马尾松造林密度试验研究

通过对马尾松4种造林密度的定位观测分析结果表明，不同造林密度对胸径、单株村积生长的影响达到显著性差异，对树高生长影响差异不显著，不同密度林分径级分布差异明显，密度为2500株／hm2和1250株／hm2的林分，其胸径≤6cm径阶的株数占57．2％和45．9％，≥8cm径阶的株数占42．8％和54．1％；而密度为10000株／hm2和5000株／hm2的林分，其胸径≤6cm径阶的株数占89．6％和76％，≥8cm径阶的株数占10．4％和24％；不同径级林分的合理密度通过胸径与树冠面积的相关关系，用回归直线方程y=a＋bx分别求得各胸径最低保留株数，作为间伐强度、间伐开始期和间伐重复期的参考依据。

Experimental Study on the Planting Density of Pinus massoniana

The study results indicated that the effect of stand densities on dbh and individual volume wassignificant while on tree height was not significant: the difference among the diameter distribution of variousstand densities was obvious: in the stands which densities were 2500 trees/hmZ and 1250 trees/hm2. the ratioof diameter distribution≤6cm were 57. 2% and 45. 9% espesially. the ratio of diameter distribution≥8cmwere 42. 8% and 54. 1 %: while in the stands which desities were 10000 trees/hm2 and 5000 trees/hm2. theratio of diameter distribution≤6cm were 89. 6% and 76. 0%. the ratio of diameter distribution≥8cm were10. 4% and 24%espesially. The least retaining densities of various dbh were calculated by a gression eguationfor the relationship between dbh and crown area y=a+bx. as a reference basis for determining the thiningintensity. first thinning and thinning interral.