摘要:
对小兴安岭长白落叶松人工林可燃物进行分层分类型调查,比较其碳储量垂直分布,分析从未成林地到成熟 林林火种类、行为和燃烧性,据此评估森林燃烧性等级,并提出可燃物处理和营林防火措施。结果表明:未成林碳 储量仅87.660 t/ hm2 ,但各层可燃物连续性好,草本着火且形成高强度地表火后,易引发树冠火,属高燃烧性林分, 应加大灌草清除;幼龄林碳储量138.574 t/ hm2 ,不易发生地表火,但枯死枝可引发树冠火,高林分密度有利于树冠 火蔓延,属高燃烧性林分,应注重整枝,兼顾地表可燃物清理;中龄林碳储量163郾884 t/ hm2 ,可能发生地表火,因间 伐修枝而抬高树冠,降低了林冠火发生的可能性,属低燃烧性林分,可计划烧除灌草;近熟林碳储量199.838 t/ hm2 , 可以发生地表火,甚至树冠火,属中燃烧性林分,应重点清理可燃物累积多的区域;成熟林碳储量253.962 t/ hm2 ,地 表存在大量可燃物,可形成高强度地表火,属高燃烧性林分,应计划烧除。
Abstract:
In order to study the interaction between fuel carbon storage (CS) distribution and combustibility of plantation ecosystem at different stages in depth, and evaluate forest fire risk grade comprehensively, the carbon storages and distribution of Larix olgensis plantations at five different stages from 7 to 48 years old were compared in representative region of Lesser Khingan Mountains (Northeast of China). First, fuels were divided into five subtle layers according to their virtual structure. Then, fuel carbon storage of each layer was estimated by DBH, height, crown area, depth, etc. , via corresponding carbon density. Finally, the fire classes, fire behavior, and fire risk of each layer at different stages were analyzed, and evaluated the forest combustibility based on the total fuel carbon. The results showed that: 1) Surface fire of immature forest can be ignited easily because of abundant herbs, and high鄄intensity crown fire could occur, but its spread rate was low because of less CS as 87郾660 t/ hm2; 2) Once crown fire occur in juvenile forest (with 138郾574 t/ hm2 CS), high density and certain dead branches would result in high鄄 intensity crown fire; 3) Because of tending and thinning, middle鄄aged stand with 163郾884 t/ hm2 CS had lower probability of surface or crown fire, but it can initiate crown fire with high spread rate once fire was ignited; 4) In near鄄mature stand (with 199郾838 t/ hm2 CS), crown fire initiation only occurs under extreme conditions, but can be on moderate鄄intensity surface fire with more possibility. 5) A mass of fuel as high as 253郾962 t/ hm2 CS could result in high鄄intensity surface fire in mature stand without effective reduction treatments to floor fuel.
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