Abstract
An experiment implementing the control method of forest management was implemented in Hokkaido University's Nakagawa Experimental Forest in 1966, to investigate management options for natural forests in northern Hokkaido. Thirty years have passed since the experiment began. This report presents the results which have been assessed to date. The working circle area in the experimental forest covered 110.3 ha, and was a natural mixed forest with a slight majority of coniferous trees (average growing stock: 225 m3). The experimental forest was divided into 10 blocks and the management period defined as 10 years. In the first management period, many low-quality trees were found, and the growth rate in each block ranged between 2.1% and 0.8%. In the same period the total number of trees decreased from 42,438 to 40,154. The growth rate in the second management period ranged from 1.1 to 3.1%, reflecting an improvement in stand structure, but the number of trees decreased from 37,039 to 35,311. Trees planted in areas of poor natural regeneration are growing well and thus an increase in the number of trees and a further increase in growth rate are expected in the third management period.
