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    Abstract
2014 (Vol. 6, Issue: 4)
Article Information:

Height-diameter Models of Chinese Fir (Cunninghamia lanceolata) Based on Nonlinear Mixed Effects Models in Southeast China

Hao Xu, Yujun Sun, Xinjie Wang and Ying Li
Corresponding Author:  Yujun Sun 

Key words:  Cunninghamia lanceolata, height-diameter models, heteroscedasticity, nonlinear mixed effects models, , ,
Vol. 6 , (4): 445-452
Submitted Accepted Published
November 04, 2013 November 13, 2013 April 10, 2014
Abstract:

Tree height and diameter at breast height are two important forest factors. The best model from 23 height-diameter equations was selected as the basic model to fit the height-diameter relationships of Chinese fir with one level (sites or plots effects) and nested two levels (nested effects of sites and plots) Nonlinear Mixed Effects (NLME) models. The best model was chosen by smaller Bias, RMSE and larger Radj2. Then the best random-effects combinations for the NLME models were determined by AIC, BIC and -2LL. The results showed that the basic model with three random effects parameters &Phi &Phi &Phi1 &Phi2 and &Phi3 was considered the best mixed model. The nested two levels NLME model considering heteroscedasticity structure (power function) possessed with higher predictable accuracy and significantly improved model performance (LRT = 469.43, p<0.0001). The NLME model would be allowed for estimating accuracy the height-diameter relationships of Chinese fir and provided better height predictions than the models using only fixed-effects parameters.
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  Cite this Reference:
Hao Xu, Yujun Sun, Xinjie Wang and Ying Li, 2014. Height-diameter Models of Chinese Fir (Cunninghamia lanceolata) Based on Nonlinear Mixed Effects Models in Southeast China.  Advance Journal of Food Science and Technology, 6(4): 445-452.
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ISSN (Online):  2042-4876
ISSN (Print):   2042-4868
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