近40a大兴安岭漠河县林火行为指标变化特征

Variation Characteristics of Forest Fire Behavior Indexes in Mohe County of Great Xing'an Mountains in Recent 40 Years

基于加拿大火险天气指标系统,研究了1971—2010年间大兴安岭漠河县林火行为指标的变化特征。结果表明:近40 a研究区的初始蔓延指标(ISI)、有效可燃物指标(IBU)、林火天气指标(IFW)和火灾难控程度指标(RSS)所分别代表的林火蔓延速度、林火释放能量、林火强度和林火持续时间具有相同的年代变化特征,即20世纪70年代为林火行为的严峻期、80～90年代出现了一次明显的年代际转型,伴随着这次年代际的转型,21世纪后的林火行为更加严峻,表现为林火蔓延速度增快、能量释放增大、林火强度增强、火持续时间增长。

A study was performed to analyze the variation characteristics of forest fire behavior indexes in Mohe County of Great Xing＇ an Mountains for the period 1971-2010 based on Canadian Forest Fire Weather Index System. Results indicated that the Initial Spread Index （Is1）, Buildup Index （ IsV ）, Fire Weather Index （ Ivw ） and Seasonal Severity Rating （ Rss ）, which respectively represented the rate of forest fire spread, the total fuel available to the spreading fire, the intensity of the spreading fire and seasonal control difficulty, had the same interdecadal variation characteristics during the last 40 years in the study region. It indicated that severe forest fires appeared in the 1970s, and then a notable decadal shift occurred in the 1980s and 1990s, and more severe forest fires appeared after the 1990s. In the early 21st century, the rate of forest fire spread increased, the total fuel available to the spreading fire enlarged, the intensity of the spreading fire enhanced, and fires were more difficult to control.