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杉木和马尾松木村密度变异的研究表明,自髓心向外基本上呈增大的趋势,自基部向上基本上呈减小的趋势,但两个树种的变异形式有所不同(图1、2);不存在一定的南、北向差异;苯醇抽提和未抽提的木材密度有显著的相关性;多数两阶段抽样样本的试件项方差分量大于样木项方差分量,说明株内变异较大,二阶抽样单元数对样本精确度有相当影响。采用木材蓄积量为权数,估算了木材密度的树种平均数X_ω(g/cm~3)及其标准差Sx_ω杉木为0.374、0.002,马尾松为0.542、0.003。
The study on the density variation of Chinese fir and Masson pine showed that the trend was basically the same from the medullary to the upward, but the variations of the two species were different ); There is no certain difference between south and north direction; there is a significant correlation between benzene extract and non-extracted wood density; the variance component of sample item in most two-stage sampling samples is larger than the variance component of sample wood, Larger, second-order sampling units have a considerable impact on sample accuracy. The average wood species density X_ω (g / cm ~ 3) and its standard deviation Sx_ω fir were 0.374,0.002 and 0.542,0.003, respectively.