A Nonlinear Mixed-Effects Height-Diameter Model with Interaction Effects of Stand Density and Site Index for <i>Larix olgensis</i> in Northeast China

Tree height is a basic input variable in various forest models, such as growth and yield models, biomass models, and carbon budget models, which serve as very important tools for the informed decision-making in forestry. The height-diameter model is the most important component of the growth and yie...

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Autores principales:	Xiaofang Zhang, Liyong Fu, Ram P. Sharma, Xiao He, Huiru Zhang, Linyan Feng, Zeyu Zhou
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	stand density effect site index effect height-diameter allometry height prediction accuracy basic versatile function Plant ecology QK900-989
Acceso en línea:	https://doaj.org/article/c39ce2beaf694478ba1fc453f31e98b1
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spelling	oai:doaj.org-article:c39ce2beaf694478ba1fc453f31e98b12021-11-25T17:37:30ZA Nonlinear Mixed-Effects Height-Diameter Model with Interaction Effects of Stand Density and Site Index for <i>Larix olgensis</i> in Northeast China10.3390/f121114601999-4907https://doaj.org/article/c39ce2beaf694478ba1fc453f31e98b12021-10-01T00:00:00Zhttps://www.mdpi.com/1999-4907/12/11/1460https://doaj.org/toc/1999-4907Tree height is a basic input variable in various forest models, such as growth and yield models, biomass models, and carbon budget models, which serve as very important tools for the informed decision-making in forestry. The height-diameter model is the most important component of the growth and yield models and forest simulators. We developed the nonlinear mixed-effects height-diameter model with the interaction effects of stand density and site index introduced using data from 765 <i>Larix olgensis</i> trees in Jingouling forest farm of the Wangqing Forest Bureau in northeast China. Among the various basic versatile functions evaluated, a simple exponential growth function fitted the data adequately well, and this was then expanded through the introduction of the variables describing the interaction effects of the stand density and site index on the height-diameter relationship. Sample plot-level random effects were included into this model through mixed-effects modeling. The results showed that the random effect of the stand density on the height-diameter relationship was substantially different at different classes of the site index, and the random effect of the site index was different for the different stand density classes. The nonlinear mixed-effects (NLME) height-diameter model coping with the interaction effects of the stand density and site index had a better performance than those of the NLME models with the random effect of the single variable of stand density or site index. To conclude, the inclusion of the interaction effects of stand density and site index could significantly improve the prediction accuracy of the height-diameter model for <i>Larix olgensis</i> Henry. The proposed model with the interactive random effects included can be applied for the accurate prediction of <i>Larix olgensis</i> tree height in northeast China.Xiaofang ZhangLiyong FuRam P. SharmaXiao HeHuiru ZhangLinyan FengZeyu ZhouMDPI AGarticlestand density effectsite index effectheight-diameter allometryheight prediction accuracybasic versatile functionPlant ecologyQK900-989ENForests, Vol 12, Iss 1460, p 1460 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	stand density effect site index effect height-diameter allometry height prediction accuracy basic versatile function Plant ecology QK900-989
spellingShingle	stand density effect site index effect height-diameter allometry height prediction accuracy basic versatile function Plant ecology QK900-989 Xiaofang Zhang Liyong Fu Ram P. Sharma Xiao He Huiru Zhang Linyan Feng Zeyu Zhou A Nonlinear Mixed-Effects Height-Diameter Model with Interaction Effects of Stand Density and Site Index for <i>Larix olgensis</i> in Northeast China
description	Tree height is a basic input variable in various forest models, such as growth and yield models, biomass models, and carbon budget models, which serve as very important tools for the informed decision-making in forestry. The height-diameter model is the most important component of the growth and yield models and forest simulators. We developed the nonlinear mixed-effects height-diameter model with the interaction effects of stand density and site index introduced using data from 765 <i>Larix olgensis</i> trees in Jingouling forest farm of the Wangqing Forest Bureau in northeast China. Among the various basic versatile functions evaluated, a simple exponential growth function fitted the data adequately well, and this was then expanded through the introduction of the variables describing the interaction effects of the stand density and site index on the height-diameter relationship. Sample plot-level random effects were included into this model through mixed-effects modeling. The results showed that the random effect of the stand density on the height-diameter relationship was substantially different at different classes of the site index, and the random effect of the site index was different for the different stand density classes. The nonlinear mixed-effects (NLME) height-diameter model coping with the interaction effects of the stand density and site index had a better performance than those of the NLME models with the random effect of the single variable of stand density or site index. To conclude, the inclusion of the interaction effects of stand density and site index could significantly improve the prediction accuracy of the height-diameter model for <i>Larix olgensis</i> Henry. The proposed model with the interactive random effects included can be applied for the accurate prediction of <i>Larix olgensis</i> tree height in northeast China.
format	article
author	Xiaofang Zhang Liyong Fu Ram P. Sharma Xiao He Huiru Zhang Linyan Feng Zeyu Zhou
author_facet	Xiaofang Zhang Liyong Fu Ram P. Sharma Xiao He Huiru Zhang Linyan Feng Zeyu Zhou
author_sort	Xiaofang Zhang
title	A Nonlinear Mixed-Effects Height-Diameter Model with Interaction Effects of Stand Density and Site Index for <i>Larix olgensis</i> in Northeast China
title_short	A Nonlinear Mixed-Effects Height-Diameter Model with Interaction Effects of Stand Density and Site Index for <i>Larix olgensis</i> in Northeast China
title_full	A Nonlinear Mixed-Effects Height-Diameter Model with Interaction Effects of Stand Density and Site Index for <i>Larix olgensis</i> in Northeast China
title_fullStr	A Nonlinear Mixed-Effects Height-Diameter Model with Interaction Effects of Stand Density and Site Index for <i>Larix olgensis</i> in Northeast China
title_full_unstemmed	A Nonlinear Mixed-Effects Height-Diameter Model with Interaction Effects of Stand Density and Site Index for <i>Larix olgensis</i> in Northeast China
title_sort	nonlinear mixed-effects height-diameter model with interaction effects of stand density and site index for <i>larix olgensis</i> in northeast china
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/c39ce2beaf694478ba1fc453f31e98b1
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A Nonlinear Mixed-Effects Height-Diameter Model with Interaction Effects of Stand Density and Site Index for <i>Larix olgensis</i> in Northeast China

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