近自然经营干扰树伐除前后林分结构对比分析

Comparative Analysis of Stand Structure Before and After Interference Tree Thinning of Forest Close-to-Nature Management

为探究近自然经营干扰树伐除对林分结构的影响,以浙江省宁波市次生林及人工林开展近自然经营的7个样地为研究对象,分析森林近自然经营干扰树伐除前后林木径级和高度级结构、空间分布、目标树邻体指数以及多样性指数的变化。结果表明:近自然经营中,目标树和干扰树主要来自森林主林层;森林径级和高度级结构包括逆J型和单峰型2类,伐除的干扰树主要为胸径大于15 cm和高度大于10 m的个体;干扰树伐除后,个体空间分布聚集的样地趋向随机,目标树邻体指数在大部分尺度上显著降低(P<0.05);干扰树的伐除对森林的物种多样性没有显著影响。说明近自然森林经营干扰木的伐除优化了林分结构,能够减弱目标树邻体竞争且对森林的物种多样性无显著影响,林下光环境的改善未来将促进森林天然更新,从而改善林分质量,引导森林正向变化。

In this study,we aimed to evaluate the change of stand structure before and after forest close-to-nature management.Seven forest plots including secondary and artificial forest were set in Ningbo,Zhejiang Province.The change of size and height class,spatial distribution,neighborhood index of the future-crop-tree and species diwersity of each plot were analyzed.The results were as follows:the future-crop-trees and the interference trees are mainly in the dominant forest layer.Size and height class of forest can divide into two type,"Inverse-J type" and "Unimodal type",and majority interference trees are belong to large size and height class(DBH>15 cm and/or Height>10 m).After thinning,the spatial distribution of forest individuals tends to be random from aggregation,and the neighborhood index of the future-crop-tree is significantly reduced(P<0.05) at most of scale.Interference tree thinning do not significantly change the species diversity of forests;forest close-to-nature management can reduce stand competition,increase future-crop-trees growth and forest regeneration,and therefore improve stand quality and accelerate forest forward succession,and should be expanded.