广东郁南尾巨桉人工林密度效应

Density Effects on the Growth of Eucalyptus urophylla × E.grandis Plantation in Yunan County, Guangdong Province

采用随机区组试验设计在广东省郁南县西江林场设置了4种株行距(1.7 m×4 m,2.0 m×4 m,2.5 m×4 m,3.0 m×4 m)试验,分析不同造林密度(1 470、1 250、1 000、833株·hm^(-2))对0.8~7.8 a生尾巨桉(Eucalyptus urophylla×E.grandis)人工林保存率、树高、胸径、单株材积和林分蓄积量的影响。结果表明:不同造林密度对林分的保存率、树高、胸径、单株材积和蓄积量均有显著的影响;除0.8 a生的林分保存率外,其它年龄的林分保存率均随着造林密度的增加而降低,1 470株·hm^(-2)与其它3种密度间的林分保存率存在显著差异;造林密度对林分平均高有一定的影响,但差异较小;随着造林密度的增加,林分平均胸径和单株材积逐步递减,1 470、1 250株·hm^(-2)与其它两种密度间的平均胸径和单株材积在2.8~7.8 a生时均存在显著差异;在7.8 a生时,以1 250株·hm^(-2)为造林密度的林分蓄积量最大,达195.0 m^3·hm^(-2),分别比造林密度为1 470、1 000、833株·hm^(-2)的林分高16.28%、5.86%和14.37%。以获得较高的林分蓄积量为目标,初步推荐1 000~1 250株·hm^(-2)的造林密度。

The effects of different planting densities（ 1 470, 1 250, 1 000, 833 trees · hm^-2） on the preservation rate, tree height, DBH, individual tree volume and stand volume of Eucalyptus urophylla × E. grandis plantation aged at 0.8 to 7.8 years in Xijiang Forest Farm of Yunan county, Guangdong province were studied by arranging a trial treated with four spacings of 1.7 m × 4 m, 2.0 m × 4 m, 2.5 m × 4 m and 3.0 m ×4 m through the randomized block experiment. The results showed that different planting densities had significant influences on the preservation rate, tree height, DBH, individual tree volume and stand volume. Except for the age of 0.8 years, the preservation rate of stand aged at other years decreased with the increasing planting density, among which there were significant differences between 1 470 trees · hm^-2 and other three types of planting density. The planting density also had eminent effects on tree height, but the difference was relatively small. The mean values of DBH and individual volume decreased gradually with the increasing of plant density, and there were significant differences in the two indicators between 1 470, 1 250 trees · hm^-2 and other two types of planting density for the stand aged at 2.8 to 7.8 years. At 7.8 years old, the volume of stand planted with 1 250 trees · hm^-2was the highest with the value of 195.0 m^3· hm^-2, which increased by 16.28%, 5.86%, 14.37% compared with the planting density of 1 470, 1 000 and 833 trees · hm^-2. Therefore, the planting density between 1 000 to 1 250 trees · hm^-2 was recommended to obtain the highest stand volume of E. urophylla × E. grandis plantation.