不同造林密度对尾叶桉生长、产量及材性影响的研究

EFFECTS OF DIFFERENT PLANTING DENSITIES ON THE GROWTH,OUTPUT AND WOOD PROPERTIES OF EUCALYPTUS UROPHYLLA

在桂中象州县，采用随机区组试验设计研究不同造林密度（８３３ 、１１１１ 、１２５０ 、１４２９ 、１６６６ 、２０００ 、２５００ 株／ｈｍ２） 对６ａ 生尾叶桉（ Ｅｕｃａｌｙｐｔｕｓ ｕｒｏｐｈｙｌｌａ） 生长、产量及木材材性的影响。经过一个轮伐期的定位观测，探讨种群密度与胸径、树高、立木单株材积、林分蓄积量、木材气干密度、木材纤维形态、冠幅、枝下高、林分保存率等的作用规律和相关模型。结果表明：密度对胸径、立木单株材积、冠幅及枝下高的影响达极显著水平；对蓄积量、木材纤维宽度、导管分子长度的影响达显著水平；对树高、木材气干密度、木纤维长度虽有一定的影响，但不显著。根据试验结果提出尾叶桉人工林的合理密度范围在１２５０ ～２５００ 株／ｈｍ２ 之间，短周期工业用材林的最佳密度为２０００ 株／ｈｍ２ ，主伐年龄为５ ～７ａ 。

The effects of different planting densities (833,1111,1250,1429,1666,2000 and 2500 trees/hm 2) on the growth,output and wood properties of 6\|year\|old Eucalyptus urophylla were studied by random block experiments in Xiangzhou county,middle of Guangxi.The functional rule and correlation model between the population density of Eucalyptus urophylla and DBH,height,individual standing volume,volume of forest\|crop,the air\|dry density of wood,form of wood fiber,crown cover,live braches height and rate of preservation have been observed and analysed.The results show that,the effects of density on the DBH,the individual standing volume,the crown cover and the live braches height are extremely remarkable,that on the volume of forest\|crop,the width of wood fiber and the length of vessel element are remarkable,and that on the height the air\|dry density of wood and the length of wood fiber are not remarkble.According to the results,the limit of reasonable density on Eucalyptus urophylla was suggested to be between 1250 and 2500 trees/hm 2.2000 trees/hm 2 is the best density for short rotation industrial forests of Eucalyptus urophylla. The final felling age of the new area in the middle part of Guangxi is 5～7 years.