林业科学2018，Vol.54Issue(2)：90-97,8.DOI:10.11707/j.1001-7488.20180210
异速生长模型的误差结构和误差函数
Error Structure and Variance Function of Allomatric Model
摘要
Abstract
[Objective] Based on allometric model,individual tree volume model was developed for Larix gmelinii and Pinus sylvestris var.mongolica in Daxing'anling.Error structure and variance function were studied.[Method] Ballantyne(2013)provides the method how to test the error structure by likelihood analysis.For comparison,nonlinear model was fitted using GNLS in S-PLUS.Variance functions (fixed variance,exponential function,power function and constant plus power function) were incorporated into general nonlinear model to reduce heteroscedasticity.Coefficient determination (R2),root mean square error (RMSE),mean absolute bias (Bias),and mean relative error (MRE),were employed to evaluate the precision of different individual volume models.[Result] 1) Through likelihood analysis,error structure of individual tree volume model is multiplicative,therefore,linear regression on the log-transformed data is suitable for individual tree volume model.2) In order to describe the variance phenomenon in the process of individual tree volume model,variance functions (fixed variance,exponential function,power function and constant plus power function) were incorporated into volume model,and all variance functions could reduce heteroscedasticity,power function and constant plus power function are best for Larix gmelinii and Pinus sylvestris var.mongolica respectively.3) Model fitting and validation indicated that the result were pretty similar for both error structures of this two species,however,volume model with additive error structure is slightly better than multiplicative error structure.[Conclusion] Error structures of individual tree volume model are multiplicative for this two species.However,through the comparison of model fitting and validation,nonlinear regression is better than linear regression on the log-transformed data.This study did not give an absolute and consistent conclusion from comparison.If model prediction is the first,error structure should be selected based on prediction precision.In summary,additive error structure was favored for individual tree volume model of Larix gmelinii and Pinus sylvestris var.mongolica.关键词
兴安落叶松/樟子松/立木材积/误差结构/误差方差函数Key words
Larix gmelinii/Pinus sylvestris var/mongolica/individual tree volume/error structure/variance function分类
农业科技引用本文复制引用
马岩岩,姜立春..异速生长模型的误差结构和误差函数[J].林业科学,2018,54(2):90-97,8.基金项目
“十三五”国家重点研发计划资助项目(2017YFB0502700) （2017YFB0502700）
国家自然科学基金项目(31570624). （31570624）
