Abstract
We established a simulator which can estimate profits from management of individual stands for landowners under numerous sets of parameters considering; diversity of logging, growth and social conditions, and analyzed most profitable timing for thinning and clearcuttting. The assumed site is a planted Sugi (Cryptomeria japonica) forest where logging systems using forest vehicles are predominant in Yamagata Prefecture. The results showed that the longest clearcutting age of 110 years assumed in this simulation was selected as the most profitable option under almost all sets of parameters along with low discount rates such as 1%. It was difficult to gain positive soil expectation value under relatively high discount rates, indicating that forest owners have little incentive to reestablish planted forests after clearcutting. Management plans with few commercial thinnings tended to be the best choices, and repetitive commercial thinnings were preferred only when the assumed condition of logging operation including road construction and maintenance was favorable and an intensive subsidy for commercial thinning was assumed. These results indicate that stand management policies of no clearcutting with repetitive commercial thinnings promoted in the current forestry policy are less profitable in many cases.
