part and south part of the district. The beginning date of fire risk season in south part is earlier than that in north part,while the finishing date of fire risk season in south part is later than that in north part. The forestry fire risk season period is relative to snow-free period of the year. The beginning and fin- ishing date matches the date in spring and autumn, which is-5℃ on daily average temperature.