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.

Content Provider	Semantic Scholar
Author	Gorgoso-Varela, José Javier Ogana, Friday Nwabueze Ponce, Rafael
Copyright Year	2019
Abstract	Aim of study: In this study, both the direct and indirect methods by conditional maximum likelihood (CML) and moments for fitting Johnson’s S BB were evaluated. To date, Johnson’s S BB 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 S BB 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 (R 2 ), 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 R 2 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 S BB distribution. Keywords : conditional maximum likelihood; moments; two-stage method; direct method; tree volume.
Starting Page	004
Ending Page	004
Page Count	1
File Format	PDF HTM / HTML
DOI	10.5424/fs/2019281-14104
Volume Number	28
Alternate Webpage(s)	http://revistas.inia.es/index.php/fs/article/download/14104/4386
Alternate Webpage(s)	https://doi.org/10.5424/fs%2F2019281-14104
Language	English
Access Restriction	Open
Content Type	Text
Resource Type	Article