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东北林区,以红松润叶林为代表的顶极群落,由于经过森林火灾和其它方式的破坏,逐渐变成了硬阔叶杂木林和阔润叶杂木林,这种次生林林分内枯技落叶多,火险等级比针叶林高。如果续继发生火灾,过火后的林地枯枝还会增加,植被向矮小灌丛方向演变,最后使林地变成荒山秃岭。这里所讲的细小可燃物,是指林地上基茎在二公分以下的枯枝和落叶。它包括从树冠上落下来的枯枝落叶,矮小灌丛枝条和地面各种草本植物。在次生林内,细小可燃物的分布格局呈层状,最上面的一层是当年落地或枯死的枝条落叶,往下是前一年,前二年的细小可燃物,三年以上的细小可燃物,除较粗树枝外,已被土壤微生物分解成半腐植质状态,并形成半腐层。高强度的火可以烧到半腐层。
In the northeastern forest area, the climax community represented by Pinus koraiensis is changed into hardwood broad-leaved mixed forest and broad-leaved mixed forest because of forest fire and other damage, Technology leaves more fire danger level than coniferous forest high. If the fire continues, the excessive dry woodland branches will increase, the vegetation evolves toward the shrubbery, and finally the woodlands become bald patches of barren hills. Speaking of small combustibles here, refers to the woody stems in two centimeters below the dead branches and leaves. It includes litter falling from the canopy, dwarf shrub branches and various herbs on the ground. In the secondary forest, the distribution pattern of fine combustibles is stratified. The uppermost layer is the deciduous branches that fall or die in the current year, the last two years are the small combustibles of the previous year and the small combustibles of more than three years , Except coarse branches, has been decomposed by soil microorganisms into a humus state, and the formation of half-layer. High-intensity fire can burn half-layer.