樟子松人工林分枝结构的分析

基于对6块樟子松(Pinus sylvestris var. mongolica)人工林固定标准地中的30株样木枝解析调查数据，通过分析不同林分、不同大小林木1级枝和2级枝的分枝概率、分枝格局和分枝角度，揭示了樟子松人工林树冠的分枝结构特点。研究结果表明：樟子松人工林1级枝和2级枝的平均分枝数量分别为3.84个和2.80个,两者分枝概率均呈正态分布；1级和2级枝条在光照条件好的几个区间（方位角46°～225°）分布较多,1级枝条的水平分布遵从均匀分布，而2级枝条则不遵从均匀分布；树冠上层枝条的分枝角度略小于树冠中、下层，上层平均分枝角度为45.6°，而中下层平均分枝角度都为49.4°。不同大小林木的1级枝分枝结构规律表明：Ⅰ级木和Ⅴ级木的每轮平均分枝数非常接近，分别为3.89和3.94个，比Ⅲ级木每轮分枝数大0.5个左右；1级枝水平分布在各区间内(45°间隔)相差在0.24%～2.81%之间，方差分析结果表明枝条水平分布与林木大小无关；不同大小林木的分枝角度有所差别，Ⅰ级木、Ⅲ级木和Ⅴ级木的平均分枝角度分别为48.5°、42.2°和50.7°。

Branching structure analysis of mongolian pine plantation

Based on the branch analysis data from 30 sample trees of 6 permanent plots for Mongolian pine (Pinus sylvestris var. mongolica) plantation, the branching structure of crown was discussed by analyzing the branching probability, branching pattern, branching angles of primary and secondary branches for different stand conditions and tree sizes in Mongolian pine plantation. The mean branching number of primary and secondary branches was 3.84 and 2.80, respectively, and both of the branching probability was followed the normal distribution. The distribution of around the bole for primary and secondary branches was mainly distributed in the range of azimuth (from 46°~225°) where had a good light condition. An uniform was appropriate to reflect branching pattern around the bole for primary branches, not for secondary branches. The branching angle at the upper part of crown was smaller than the middle and lower part of crown, and mean branching angle in the upper crown and the middle or lower crown was 45.6°and 49.4°, respectively. The branching structure of primary branches for different sizes showed the average number of branches in each whorl was similar between dominant and suppressed trees, 3.89 and 3.94, respectively, and they were larger about 0.5 than middle trees. The differences of horizontal distribution for primary branches in each azimuth intervals (45° class size) were 0.24%~2.81% and they were not significant from ANOVA for different tree sizes. The mean branching angles for dominant, middle, and suppressed trees were 48.5°、42.2°、50.7°, respectively.