Wood quality of 2 x 4 lumber obtained from sugi [Cryptomeria japonica] originated from seedlings planted in a stand with different slopes

The object of the present study is to clarify the effects of stand condition on wood quality of sugi (Cryptomeria japonica) 2 x 4 lumber. Annual ring width, air-dried density, and modulus of elasticity (MOE) and modulus of rupture (MOR) in static bending were investigated. Twenty-six-year-old sugi trees, which were originated from seedlings, were harvested from a stand with three different slopes (lower plot with flat slope, central plot with gentle slope, and upper plot with steep slope). Two by four lumber sawn from harvested trees was supplied for the test after being air-dried (moisture content: 12-15%). Annual ring width of lumber from upper plot was smaller significantly than those from central and lower plots (significant at 5% level). On the contrary, there was no significant difference in MOE of 2 x 4 lumber among three plots. As for both air-dried density and MOR, on the other hand, slight differences were found among three plots. These results indicated that slope angle of stand might affect largely on annual ring width, but not on MOE of sugi 2 x 4 lumber.