Deformação Residual Longitudinal de Clones de Eucalyptus em Local Sujeito a Ventos

Abstract

RESUMODurante o desenvolvimento das árvores, esforços mecânicos são gerados com o intuito de mantê-la em equilíbrio e ereta em resposta a diversos fatores ambientais. Estes esforços são conhecidos como tensões de crescimento e variam na sua distribuição e intensidade nas diferentes espécies do gênero Eucalyptus. Portanto, objetivou-se avaliar a deformação residual longitudinal (DRL) e sua relação com as características de crescimento da árvore, propriedade física e mecânica da madeira de clones do híbrido Eucalyptus urophylla × Eucalyptus grandis com 30 e 35 meses de idade, em plantios florestais na região do Vale do Rio Doce, Minas Gerais, em áreas sujeita a forte ação dos ventos, que tem como consequência o tombamento e até mesmo a quebra dessas árvores. A DRL média foi de 0,086mm, e quando associada as outras características da madeira, as correlações não foram significativas. As características de crescimento das árvores, a densidade básica, o módulo de elasticidade (MOE) e módulo de ruptura (MOR) e trabalho absorvido não foram suficientes para explicar o comportamento da DRL.Palavras-chave: tensão de crescimento, vento, Eucalyptus urophylla × Eucalyptus grandis. Longitudinal Residual Strain of Eucalyptus Clone in Location Subject to Action of Winds ABSTRACTDuring development and growth of trees, mechanical stresses are generated in order to keep it balanced and upright in response to various environmental factors. These efforts are known as growth stresses and can vary in distribution and intensity across different species of the genus Eucalyptus. Thus, the objective was to evaluate the longitudinal residual strains (LRS) and its correlations with tree growth features, physical and mechanical properties of the Eucalyptus urophylla × Eucalyptus grandis hybrid clones. Trees were 30 and 35 months old, located in forest plantations of Vale do Rio Doce, Minas Gerais, in areas subject to wind action, with damping effect and even the breaking of these trees. The LRS measured with extensometer was on average 0.086mm and when associated with other characteristics of the wood, the correlations were not significant. The growth characteristics of trees, basic density, modulus of elasticity (MOE) and modulus of rupture (MOR), and absorbed work were not enough to explain the LRS behavior.

Artificial intelligence to growth stresses predicting in Eucalyptus clones using dendrometric variables and wood density

“…However, the significant relationship in E. dunnii was found only at the age of 15, and at the ages of 8, 13, and 19 it was not significant (Trugilho and Oliveira 2008). The relationships between LGS and BWD not significant in Eucalyptus were also presented in other studies (Beltrame et al 2012, Braz et al 2017. These results demonstrate the importance of BWD as a predictor parameter for LGS, but it shows attention according to the species and age evaluated.…”

“…For example, in the LGS evaluation of 20 Eucalyptus grandis x E. urophylla hybrid clones, of 13 year sold, the LGS results varied between 0,037 mm and 0,116mm, with two statistically distinct groups and 11 clones in the group with the highest LGS (França et al 2017). In another study, the LGS found in ten hybrids of E. urophylla × E. grandis clones of approximately three years old, varied significantly between 0,060 mm and 0,116mm (Braz et al 2017). Unlike these studies, using the ANNs, it was possible to include the variable clone to predict LGS and this parameter was the most relevant (Figure 3).…”

“…Growth stresses are important, as they help to reorient stems and branches in trees. These stresses are also important to achieve vertical growth and to avoid external influence on a plant, such as the wind (Archer 1986, Fournier et al 1994, Braz et al 2017, Gril et al 2017. In fast-growing trees like those of the Eucalyptus genus, these tensions are higher and interfere with the quality of timber products (Trugilho et al 2006, Gril et al 2017.…”

“…Factors such as species and silvicultural treatments influence growth stresses (Fournier et al 1994, França et al 2017, Gril et al 2017. In addition to these factors, the trees are exposed to various external disturbances that can cause a permanent change in the orientation of the trunk and change the angle or position of the branches, for example, due to soil properties, extreme snow load, and exposure to prevailing strong winds (Archer 1986, Braz et al 2017. Also, little is known about the effect of dendrometric variables on growth stresses and, consequently, on wood quality.…”

“…Also, little is known about the effect of dendrometric variables on growth stresses and, consequently, on wood quality. Some studies have shown a low or even no correlation between the diameter and the height of the trees and growth stresses (Braz et al 2017, França et al 2017.…”