长白山北坡森林群落结构组成及其海拔变化

Structure of forest communities on the northern slope of Changbai Mountain and its variation along elevation gradients

对长白山北坡海拔 70 0～ 190 0m的 13个森林群落进行了群落组成、结构随海拔上升变化情况的研究。结果表明 ,随着海拔的升高 ,群落的建群种组成、层次结构等 ,都表现出由复杂多样逐渐向简单单一过渡的变化趋势 ,从 70 0m至 170 0m ,针叶树所占的比例随海拔的升高呈明显的增加趋势 ,阔叶树比例随之减少 ,到林线时针阔叶树种均急剧减少 ,沿海拔梯度存在明显的树种更替现象。从群落的平均胸径及胸高断面积和可知 ,最大值出现于 90 0～ 110 0m及 16 0 0m ,这 2个海拔段正是不同森林群落类型间的过渡区。除海拔 180 0m的岳桦林之外 ,其它群落径级结构都呈倒J形分布 ,即各径级树木中 ,更新幼苗、幼树在数量上占绝对优势 ,随着胸径的增大 ,立木株数逐渐减少 ,这种径级结构表明 ,长白山北坡各海拔群落更新良好 ,群落处于稳定的发展状态。

The structure of thirteen forest communities from 700～1?900?m along the northern slope of Changbai Mountain was studied. The results showed that composition of dominant tree species and layer structure displayed the transitional tendency from complexity to simplicity with the increase of elevation. The proportion of coniferous species obviously increased and broad-leaved trees decreased from elevation 700～1?700?m. At timberline, coniferous and broad-leaved species sharply decreased and species obviously subrogated along altitude gradient. The peak value of average DBH and basal area in the community appeared at elevation segment of 900～1?100?m and 1?600?m. The two elevation segments were exactly the transitional zone of different forest communities. Except for Betula ermanii forest at 1800m, the structure of diameter class in other communities took on toppled “J' Shape. Namely, among tree species of each diameter class, updated seedlings and saplings predominated quantitatively. With the increase of DBH, the numbers of stumpage decreased gradually. The structure of diameter class showed that communities at each elevation on the northern slope of Changbai Mountain updated well and communities were in the status of stable development.