tailieunhanh - Báo cáo lâm nghiệp:"Optimising the management of Scots pine (Pinus sylvestris L.) stands in Spain based on individual-tree models"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí lâm nghiệp đề tài:"Optimising the management of Scots pine (Pinus sylvestris L.) stands in Spain based on individual-tree models" | Ann. For. Sci. 60 2003 105-114 INRA EDP Sciences 2003 DOI forest 2003002 105 Original article Optimising the management of Scots pine Pinus sylvestris L. stands in Spain based on individual-tree models Marc Palahía and Timo Pukkalab a European Forest Institute Torikatu 34 80100 Joensuu Finland b University of Joensuu Faculty of Forestry PO Box 111 80101 Joensuu Finland Received 31 August 2001 accepted 13 May 2002 Abstract - The article describes a simulation-optimisation system SPINE for the management of Pinus sylvestris L. stands in Spain. The simulation sub-system is based on an individual-tree diameter growth model a static individual-tree height model and models for the selfthinning limit and the probability of a tree to survive for the coming 5-year period. The simulation sub-system was combined with the optimisation algorithm developed by Hooke and Jeeves. The combined simulation-optimisation system is able to find the optimal timing and intensity of thinnings and the optimal time to commence regenerative cuts. The set of regenerative cuts consisted of a preparatory cut a seed cut 10 years later and a final cut 20 years after the preparatory cut. The decision variables were thinning times expressed as years since stand establishment or previous thinning and the remaining stand basal area after each thinning. The system was used to find optimal management schedules of Pinus sylvestris stands on site indices 17 24 and 30 m dominant height at 100 years . When soil expectation value with 2 discounting rate was maximised the optimum management schedule included five thinnings on all site indices. The optimal rotations from stand establishment to the final cut were 119 90 and 94 years respectively on site indices 17 24 30 m. On all sites the optimal management schedules were sensitive to the discounting rate management objective soil expectation value forest rent or mean annual harvest and fixed harvesting costs. Changes of up to 30 percent from the .