Quality of lower trees in compound storied forests of Sugi(Cryptomeria japonica D.DON)

研究了13个不同类型的复合层林、1个群选林、5个二分林和7个选林的下层乔木的树木性状和木材品质。所得结果如下：1)光照条件对形态比（树高/胸高茎粗）有影响。由于在均匀林分中，各林分的光照条件基本相同，所以形态比的变化较小。另一方面，复合层状林分的光照条件因林分不同而不同，因此在形态比上存在波动。光照有利条件下低矮乔木形态比大，光照不利条件下低矮乔木形态比小。2)影响下孔锥度的主要因素是人工修剪，而不是森林类型。3)积雪淤积和积雪移动引起的扫尾。因此，在积雪地区的森林中，在没有阻止积雪移动的上层树木的均匀林分中，扫尾变大。4)复合斑驳林下低处林木的扫茎量大于均匀林分。然而，频繁的密集修剪可以防止茎扫，并且随着树木年龄的增长，茎扫变小。5)双栅林分下乔木表现出优良的强度特性。这是由于光照条件的控制和密集的修剪。

Tree character and wood quality of lower trees were investigated in thirteen various compound storied forests,one group-selection stand, five two-stried stands and seven tree-selection stands.The obtained results are as follows.1)The form ratio(tree height/stem diameter at breast height) was afected by light condition. Since in uniform stands,the light condition was much the same among each stand, the variation of form ratio was small. On the other hand, the light condition of compound storied stands was varied with each stand, therfore there was a fluctuation in form ratio. Form ratio of lower trees in favorable light condition was large, while that in inforior light condition was small.2) The tapering of lower bole was affected by artificial pruning rather than forest type.3) The butt-sweep in caused by snow deposit and snow moving. Therefore the butt-sweep became larger in forest of snowy areas and in uniform stands without upper trees which prevent a movement of snow deposit.4) The stem-sweep was larger in lower trees of compound stried forests than uniform stands. However frequent intensive pruning can prevent the stem-sweep and it was recognized that stem-sweep became smaller as tree grows older.5) The lower trees in two-stried stands exhibited an excellent strength properties. It is due to the control of light condition and intensive pruning.