The decay resistance of black locust ( Robinia pseudoacacia L.) heartwood was evaluated on standardized test specimens taken from mature and juvenile wood in 25 trees distributed over five sites in Wallonia, Belgium. The percentage mass losses caused by the wood-destroying fungi Coriolus versicolor CTB 863 A and Coniophora puteana BAM Ebw.15 were evaluated according to Cen/ts 15083-1 (Cen/ts 15083-1. 2005. Durability of wood and wood-based products — determination of the natural durability of solid wood against wood-destroying fungi, test methods — Part 1: Basidiomycetes. European Comm. for Standardization, Brussels). Black locust is classified as a “very durable” wood (class 1), while the juvenile heartwood (located near the pith) is classified in classes 1 to 2. The statistical analysis does not reveal any significant differences among the sites, suggesting that the growth environment of the trees has no effect on their natural durability. However, statistical analysis shows very highly significant differences among trees and between the two radial positions in the tree, with mature wood being more resistant than juvenile wood. Using such a naturally very durable species could reduce reliance on preservative treatment and the use of tropical species generally recommended for outdoor woodwork.
