tailieunhanh - Báo cáo lâm nghiệp: " Optimising the management of uneven-aged Pinus sylvestris L. and Pinus nigra Arn. mixed stands in Catalonia, north-east Spain"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: " Optimising the management of uneven-aged Pinus sylvestris L. and Pinus nigra Arn. mixed stands in Catalonia, north-east Spain" | Ann. For. Sci. 61 2004 747-758 INRA EDP Sciences 2005 DOI forest 2004071 747 Original article Optimising the management of uneven-aged Pinus sylvestris L. and Pinus nigra Arn. mixed stands in Catalonia north-east Spain Antoni TRASOBARESa Timo PUKKALAb a Centre Tecnològic Forestal de Catalunya Pujada del seminari s n 25280 Solsona Spain b University of Joensuu Faculty of Forestry PO Box 111 80101 Joensuu Finland Received 9 July 2003 accepted 19 March 2004 Abstract - This study uses a simulation-optimisation system PINUSMIX to optimise the structure and management of uneven-aged mixtures of Pinus sylvestris L. and Pinus nigra Arn. in Catalonia north-east Spain . The simulation sub-system consists of a method for drawing the initial tree diameters from a Weibull distribution and a stand growth and yield simulator based on individual-tree growth height ingrowth and survival models. The simulation sub-system was combined with the optimisation algorithm of Hooke and Jeeves. The system was used to optimise the management of uneven-aged mixtures of P. sylvestris and P. nigra on medium site characteristics in the region. When the land expectation value with a 20-year cutting cycle and a 2 discounting rate was maximized the land expectation value was 1331 euro ha-1 and the optimal prior-thinning stand volume was 86 m1 3 ha-1. In the optimal stand structure P. sylvestris dominated. The effects of discounting rate cutting cycle length objective function site timber prices type of diameter distribution and biodiversity considerations were logical. Increasing discounting rate and shortening the cutting cycle decreased the optimal prior-thinning stand densities. Maximising wood production or net income resulted in higher volumes of growing stock than did maximising profitability. Forcing the inclusion of large trees in the stand for biodiversity reasons clearly decreased profitability but had no effect on wood production. simulation continuous cover forestry investment .