Nondestructive detection of heart rot of Acacia mangium trees in Malaysia.

Abstract

Stress wave velocity in the radial direction across the stem was measured at the breast height of Acacia mangium trees. An increment core was taken from just beneath each measurement position to investigate the relationship between wood properties and stress wave velocity. The velocity was much higher in sound stems than in hollowed stems decayed by heart rot. The velocities of sound and affected stems ranged from 928 to 1259 m/sec. (average 1087 m/sec.), and from 357 to 876 m/sec. (average 563 m/sec.), respectively. It was possible to detect hollows located in the central region of the stems. The threshold velocity between unaffected and hollowed stems was around 800 m/sec. Specific gravity was a main factor influencing the velocity, in addition to hollows in the center of the stems. Nondestructive testing using stress waves would be a useful method to detect hollows caused by heart rot in A. mangium trees.