Spatial Distribution of Leaves, Branches and The Vessel Characteristics in Betula platyphylla | 白桦枝叶的空间分布及导管特征

chinois. 分别从8个不同方位测定7株白桦解析木树冠上层、中层和下层一级枝的叶面积、枝长与倾角及其导管直径、管孔密度和导管组织比量。结果表明：叶面积在树冠下层南向最大,上层东北方向最小。枝的数量在树冠下层东向最少,中层北向最多。在树冠下层的东南方向枝最长,东向倾角最大;在树冠上层东北方向,枝最短,倾角最小。导管直径和组织比量是树冠中层西向最大,树冠上层南向最小;管孔密度是树冠下层南向最小,上层西北方向最大。研究结果表明白桦树冠不同部位的叶、枝及其导管特征存在差异。讨论了白桦树冠叶、枝及其导管特征与微环境的关系。

anglais. In this study, leaf area, branch length and angle, vessel diameter, vessel density and the tissue proportion of the first order branch were investigated in upper crown, middle crown and lower crown of 7 Betula platyphylla sample trees from 8 different orientations. The results showed that leaf areas were smallest in the northwest of upper crown and largest in the south of lower crown, and the number of branches was least in the east of lower crown and most in the north of middle crown. The branch lengthes and branch angles were shortest and least in the northwest of upper crown, and the branch length was longest in the southeast and the branch angle was biggest in the north of lower crown. Vessel diameters and the tissue proportion were maximal in the west of middle crown and minimal in the south of upper crown. The vessel density was maximal in the northwest of upper crown and minimal in the south of lower crown. These results indicated that there were spatial differences in the distribution of leaves, branches and their vessel characteristics among the orientations of different crown layers. In addition, the relationships between leaves, branches and their vessel characteristics of the crown and microenvironment were discussed.