The Effect of Xylem Extractives on Natural Durability of Yew Wood against different rotting fungi

The natural durability of a wood in laboratory is usually determined by measuring the resistance of its heartwood against a specific rotting-fungi species. The most common way for the measuring of the natural durability is the standard guidelines given in EN 113. Although the heartwood of yew trees is experimentally known as a very durable wood, but so far no data is recorded about its resistance against fungal decay. In this study, the natural durability of yew wood was measured against different types of rotting fungi, and then the impact of extractive materials was discussed on that. The density (660.89 kg m-3) and the extractives content (10.75 %) of yew’s heartwood was similar to other softwood species. The result of fungal test showed that the heartwood of yew tree is very durable against rotting fungi. The samples showed below 1% weight loss after 16 weeks incubation with fungi including Trametes versicolor (as white rot), Coniphora puteana and Antrodia vallanti (as brown rot), while at the same time the controls from beech and sapwood of pine lost approximately 45 and 60 % of their initial weight against C. puteana. The extraction with hot water and or ethanol/aceton markedly decreased resistance of samples against rotting fungi. This proves that the extractive content of heartwood in yew tree is the main factor could affect its natural durability. No clear difference was observed between different ways of extraction on the durability of yew’s wood.