红松杈干类型与林分密度、个体生长指标及丰年株均结实量的关系

Relationships between multi-stem type and stand density,tree growth index and mast year cone yield in Pinus koraiensis plantation

选取4种密度的红松人工林,设置15块25 m×40 m的临时样地,采用单因素Logistic回归分析和Meta分析方法定量分析了不同杈干类型与红松林分密度、树高、胸径、冠幅及丰年结实量的关系。结果表明:杈干率随着密度的增大呈现降低趋势,与密度600株·hm^(-2)相比,密度750、900和1200株·hm-2的杈干发生概率分别降低了24%、51%和59%;3种杈干类型中以双杈为主,样地内双杈类型株数占杈干总株数的60%以上;杈干对红松各项生长指标和丰年结实量均有显著影响(P≤0.05),杈干木的平均树高、胸径、冠幅和丰年单株球果产量与未杈干木相比分别增加了2.12%、4.69%、4.89%和29.57%;不同杈干类型对红松树高、胸径和结实的影响规律不同,单杈类型对红松生长和结实指标影响不显著(P>0.05),其平均树高、胸径、冠幅、丰年单株结实量分别比未杈干类型增加了1.49%、1.99%、1.47%和20.64%;双杈和多杈干类型的各指标与未杈干类型相比有显著差异(P≤0.05),其平均树高、胸径、冠幅及丰年单株球果产量比未杈干木分别增加了2.07%和2.90%,6.00%和6.09%,6.29%和5.99%,及34.61%和26.22%。Logistic回归模型和Meta分析结果证明,红松杈干木对生长结实的促进效应明显,其中双杈和多杈干类型的促进效应表现明显,单杈木的杈干效应不明显,40 a左右的红松人工林杈干效应在林分密度600~750株·hm^(-2)是最佳的。

A study was carried out to assess the influence of multi-stem phenomenon on cumulative volume and cone yield in 40-year-old Pinus koraiensis plantations. Four stand density levels （600, 750, 900 and 1200 trees·hm-2） were sampled （15 plots in 25 m×40 m） to determine the relationships between stem types （single stem, two branching stems, and three or more branching stems） and stand density, tree height, diameter at breast height （DBH）, crown diameter, mast year cone yield using one variable Logistic model and Meta analysis. The frequency of multistemmed trees decreased as the stand density increased. The frequencies in the stands of 750, 900, 1200 trees·hm-2 were reduced by 24%, 51% and 59%, respectively compared with that in the stand of 600 trees·hm-2. The frequency of double multi-stemmed type that exceeded 60% was the highest among the three multistemmed types. The multistem phenomenon had significantly promoting effect on DBH, tree height, crown diameter and cone number per tree by increasing 2.12%, 4.69%, 4.89% and 29.57%, respectively, compared with non multistemmed trees. The multistemmed types had different effects on cone production and tree height, DBH and crown diameter. The DBH, tree height, crown diameter and cone number per tree of single multistemmed trees were 1.49%, 1.99%, 1.47% and 20.64% higher than those of non multistemmed trees, respectively, but there were no significant differences. The doublestemmed and multiplestemmed trees had significant positive effect on cone production and stand growth indexes. The tree height of doublestemmed tree and multiplestemmed trees were increased by 2.07% and 2.90%, respectively; the DBH increased by 6.00% and 6.09% respectively; the crown diameters increased by 6.29% and 5.99%, respectively; the cone number per tree increased by 34.61% and 26.22%, respectively. In conclusion, the results of Logistic regression and Meta analysis suggested that the multistemmed trees had evident promotion effect on cone production, in which multiplestemmed trees and doublestemmed trees had more significant effect on tree growth and cone production. The multistem effects decreased with the increasing stand density. The highest multistemmed effect was observed in 40-year-old Korean pine plantation with the stand density of 600-750 trees·hm-2.