昆明西山林场5种可燃物的火行为研究

【目的】通过估测西山林场内主要可燃物特征,预测潜在的火行为大小,为西山林场的防火管理提供科学参考。【方法】通过外业调查,对柏木(Cupressus funebris)、旱冬瓜(Alnus nepalensis)、云南松(Pinus yunnanensis)、华山松(P. armandii)和麻栎(Quercus acutissima)5种可燃物采样,估算西山林场内主要可燃物载量大小,并在实验室内进行燃烧模拟试验,量化火行为特征,包括引燃时间、火焰维持时间、无焰燃烧维持时间、蔓延时间、火焰高度、火焰温度、无焰燃烧温度、火焰热辐射、无焰燃烧热辐射等。【结果】云南松林内的载量达到2.35 kg/m²、燃烧火焰最高温度628 ℃、燃烧火焰最大高度70 cm、最大热辐射为6.92 kW/m²、燃烧后无焰燃烧的最高温度266 ℃,均与每年进行计划烧除时云南松纯林内的载量1.15 kg/m²、火焰最高温度697.6 ℃、火焰最大高度44.5 cm、最大热辐射8.02 kW/m²,无焰燃烧的最高温度194.3 ℃有差异。不同林种可燃物的火强度大小依次为:云南松(786.07 kW/m) >麻栎(564.39 kW/m)>华山松(275.30 kW/m) >柏木(6.26 kW/m),其中云南松的火强度(786.07 kW/m,中强度火)与云南松纯林计划烧除时的火强度403.60 kW/m(低强度火)有差异。【结论】森林可燃物的载量对火强度影响较大,麻栎和华山松属于低强度火,柏木的火强度几乎可以忽略不计。森林抚育更新等人为干预措施,可对林内可燃物进行有效调控,减少和预防森林火灾的发生。

Fire behavior of five kinds of fuels in Xishan Forest Farm,Kunming City

【Objective】This study aimed to improve fire prevention management for Xishan Forest Farm by estimating the main fuels characteristics and predicting potential fire behavior.【Method】Based on a field survey and sampling,the status of fuel was analyzed in the Xishan Afforestation Community.There were five main types of combustibles:Cupressus funebris,Alnus nepalensis,Pinus yunnanensis,P.armandii,and Quercus acutissima.Their combustion was measured in the laboratory,and the fire behavior was calculated,including ignition time,flame maintenance time,flameless combustion maintenance time,spread time,flame height,flame temperature,flameless combustion temperature,flame heat radiation and flameless combustion heat radiation.【Result】In the P.yunnanensis forest,the fuel load was 2.35 kg/m²,the maximum flame temperature was 628℃,the maximum flame height was 70 cm,the maximum flame heat radiation was 6.92 kW/m²,and the maximum temperature for flameless combustion was 266℃.During the prescribed burning every year in P.yunnanensis,the load was 1.15 kg/m²,the highest temperature of the flame was 697.6℃,the maximum flame height was 44.5 cm,the maximum heat radiation of the flame was 8.02 kW/m²,and the maximum temperature for flameless combustion was 194.3℃.There was a difference between the prescribed burning and Xishan forest farm of P.yunnanensis.The fire intensity order was P.yunnanensis>Q.acutissima>P.armandii>C.funebris,and the intensity values were 786.07,564.39,275.30 and 6.26 kW/m,respectively.Among these,the fire intensity of P.yunnanensis of 786.07 kW/m(medium-intensity fire)was different from the fire intensity of 403.60 kW/m(low-intensity fire)when P.yunnanensis of pure forest is planned to be burned.【Conclusion】The fuel load had the greatest impact on the fire intensity of combustibles.Q.acutissima and P.armandii were low-intensity fires,and the fire intensity of C.funebris was almost negligible.It is recommended that the Xishan Afforestation Community adopt human intervention to effectively treat forest combustibles and to prevent forest fires.