Wood description and timber use investigation of Pachyelasma tessmannii (Harms) Harms

Abstract :

In Central Africa more than 75% of the total log production is focussed on only four timber species, whose populations are progressively being depleted. Reducing the impact on those flagship species by diversifying the exploitation could lead to better forest management in the long term. Pachyelasma tessmannii is a species whose trees are among the largest in the forests of Central Africa. Yet the properties of its wood are poorly documented. The aim of this study is to evaluate the possibility of using this species with a view to diversify forest production in Central Africa. Its physical and mechanical properties, its natural durability, and quantified radial variation were investigated. By using Hierarchical Clustering on Principal Component (HCPC), heartwood was classified among 98 other Central African timber species. P. tessmannii has a wavy grain and a coarse texture with a wide well-discernible sapwood. The wood is “heavy” with disadvantageous dimensional stability parameters. All mechanical properties are “medium”, except for “low” impact bending strength. Heartwood is very durable against white and brown rot. All properties were significantly influenced by radial variation, except for axial compression strength. According to the HCPC, P. tessmannii should be suitable for stairs (inside/outside), flooring, decking, veneer (back and face of plywood), sliced veneer, furniture (inside/outside), exterior panelling, cabinetry, and joinery (inside/outside). The results obtained concerning the radial variation of basic density could suggest that the species is light-demanding. Considering that the sustainable exploitation of light-demanding species is often confronted with the problem of their lack of regeneration in closed-canopy rainforests, further studies are needed before promoting this species on international markets.