无风条件下蒙古栎—红松混交林下地表可燃物3种火源点燃的能力分析

Analysis of the ignition ability of three kinds of fire sources under the condition of the mixed forests of Quercus mongolica and Pinus koraiensis under no-wind conditions

森林火灾发生需要有火源引燃,不同火源引燃可燃物的能力不同,搞清常见火源引燃可燃物的能力及引燃后的一些火行为指标,分析床层特征对火源引燃能力的影响,建立相应的点燃概率模型,对林火预防及扑救意义重大。在春防期,以燃烧着的烟头、火柴、燃烧着阔叶为火源,在无风条件下点燃蒙古栎-红松混交林下的非破坏性地表可燃物,分析了不同火源的点燃能力及床层特征对点燃能力的影响,并建立相应预测模型。结果表明:(1)火柴的平均点燃概率最大,燃烧着阔叶点燃概率次之,所有试验条件下,烟头都不能点燃可燃物床层;(2)火柴与燃烧着阔叶的点燃概率和火焰高度没有显著差异,烟头与2种火源的点燃概率有显著差别;(3)火柴和燃烧着阔叶的点燃概率都与床层含水率负相关关系,两者能引燃的最大床层含水率分别为26%和24%。火柴引燃概率随着床层密实度的增加,先增加后减小,燃烧阔叶点燃概率随着床层密实度的增加在下降;4)火柴和燃烧着阔叶2种火源的点燃概率预测模型都具有统计学意义,其中火柴点燃概率预测模型的预报精度为72.9%,误报率为32.3%;燃烧着阔叶预报模型的准确度为71.4%,误报率为25.8%。本研究是在春防期间进行,可燃物含水率低于30%的天数占防火期内一半以上,被火源引燃发生森林火灾的可能性极大,对于特别稀松或者紧实的可燃物床层,火源引燃概率较低,建议林区管理人员根据不同床层密实度进行管理,提高效率。

Firebrand is a necessary condition for forest fire,the capacity of various fire sources is different.Find out the ability of common firebrands to ignite fuel some fire behavior index after ignition,analyze the effect on ignition probability of fuel bed characteristics and establish the model of ignition probability are great significant to forest fire prevention and fighting.The study was conducted during the spring forest fire prevention.In the absence of wind conditions,select the cigarette butts,matches,burning the broad-leaves as the fire source to ignited the surface fuel of the Mongolica oak-Pinus Koraiensis stand,analyzed the ignition ability of different fire sources.The results show that1)the average ignition probability of the match is the largest,followed by the burning of the broad-leaves,cigarette butts cannot ignite fuel bed under all test conditions.2)There is no significant difference in the ignition probability and flame height between the match and the burning broadleaf,there was a significant in the ignition probability and flame height between the cigarette butts and the other fire sources.3)The ignition probability of matches and burning broadleaves is negatively correlated with fuel bed moisture content and the maximum moisture content of fuel bed can be ignited by the match and burning broadleaf is26%and24%,respectively.With the increasing of the fuel bed compactness,the ignition probability of match is increase and then decreases,the burning broadleaves is negatively correlated with fuel bed compactness.4)The ignition probability prediction model of two kinds of fire sources was statistically significant,the accuracy of the prediction model of the match is72.9%and the false positive rate is32.3%,the accuracy of the prediction model of the broadleaves is71.4%and the false positive rate is25.8%.Fuel moisture content less than30%of the days accounted for more than half of the spring forest fire prevention period,the fuel is easily ignited via firebrand.For the special sparse or compact fuel bed,the ignition probability is low and it is suggested that forest managers should manage according to different fuel bed compactness and improve their efficiency.