Variation in apparent wood density of Tachigali vulgaris as affected by tree diameter, height, forking, and soil conditions in Amazonian plantations

Abstract

Abstract Tachigali vulgaris has potential for energy purposes in the Amazon, but the relationship between several silvicultural factors and wood quality requires further investigation. This study evaluated the variation in the apparent density of T. vulgaris wood in two pure plantations in the Amazon. The tested factors were diameter, height, stem forking, fertilization, and soil texture. Two 11-year-old trial plantations located on yellow oxisols with sandy loam and very clayey textures were evaluated, both with and without phosphorus and potassium fertilization. Discs were sampled along the stem heights, and apparent wood density was determined by X-ray densitometry. The Linear mixed-effects model showed that wood density was significantly associated with quadratic mean diameter and commercial height, unlike stem forking, soil texture, or fertilization. A marginal interaction between fertilization and soil textural class occurred. Despite no significant effect of stem forking on wood density, forked trees were more heterogeneous longitudinally. Multivariate analysis of variance indicated that the longitudinal variation within trees accounted for 69% of the total density variation, while variation among trees accounted for 31%. X-ray densitometry showed wood density increased over eleven cambial years, with average values ​​ranging from 0.619 g cm −3 to 0.729 g cm −3 . Moreover, it decreased from the base (0.725 g cm −3 ) to approximately 50% of the commercial height (0.539 g cm −3 ), then increased towards the top (0.605 g cm −3 ). The disclosure of a wide variation in the wood density of T. vulgaris will support its sustainable management regarding optimized bioenergy plantations in the Amazon.