Optimising the management of Scots pine (Pinus sylvestris L.) stands in Spain based on individual-tree models

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 optimal value in a single decision variable did not affect much the soil expectation value. simulation / management schedule / forest management Résumé -Optimisation de l'aménagement des peuplements de pin sylvestre en Espagne basée sur des modèles simulant la croissance individuelle des arbres. L'article décrit un système de simulation et optimisation, SPINE, pour la sylviculture des peuplements de pin sylvestre en Espagne. Le sous-système de simulation est basé sur un modèle de croissance en diamètre et un modèle statique de centrés-individu, et des modèles pour la limite d'éclaircie naturelle et la probabilité de survie pendant la période des 5 années suivantes. Le sous-système de simulation était combiné avec l'algorithme d'optimisation développé par Hooke et Jeeves. La combinaison des systèmes simulation-optimisation est capable de trouver le rythme et l'intensité optimale des éclaircies ainsi que le temps optimal pour commencer les coupes de régéneration. Les coupes de régéneration consistaient en une coupe préparatoire, une coupe d'ensemencement 10 ans plus tard et une coupe finale 20 ans après la coupe préparatoire. Les variables de décision étaient des périodes d'éclaircies, exprimées comme années après l'etablissement du peuplement ou années après l'éclaircie précédente, et la surface terrière du peuplement résiduel après chaque éclaircie. Le système était utilisé pour trouver des scénarios sylvicoles optimaux pour les peuplements de pin sylvest...

Using past growth to improve individual-tree diameter growth models for uneven-aged mixtures of Pinus sylvestris L. and Pinus nigra Arn. in Catalonia, north-east Spain

“…It can be applied with the data normally available from stand inventories in the region, and it applies to all age structures and degrees of mixture, including pure and even-aged stands. Models that include the growth index can also be used to optimize the stand management and to evaluate alternative management regimes for P. sylvestris and P. nigra stands in Catalonia [12,18]. …”

Site quality equations for Pinus sylvestris L. plantations in Galicia (northwestern Spain)

“…Most of the equations were derived from functions frequently used in forest growth modelling, by means of the algebraic difference approach [5,12,20,37] and the generalized algebraic difference approach [18]. Other recent studies related to growth and yield of Scots pine in Spain are from Palahí et al [43], Palahí and Pukkala [42], Bravo and Montero [8], and Bravo and Díaz-Balteiro [6].…”

Economic analysis and revenue optimization in management regimes of Pinus taeda

“…In this scope, algorithms are powerful tools in the process of objective function optimization such as those presented by Soares et al (2003), Palahí & Pukkala (2003), Arce et al (2004), Mello et al (2005), Gomide et al (2010), among others.…”

“…The combinations of these and other variables represent the possible forest management regimes, which are different in growth and production when subjected to different management practices (Soalleiro et al, 2000, Palahí & Pukkala, 2003, Pukkala & Miina, 2013. The interaction of these variables converges to a complex problem, especially when economic variables are included such as minimal attractiveness rate, production cost and wood price.…”