Abstract:

In order to improve the accuracy and the reliability of identification of defects and to realize the maximal utilization of wood in winter, 10 main species in the northeast forest area of Harbin Forest Experimental Station were tested for comparison of stress wave propagating velocities（SWPV）both in frozen state and in normal temperature state. The results showed that the longitudinal and radial propagating velocities of stress wave in frozen standing trees were obviously higher than those in normal temperature standing trees, and there was a high positive correlation relationship between longitudinal velocities in frozen and normal temperature states. While the moisture content of standing trees exceed the fiber saturation point（f.s.p）, the longitudinal stress wave propagating velocities in frozen state were affected significantly by moisture content, but it was not obvious in the normal temperature state.

Key words: stress wave, standing tree, frozen state, normal temperature state, propagating velocity