大兴安岭天然林白桦和山杨的自然整枝特征  

Characteristics of Betula platyphylla and Populus davidiana self-pruning in the natural forest of the Daxing’an Mountains

作　　者：玉宝 YU Bao(National Academy of Forestry and Grassland Administration,Beijing 102600,China)

机构地区：[1]国家林业和草原局管理干部学院,北京102600

出　　处：《森林与环境学报》2022年第5期506-513,共8页Journal of Forest and Environment

基　　金：国家科技支撑计划项目“内蒙古大兴安岭过伐林可持续经营技术研究与示范”(2012BAD22B0204)。

摘　　要：为确定天然林自然整枝的主要影响因子,分析天然林自然整枝规律,以期为森林抚育经营和促进自然整枝提供参考依据,以大兴安岭中幼龄天然林为研究对象,利用26块样地共971株白桦和61株山杨立木实测数据,以活枝下高(h)、活枝下高占树高的比例(h/H)作为自然整枝指标同林木和林分因子进行相关性分析,探讨不同结构林分自然整枝规律,通过逐步回归分析确定影响自然整枝的主要因子。结果表明,白桦和山杨平均h分别为4.8和6.5 m,平均h/H分别为46.6%和59.2%,相比之下,山杨自然整枝明显好于白桦;不同林分密度和聚集系数林分的自然整枝指标在0.01水平上差异极显著。相关性分析结果表明,胸径、树高、冠幅、平均胸径、平均树高、林分密度和聚集系数均会影响自然整枝,但各因子主要影响h;除了林木冠幅与白桦h/H呈极显著负相关(P<0.01)以外,其他因子与自然整枝指标呈极显著(P<0.01)或显著(P<0.05)正相关。林分生长越好则自然整枝越强,林分密度和聚集系数增大,能够促进自然整枝,但林分密度对自然整枝的影响与密度范围有关,林分密度超过3000株·hm时对白桦自然整枝的影响趋于减小。逐步回归分析结果表明,树高、冠幅、林分密度、聚集系数、平均树高5个因子是影响白桦和山杨自然整枝的主要因子。其中,影响白桦自然整枝的主要因子为树高、冠幅、平均树高、林分密度、聚集系数,影响山杨自然整枝的主要因子为林木树高。h较h/H能更好地表征自然整枝强度。In this study,we analyzed the pruning laws of natural forests,determined the main factors influencing natural pruning,and provided the basis for forest tending and the promotion of natural pruning.Betula platyphylla and Populus davidiana natural forests in the Daxing’an Mountains area were the subjects of the study.Data from 971 B.platyphylla and 61 Populus davidiana standing trees in 26 plots were used to determine the height under live branches and the proportion of the height under live branches to the tree height as natural pruning indicators.Correlation analysis was performed for forest tree and stand factors to explore the natural pruning laws of forest stands with different structures.Stepwise regression analysis was performed to determine the main factors that are likely to affect natural pruning.The results showed that the average differences in the height under live branches of B.platyphylla and P.davidiana natural forests were 4.8 and 6.5 m,respectively.The average proportions of the height under live branches to tree height were 46.6%and 59.2%for B.platyphylla and P.davidiana,respectively.Thus,the natural pruning of P.davidiana was clearly better than the natural pruning of B.platyphylla.The natural pruning indicators of forest stands with different densities and aggregation coefficients were significantly different(P<0.01).Based on the results of the correlation analysis,the factors affecting natural pruning included the tree diameter at breast height,tree height,tree crown width,stand average DBH,stand average tree height,stand density,and aggregation coefficient.However,each factor mainly affected the indicator of the height under live branches.Tree crown width showed a highly significant(P<0.01)negative correlation with the proportion of the height under live branches to tree height in B.platyphylla.However,the other factors showed either highly significant(P<0.01)or significant(P<0.05)positive correlations with natural pruning indicators.If the forest stand had better growth,it also had better

关 键 词：大兴安岭 白桦 山杨 自然整枝 活枝下高 天然林 

分 类 号：S750[农业科学—森林经理学]