施肥对尾巨桉生长及大径材材性的影响分析

摘要

对3种追肥处理1(N300P200K200)、处理2(N200P100K150)和处理3(N100P50K50),从12、27、42、50、62、75、88、99、110、144到192月生的尾巨桉生长量数据进行了统计分析,并在198月生时对每种施肥处理取7株样木进行了木材的基本密度、抗弯强度、弹性模量、硬度、干缩率以及皱缩率等指标开展研究,结果如下:追肥量与生长量成正相关关系.追肥量越多,生长量越大,这种差距从追肥后就开始产生,一直到192月生时都存在;但是,这种差距在大部分时间里都未达到显著水平:达到显著差距的只有施肥处理1和处理3之间,27月生时DBH达到0.01的显著性差异、平均高在12、27和37月生时达到0.05的显著性差异、蓄积量在27、37、42和50月生时达到0.05的显著性差异.材性指标上,大径材木材材性与追肥量的关系密切,增大施肥会影响木材材性,包括降低抗弯强度,增加弹性模量,降低端、径面和弦面硬度,降低基本密度,增加木材含水率等;达到显著差异的有:木材的抗弯强度、径面硬度被显著降低,达到了0.05的显著水平.木材边材基本密度降低更大,达到了0.01的极显著水平.经过多重比较的分析,都是常规施肥处理3与处理2和常规施肥处理3与处理1两两之间差异显著.处理1和2比处理3的抗弯强度平均分别降低了12％和14％、径面硬度分别降低了11.7％和14.1％,而边材基本密度分别降低了8.6％和8.1％;因此,在培育桉树大径材时,一定要考虑合理施肥量.%An Eucalyptus urophylla × E.grandis fertilizer trial established in Dongmen Forest Farm,Guangxi,China,with three treatments-1.N300P200K200,2.N200P100K150 and 3.N100P50K50-was assessed for growth at the ages of 12,27,42,50,62,75,88,99,110,144,and 192 months.Wood properties including basic density,bending strength,modulus of elasticity,hardness,collapse recovery and shrinkage were assessed at age 198 months.The amount of fertiliser applied and tree growth were positively correlated,and whilst higher fertiliser levels resulted in faster growth from the time of application through to the last growth measurement (age 192 months),differences between treatments were only significant up to age 50 months.The differences that did prove significant included those between treatment 1 and 3 for DBH at age 27 months (P＜0.01),for mean height at ages 12,27 and 37 months (P＜0.05) and for stand volume at ages 27,37,42 and 50 months (P＜0.05).Higher rates of fertiliser application were found to affect wood properties,including reduced bending strength,increased modulus of elasticity,lower end collapse,reduced radial and tangential hardness,reduced basic density and increased moisture content.Some wood properties showed significant differences between treatments:bending strength and radial hardness were significantly lower with higher fertilizer rates (P＜0.05) and basic density of sapwood was also lower with higher fertiliser rates (P＜0.01).Multiple comparison analysis revealed significant differences between conventional-fertiliser (treatment 3) and treatment 2,and also between conventional-fertiliser and treatment 1.Comparing treatments 1 and 2 with treatment 3,bending strength dropped an average of 12％ and 14％ respectively,the radial hardness dropped 11.7％ and 14.1％ respectively,while basic density of sapwood dropped 8.6％ and 8.1％.It was concluded that reasonable fertilization levels should be used while cultivating Eucalyptus species for production of larger diameter logs for solid wood end products.