柚木冠幅与树高、胸径的回归分析

为考察柚木生长因子与冠幅的关系,准确反映各生长因子与冠幅之间的关系,建立冠幅预测模型,为柚木人工林目标树经营提供理论依据。以广西凭祥、云南德宏、云南景洪、海南乐东4个地区不同林龄阶段的柚木人工林中优势木为研究对象,以胸径、树高、冠长、林龄4个因子作为变量与冠幅进行回归分析,筛选关键因子建立柚木冠幅生长的预测模型。结果表明,胸径(R=0.5342,P=0.0001)、树高(R=0.1798,P=0.0026)是影响柚木冠幅的关键因子;胸径、树高与冠幅的一元回归方程:冠幅与胸径y=15.7893x+1.84766(F=516.4180,P=0.0001),冠幅与树高y=0.3717x-0.60189(F=174.2954,P=0.0001)。并应用胸径、树高2个关键因子与冠幅建立回归模型:y=13.5658x1+0.1064x2+0.35866(F=279.5048,P=0.0001),计算结果与实际测量结果差异性较小(F=0.0140,P=0.9072)。可以根据目标树的培育目标胸径、树高因子,利用该模型来预测该目标树的冠幅,从而确定单位面积内保留目标树的数量。

Regression Analysis of Teak Crown Growth with Tree Height and DBH

In order to investigate the relationship between teak growth factors and crown width,the crown growth prediction model was established to provide a theoretical basis for teak plantation target tree management.Taking the dominant trees in the teak plantations with different forest ages in Pingxiang of Guangxi,Dehong of Yunnan,Jinghong of Yunnan and Ledong of Hainan as the research objects,the four factors,including diameter at breast height (DBH),tree height,crown length and forest age were used as variables and regression analysis was performed with the crown width,to select the key factors and establish a predictive model for teak crown growth.The results showed that the DBH ( R =0.534 2, P =0.000 1) and tree height ( R =0.179 8, P =0.002 6) were the key factors affecting the crown width of teak.The one-dimensional regression equations for the DBH,tree height with crown width were established:crown width with the DBH y =15.789 3 x +1.847 66 ( F =516.418 0, P =0.000 1),crown width with tree height y = 0.371 7 x - 0.601 89 ( F =174.295 4, P =0.000 1).The regression model was established by applying two key factors of DBH and tree height with crown width: y =13.565 8 x 1 +0.106 4 x 2 +0.358 66 ( F = 279.504 8, P =0.000 1),and the difference between the calculation result and the actual measurement result was small ( F =0.014 0, P =0.907 2).The model could be used to predict the crown width of the target tree according to the DBH and tree height,thereby determining the number of target trees retained per unit area.