VARIAÇÃO DAS DIMENSÕES CELULARES NO SENTIDO MEDULA-CASCA E BASE-TOPO DE ÁRVORES DE "AROEIRA" Myracrodruon urundeuva F.F. & M.F. Alemão (Anncardiaceae) I - FIBRAS

Abstract

The dimensions of the xylem cells have a marked effect on the quality of wood. In general, the anatomical characteristics vary noticeably within and among trees. Our investigation has tried to obtain further information about this subject. Its specife goal was to determine the variation in fiber dimensions in the pith-bark and basc-top directions. Twelve trees were felled according to diameter class in cach of four kinds of spacing at 26-year-old experimental plantations of "aroeira" Myracrodruon urundeuva F. F. & M. F. Allemão, at the São José do Rio Preto Experimental Station, from the Forest Institute, State of São Paulo. Wooden dises were removed from cach tree at base, DBH, 50% and 100% of commercial height. In order to allow the investigation of the variation in fiber dimensions, in each dise samples were taken at 0%, 50% and 100% of the radius. The results indicare that: a) spacing and diameter classes had no influence on fiber characteristics; b) length increased from base to top up to 50% of commercial, height, decreasing toward the top; tangential diameter decreased in DBH and increased agam; the lumen did not show any clear tendency and wall thicknees decreased; c) from pith to bark the length increased, whercas tangential diarneter, lumen and wall thicknees did not show any clear tendency.