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This study analyzes the optimal management of Scots pine (Pinus sylvestris L.) stands by applying recent developments in numerical optimization methods and forest production ecology. Our approach integrates a process-based, stand-level growth model and a detailed economic description of stand management. The variables optimized include the initial stand density, the number, timing, type, and intensity of thinnings, and the rotation period. A generalized pattern search is used to maximize the present value of net timber revenue over an infinite time horizon. The model adopts quality pricing, which takes branch size and quality into account, to differentiate among five different timber assortments. The analysis also covers five different site types. The results demonstrate the necessity of optimizing all of the management variables simultaneously. Given a low interest rate, optimized thinning significantly increases the rotation period, volume yield, and economic outcome. At higher interest rates, optimal rotation may be shortest under the least fertile growth conditions. The inclusion of a detailed price structure reveals that previous results concerning sensitivity to timber price and the relationship between maximum sustainable yield and economic solutions do not hold true in models that provide a more realistic description of forest management.

We optimize timber and bioenergy production combined with carbon storage in Scots pine (Pinus sylvestris L.) stands, using an ecological-economic model. Forest growth is specified with a highly detailed process-based growth specification, and optimization is based on an efficient generalized pattern search algorithm. The optimized variables are rotation length, initial stand density, and the number, intensity, timing, and type of thinnings. The carbon pool includes all aboveground biomass (including dead trees) and timber products. The analysis includes the comparison of different carbon subsidy systems. The results are presented for the most relevant site types and thermal zones in Finland. Carbon storage increases the optimal rotation length, number of thinnings, and initial density at all forest sites. Carbon storage effects on stand density and harvests are strongest at poor sites. Timber output increases with carbon price. High natural mortality in our results implies notable carbon storage in dead trees and a positive contribution to biodiversity. The stand-level analysis is extended to a cost-efficient national-level carbon storage plan.

We combine a process-based growth model for even-aged Norway spruce (Picea abies (L.) Karst.) with economics and optimization. Carbon storage is subsidized based on stand growth and product decay. We include detailed optimized thinnings and timber quality features and present cost functions for stand-level CO 2 storage. In contrast to earlier studies, our results suggest that changing thinning strategies and postponing thinnings are at least as important as lengthening the rotation period when considering economically efficient carbon storage. The role of thinning is most important in less fertile sites. Contrary to the generic Faustmann model, a higher interest rate increases rotation length on our fertile site. Including carbon release from decaying timber products as reductions from carbon subsidies only has minor effects on optimal solutions. The fertile site stores more discounted carbon. However, with a 1% interest rate, the less fertile site is cost-efficient up to 13 CO 2 t·ha −1 , and with a 3% interest rate, it is cost-efficient up to 14 CO 2 t·ha −1 . After these points, carbon storage on the fertile site becomes cheaper. The economic costs of carbon storage suggest that it is optimal to apply carbon storage in Norway spruce forests to meet greenhouse gas reduction commitments.Résumé : Nous combinons économique et optimisation à un modèle de croissance à base écophysiologique pour l'épicéa commun (Picea abies (L.) Karst.) en peuplement équienne. Le stockage du carbone est subventionné sur la base de la croissance des peuplements et la décomposition des produits du bois. Nous incluons des caractéristiques détaillées de qualité du bois et des éclaircies optimisées et nous présentons des fonctions de coût pour le stockage du CO 2 à l'échelle du peuplement. Contrairement aux études précédentes, nos résultats indiquent qu'il est au moins aussi important de modifier les stratégies d'éclaircie et de retarder les éclaircies que d'allonger la période de rotation lorsqu'on tient compte de l'efficacité du stockage du carbone du point de vue économique. Le rôle de l'éclaircie est très important dans les stations moins fertiles. Contrairement au modèle générique de Faustmann, un taux d'intérêt plus élevé allonge la période de rotation dans notre station fertile. L'inclusion du carbone libéré par la décomposition des produits du bois, qui contribue à réduire les subventions pour le carbone, n'a que des effets mineurs sur les solutions optimales. La station fertile emmagasine plus de carbone actualisé. Cependant, la station moins fertile est rentable jusqu'à 13 t·ha −1 de CO 2 avec un taux d'intérêt de 1 % et jusqu'à 14 t·ha −1 de CO 2 avec un taux d'intérêt de 3 %. Au-delà , il devient moins coûteux d'emmagasiner le carbone dans la station fertile. Le coût économique du stockage du carbone indique que l'utilisation des forêts d'épicéa commun à cette fin, dans le but d'honorer les engagements concernant la réduction des gaz à effet de serre, est une solution optimale. [Traduit par la Rédaction]

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