黄金宝树幼龄木枝系构型特征及影响因素

Branching Architectural Characteristics and Factors of Melaleuca bracteata Young wood

为分析黄金宝树（Melaleuca bracteata）幼龄木不同生长高度的枝系构型特征及影响因素,通过统计分析不同高度阶段的枝系构型指标,并采用主成分分析法分析影响枝系构型的因素。结果表明：随着高度的增加,树高、地径、冠幅均值、树冠体积、逐步分枝率1,2与枝径均值对枝系构型的影响趋于上升;总体分枝率、逐步分枝率2,3、逐步分枝率3,4与枝条倾角均值对枝系构型的影响则增减不一。第1主成分的贡献率在23.61%-60.32%间,当高度小于60 cm时,树冠体积、枝径均值及冠幅均值是影响枝系构型的主要影响因素;高度在60-80 cm时,树冠体积和冠幅均值是主要影响因素;高度在80-100cm时,逐步分枝率1,2和总体分枝率是该阶段的主要影响因素;高度在100-120 cm时,逐步分枝率1,2、冠幅均值及枝径均值为主要影响因素。高度超过120 cm时,逐步分枝率1,2的绝对值最大,说明其为该阶段影响枝系构型的主要因素。

For analysis of the branching structure characteristics and its influence factors in different height of Melaleuca bracteata young wood, we study the statistical analysis of branching configuration indexes in different height and using principal component analysis method to analysis factors which affecting branching structure. Results show that： as the increasing of tree height, basal diameter, crown diameter mean value, crown volume, stepwise bifurcation ratio （SBR1：2）and branch diameter mean value showed an upward trend, while the overall bifurcation ratio, stepwise bifurcation ratio （SBR2：3）, stepwise bifurcation ratio （SBR3：4） and branch angle value tend to upward or downward. Contribution of the first component accounted between 23.61% to 60.32%, when the height is less than 60 cm, crown volume, crown diameter mean value and branch diameter mean value are the main factors which influent branch structure; while height in 60 to 80 cm, crown volume and crown diameter mean value become the two main factors; stepwise bifurcation ratio （SBR1：2） and overall bifurcation ratio turn to be the main effect factors in the height 80 to 100 cm; between 100 to 120 cm, which is mainly influenced by stepwise bifurcation ratio（SBR1：2）, crown diameter mean value and branch diameter mean value;last, when exceed 120 cm, absolute value of stepwise bifurcation ratio（SBR1：2） became the most which show the main factors affecting branching structure during this phase.