Abstract
Axial and radial variations of spiral grain on thirty tree of Larix leptolepis sampled from a 45-year-old plantation in Chubu district were observed.
The results are summarized as follows:
1) The variation curve of the average twisting angle in relation to ring number from pith is shown in Fig. 1. From the variation curve, it can be said that the unwinding (Nejire-kaeshi) of twisting fiber in this stand may occur at about forty-seventh growth ring from pith.
2) According to the analysis of variance of the average twisting angle, variations between sample trees, between juvenilewood and adultwood, and interaction between sample tree and radial direction in wood were statistically significant (Table 2).
3) In axial variation of spiral grain in tree trunks, the value of average twisting angle increases as height increases (Fig. 3). There was significant difference between juvenilewood and adultwood in the average twisting angle at any height from ground level (Table 3 and Fig. 4).
4) The value of twisting angle in the same growth ring within a tree increases as height increases (Fig. 5).
