摘要
以云南森林自然中心抚育后的华山松林为研究对象,通过外业调查和室内测定、模拟燃烧试验相结合的方法,评估可燃物的含水率、灰分含量、粗脂肪含量、燃点、热值等燃烧性指标,研究分析修枝剪条、间伐等抚育措施对华山松林地表可燃物燃烧性的影响.结果表明:抚育后的华山松林,枝下高增加至6.3～8.5 m、林分密度为1 900～2 700株/hm2;地表可燃物含水率低于15%、灰分和粗脂肪含量分别为2.94%～5.58%和7.94%～8.09%,燃点270℃左右、热值20 020～21 084 kJ/kg;室内模拟燃烧中,可燃物的引燃速度不超过2 s、火焰温度为462.0～475.8℃、火焰辐射介于6～7 kW/m2.抚育后的地表可燃物含水率降低,有利于幼苗生长,林内枝下高增加,同时地表火焰高度为0.45～0.51 m.抚育后的华山松林内地表可燃物含水率和载量较低、灰分和粗脂肪含量中等、燃点和热值较高.抚育措施能阻止地表火发展为树冠火,有效降低森林火灾的发生风险等.研究结果有利于当地采取更合理的措施,从而实现科学火管理.
Abstract
This paper aims to study on the Pinus armandii forest after nurturing in the Yunnan Forest Nature Center through a combination of field surveys,indoor measurements,and simulated combustion tests,to analyze the impact of pruning and thinning measures on the combustibility of the surface combustible fuels such as moisture,ash,crude fat,burning point,and calorific etc.The results showed that after nurturing,the height be-low the branches of the Pinus armandii forest increased to 6.3～8.5 m,the forest contains 1 900～2 700 trees per hectare,the moisture was below 15%,the ash contents were 2.94%～5.58%,the crude fat contents were 7.94%～8.09%,the ignition point was around 270℃,and the calorific value was 20 020～21 084 kJ/kg.In indoor simu-lated combustion,the ignition speed of combustible fuels did not exceed 2 s,the flame temperature was 462.0～475.8℃,and the flame radiation was between 6～7 kW/m2.The moisture of the surface combustible fuels de-creased after nurturing,which was beneficial for seedling growth.And the height below the branches in the for-est increased while the height of the surface flame was 0.45～0.51 m.Accordingly,after nurturing,the surface combustible fuels in the Pinus armandii forest features low moisture and load,moderate ash and crude fat con-tent,high burning point and calorific.At the same time,the nurture measures can prevent surface fires from de-veloping into canopy fires and effectively reduce the risk of forest fires.The results are conducive to the adop-tion of more reasonable measures by the local area,thus achieving scientific fire management.
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