造林密度对马尾松优良家系人工林生长及直径分布的影响

Effects of Planting Densities on Growth and Diameter Distribution of Superior Family of Pinus massoniana Plantations

对4种不同造林密度马尾松(Pinus massoniana)优良家系人工林的林分生长及直径结构进行研究。结果表明,林分胸径、单株材积及两者的年均生长量均随密度增大明显减小;密度对林分蓄积量和树高的影响不显著。密度从低到高的数量成熟林龄分别为13年、12年、12年和11年,较广西工业原料林主伐林龄早。林分直径结构近似服从正态分布;2500株/hm^2密度林分直径分布的偏度逐年增大,直径分布变异系数低,利于大径材的培育;4500株/hm^2密度林分蓄积量大,适合培育短周期工业用材林。

Growth and diameter structure of superior family of Pinus massoniana plantations with four different planting densities were studied.Results showed that DBH,individual volume and annual average increments of both decreased significantly with increasing density.Density had no significant effect on stand accumulation and tree height.Quantitative mature ages with planting densities from low to high were 13,12,12 and 11,respectively,which were smaller than felling age for industrial raw material forest in Guangxi.Stand diameter structures approximately followed normal distribution.The skewness of diameter distribution in stand of density 2500 plant/hm^2 increased year by year.Coefficient of variation was low,which facilitated cultivation of large diameter timber.Stand accumulation of density 4500 plant/hm^2 was large,which was suitable for cultivation of short-rotation industrial plantation.