塞罕坝地区华北落叶松干形特征研究

Research on stem of Larix principis-rupprechtii in Saihanba area

为了解塞罕坝地区华北落叶松的干形特征,以指导华北落叶松的培育,提高木材质量及木材利用率,在塞罕坝机械林场的坝上及坝缘山地进行取样,对华北落叶松的干形质量进行调查和分析,并拟合了华北落叶松干形曲线。结果表明:塞罕坝地区华北落叶松的干型较好,树干通直率达到88.47%,其中,坝缘山地干形好于坝上地区,其通直林木占比达92.1%;在弯曲林木中,坝上地区一个弯点的林木比例(61.9%)低于坝缘山地(73.68%),且弯点多位于3m以下(占比52.38%),而坝缘山地弯点多位于6m以上(占比42.11%);塞罕坝地区华北落叶松分杈林木占比不足10%,且分杈位置多位于6m以上;华北落叶松干形曲线以三项式模型效果最佳,相关系数最高,为0.970 6;不同干形曲线在模拟树干不同部位的精度不同,各个模型在树干上部拟合效果都相对较差,在模拟树干中下部和基部的平均相对误差均比较小的模型是二次多项式(分别为0.019 8,-0.007 8)和三次多项式(分别为-0.010 6,0.012 2)。

In order to get the tree stem from and improve the timber quality and utilization, stem froms of Latin principis rupprechtii were surveyed in the Bashing and Bayuan regions in Saihanba mechanical forest farm. The stem profiles were modeled by the survey data. The results showed： the overall stem forms of Latin principis rupprechtii were good, and the rate of straight trees was 88. 470/00. and the stem forms in the mountain area, located in the edge of saihanba were better than the trees in bashang area. The rate of straight trees in the mountain area was 92.1%. The rate of bending trees with one bending point in bashang area （61.9%） was lower than trees in the mountain area, and these bending point always below 3 meter height （52. 38%）. Trees with bending points above 6 meter has the proportion of 42.11% in the mountain area. The rate of trees with obvious branch was less than 10%, and the position of branch always higher than 6 meter. Trinomial stem curve model was best in the stem form simulation, The correlation coefficient was 0. 970 6. Stem curve models had different predict precision in the different position of stems. The fitting effect was bad when predicting the upper stems, and second order polynomial model （0. 019 8, 0. 007 8） and third order polynomial model （ 0. 010 6,0. 012 2） had the lower mean relative error when modeling the middle and lower part of tree stem.