不同造林密度对尾叶桉生长及产量的影响

Effects of Different Planting Densities on the Growth and Volume of Eucalyptus urophylla

在广西象州石龙镇，用随机区组试验设计探讨不同造林密度（８３３株／ｈｍ２、１１１１株／ｈｍ２、１２５０株／ｈｍ２、１４２９株／ｈｍ２、１６６６株／ｈｍ２、２０００株／ｈｍ２、２５００株／ｈｍ２）对４．５年生尾叶桉（Ｅｕｃａｌｙｐｔｕｓｕｒｏｐｈｙｌａ）生长及产量的影响。结果表明：在供试密度中，密度对胸径生长的影响达极显著水平，胸径生长量随密度的增大而减小；密度对树高生长的影响不显著；立木单株材积在１１１１株／ｈｍ２～２５００株／ｈｍ２内随密度的增大而减小，但８３３株／ｈｍ２密度的林分的立木单株材积并非最大；蓄积量随密度的增大而增大。据此提出尾叶桉工业用材林造林密度为２０００株／ｈｍ２～２５００株／ｈｍ２，桂中新引种区主伐年龄为５年～７年。

The effects of different planting densities(833,1111,1250,1429,1666,2000,2500 individuals/hm 2) on the growth and volume of 4 5 years Eucalyptus urophylla were studied by random blocks experiment at Shilong town, Xiangzhou county,middle of Guangxi.Within the densities in the trial, the effects of different densities on the increment of tree breast height diameter were significant different(P<0 01).The increment of the breast height diameter decreased with the increase of density.The effect of density on the increment of the stand height was not significant (P<0 05). The individual tree volume decreased successively from 1111 to 2500 individauls per hectare,but the individual tree volume of the standing forest at 833 trees per hectare was not the heighest.The volume increased with increasing density.According to the results,the density for industrial forest of Eucalyptus urophylla was suggested to be between 2000 and 2500 individuals per hectare,and the final felling age for the new area in the middle part of Guangxi to be 5 to 7 years.