不同立地条件与造林密度对苦楝枝下高生长效应的影响

Effects of Different Site Conditions and Afforestation Density on Growth Effect of Melia azedarach Height under Branch

摘要: 采用双因素随机区组试验设计方法，在寿宁县南阳镇境内选择立地条件中等以上的林地，进行苦楝造林试验。通过对6年生苦楝人工林的胸径、树高、枝下高等因子生长状况调查结果表明：造林密度对胸径有显著影响(FA = 6.84 > F0.05 = 3.84)；立地条件对胸径有极显著影响(FB = 10.22 > F0.01 = 8.65)，对树高生长有显著影响(FB = 8.57 > F0.05 = 4.46)，对枝下高生长有极显著影响(FB = 9.89 > F0.01 = 8.65)；幼龄期是苦楝树高生长的关键时期，苦楝幼龄期树高生长快慢是影响其枝下高高低的关键因素，选择立地条件好的林地造林，是促进苦楝幼树生长，增加枝下高，提高规格材出材量的有效方法之一。

Abstract: Adopting the method of two-factor random block experiment design, the afforestation experiment of Melia azedarach was carried out in Nanyang Town, Shouning County. The growth status of six-year-old Melia azedarach plantation in DBH, tree height and height under branches was investigated: Afforestation density has a significant effect on DBH (FA = 6.84 > F0.05 = 3.84); site conditions have a very significant impact on DBH (FB = 10.22 > F0.01 = 8.65), tree height (FB = 8.57 > F0.05 = 4.46) and height under branches (FB = 9.89 > F0.01 = 8.65). Young age is the key period for height growth of Melia azedarach. The growth rate of height in young age is the key factor affecting its height under branches. Therefore, selecting the forest land with good site conditions is one of the effective ways to promote the growth of young Melia azedarach trees, increase its height under branches and the output of standard timber.