Abstract:

Pinus massoniana is a main has planting species in south of China which accounts for a large proportion among plantations, but its problem of density control has always not been solved very well. In this paper based on density control model of P. massoniana plantation established by dynamic programming, Genetic Algorithm was applied to select optimal decision in determining thinning age, optimal density and cutting age during stand management, which was on the basis of the density effect model, took the stand density as objective function and maximal present net worth (PNW) as standard. The density optimal projection of P. massoniana plantation during its management showed that combination of Genetic Algorithm and method of economic evaluation obtained satisfactory results. The optimized results showed that two times were optimal for thinning of P. massoniana plantation during its management where the site index was 10～18. The first time for thinning was in 11～12 years, the second time was in 16～17 years, the optimal time for final cutting was in 22～25 years. And P. massoniana plantation in each site index had its own optimizing management projection by which the highest PNW could be achieved, and IRR was more than 12%. So the results of this study will provide a theoretical reference for density management of P. massoniana plantation.

Key words: Genetic Algorithm, Density control, Pinus massoniana, PNW, IRR