Effects of stand density on the productivity ofCryptomeria japonica male flowers

We have studied male flower production and relative illumination in clonal sugi (Cryptomeria japonica) forests planted at densities of 1,500/ha, 3,000/ha, and 5,000/ha, to clarify the effects of forest management on male flower production. Both the relative illumination and male flower production decrease as the stand density increases. The lowest position at which male flowers are formed decreases as the density of the stand decreases. High thinning intensity promotes male flower production and light pruning is ineffective to reduce male flower production. Therefore, traditional management methods used in sugi forests (i.e. planting at high density, frequent light thinning, intensive pruning and short rotation) are ideal strategies for limiting male flower production.