2017 Volume 99 Issue 1 Pages 41-45
To clarify the effects of reduced planting density on stand structure and growth of sugi (Cryptomeria japonica) plantation, we examined stands planted 11 years ago at densities of 1,000, 2,000, and 2,500 trees ha-1 in Akita, Japan. Sugi trees in a 1,000 trees ha-1 stand had significantly larger diameter and diameter growth than those planted at other densities. Nevertheless, the larger tree height in this stand, along with the comparable height: diameter ratio and height to the lowest branch among the three planting densities, suggested a limited effect of competition among planted sugi trees. The proportion of sugi trees with defects, such as bent or forked stems, was higher in the stands planted at a lower planting density. Naturally regenerated trees other than sugi exceeded 40% of the total tree density in 1,000 and 2,000 trees ha-1 stands. Stem density above median sugi height in these trees was higher in these stands than in the 2,500 trees ha-1 stand, suggesting that trees in these stands suppress sugi trees and cause large variations in sugi heights.
