Efeitos da bifurcação, espaçamento e idade na qualidade da madeira de Tachigali vulgaris proveniente de plantações homogêneas para geração de bioenergia na Amazônia.

Abstract

In recent years, studies on the potential of native species for the composition of plantations for bioenergy purposes have gained prominence. Among the species investigated, Tachigali vulgaris shows promising characteristics for alternative use to Eucalyptus in the Amazon region. However, a problem observed is the occurrence of significant rates of bifurcation in experimental areas. The objective of this study was to understand the effects of forking, age, and spacing on the variation pattern of basic and bulk density in the stem, and the characteristics of the growth rings in the wood of T. vulgaris from experimental plantations for energy purposes in the Amazon. The material was collected from a plantation belonging to the Jari Celulose S.A. company, located in the Almeirim municipality, in the lower Amazon region of Pará. The experiment was set up in 2010 in which 6 different spacings were evaluated (3.0 x 1.5 m; 3.0 x 2.0 m; 3.0 x 2.5 m; 3.0 x 3.0 m; 3.0 x 3.5 m and 3.0 x 4.0 m). Eighteen non-forked and 36 forked trees were evaluated, from which 5 cm thick discs were taken at determined positions of 0%, 1.30 m, 25%, 50%, 75%, and 100% along the commercial height. The present dissertation was divided into two chapters. The first chapter evaluated the variations in basic and relative bulk density along the commercial height and the proportions of heartwood and sapwood at DBH height in forked and nonforked trees. The second presented the potential of evaluating the wood quality of T. vulgaris by X-ray densitometry. The results show that for basic density, the wider spacings of 3.0 x 3.0 m, 3.0 x 3.5 m, and 3.0 x 4.0 m showed a higher amount of trees with average DB (≥ 0.50 g cm-³), ranging from 62% to 71%. Mean heartwood percentages were 60.03% ±11.98 for non-forked and 61.54%±11.98 for forked trees. Mean bulk density values were homogeneous from the beginning of tree growth, ranging from 0.676 to 0.696 g cm-3 for non-bifurcated trees and from 0.400 g cm-3 to 0.860 g cm-3 for forked trees. Ring width decreased as a function of cambial age in both stem types and spacings. Higher percentages of initial wood were observed at all spacings. In all variables studied T. vulgaris obtained a good performance about the desirable parameters for charcoal production and potential for deployment on large scale, even containing significant rates of forking.