紫茎泽兰的燃烧火行为特征

紫茎泽兰(Eupatorium adenophorum Spreng)是一种外来入侵物种,干枯的紫茎泽兰植株具有较好的易燃性,并且紫茎泽兰植株枯死期正是昆明地区的森林防火期,对森林防火具有重要的影响。在昆明周边的林区内进行外业调查、采集紫茎泽兰样品,并在可控条件的实验室内利用热电偶等测定紫茎泽兰的燃烧火行为特征(包括点燃时间、辐射热、火焰高度和蔓延时间等)。结果表明:(1)垂直燃烧的平均点燃时间、蔓延时间和火焰最大高度都大于水平燃烧(31、1 s;3.50、1.67 min;300、120 cm)。(2)水平燃烧的平均火焰最高温度大于垂直燃烧(761、611℃);(3)水平燃烧和垂直燃烧的平均热辐射没有明显差异。紫茎泽兰水平燃烧和垂直燃烧时的温度高,释放能量大,热辐射强,是地表火垂直转换为树冠火的重要介质,也是地表火水平快速蔓延的通道。紫茎泽兰垂直燃烧的火灾危险性较大,且燃烧后具有较大发生复燃的可能性。应在防火期来临前对紫茎泽兰进行清除,以减少森林火灾发生的频率和强度。

Burning Characteristics of Herbaceous Eupatorium adenophorum Spreng

Field investigation was carried out in the forest area around Kunming, and with Eupatorium adenophorum Spreng the characteristics of fire behavior(including ignition time, radiant heat, flame height and spread time, etc.) were measured by thermocouple in the laboratory under controlled conditions. The average time of ignition, spreading time, flame height and burning loss rate of the vertical burning is greater than that of horizontal burning(31 vs. 1 s;3.50 vs. 1.67 min;and 300 vs. 120 cm, respectively). The average of the maximum flame temperature of horizontal combustion is higher than that of vertical combustion(761 ℃ vs. 611 ℃). There was no differences for the average of flame heat radiation between horizontal and vertical combustion. The high temperature, high energy release and strong thermal radiation of E. adenophorum during horizontal and vertical combustion are the important medium for vertical conversion of surface fire into crown fire, and also the channel for horizontal rapid spread of surface fire. The fire hazard of vertical combustion of E. adenophorum is greater, and the highpossibility of reignition occurs after combustion. Before fire prevention perioddry E. adenophorum should be cleared away to reduce the frequency and intensity of forest fire.