林火生态因子时空动态的研究

THE RESEARCH OF SPACE-TIME DYNAMIC OF THE ECOLOGICAL FACTORS OF FOREST FIRE

从林分的时空角度入手 ,着重分析了与林火发生密切相关的林分因子 :不同林分、林龄、郁闭度。它们随时间的推移导致森林火灾危险性的变化 ,其一般规律是 :中郁闭度林分 ,年龄增加、郁闭度增加 ,林木枝下高增加快 ,从而地表火发生率降低 ,树冠火危险性增大 ;长期未郁闭的疏林 ,地表火危险长期存在 ,林分生产力低 ;灌木、草坡是地表火发生率最高 ,生产力最低的类型。所以 。

From the angle of time-space, the paper mainly analyses that the time-variation of forest factors such as the type of forest, forest age, canopy density, which are close relatied to forest fire, gives rise to the variation of forest fire risk. Generally, the law is that, in the forest of moderate density, with age increasing, canopy density increases, the growth of a tree trunk below a canopy increases. Because of these, the frequency of land-surface fire decreases, the risk of tree canopy fire grows greater(the loss of forest fire is enlarged); that in the sparse forest which can not reach canopy closure for many years, the risk of lad-surface fire exists for a long time, the productivity of forest is low; that brush and grass land are the types in which the frequency of land-surface fire is the highest, productivity is lowest. This paper propounds the reasonable measures of preventing fire by managing forest.