Abstract
To estimate the influence of site qualities on profitability, an economic evaluation based on an empirical yield table for an artificial forest of Cryptomeria japonica, is developed. In this evaluation, 6 cases (3 levels of site quality and 2 levels of planting density) have been simulated respectively, and a normal forest is assumed. Each stand which forms a normal forest have a area of 100 meters square with 100m road in the uppermost part. Commercial thinning can be carried out after 26〜27 years old in stands with high site quality, while commercial thinning cannot be carried out until final cutting in stands with low site quality. Final cutting can be carried out in stands with high site quality after 45 years old, while final cutting cannot be carried out in stands with low site quality until 80 years. The cause of these differences is the shortage in utilizing volume in stands with low site quality. The utilizing volume in stands with high site quality is 3.18 times higher than that in stands with low site quality. Next, years of break-even point are simulated on the condition that a wage level fluctuates. The result of this simulation indicated that in case of the wage level is low, profitability from stands with low site quality would be close to the one of high site quality. As the wage level increases, profitability from stands with low site quality decreases rapidly. As a consequence, artificial forests must be managed separately with a viewpoint of site quality.
