Abstract
Yield tables are prepared by all prefectures and are used to update Shinrinbo data for private forests in Japan. Therefore, the yield table is the most important source of data for the forest database. The characteristics of the yield tables of Cryptomeria japonica , Chamaecyparis obtusa and broad-leaved species in all twenty-eight prefectures in Western Japan were analyzed based on the parameters of the Richards growth function. Richards function fitted all yield tables very well. Parameter m , denoting the shape of growth pattern, was smaller than 1 for all yield tables, which means that all yield tables showed a Mitscherlich growth pattern. Both total means of parameter k and m denoted nearly equal values in Cryptomeria japonica and Chamaecyparis obtusa. A slightly positive relationship was observed between parameter A and the total yield value in the yield-table for national forests between districts, but no relationship was observed between parameter A and prefectural forest productivity within each district. The mean value of parameter A , denoting the maximum yield table volume, were 589.3, 451.6 and 172.7m^3/ha for Cryptomeria japonica, Chamaecyparis obtusa and broad-leaved species, respectively ; the mean age at the maximum mean increment of stand volume, 38.3, 40.1 and 31.8 years, respectively, and the mean maximum value at that age 8.9, 6.4 and 2.9m^3/ha respectively.
