福州市米槠林分相容性胸径生长模型和树高曲线模型研究

A study on Compatible System of Diameter Growth Models and Height-diameter Curve Model for Castanopsis carlesii Forest in Fuzhou

根据福州市森林资源二类调查数据,利用非线性度量误差联立方程组方法,分别建立基于5种经验生长方程的胸径生长模型和树高曲线模型系统,以均方差(RMSE)、平均绝对偏差(MAD)、决定系数(R2)和预估精度(P)作为模型评价指标,对比5种模型的拟合效果。结果表明:5种模型的预估精度均大于90%,其中Logistic模型拟合效果最优,胸径生长过程曲线和树高曲线的模型预估精度分别为92.85%和95.15%。经配对t检验,胸径和树高的实测值与预测值之间无明显差异,拟合效果优良。数据分析显示,米槠林分胸径快速生长期滞后于树高快速生长期,均处于林分中、幼龄林时期,然后生长速度逐渐变缓。该模型可以用来描述福州市米槠林分胸径和树高的生长变化规律,在优化模型结构的同时,减少误差对预测结果的影响,并建立了胸径、树高和林龄3者之间的相容性和一致性,为米槠林分的生长预测提供参考。

According to Forest Resource Inventigation Data from Fuzhou,by using the simultaneous equations method of nonlinear error measurement,the simultaneous equations of diameter growth models and height-diameter curve of five empirical growth models were established.Root mean square error(RMSE)、mean absolute deviation(MAD)、Coefficient of determination(R2)and prediction accuracy were selected to be the model evaluation indicators for comparing the fitting effect of five models.The results showed the fitting accuracy of the five models were all greater than 90%and the Logistic model was the optimal model,the prediction accuracy of diameter-age curve and height-diameter curve were 92.85%and 95.15%respectively.After paired t-test,there was no significant difference between measured and predicted values of average DBH and average height,with fair fitting effect.Analysis data shows that the rapid growth period of DBH of Castanopsis carlesii stand lags behind the rapid growth period of tree height and they are all in the young and middle-aged forest period,then the growth rate gradually slows down.The model can be used to describe the growth law of Castanopsis carlesii forest in Fuzhou,optimize the model structure,reduce the influence of errors on the prediction results,and establish the compatibility and consistency among DBH,tree height and age of forest,which provides reference for Castanopsis carlesii forest growth prediction.