采用二元广义β分布(GBD-2)和Johnson's SBB分布对美国东北部云冷杉林的水平和垂直分布进行拟合.拟合优度检验结果表明:无论是胸径、树高边缘分布和联合分布,还是树高和材积的预估,GBD-2分布的拟合效果均比SBB分布要好.使用常用的林分变量如林分密度、公顷断面积、林分平均胸径、平均树高、平均冠幅和冠长建立回归模型对GBD-2分布的参数进行估计,表明未来林分水平和垂直结构可以由这些变量进行预测.所建立的二元分布模型可以为研究树木胸径、树高的实际关系和动态提供信息.%The horizontal and vertical structures of the spruce-fir stands in the northeast,USA were modeled by the bivariate generalized beta distribution (GBD-2) and Johnson's SBB distribution.The goodness-of-fit tests indicated that GBD-2 performed better than did Johnson's SBB in fitting both marginal and joint distributions of tree diameter and height,and in predicting tree height and volume.Regression models were developed for predicting the parameters of the GBD-2distributions using ordinary stand variables as predictors,such as stand density,basal area,mean tree diameter,mean tree height,and mean crown length and width.Thus,the future stand horizontal and vertical structures can be predicted when the future values of these stand variables were available.The bivariate distribution models developed in this study will provide useful information on the realistic relationships and dynamics of tree diameter and height.
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