M. Yoshida, O. Yamamoto, T. Okuyama
Strain Changes on the Inner Bark Surface of an Inclined Coniferous Sapling Producing Compression Wood
Summary
The tangential strain on the inner bark of Cryptomeria japonica saplings grown in a growth chamber was
continuously measured using strain gauges. Compression wood formation was induced by artificial
inclination. The diurnal changes in tangential strain during light/dark cycles in the growth chamber differed
from those observed in the field. The total strain increased daily, increasing incrementally during
dark periods and decreasing in the light, as observed in the field. In the growth chamber, however, steep
increases and rapid decreases in strain were found immediately following lights-off and lights-on. In the
inclined saplings, the strain increased more on the lower side of the stem than on the upper side; and the
increment of the strain in the dark and the decrement in the light were larger on the lower side than on
the upper side. The change in tangential strain on the inner bark surface arises from changes in the volume
of differentiating cells, corresponding to turgor pressure changes and cell-wall extensibility
changes. Therefore, the differentiating tracheids into compression wood appear to expand at night and
shrink in the daytime more than the differentiating tracheids into normal wood.
Holzforschung, Walter de Gruyter
Print ISSN: 0018-3830
Volume: 54, 10/2000
Pages: 664 - 668
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