Evaluating wood strength properties of subtropical urban trees using fractometer II

Estimating the extent and severity of decay during tree risk assessment is essential for evaluating tree defects. A portable device that serves this purpose in the field would enhance decay evaluation. A fractometer is a handy device that breaks increment core at radial and longitudinal dimensions for the measurement of wood strength which enables us to obtain reference data for wood quality. In this study, wood strength properties of 25 healthy common broadleaf tree species in Hong Kong were evaluated using Fractometer II. A total of 2656 sections were tested for radial bending strength and angle and 4779 sections for longitudinal compressive strength. There was significant and positive correlations between radial bending strength and longitudinal compressive strength, suggesting a tight interrelationship in physical arrangement contributing to radial and longitudinal mechanical strengths. The ratio of longitudinal compressive strength to radial bending strength which ranged from 1.82 to 3.58 indicated differences of woody plants in construction investment of wood materials in vertical and radial scale. Hierarchical clustering and multidimensional scaling analysis revealed clear grouping of tree species into different types of wood properties.