Effect of Competition in Dimensional Relations of Araucaria

ABSTRACT This study aimed to describe the effect of competition in the dimensional relations of Araucaria angustifolia (Bertol.) Kuntze. Covariance analysis was used to compare tendency dimensional relationship for the group of open grown in fields and under competition in the forest. Trees growing under competition when compared to those with open grown presented, on average, regression lines with superior intercept for height, height of crown insertion point, height/diameter ratio, when evaluating the same diameter at breast height. Decreased tree competition increases the crown length and reduces height of crown insertion point. The inclusion of variable competition index in models improved fit and accuracy of dimensional relations in forest trees, which allows to use the equations fitted to estimate the crown dimensions as assistance for silvicultural activities of araucaria.

摘要
本研究旨在阐明竞争作用对狭叶南洋杉（Araucaria angustifolia (Bertol.) Kuntze）各维度性状关系的影响。本研究采用协方差分析（covariance analysis），对比了露地生长组与林内竞争生长组的维度性状关系变化趋势。在控制相同胸径（diameter at breast height）的条件下进行评估时，竞争生长的林木其树高、枝下高以及高径比的回归截距平均值均高于露地生长林木。当林木间竞争程度减弱时，冠长会增加，枝下高则会降低。在模型中引入竞争指数变量后，可提升林木维度性状关系模型的拟合优度与预测精度，因此可利用拟合得到的方程估算冠部性状参数，为该南洋杉的营林抚育作业提供辅助支撑。