不同桉树无性系及树干高度木材的干缩特性研究

对不同桉树无性系、不同树干高度位置木材进行干缩性研究,探索气干和绝干两种状态下的弦向、径向、体积等14个主要评估木材干缩性能的指标。结果显示:11个无性系木材除气干状态的差异干缩的显著水平为0.01存在极显著差异外,其余各干缩指标显著水平更高均≤0.001。不同树干高度位置木材的干缩特性,除全干状态的弦向干缩率存在极显著差异和体积干缩率显著差异外,其余指标无论是在气干状态还是在绝干状态均无明显差异。无性系木材干缩特性的变异较小,总体平均值为3.7%,变幅为2.5%～5.4%。3个不同树干高度的木材干缩特性变异相对较大,其中树干中间段(地面高2.6～5.2m)木材的干缩变异系数相对较小。气干状态木材干缩特性变异系数较全干状态高2倍。系统聚类可将11个无性系分为3个类群,每个类群具有独特的干缩特性。

Dry Shrinkage Properties of Different Eucalypt Clones and Stem Heights

Wood dry shrinkage properties of the timber of different eucalypt clones and stem heights were investigated to examine the impacts of air and oven drying methods on 14 indices such as tangential and radial directions,volume,etc.Remarkably significant differences in all shrinkage indices among 11 clones were observed in air-dry state at the level of p≤0.001,and highly significant differences were found in both air and oven dry state at the level of p≤0.001.For the shrinkage properties of the timbers with different tree heights,except that tangential shrinkages of the timber in oven-dry state were highly and significantly different(p≤0.01),other indices either in oven dry or in air dry were not significantly different.The total average of phenotypic shrinkage variation coefficient was relatively small,with the value of 3.7%,ranging from 2.5%~5.4%.But the phenotypic shrinkage variation coefficient of the timbers from 3 different stem heights was relatively large,among them,the middle stem which was 2.6 m~5.2 m high had relatively smaller variation coefficient.The wood shrinkage variation coefficient in air-dry state was twice than that in oven-dry state.Three groups were divided among 11 clones according to the cluster analysis,each group possessed special shrinkage properties.