Abstract
Brazil is a major producer in the timber sector, mainly with the use of wood from species of the genus Eucalyptus, with 26.1% of planted forests located in Minas Gerais. Researchers and manufacturers have been searching for techniques with the objective of making full use of these forests, with a primary focus on greater growth. A modeling of growth curves is an alternative for the estimation of oral production andan important aid tool for the researcher's decision making. Growth curves are commonly studied by nonlinear regression models, which have important assumptions that if not met should be added to the model. The present work aims to select among nonlinear Logistic, Gompertz and von Bertalany regression models the most suitable to describe the growth in wood volume of Eucalyptus urophylla x Eucalyptus grandis hybrids in three Forest Site categories, including whether assumption deviations are required. Methods were executed by the Gauss-Newton iterative method implemented in nls() and it gnls() functions of the R software. Determination coecient, Akaike information criterion (AICc) and Residual Standard Deviation (RSD) were used as selection evaluators of the best model. The results demonstrate that for all site categories, the Gompertz model with addition of autoregressive parameters AR (1) is the most appropriate to describe the growth in wood volume of Eucalyptus urophylla x Eucalyptus grandis hybrids. The addition of the rst-order autoregressive parameter does not aect the quality of t, but it is the correct procedure. Site I, which presents the largest trees according to pre-dened variations, recorded 308 m3/ha of wood volume, followed by 286 m3/ha and 263 m3/ha for Sites II and III, respectively. The time for Site III to reach the maximum point of volume growth is between the fourth and sixth year, while the other sites are more precocious, reaching this point between the second and third year.
Highlights
Planted wood of the genus Eucalyptus has great potential due to its availability in a short period of time and use in the production of raw material for cellulose, charcoal and poles
The aim of the present work was to select among the nonlinear regression models Logistic, Gompertz and von Bertalanffy, the most adequate to describe the growth in wood volume of Eucalyptus urophylla x Eucalyptus grandis hybrids in three site classifications, considering assumption deviations if necessary
Pereira et al (2016), considering the residual autocorrelation with the addition of the first-order autoregressive parameter AR (1), obtained the lowest values in all densities and irrigation regimes analyzed for the height growth of coffee plants
Summary
Planted wood of the genus Eucalyptus has great potential due to its availability in a short period of time and use in the production of raw material for cellulose, charcoal and poles. According to data from IBGE (2018), Brazil has around 9.9 million hectares of planted forests, of which 7.5 million are eucalyptus, with the southeastern region being responsible for 42.3% of the total planted area in Brazil, mainly in the states of Minas Gerais (26.1%) and Sao Paulo (12.2%). For maximum use of these hectares, researchers have been looking for more efficient ways to use the forest, mainly in the breeding of trees and forest management. In a forestry company, production planning is essential and, in this context, forest growth and production modeling is a tool that assists researchers in making decisions. Other strategies to assist growth are better management of fertilizers, the use of high-quality seedlings and the control of weeds, pests and diseases (ELLI et al, 2019)
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