Abstract:

The well distributed and planted poplar clone 107 was selected as studying materials in this study. Surface longitudinal growth strain of eccentric growth standing tree and inner residual longitudinal growth strain of eccentric growth fallen tree were determined. Both variation patterns of the surface strain and the inner strain were deduced. According to two variation patterns above, mechanism of some factors which affect growth strain was discussed. The result indicated that varied scope of the surface strain was -2 243-348 με. Generally, the maximum of surface strain located at the lowest part of leaned trunk or convex part of bended trunk, and it was increasing along decreasing distance from testing position to lowest part or convex part. Multiple factors variance analysis shown the surface strain varied significantly among different trees and different position at periphery, however, different height of same tree could not significant affect the surface strain. Varied scope of the inner strain was -1 763-2 279 με. General radial variation trend of inner longitudinal growth strain of fallen tree was similar to parabola with upward opening, and peak located at pith. Outer part of trunk shown compressive strain (tensile stress), while tensile strain (compressive stress) was illustrated at inner part of trunk. In addition, value of the inner strain at tension wood zone was smaller than corresponding value at opposite wood zone according scatter map. It meant that tensile stress of tension wood zone was greater than the opposite zone.

Key words: poplar clone 107, eccentric growth, growth strain