Variability of Black locust hardness in relation to different measurement direction and location along the stem
The variability of black locust wood hardiness along the stem determines potential uses for this type of material. Characterization of this parameter was conducted based on samples taken from black locust stands in the western of Poland. Study material drawn from each sample tree was divided into three groups (lower stem part, center of the stem and base of live crown) and measuring was performed in three directions (radial, longitudinal and tangential). Due to bimodal distribution of the data, longitudinal direction was analyzed separately from radial and tangential directions. For the longitudinal direction, significance of differences between various stem parts was confirmed (p<0.001), as well as the significance of differences between study sites (p<0.001). For the radial and tangential directions, significance of differences between sites, stem parts and trees was confirmed (p<0.001; p=0.001; p=0.005, respectively). Preferred wood material should come from lower stem part, taking into account the highest hardiness in the longitudinal direction.