Variation in Wood Density and Tracheid Length inPinus patulagrown in Zimbabwe

Abstract

SYNOPSIS Within-tree variation of wood density was studied for 14-and 25-year-old Pinus patula Schiede & Deppe trees grown at two plantation sites in Zimbabwe. Three trees of each age per site were selected and disc samples obtained at six relative height levels. A diametric strip was prepared from each sample disc and cut into two sample strips. Conditioned density was measured along the first strip using an x-ray densitometer. The second strip was pulped while clamped between perforated plates and tracheid length measured with the Kajaani FS 200 fibre analyser. At both sites, 25-year-old trees had higher density and longer tracheids than 14-year-old trees (0,557 and 0,544 g/cm3 as against 0,476 and 0,492 g/cm3; 3,55 and 3,84 mm against 3,48 mm and 3,07 mm), There were minimal differences in wood density between sites, but tracheid length showed substantial differences between sites. Wood density and tracheid length increased with growth ring age, with a rapid increase occurring in the first 14 years for...