Optimising the management of uneven-aged <i>Pinus sylvestris</i> L. 
and <i>Pinus nigra </i>Arn. mixed stands in Catalonia, north-east Spain

Trasobares, Antoni; Pukkala, Timo

doi:10.1051/forest:2004071

Cited by 37 publications

(26 citation statements)

References 28 publications

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“…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]. …”

Section: Discussionmentioning

confidence: 99%

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

Trasobares

Pukkala

2004

Ann. For. Sci.

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-In this study, growth models of individual tree diameter for uneven-aged mixtures of P. sylvestris and P. nigra in Catalonia were developed using a past growth index as site descriptor. These models were compared to an earlier model, based on the same data, that did not use past growth as a predictor. The growth index was calculated as a ratio of the measured and predicted past growth of sample trees within a given stand, the predictors pertaining to an average site. The models for future growth were based on 7 982 and 5 673 observations, and the models for past growth on 1 997 and 1 686 observations for P. sylvestris and P. nigra, respectively. Due to the applied Snowdon correction, the biases for the diameter growth models were zero. The relative RMSE values were 56.3% for the earlier P. sylvestris model and 52.0% for the new model, and 48.7% for the earlier P. nigra model and 47.1% for the new model. The accuracy of stand-level predictions (10-year change in basal area of living pines in the inventory plots) was better for the new models (Bias % = 2.79 and RMSE % = 34.79) than for the earlier ones (Bias % = 3.27 and RMSE % = 41.54). The results indicate that the new models adapt to specific stand conditions better than models that omit past growth measurements. growth index / mixed models / mixed stand / Scots pine / black pine Résumé -Utilisation de la croissance passée pour l'évaluation du site dans des modèles non spatialisés de croissance en diamètre pour des peuplements irréguliers et mélangés de Pinus sylvestris L. et Pinus nigra Arn. en Catalogne (Nord-Est de l'Espagne). Dans cette étude, des modèles de croissance en diamètre pour des peuplements irréguliers et mélangés de Pinus sylvestris L. et Pinus nigra Arn. en Catalogne ont été développés en utilisant un indice de croissance passée comme prédicteur du site. Ces modèles étaient comparés avec un modèle antérieur, à partir des mêmes valeurs, qui n'utilisait pas la croissance passée comme prédicteur. L'indice de croissance a été calculé comme un rapport de la croissance passée mesurée et la croissance passée prédite des arbres échantillonnées dans une placette donnée, avec des prédicteurs concernant un site moyen. Les modèles pour la croissance future correspondent à 7 982 et 5 673 observations, et les modèles pour la croissance passée à 1 997 et 1 686 observations pour P. sylvestris et P. nigra, respectivement. Les biais pour les modèles de croissance en diamètre sont zéro en raison de l'application de la correction de Snowdon. Les valeurs relatives du RMSE étaient 56.3 % pour le modèle antérieur de P. sylvestris et 52.0 % pour le nouveau modèle, et 48.7 % pour le modèle antérieur de P. nigra et 47.1 % pour le nouveau modèle. La précision des prédictions au niveau des placettes (dérive en surface terrière pour 10-années des arbres vivants dans les placettes d'inventaire) était meilleure pour les nouveaux modèles (Biais % = 2.79 et RMSE % = 34.79) que pour les modèles antérieures (Biais % = 3.27 et RMSE % = 41.54). Les résultats indiquent qu...

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Section: Discussionmentioning

confidence: 99%

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

Trasobares

Pukkala

2004

Ann. For. Sci.

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“…It differs from direct search methods so that, instead of seeking optimal values for continuous decision variables, it finds the optimal sequence of stand states defined by classified values of several growing stock characteristics (for instance, basal area, mean diameter, and stand age). Direct search methods can be used in both even-aged and uneven-aged forestry (Trasobares and Pukkala 2005). Uneven-aged management can also be optimized using linear programming and a transition matrix model (e.g.…”

Section: Introductionmentioning

confidence: 99%

Population-based methods in the optimization of stand management

Pukkala¹

2009

Silva Fenn.

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In Finland, the growth and yield models for tree stands are simulation programs that consist of several sub-models. These models are often non-smooth and non-differentiable. Direct search methods such as the Hooke-Jeeves algorithm (HJ) are suitable tools for optimizing stand management with this kind of complicated models. This study tested a new class of direct search methods, namely population-based methods, in the optimization of stand management. The tested methods were differential evolution, particle swarm optimization, evolution strategy, and the Nelder-Mead method. All these methods operate with a population of solution vectors, which are recombined and mutated to obtain new candidate solutions. The management schedule of 719 stands was optimized with all population-based methods and with the HJ method. The population-based methods were competitive with the HJ method, producing 0.57% to 1.74% higher mean objective function values than HJ. On the average, differential evolution was the best method, followed by particle swarm optimization, evolution strategy, and Nelder-Mead method. However, differences between the methods were small, and each method was the best in several stands. HJ was alone the best method in 7% of stands, and a population based method in 3% (Nelder-Mead) to 29% (differential evolution) of stands. All five methods found the same solution in 18% of stands.

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“…In Table 3, we provide the stumpage prices we used in the objective function. Industrial destinations and diameter classes considered are based on those used in previous studies [27,31]. The regression models adjusted to these data appear in Figure 2.…”

Section: Stumpage Value Modelmentioning

confidence: 99%

“…pallasiana in Turkey, and from the observed data, they estimated an overall annual mortality rate of 1.41%, equivalent to a 13.24% mortality rate in a 10-year period. Trasobares and Pukkala [27] As shown in the Introduction, the "sustainable/stable" harvesting strategy is aimed at reaching in each harvest the proportions of stems/ha in each class corresponding to the stable diameter distribution of the stand, yielding the following "sustainable/stable" harvest rate: s = for all the diameter classes and time steps (s also includes the natural mortalities). This rate corresponds to the case in which the right eigenvector associated with the dominant eigenvalue Ȝ = 1 of the transition matrix with harvests is W 0 .…”

Section: Natural Mortalitiesmentioning

confidence: 99%

Are the Economically Optimal Harvesting Strategies of Uneven-Aged Pinus nigra Stands Always Sustainable and Stabilizing?

López-Torres

Ortuño-Pérez

García-Robredo

et al. 2013

Forests

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Traditional uneven-aged forest management seeks a balance between equilibrium stand structure and economic profitability, which often leads to harvesting strategies concentrated in the larger diameter classes. The sustainability (i.e., population persistence over time) and influence of such economically optimal strategies on the equilibrium position of a stand (given by the stable diameter distribution) have not been sufficiently investigated in prior forest literature. This article therefore proposes a discrete optimal control model to analyze the sustainability and stability of the economically optimal harvesting strategies of uneven-aged Pinus nigra stands. For this model, we rely on an objective function that integrates financial data of harvesting operations with a projection matrix model that can describe the population dynamics. The model solution reveals the optimal management schedules for a wide variety of scenarios. To measure the distance between the stable diameter distribution and the economically optimal harvesting strategy distribution, the model uses Keyfitz's delta, which returns high values for all the scenarios and, thus, suggests that those economically optimal harvesting strategies have an unstabilizing influence on the equilibrium positions. Moreover, the economically optimal harvesting strategies were unsustainable for all the scenarios. OPEN ACCESSForests 2013, 4 831

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Optimising the management of uneven-aged Pinus sylvestris L. and Pinus nigra Arn. mixed stands in Catalonia, north-east Spain

Cited by 37 publications

References 28 publications

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

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

Population-based methods in the optimization of stand management

Are the Economically Optimal Harvesting Strategies of Uneven-Aged Pinus nigra Stands Always Sustainable and Stabilizing?

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