【作者】 金文斌；

【导师】 赵秀海；

【作者基本信息】 北京林业大学 ， 生态学， 2010， 博士

【摘要】 长白山林区已连续29年未发生重大森林火灾,一般性森林火灾的发生率也有所下降。长白山林区属于较难燃的天然林区,随着无重大森林火灾年份不断延长,林下积累了大量森林可燃物,在长期干旱气候条件作用下,长白山林区火灾隐患逐年增大。本文分析了长白山林区不同气候条件(如湿度、风速等)下,森林可燃物负荷量动态;以美国林火行为可燃物模型划分方法为基础,采用罗瑟梅尔模型分析了长白山林区林火行为可燃物模型。研究结果为准确预测长白山林区森林火灾发生可能性,增加了森林火灾发生的可预见性;为合理制定森林林火预防规划、预防措施以及相应的灭火作战措施奠定了理论基础。具体研究结果简述如下:森林可燃物输入量动态分析表明:次生林(次生杨桦林、次生针阔混交林)与原始阔叶红松林中,阔叶类、针叶类及小枝类可燃物输入主要发生在9、10月份,可燃物输入量一般在9月下旬至10月中旬出现峰值。次生林(次生杨桦林、次生针阔混交林)与原始林(原始阔叶红松林)内森林可燃物输入量顺序均为:阔叶类可燃物＞针叶类可燃物＞小枝类可燃物。2006-2007年阔叶类、针叶类、小枝类森林可燃物年输入量顺序均为:原始阔叶红松林＞次生针阔混交林＞次生杨桦林。不同林型中森林可燃物年总输入量(阔叶类+针叶类+小枝类)顺序均为:原始阔叶红松林高于次生林(次生针阔混交林及次生杨桦林),次生针阔混交林与次生杨桦林中可燃物年总输入量则差异不大。森林可燃物年总输入量在5.2hm~2次生林监测样地中具有较强的空间异质性。不同林型中灰分含量、粗脂肪含量、热值顺序为:次生杨桦林＞原始阔叶红松＞次生针阔混交林。长白山主要林型林火行为研究显示:长白山林区不同林型林火蔓延速率、单位面积热量随着湿度的增加而减小。在研究的13个林型中,低湿度条件下,最大火焰平均风速均大于8m/s;中湿度条件下,最大火焰平均风速均大于8m/s;高湿度条件下,岳桦成熟林中最大火焰平均风速为7.11m/s,白桦成熟林中最大火焰平均风速为7.35m/s,其它林型最大火焰平均风速均大于8m/s。无论在低湿度、中湿度或高湿度条件下,白桦近熟林着火后林火蔓延速率最大、落叶松近熟林最小;云冷杉中龄林和云冷杉-红松混交林中单位面积热量最大、岳桦成熟林最小。根据低、中、高湿度条件下不同林型林火行为特征,可将13个林型最终划分为八大类。八种可燃物类型、13种可燃物模型潜在林火行为分析显示:岳桦成熟林外,其它林型林火蔓延速率均随火焰平均风速增加而增大。林火蔓延速率受森林可燃物湿度影响,林火蔓延速率顺序为:低湿度＞中湿度＞高湿度。0-8m/s火焰平均风速范围内,单位面积热量、最大可靠风速均保持恒定。单位面积热量、最大可靠风速受森林可燃物湿度影响,大小顺序为低湿度＞中湿度＞高湿度。八类林型的火线强度、火焰长度均随着火焰平均风速增加而增大。白桦成熟林中林火蔓延速率最大,白桦幼龄林和落叶松近熟林次之。此类林型单位面积释放热量较低,林火火线强度较小,适于采取直接灭火法进行扑救。白桦中龄林和落叶松成熟林中林火蔓延速率最小,云冷杉中龄林和云冷杉-红松林次之。此类林型单位面积释放热量较高、林火火线强度较大,适于采取间接灭火法进行扑救。更多还原

【Abstract】 There was no serious forest fire in the Changbai mountain forest region for 29 years and the general incidence of fires declined. This region belongs to an uninflammable virgin forest. With the extension of the years that there is no large fire happened and the accumulation of understory fuel loads, the fire risk in the region of Changbai mountain increased yearly under the effect of dry climate condition in a long time. The dynamic of forest fuel loads was analyzed in this paper combined with climatic conditions in Changbai Mountain forest region. Base on the partition method of U.S. Fire Behavior Fuel Model, the Rothermel model was used to evaluate the behavior fuel model in Changbai mountain forest regions. The results can provide the possibility to predict forest fires in Changbai Mountain forest accurately, increase the predictability of forest fires and lay a theoretical foundation for establishing the prevention programs, preventive measures and fire-fighting measures of forest fires reasonably. The main research results as follows:The temporal dynamics of input on fuel show that the input of broadleaf, needles and branchless in Secondary Populus davidiana-Betula platyphylla forests, Secondary conifer and broadleaved mixed forest and the original broad-leaved Korean pine forest were mainly concentrated in September and October, reached the peak in late September to mid-October. The order of input on fuel of different type in these forest stands were that the broadleaf > needles > branchless. The total input of broadleaf, needles and branchless in 2006 and 2007 were that Original broad-leaved Korean pine forest > Secondary conifer and broadleaved mixed forest > Secondary Populus davidiana-Betula platyphylla forests. The total input (including broadleaf, needles and branchless) of differential forest types in the year of 2006 and 2007 were that the original broad-leaved Korean pine forest > Secondary conifer and broadleaved mixed forest =Secondary Populus davidiana-Betula platyphylla forests. The total input of fuel in a 5.2ha dynamic forest plots in Secondary conifer and broadleaved mixed forest show an obvious spatial heterogeneity. The content of ash content, crude fat content, heat value were in the same order that Secondary Populus davidiana-Betula platyphylla forests > Original broad-leaved Korean pine forest > Secondary conifer and broadleaved mixed forest.Base on the partition method of American fire behavior fuel model, we established the behavior fuel model in Changbai mountain forest regions. The results of fire fuel model displayed that the spread rate of forest fire and the heat per unit fire area in different stands of Changbai mountain were decrease with the increment of humidity; In the condition of low and middle humidity, the average wind speed of maximum flame in different stands were greater than 8m/s; In the high humidity, the average wind speed of maximum flame in the plot 2 of Betula ermanii forest and the plot 3 of Betula platyphlla forest were 7.11m/s and 7.35m/s separately , the average wind speed of maximum flame in other forest types are greater than 8m/s. In any situations of low, middle and high humidity, the spread rate after forest fire happened in near-mature stand of Betula platyphlla forest is the fastest and the lowest one is in near-mature stand of Larix olgensis forest; The heat per unit fire area in mid-age stand of Abies-Picea forest and mixed forest of Abies-Picea forest and Pinus koraiensis forest are the greatest, while the smallest one is in mature stand of Betula ermanii forest. According to the character of fire behavior in different stands under the low, middle and humidity condition, 13 forest types were finally divided into 8 classes.The analysis of potential forest fire behavior of 8 types of fuel and 13 fuel models show that in addition to mature stand of Betula ermanii forest, the spread rates of fire accelerated with increment of the average flame speed. The spread rates of fire were influenced by the forest fuel humidity, which were low humidity >middle humidity >high humidity in order. Within 0～8 m/s average wind speed of flame, the heat per fire area and maximum reliable wind speed were both keep constant. They were influenced by the forest fuel humidity, the order of which were low humidity >middle humidity >high humidity. The flame length and fire intensity of 8 forest types were also increased with the acceleration of the average flame speed. The spread rates of fire in mature stand of Betula platyphlla forest were greatest, followed by young stand of Betula platyphlla forest and near-mature stand of Larix olgensis forest. Their heats from per fire area were much lower and fire intensity was small, which was suitable to take fire direct extinguishing. The spread rates of fire in mid-age stand of Betula platyphlla forest and the mature stnad of Larix olgensis forest were the smallest, followed by mid-age stand of Abies-Picea forest and mixed forest of Pinus koriensis and Abies-Picea.The heats of per fire area from these types were higher and the fire intensity was greater, which was adopted to take fire indirect extinguishing.更多还原