川西南森林可燃物分布调研及潜在火行为研究

Research on the distribution of combustible materials and potential fire behavior in southwest Sichuan forests

以川西南地区森林为研究对象,实地调研了凉山州木里县6种植被类型不同层次的可燃物特征和空间分布,运用BehavePlus软件模拟探究不同燃烧条件下潜在火行为。研究结果表明:由于燃料床厚度较低,林下层无灌木和草本的林分可燃物模型无法形成稳定蔓延的地表火,而林下覆盖有灌木层或草本层的林分模型可燃物垂直分布连续性较好,可形成高强度地表火,同时能形成稳定燃烧的遍燃型树冠火。地表火蔓延速度、火线强度、火焰高度、树冠火转化率等潜在火行为均随风速和坡度增加而增加,且增长幅度与燃料床厚度和高度相关,树冠火蔓延速度随风速增加大体呈指数型增长。

Taking forests in southwest Sichuan as the research object,the characteristics and spatial distributions of fuels at different levels in six vegetation types were investigated in Muli County,Liangshan Prefecture,and the potential fire behaviors under different burning conditions were numerically explored by using BehavePlus software.The results of the study showed that the stand fuel model without shrubs or herbs could not form a stable spreading surface fire due to the low thickness of the fuel bed,while the stand fuel model with shrubs or herbs in the understory had a better vertical distribution continuity of fuels,which could form an active crown fire with high intensity surface fire.The potential fire behaviors of surface fire spread rate,surface fireline intensity,flame length,and crown fire transition ratio increased with wind speed and slope steepness,and the increase rate was highly correlated with the thickness of fuel bed.Moreover,generally,the crown fire spread rate increased exponentially along with wind speed.