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比较了带状疏伐、选择性疏伐和未疏伐的35年生花旗松[Pseudotsuga menziesii(Mirb)Franco]林分各小区的林木生长,所有疏伐处理伐后五年与伐前五年断面积增量之比都大于对照。但距伐带边缘10英尺以外的林木则无反应。按断面积计算的疏伐强度相同时,选择性疏伐区的单株生长和林分断面积净增量都高于带状疏伐区。甚至疏伐株数高出20％以上时,选择性疏伐区伐后五年的林分断面积净增量也较带状疏伐区为大。尽管如此,因为带状疏伐费用低,伐后又便于造林,在某些情况下仍然值得采取。
The community growth of 35-year-old Pseudotsuga menziesii (Mirb) Franco was compared with that of thinning, selective thinning and thinning. All thinning treatments were compared with those of the previous five years Area increment ratio is greater than the control. However, there was no response from the trees 10 feet away from the edge of the cut. When the same thinning intensity was calculated according to the cross-sectional area, the net increment of individual growth and stand area of selective thinning was higher than that of strip-shaped thinning. Even when the number of sparsely planted trees is more than 20%, the net increment of the sectional area of the forest in the five years after selective thinning is larger than that in the strip-shaped thinning. However, because of the low cost of strip thinning and the ease of afforestation after the cut, it is still worthwhile in some cases.