摘要
以杉木为例,探讨了基于导向曲线的Richards多形地位指数模型的研建新方法——参数置换法。研究发现:利用差分方程途径可以直接推导出全新的Richards多形地位指数模型。该模型在标准年龄较低(T=4 a)时能对优势高生长进行正确预估,并且其参数值与导向曲线的模型参数拟合结果非常接近。研究还进一步从绝对平均误差(MAE)、相对平均误差(MRE)、均方根误差(RMSE)、决定系数(R2)和修正决定系数(R2adj)等5个方面对导向曲线参数值替代非同形曲线的模型参数值的有效性进行了分析。结果表明:替代与否各指标间几乎无差异,亦即用导向曲线参数值直接替代非同形曲线的模型参数值是可行的。这一研究结果为在事先无地位指数表的情况下利用临时样地的年龄-树高调查数据或间隔数据进行立地质量评价提供了可能,还为直接通过导向曲线实现多形地位指数建模提供了方法。
A new method for establishing Richards polymorphic site index model was developed.And the Cunninghamia lanceolata was taken as an example.Data from stem analysis of 164 trees were used.It shows that the Richards polymorphic site index model can be directly derived by using the difference equation.This model has no systematic error when the base-age（T） is relatively low（T=4）,therefore,be selected as the final model,and its parameter values are close to the parameter values of the guide curve.So parameters of this model were replaced by the parameters of guide curve.The five indicators： mean absolute error（MAE）,mean relative error（MRE）,root mean squared error（RMSE）,coefficient of determination（R2） and adjusted coefficient of determination（R2adj） were selected to analysis the validity of this parameters replacement.The results showed that they were almost identical among the various indicators before and after replacement.Hence,the method for using the parameters of guide curve to directly replace the parameters of polymorphic curve model is feasible.This result provides a possibility for the site quality evaluation by using the investigation data of age-height about temporary sample plot or interval data without site index table in advance.And it also provides a method for establishing polymorphic site index model directly through the guide curve.
出处
《林业科学研究》
CSCD
北大核心
2010年第4期481-486,共6页
Forest Research
基金
“十一五”林业科技支撑课题(2006BAD03A0803)
