Variation in wood properties and longitudinal permeability of Hildegardia barteri (Mast.) Kossern-- a tropical pioneer species.

摘要

Hildegardia barteri is a diffuse-porous species in which the annual rings are indistinct. A total of 360 cores and 36 logs were obtained from four sites, with two each located in the lowland rain-forest and derived savanna respectively. Specific gravity (SG) was determined by the maximum moisture content; wood softening for sectioning by ethylenediamine process; and longitudinal permeability by the falling water-volume displacement method. Statistical analyses were used to study the effects of site, within-tree, among-trees, and growth factors (soils and rainfall regime) on the variability of wood properties and longitudinal permeability in Hildegardia.;Hildegardia wood is characterized by abundant parenchymatous tissues, low fiber and vessel volumes, the combination of which is reflected by the low wood SG (mean, 0.260). The fibers are relatively long (mean, 2.3mm) and thick-walled (mean, 8.7um - double wall thickness) while the vessels are small-to-moderately wide (86 to 245um). Within-tree effect (primarily across stem radius) was most significant (P.05) and had coefficient of variation which ranged from 6.5 to 40.7 percent, with most wood properties (SG, fiber and vessel characteristics) increasing from the inner wood to outer wood for all sites combined, for individual sites and for individual trees. The wood had relatively low extractive contents, the bulk of which constituted hot water extractables. The effects of growth factors on wood property variation were less distinct probably due to lack of macro-environmental variation among the study sites and to the indirect effect of soil chemical properties on wood formation.;Longitudinal permeability was relatively moderate but much lower than would be expected for a low-density, diffuse-porous, and sapwood species like Hildegardia. Low vessel volume and slip flow through the pit membranes of the axial and ray parenchyma cells might be responsible for the low permeability to gas. Low SG and poor fiber characteristics may limit full utilization of the wood as a sole raw material for solid wood products and for pulp and papermaking. However, these deficiencies may be optimized to greater advantage for particleboard manufacture and in hardwood mix for pulp production.