QUALITY OF REACTION WOOD IN Eucalyptus TREES TILTED BY WIND FOR PULP PRODUCTION

Walter Torezani Neto Boschetti,Marina Donária Chaves Arantes,Graziela Baptista Vidaurre,Juarez Benigno Paes,João Gabriel Missia Da Silva

doi:10.1590/01047760201723032286

Walter Torezani Neto Boschetti, Marina Donária Chaves Arantes + Show 3 more

Open Access

https://doi.org/10.1590/01047760201723032286

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Abstract

ABSTRACT This study aims to evaluate the quality of normal, tension and opposite wood of eucalyptus trees lengthwise, in straight and inclined stems, affected by wind action. It also aims to explain the pulping parameters resultant from the quality of the wood. The trees were grouped into four tilt ranges, ranging from 0 to 50º, and the basic density, chemical composition of the wood, and performance in kraft pulping were assessed. Normal and tension wood had similar basic densities; while for opposite wood, the density was lower, being responsible for a decrease in reaction wood density. The chemical composition of the wood was influenced by the presence of reaction wood in the stem. Tension and opposite wood showed lower levels of extractives and lignin and higher holocellulose content when compared to normal wood, with favorable wood quality for pulping. The increase in holocellulose content and the reduction of lignin and extractives content contributed positively to a more delignified pulp and reduction of the Kappa number. However, after cooking the reaction wood under the same conditions as those of normal wood, reaction wood pulping tends to have a lower screen yields. Due to differences in basic density and chemical constituents between opposite and normal wood, it is recommended not to designate the opposite wood as normal wood.

Highlights

Wood from fast-growing forest species, such as eucalyptus clonal hybrids for the pulp industry, is the main driver for the improved performance of the forestry plantation sector in Brazil.young trees with very tall stems have high slenderness indexes and are more vulnerable to wind action, which is a natural and uncontrollable factor
This study aims to evaluate the quality of normal, tension and opposite wood of eucalyptus trees lengthwise, in straight and inclined stems, affected by the action of winds, as well as to explain the pulping parameters due to the quality of the wood
The average values of wood density to the tilting ranges are shown in Table 1, which indicates the behavior of the density of normal and reaction wood according to the variation of the severity of inclination of the stems

Summary

Introduction

Young trees with very tall stems have high slenderness indexes and are more vulnerable to wind action, which is a natural and uncontrollable factor. Such occurrences in commercial plantations can create stress on the trees, and in more dramatic scenarios, strong winds can cause damage, such as the tilting of the stem at different angles in trees of a single plantation and in trees with ages below the rotation cycle for cutting. Reaction wood is induced in inclined stems in an effort to return the tree to its vertical axis through symmetry biomechanics. Reaction wood is called tension wood, and it occurs in the upper part of the inclined stem (DONALDSON; SINGH, 2016). Some authors have mentioned an excessive porosity in this type of wood (AGUAYO et al 2010; BOSCHETTI et al, 2015a)

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