Representativeness of wood biomechanical properties measured after storage in different conditions

Abstract

Obtaining representative values of green wood properties is essential for studies investigating the biomechanical aspects of tree development and ecology. Here, we compare the biomechanical properties of wood stored in various conditions between their collection in the field and their measurement. The study was performed on a large sample of wood specimens from different tropical species and different location in the trees, representing a wide diversity in wood structures. Elastic and viscoelastic properties are measured on green wood, and measured again after storage in different conditions: immersion in cold water during various durations, storage in an ethanol solution with or without washing in water, and air drying with or without rehydration. The systematic and random errors induced by these storage methods are quantified. Storage in cold water is the best way to preserve wood native properties. Soaking in ethanol is a fair alternative regarding elastic properties, but induces a significant change in viscoelastic properties. Air drying causes important, and partly irreversible, changes in mechanical properties. However, regarding elastic properties, this change is a systematic bias so that the air-dried elastic modulus provides a good basis for comparative studies of green wood stiffness.