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    北京市十三陵林场油松林地表火行为模拟

    Simulation of surface fire behavior of Pinus tabuliformis forest in Ming Tombs Forest Farm in Beijing

      摘要
    • 摘要:
      目的油松林是华北地区典型针叶林分，易发生森林火灾。通过对油松林地表火行为模拟研究可以为森林可燃物管理，林火预防及扑救提供科学依据。
      方法本研究以北京市十三陵林场油松林为研究对象，通过野外调查地表枯死可燃物(1、10、100 h时滞)和灌层可燃物，记录林分因子(第1枝下高、树高、林龄和胸径)和环境因子(坡度、坡向和海拔)。结合内业实验测可燃物含水率和热值，利用火行为模拟软件BehavePlus5.0，对1 h时滞可燃物设定不同含水率和风速值，模拟所研究林分地表火蔓延速度、火线强度、火焰高度以及单位面积发热量4个重要的火行为指标。
      结果1、10、100 h时滞和灌层可燃物占总可燃物载量比分别为78%、5%、4%和13%。基于实测可燃物载量和含水率，油松林地表火蔓延速度平均值为2.1 m/min，火线强度平均值为270 kW/m，火焰高度平均值为0.95 m单位面积发热量平均值为7 139 kJ/m2。油松林1 h时滞可燃物载量显著高于10 h时滞和灌层可燃物载量。在1 h时滞可燃物含水率为6%，风速为40 km/h的强风和干旱天气条件下，油松林地表火蔓延速度平均值为15.1 m/min，火线强度平均值为3 278.5 kW/m，火焰高度平均值为3.1 m，单位面积发热量平均值为12 337.5 kJ/m2。
      结论油松林内1 h时滞细小可燃物载量高于其他类型可燃物载量。地表火蔓延速度慢，火强度低，火焰高度低于第一枝下高，在正常天气条件下容易被扑灭。模拟结果表明油松林在低含水率的条件下，风速会显著增加地表火蔓延速度，难以人为扑灭，需清理地表可燃物，降低火险。

       

      Abstract:
      ObjectivePinus tabuliformis is a typical coniferous forest in North China, which is prone to forest fires. By simulating the surface fire behavior of Pinus tabuliformis, it can provide a scientific basis for forest combustibles management, forest fire prevention and fire fighting.
      MethodTaking Pinus tabuliformis forest as the study objective, we simulated the surface fire behavior with BehavePlus5.0 software.
      ResultThe fuel load of 1 hour timelag, 10 hour timelag, 100 hour timelag and shrub accounted for 78%, 5%, 4% and 13%, respectively. According to the research date, the average value of the surface fire spread rate of Pinus tabuliformis forest was 2.1 m/min, the average value of the fire line intensity was 270 kW/m, the average value of the height of the flame is 0.95 m, and the average value of the heat per unit area was 7 139 kJ/m2. Under the conditions of strong wind and dry weather with 1 hour timelag fuel moisture of 6% and a wind speed of 40 km/hour, the average value of the surface fire spread rate of Pinus tabuliformis forest was 15.1 m/min. The average value of the fire line intensity was 3 278.5 kW/m, and the average flame height was 3.1 m, the average value of the heat per unit area was 12 337.5 kJ/m2. Simulation of surface fire behavior study can provide a reference for the pruning height of Pinus tabuliformis.
      ConclusionThe results show that 1 hour timelag fuel load was significantly higher than the other type of fuel. The surface fire spreads slowly, the fire intensity was low, the flame height was lower than the first branch, and it was easy to be extinguished under normal weather conditions. The simulation results show that under the condition of low water content, the wind speed of the Pinus tabuliformis forest will significantly increase the surface fire spread speed, which is difficult to extinguish artificially. It is necessary to clean up the surface fuel and reduce the fire risk.

       

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