Variability of the chemical composition of the wood and bark of two tropical hardwoods from Ghana | Variabilnost kemične sestave lesa in skorje dveh tropskih listnatih drevesnih vrst iz Gane

English. The study aims to investigate the chemical properties of the wood and bark of two tropical tree species Nesogordonia papaverifera and Holarrhena floribunda from Ghana to increase the efficiency of their utilization. For this purpose, for each of the species five mature trees with similar diameters at breast height were selected. Lignin, cellulose, hemicellulose, and total extractive content were determined from the sapwood and heartwood and bark of stems and branches of both species. The tests were conducted using the Technical Association of the Pulp and Paper Industry (TAPPI) standards. The lignin, cellulose, hemicellulose, and total extractive content vary along different locations in the stems and branches in both species. The sapwood generally had higher cellulose and hemicellulose content, while the heartwood and bark had a greater amount of lignin and extractives. This may affect the lower durability of sapwood. This study shows that heartwood of both Nesogordonia papaverifera and Holarrhena floribunda can be considered a source of value-added compounds.

Slovenian. Raziskana je bila kemična zgradba lesa in skorje dveh tropskih listavcev, Nesogordonia papaverifera in Holarrhena floribunda iz Gane za izboljšanje uporabe. V ta namen je bilo za raziskave izbranih pet odraslih dreves vsake vrste. Debla so imela podobne premere na prsni višini. Določena je bila vsebnost ekstraktivov, lignina, celuloze in hemiceluloz v beljavi in jedrovini ter skorji debel in vej. Testi so bili izvedeni v skladu s standardi tehničnega združenja za celulozo in papir (TAPPI). Vsebnost lignina, celuloze, hemiceluloz in celokupna vsebnost ekstraktivov je bila primerljiva v lesu debel in vej pri obeh vrstah. Vsebnost celuloze in hemiceluloz je bila pri obeh vrstah manjša v skorji kot v lesu. V beljavi smo zabeležili večjo vsebnost celuloze in hemiceluloz, v jedrovini in skorji pa večjo količino lignina in ekstraktivov. To utegne vplivati na slabšo odpornost beljave proti škodljivcem. Študija kaže, da sta jedrovina in skorja obeh vrst Nesogordonia papaverifera in Holarrhena floribunda lahko vir spojin z visoko dodano vrednostjo.