Correlations between age, wood quality and charcoal quality of eucalyptus clones

Abstract

Brazil is world's greater producer of charcoal, and the Brazilian state Minas Gerais presents the greater production of said product. The wood proprieties influence the charcoal quality, making important to know them, it is known that these proprieties vary according to the age of the tree. With that being said, this research aimed to determine the correlations existing between age, the proprieties of the wood and charcoal proprieties. Three Eucalyptus sp. clones from Gerdau S/A were evaluated, at four ages, 3, 4, 5 and 7. From each tree, five discs were removed (0%, 25%, 50%, 75% and 100% corresponding to the commercial height of the trunk). We determined the core/sapwood relationship, basic density, chemical composition of the wood, the calorific value of the wood and of the charcoal, the gravimetric yields, apparent relative density and charcoal chemical analysis, in addition to the analysis of the condensable and non-condensable gases. Correlations between age, proprieties of the wood and charcoal were performed. It was observed a negative correlation between the age of the wood and charcoal ashes content, regardless the clones evaluated. A positive correlation between the basic density of the wood and the apparent density of the coal and a positive correlation between the lignin of wood content and the coal apparent density were observed, as well. The siringil/guaiacil relation, which determines the quantity of each type of lignin existent on the wood, presented a negative correlation with the gravimetric yields in charcoal. Therefore, it is concluded that the age of the tree influenced the proprieties of the wood, regardless the clone; the age of the genetic material did not influence the gravimetric yield in charcoal; the GG 680 clone presented greater potential to produce charcoal, considering only the proprieties of the wood.