Abstract
Forest stand characteristics as the individual size is not reflected in the biomass estimations, because the biomass expansion factors (BEF) of Japan are a constant value by the stand age and the tree species. In this study, the biomass expansion factors of Pinus thunbergii coastal forests were estimated. We discussed about the relationship between the each BEF and individual size, individual growth. In addition, we considered the distributions of the BEF of the each DBH in the forest stand. As a result, the value of the BEF was decreasing with passage of time (growth) at the same individual, and thereafter it became constant. In addition, the distributions of the BEF in the forest stand were seen that small-diameter trees had large values and in more big-diameter trees had constant values. From the above, the values of the BEF were considered possibility different depending on the percentage of decrease of BEF with individual's growth, and the stand composition. Therefore, it is necessary to calculate the BEF at a level of individual tree, forest stand or region.
