Are models of volumetric production at the diametric distribution and total stand level mutually compatible?
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ORIGINAL PAPER
Are models of volumetric production at the diametric distribution and total stand level mutually compatible? Marcos Felipe de Oliveira Valeriano1 • Eder Pereira Miguel1 • Pedro Guilherme de Andrade Vasconcelos1 • Mauro Eloi Nappo1 • Humberto Angelo1 • Alba Vale´ria Rezende1 • Renan Augusto Miranda Matias1 Leonardo Job Biali1 • Ilvan Medeiros Lustosa Junior2
•
Received: 14 August 2018 / Accepted: 11 October 2018 Northeast Forestry University 2018
Abstract The objective of this work was to compare estimates generated by a diametric distribution model and a total stand model against the pre-cut inventory. The model efficiency was also evaluated. Data were evaluated from 30 permanent sample plots in a Eucalyptus urophylla stand, comprising 24 sample plots used for model fitting, and six sample plots for validation. The volume of wood per hectare was estimated for different productive units (sites), using 7 years as the reference age. The model adjustment quality was verified by adjustment and precision statistics: the correlation between observed and predicted variables, root mean square error percentage, graphical analysis of residual distribution, and a frequency histogram for classes of relative errors and validation. Although the two-parameter Weibull probability density function adhered to the data for tree evolution in diameter classes for the reference age (7 years) in the different productivity classes, it generated imprecise estimates of the number of individuals. Consequently, it produced inaccurate volumetric production estimates. The total stand model provided reliable projections of production volumes in different productivity
Project funding: The work was supported by the University of Brasilia and the National Council for Scientific and Technological Development (CNPq). The online version is available at http://www.springerlink.com Corresponding editor: Tao Xu. & Pedro Guilherme de Andrade Vasconcelos [email protected] 1
Department of Forestry Engineering, University of Brasilia (UnB), Brası´lia, Brazil
2
Federal Institute of Brası´lia (IFB), Brası´lia, Brazil
classes for both adjustment types, showing compatibility with the pre-cut inventory according to a Tukey test. In summary, the total stand model generated estimates that were compatible with the pre-cut inventory while the diametric distribution model did not. Keywords Clutter model Diameter class Eucalyptus Prognosis
Introduction The great economic and commercial relevance of eucalyptus plantations has led to their worldwide recognition (Eldridge et al. 1994; Nakhooda et al. 2014), with the Brazilian planted forest sector becoming one of the most globally relevant. It encompasses an area of 7.84 million hectares of planted trees and is responsible for 91% of wood produced for industrial purposes in the country. It also has great potential for contributing to building a green economy by meeting demand and preserving resources (Carrijo et al. 2017; Iba´ 2017). To optimize use of these forests, it is importa
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