Evaluation of direct and indirect methods for modelling the joint distribution of tree diameter and height data with the bivariate Johnson’s SBB function to forest stands

Forest Systems

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Title Evaluation of direct and indirect methods for modelling the joint distribution of tree diameter and height data with the bivariate Johnson’s SBB function to forest stands
Creator Gorgoso-Varela, Jose Javier
Ogana, Friday Nwabueze
Alonso Ponce, Rafael
Description Aim of study: In this study, both the direct and indirect methods by conditional maximum likelihood (CML) and moments for fitting Johnson’s SBB were evaluated. To date, Johnson’s SBB has been fitted by either indirect (two-stage) method using well-known procedures for the marginal diameter and heights, or direct methods, where all parameters are estimated at once. Application of bivariate Johnson’s SBB for predicting height and improving volume estimation requires a suitable fitting method.Area of study: E. globulus, P. pinaster and P. radiata stands in northwest Spain.Material and methods: The data set comprised of 308, 184 and 96 permanent sample plots (PSPs) from the aforementioned species. The suitability of the method was evaluated based on height and volume prediction. Indices including coefficient of determination (R2), root mean square Error (RMSE), model efficiency (MEF), Bayesian Information Criterion (BIC) and Hannan-Quinn Criterion (HQC) were used to assess the model predictions. Significant difference between observed and predicted tree height and volumes were tested using paired sample t-test at 5% level for each plot by species.Main results: The indirect method by CML was the most suitable method for height and volume prediction in the three species. The R2 and RMSE for height prediction ranged from 0.994 – 0.820 and 1.454 – 1.676, respectively. The percentage of plot in which the observed and predicted heights were significant was 0.32%. The direct method was the least performed method especially for height prediction in E. globulus.Research highlights: The indirect (two-stage) method, especially by conditional maximum likelihood, was the most suitable method for the bivariate Johnson’s SBB distribution.Keywords: conditional maximum likelihood; moments; two-stage method; direct method; tree volume.
Publisher INIA
Contributor Government of Spain, Department of Economy, Industry and Competitiveness, Gobierno del Principado de Asturias, Ministerio de Ciencia e Innovación, Ministry of Science and Innovation of Spain
Date 2019-06-07
Type info:eu-repo/semantics/article
Format application/pdf
Identifier http://revistas.inia.es/index.php/fs/article/view/14104
Source Forest Systems; Vol 28, No 1 (2019); e004
Forest Systems; Vol 28, No 1 (2019); e004
Language eng
Relation http://revistas.inia.es/index.php/fs/article/view/14104/4386
Rights info:eu-repo/semantics/openAccess
Copyright (c) 2019 Forest Systems

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