Abstract
The maturity and sustainability of plantation forests in Japan have not been confirmed yet partly because approximately half of the total plantation area still requires silvicultural operations such as thinning and partly because the amount of reforestation has decreased drastically in recent years. The purpose of this paper was to develop a method for assessing maturity and sustainability of forest resources based on two previously created methods by Nagumo and Shiraishi. Nagumo's method, which assesses in reference to the normal forest with the same rotation, was more likely to underestimate maturity due to the high requirements of sustainability. While Shiraishi's method was easy to use, but was not applicable to the forests with entirely uneven age-class distribution. We integrated these methods, and then provided the new method which was simple and informative. Using this, the plantation forests in Japan were proved to be mature enough and to be sustainable with 70-year rotation.
