Características tecnológicas da madeira de cedro australiano (Toona ciliata M. Roem) produzida no sul do estado de Minas Gerais

Abstract

The decrease in the offer of wood of native species considered noble, for several restrictions, has been fostering the investigation of alternative species, such as the Australian Cedar (Toona ciliata M. Roem.). The objective of this work was to study the technological properties (physical, anatomical and chemical properties) of the Australian Cedar wood originating from three municipal districts in the South of Minas Gerais, aiming at contributing to the generation of information for the forest basis sector. The holocellulose, lignin, extractive and ashes contents were quantified through ABTCP's norms (1974). Histological sheets were made for anatomical study of the wood, and the description was made according to IAWA (1989). The physical properties of basic density and shrinkage were determined according to the NBR 11941 - 02 (ABNT, 2003) and NBR 7190 - 97 (ABNT, 1997) norms, respectively. The behavior of those, in the radial and longitudinal directions, was evaluated. Polynomial patterns were also tested to determine the physical properties based on the height of the samples’ collection in each one of the places which were studied. The holocellulose, lignin, extractive and ashes contents were determined in 64,13%, 20,31%, 14,87% and 0,89%, respectively. Among the general characteristics of the wood, the species presented medium texture, rectilinear vascular lines, pleasant smell when it was cut and little shiny radial surface. Layers of different growth were found due to the thickness of the wall of the fibers; there were vessels in semi-porous rings, with medium diameters predominance; scarce paratracheal axial parenchyma; libriform fibers with tiny pits and; type III heterogeneous radial parenchyma. The average basic density of the Australian Cedar wood was 0,306 g/cm3. We can observe, through the variance analysis result, that the wood basic density was significantly different among the positions, in the marrow-peel way, for the regions of Campo Belo and Santo Antônio do Amparo. For the region of Cana Verde significant difference was observed among the positions, in the bottom-up way. It could be observed that among the linear contractions of the wood, the tangential linear contraction differed significantly among the positions, in the bottom-up way, for the three studied areas, where it is possible to verify a decrease tendency that way. For the region of Cana Verde significant difference was observed among the positions, in the radial way, for the radial contraction. For the volume contractions there was significant effect among the different positions along the axial axis in the municipal districts of Campo Belo and Cana Verde. The anisotropy coefficient differed among the positions, in the marrow-peel way, for the region of Cana Verde, presenting high values. The tested patterns returned results with R2 ranging from 0,65 to 0,99.