大兴安岭落叶松不同采伐强度的最优树高曲线模型1）

在大兴安岭落叶松林选择18块采伐强度不同的样地，以10种常用的树高曲线模型作为候选模型，比较同一树高曲线、不同采伐强度时，获得的决定系数（ R2）；比较同一采伐强度、不同树高曲线时，获得的R2。结果表明：两种情况获得的R2的极差均较大；前一种情况获得的R2的离散性（ R2的标准差都在0．17左右），较后一种情况获得的R2的离散性（ R2的标准差大多在0．05以下，仅有一种情况为0．148）大；证明采伐强度，是影响树高曲线模型选择的重要因素。以R2、残差平方和、均方差作为模型优劣的评价指标，对18块样地的10个树高曲线候选模型进行了对比：采伐强度低于15％时，大兴安岭落叶松的树高曲线模型宜选用Richard（1959）模型；采伐强度为15％～40％时，宜选用Logistic模型；采伐强度为40％及以上时，宜选用Weibull（1978）模型。

Optimal Tree Height Curve Model of Larch in Daxing’ an Mountains under Different Logging Intensity

We selected 18 plots under different logging intensity with 10 kinds of commonly used tree height curve model as a candidate model to compare R2 from the same tree height curve and different logging intensity, and R2 from the same cut-ting intensity and different tree height curve.Two case of R2 were larger, and the discreteness of R2 from the former case was larger than the latter with the standard deviation of the former of 0.17, standard deviation of the latter of below 0.05 ex-cept one case of 0.148.The logging intensity is an important factor to select the tree height curve model.We compared 10 tree high curve candidate models in 18 pieces different samples with R2 , SSE, RMSE as evaluation indexes to judge the models.Larch tree height curve model in Daxing’an Mountains should be built by Richard (1959) model when the logging intensity is lower than 15%, by Logistic model when the logging intensity is 15%-40%, and by Weibull ( 1978) model when the logging intensity is 40%or more.