Abstract
The authors demonstrated the procedure for deriving a diameter distribution model from the space occupation model of crowns with equal distribution of the total basal area of crowns through the relationship between diameter at breast height and basal area of crown, and height of crown base. In order to access the efficiency of this procedure, the diameter distribution model was induced using data from the selection forest at Imasu and this was compared with the actual diameter distribution of a stand. After testing by statistical method, there were no siginificant differences in either basal area of crown or height of crown base between Cryptomeria japonica and Chamaecyparts obtusa. Therefore, regressional equations between diameter at breast height and basal area of crown, and height of crown base were calculated without distinguishing tree species. Based of these results and the upper limit of total crown basal area, 12,000m^2/ha, in the stand, a diameter distribution model was obtained. This model was suitable for trees of middle and large diameter. However, it gave too much number for trees of small diameter.
