林业科学2016，Vol.52Issue(2)：17-25,9.DOI:10.11707/j.1001-7488.20160203
大兴安岭不同区域兴安落叶松可变指数削度方程
Variable-Exponent Taper Models for Dahurian Larch in Different Regions of Daxing’anling
摘要
Abstract
Objective]The aim of this study was to develop taper functions of dahurian larch( Larix gmelinii) based on widely used variable-exponent taper models developed by Kozak(1988),Kozak(1994),Kozak(2001)and Kozak(2002), and the significances of different regions were also tested. [Method]Stem taper data of dahurian larch was collected from three regions of Daxing ’anling. SUR method in SAS software was used to fit the four taper equations. Coefficient determination( R2adj ) ,mean absolute bias( MAB) ,root mean square error( RMSE) ,mean percentage of bias( MPB) and prediction accuracy(P%)were employed to evaluate the precision of different models combining multicollinearity (CN) and graph of the residuals. The non-linear extra sum of squares method was used for regional comparison. The method required the fitting of full model and reduced model. [Result]1 ) Variable-exponent taper models developed by Kozak (1988)and Kozak(1994) were better based on goodness of fit statistics and prediction precision,but they had high multicollinearity. The other models decreased multicollinearity and improved prediction precision of upper stem diameters. 2 ) F-test of regional comparison showed that stem taper in region 3 had large differences with region 1 and region 2 . Stem taper in region 1 had small difference with region 2. Any two regional test showed significant difference(P<0. 000 1). It was indicated that any two regions could not use the same parameter estimates and separated parameter estimates were necessary. 3)Through the stem taper curve simulations in three regions,it could be seen that the same model showed the different taper curve simulations in three regions,especially the taper curves of model 3 showed significant difference in three regions. The taper curve simulations of other models showed small differences with region 1 and region 2,and significant difference was found for region 3. The results of simulations were consistent with the results from F-test. Different region had a significant effect on tree stem curve. Incorrectly application of taper models in different regions would result in larger prediction error.[Conclusion]Taper model developed by Kozak ( 2002 ) showed the consistent performance on fitting statistics,residual distribution,and multicollinearity. The prediction precision was more than 99%,and could be selected as the best taper equation for the three regions of Daxing’anling.关键词
可变指数削度方程/多重共线性/哑变量/非线性回归Key words
variable-exponent taper models/multicollinearity/dummy variables/nonlinear regression分类
农业科技引用本文复制引用
姜立春,马英莉,李耀翔..大兴安岭不同区域兴安落叶松可变指数削度方程[J].林业科学,2016,52(2):17-25,9.基金项目
十二五国家科技支撑计划项目(2012BAD22B0202) （2012BAD22B0202）
国家自然科学基金项目(31170591，31570624)。 （31170591，31570624）
