Variação longitudinal e transversal nas propriedades da madeira do Tauari Vermelho (Cariniana micrantha Ducke – Lecythidaceae)

Abstract

The work had the objective of studying the variation of density, shrinkage and fiber length from pith-bark and base to top direction of the tree. The samples were collected from five equidistant positions in the pith-bark direction, corresponding to 0%, 25%, 50%, 75% and 100%, and in the heights of base, DAP, 50%, 75% and 100% of the tree. Three trees were used and the samples had nominal dimensions of 2,0 x 3,0 x 5,0 cm. The results showed that occurred tendency of basic density variations in pith-bark and base-top directions. In the pith-bark direction the density increased until the position of 50% (heartwood) and followed by decreasing to minimum values on sapwood near bark (100%). Minimum values of density were observed on sapwood and maximum values on heartwood. In the base-top direction, a tendency of decreasing density was observed for samples from sapwood. Minimum values were found on sapwood (100%) where it was practically free of extractives. In the other positions there were not obvious tendencies of density behaviour which may be caused by extractive. Volumetrics and linear shrinkages had tendency to decrease in the pith-bark direction, independently of position of the sample in the trunk. The anisotropic factor (T/R), was lower in the area near pith, increasing substantially towards the sapwood. Area near pith showed smaller rate of anisotropic factor and heartwood and sapwood showed greater rate of anisotropic factor. There was no statistic difference for basic density and volumetric, tangencial and radial shrinkages in the longitudinal direction of the trunk of tauari . But, there was significant statistic differences in the radial direction. The test Tukey of multiple comparisons of averages showed statistic differences on basic density only among the position of 100% and the others. While these were statistically the same to each other, in other words, the density of the heartwood was statistically larger than the density of the sapwood. The same relationship was found in the radial path for tangential and radial shrinkages. Thus, the position of 100%, smaller shrinkage value, was statistically different to the others, with the neighbor's 75% exception. While the shrinkages verified in the positions of 0%, 25%, 50% and 75% did not differ. The results were comparable to the radial volumetric shrinkage. The anisotropic factor, as well as fiber lengths were statistically non significant on both directions (longitudinally and radially).