Abstract:

In this paper, CIRAD-Foret method and strain gauge method were used to measure the longitudinal surface growth strains released from fallen woods. Comparison was also done between two methods for measurements at the same point (sawing grooves inside the position pins)and at two points. Results showed that the values obtained from the CIRAD-Foret method were bigger than those from strain gauge method. The former was 1.3 times as high as the latter for the measurement at two points, and it was 2.0 times as high as the latter for the measurement at the same point. There was no distinct difference in the longitudinal surface growth strains from strain gauge method with measuring way at the same point and two points. However, the differences were obvious for the strains from CIRAD-Foret method with two measuring ways. They indicated that there was little effect on the values from strain gauge method with measuring way at the same point or at two points, and that the measuring way would influence measured result when CIRAD-Foret method was applied. In general, in comparison with CIRAD-Foret method, strain gauge method was more stable.

Key words: growth stress, Eucalyptus urophylla×, E.grandis, strain gauge method, CIRAD-Foret method, longitudinal surface growth strains