公告日期 : 2013-12-27
Stress Wave Tomogram and Wood Density Profile in a Royal Palm Tree: a Case Study
Authors：Yue-Hsing Huang, Chih-Hsin Chung, Meng-Ling Wu, Cheng-Jung Lin
Key words：evaluation of hazardous trees, tomogram, stress wave, tree risk assessment, wood density profile.
This study examined transverse stress wave tomographies and wood density (D) profiles of a royal palm (Roystonea regis) tree trunk at different heights. Moreover, effects of different moisture contents (MCs of 60~270%) on the transverse stress wave velocity (V) during desorption were investigated. Results showed that the highest V and D values on the tree trunk were both located in the peripheral region at 2 m above the ground, while the lowest V and D values on the tree trunk were found in the inner region at 5~6 m above the ground. Corresponding radial V values of the undamaged disc cross-section from the peripheral region to the inner region showed a symmetrical layered structure. Visual inspection of disc cross-section revealed a larger thickness and ratio of the peripheral region in the tree trunk at the tree base. The relationship between the D (at about 12% MC) and V (green) can be expressed by a second-order polynomial regression (R2 = 0.82, p < 0.01). The V was significantly (R2 = 0.61, p < 0.01) affected by the MC and tended to increase with an increasing MC. When making an acoustic inspection, it is necessary to adjust the V of standing trees with different MCs for comparison purposes and to achieve higher accuracy, which would in turn yield more-accurate tree inspection assessments.