兴安落叶松天然林林木直径与树高分布的分层特征

The Layered Characteristics of DBH and Height Distribution of Larix gmelini Nature Forest

[目的]通过分析大兴安岭呼中林区兴安落叶松天然林胸径和树高的一元、二元分布特征,揭示脆弱地带森林群落的林木大小分布特征。[方法]在大兴安岭呼中林场设置3种不同类型兴安落叶松林固定样地,利用整体和分层的方法,对样地林分胸径和树高的变化规律以及两者之间的关系进行研究。[结果]表明:(1)草类-落叶松林直径分布为单峰分布,其他2块样地为双峰分布; 3块样地林木直径分布均呈左偏。杜鹃-落叶松林树高分布为多峰分布,其他2块地均为单峰分布; 3块样地林木树高分布均呈右偏。(2) 3块样地上、下层林木的直径分布均为单峰分布,上层木直径分布均呈左偏,下层木直径分布草类-落叶松林右偏,杜鹃-落叶松林左偏,杜香-落叶松林为近似正态。杜鹃-落叶松林的树高上、下层分布为双峰,其他2块样地均为单峰,3块样地上层木树高分布均左偏,而下层木树高分布均右偏。(3)草类-落叶松林和杜鹃-落叶松林小径阶林木株数占绝大多数。3块样地林分中树高与胸径的比值在小径阶林木中明显大于大径级林木。草类-落叶松林和杜鹃-落叶松林上层木中小径阶林木株数所占比例稍大,杜香-落叶松林和杜鹃-落叶松林下层木中大径阶林木株数比例稍大,但3块样地上层和下层木树高与胸径的比值在大小径阶林木中均无明显差异。[结论]高密度的杜鹃-落叶松林平均树高要高于低密度的杜香-落叶松林和草类-落叶松林平均树高,而平均胸径无明显差异。3块样地林分中树高与胸径的比值小径阶林木中明显大于大径级林木,但其差异在上层和下层林分中均表现不明显。

[Objective]To analyze the univariate and bivariate distribution characteristics of DBH and tree height of Larix gmelini natural forest in Huzhong forest zone of Greater Khingan Mountains Region,and to reveal the size distribution of forest fragile zones of forest communities. [Method]Three sample plots of L. gmelini forest with different species composition（ herbage-Larix,Rhododendron-Larix,and Ledum-Larix） were set up in Huzhong Forest Farm,the relationship between the DBH and the tree height was studied by the whole and layered method. [Result]（ 1） The DBH distribution of herbage-Larix forest followed a single peak distribution and the other two plotsfollowed a bimodal distribution. The DBH distribution of the three plots was left-biased. The tree height distribution of Rhododendron-Larix forest was multimodal,and the other two plots were unimodal.（ 2） The DBH distribution of the upper and lower layers of the three plots were all unimodal. The DBH distribution of the upper layer on all the three plots was left-biased,the lower layer of the herbage-Larix forest was right-biased,the Rhododendron-Larix forest was left-biased,and the Ledum-Larix forest was approximately normal. The height distribution of RhododendronLarix forest in the upper and lower layers was bimodal,and the other two plots followed single distribution. The height distribution of the upper layers of these plots was the left-biased,while the height distribution of the lower layers of the three plots was right-biased.（ 3） The percentage of small diameter trees in herbage-Larix forest and Rhododendron-Larix forest was significantly higher than that in the large diameter forest. The ratio of tree height to DBH in small diameter forests was significantly higher than that in large diameter forest. The ratio of small diameter trees in the upper layer of herbage-Larix forest and Rhododendron-Larix forest was larger than that of the large diameter forest,the ratio of large DBH trees in the lower layer of Ledum-Larix forest and Rhododendron-Larix forest was higher than that of small diameter forest. However,no significant difference was found in the ratio of height and DBH between the upper and lower layers of the three plots. [Conclusion] The average height of the high-density Rhododendron-Larix forest is higher than that of the low-density Ledum-Larix forest and herbage-Larix forest,and the average DBH has no significant difference in different density and different typed forests. The ratio of tree height to DBH in small diameter forest is significantly higher than that in large DBH forest,but the difference is not obvious in upper and lower standings.