火干扰对天然红松林结构和演替过程的影响

THE EFFECT OF FIRE DISTURBANCE ON STRUCTURE AND SUCCESSION IN MIXED DECIDUOUS/PINUS KORAIENSIS FOREST

1990—1992年期间对小兴安岭凉水林场天然红松林土壤中木炭、火烧木疤痕和林分组成进行了调查。探讨火干扰对森林形成和演替的生态作用。在不同火干扰年代的林分中,抽样挖掘木炭,测量木炭块的大小和分布深度,记录各林分结构特征和红松更新状况,并根据树木火疤园盘确定火干扰年代。选择了50 hm^2火干扰林分,对火烧疤痕木进行详细调查,并在其中设置样地,调查各样地林分组成和红松径阶结构。结果表明:Ⅰ.不同火干扰年代的林分。土壤中的木炭平均深度与火干扰发生的时间关系密切。Ⅱ.根据50 hm^2火干扰林分中火烧木疤痕的调查,绘制了火行为动态图。火烧方向和火干扰程度与立地条件关系密切。Ⅲ.火干扰并未完全破坏森林,导致林分中不同地点上林分组成和红松径阶结构的差异明显。在火干扰后,整个林分的水平结构是一个由不同树种组成和不同红松径阶结构的树木群团构成的镶嵌体,各树木群团的演替趋势不同。在火干扰较重的地点,阳性阔叶林占优势,在阔叶树下更新着大量的红松小树。在火干扰较轻的地点,耐阴性阔叶树种占优势,并有少量大径阶红松。火干扰轻微的地点,大径阶的红松占优势。

The charcoal and fire-scarred trees were investigated in mixed deciduous/Pinus koraiensis forest on Liangshui Farm in Xiaoxingan Mountains from 1990 to 1992. The depth and size of charcoal in soil was measured by sampling small plot under the different stand that the time fire are variety, the time of fire happening were determined by sawing cross-sections from fire-scarred tree. On 50 hectares forest, each tree fire scar was recorded with the fire evidences——include the species, diameter, location of the tree, approximate dimensions of fire wound, the number of visible fire scars, and extend of decay. The size class structure of korean pine and community structure on the stand were investigated by sapling plot. Conclusions as following:Ⅰ. The average depth of charcoal in the soil is related with the time of fire happening.Ⅱ. Depending on the characteristic of tree fire scar, the picture of fire action is draw on a topographic map, the dimension and extent of fire is closely related with site conditions.Ⅲ. Wildfires burn only portions of stands, leaving variety of tree composition and tree size structure of korean pine in different places on a stand, the horizontal community structure is a mosaic of different deciduous species and different size korean pine patch. On the different place, the tree patch dynamics are different. On the heavy firing place, the intolerance hardwood trees were dominated, rich small size korean pine tree in the stand. On the middle place, the tolerance hardwood trees were dominated, some large size korean pine trees on the stand. On the light, large korean pine trees were dominated.