Résumé
Empirical knowledge on particular wood species can highlight complex behaviour of the physical and mechanical properties, and can help in a better understanding in term of biomechanics of trees and fundamental knowledge on wood properties.From a craftsmen point of view, boxwoods (all the different species of Buxus) are well known and appreciated for specific applications since a long time and all over the world. From the materials science point of view, boxwoods are much less known and studied. Indeed, there are almost no scientific publications about its physical-mechanical properties. Nevertheless, box-trees are known to have an atypical gravitropic reorientation process for hardwoods. In the laboratory, a wide experimental plan has been realized on 6 trees of Buxus sempervirens in order to measure the mechanical properties of dry wood at different radial position in the stem cross section. An other experimental plan has also been realized on a living « archetypal » tree of 110 years, which restored verticality in a steep mountain slope of South of France. The physical and mechanical properties of boxwood compression wood have been found similar to what is generally observed in softwood compression wood. But, the ratios of the properties between compression wood and opposite wood are clearly different from what is observed in softwood. The hygrothermal recovery process affects the compression wood and normal wood in the same way, with a slight decrease of the specific modulus and strong increase of the damping (about 40% higher). This result asks questions in term of biomechanics and wood material science that will be developed in the presentation.