经营密度对华北落叶松人工林生长的影响

Effects of forest density on Larix principis-rupprechtii plantation

林木密度管理是培育大径级林木的关键。以小五台山林区林龄35 a和50 a华北落叶松人工林为研究案例,采用固定样地连续观测法,调查分析了不同经营密度4 a间对林分生长的影响。结果表明:密度越小越有利于促进林木的个体发育,其中对胸径生长的促进作用较树高明显。在本区中上水平立地条件下,35年生林分的适宜经营密度约720株/hm^2;50年生林分适宜的经营密度为557~615株/hm^2,林分蓄积生长量约10 m^3·hm^(-2)a^(-1),蓄积生长率4.3%,但出材仍以中、小径材为主,生产上需要适当延长主伐期。

Forest density management is key factor to cultivate large diameter trees. According to 35-year-old and 50-year-old Larix principis-rupprechtii plantation in Xiaowutai mountain, the stand growth during 2011-2015 were researched which of different trees density in permanent sample plot. It showed that small density is beneficial to the tree growth, Especially significant on growth of diameter at the breast height. In Xiaowutai mountain, 720 trees/hm-2 is the suitable density for 35 a Larix principis-rupprechtii plantation of middle and superior site condition. The suitable density is 557 to 615 trees/hm-2 for 50 a Larix principis-rupprechtii plantation, the stand volume growth is 10 m-3/hm-（-2）·a-（-1）,and the volume growth rate is 4.3% , but the middle and small diameter log is major, the large diameter log is scare. Therefore, the age of harvest cutting should appropriate extended.