Natural durability of eight tropical hardwoods species from Africa
P Nzokou, K Wehner, D P Kamdem
Current forest inventory results reveal that there are more than 700 hundred-hardwood species in tropical forests, of which less than 10 percent are harvested and used for commercial purposes. The increased use of lesser-known species can decrease the pressure on current commercial species, increase the value of the forest and lead to better management practices. However basic information on physical, mechanical, treatability, and durability properties of these lesser-known species are necessary before they can be advertised as suitable replacements for current species.
This project investigates the natural durability to brown rot and white rot fungi of eight tropical commercial and secondary hardwood species: Ayous (Triplochiton scleroxylon), Acajou (Khaya ivorensis), Frake (Terminalia superba), African padauk (Pterocapus soyauxii), Amouk (Microberllinia brazzavilensis), Ilomba (Pycnanthus angolensis), Iroko (Chlorophora excelsa) and Parassolier (Mussanga cecropioides).
The soil block test procedure was conducted according to ASTM D2017-81 standard. A classification scheme based on above ground and ground contact end uses was developed. In addition the eight species were ranked using a Wilcoxon matched pair statistical test on SAS.
Seven of the eight species investigated were susceptible to white rot fungi, while Iroko and African padauk were the only species highly resistant to brown rot fungi. Based on the end use classification scheme, Amouk, Frake, African mahogany, African padauk and Iroko all showed potential for above ground applications, while only African padauk and Iroko showed potential for ground contact applications.