María Pasalodos-Tato

Optimal management of Pinus pinaster in Galicia (Spain) under risk of fire

Pinus pinaster is the most important conifer in Galicia in terms of volume and production, occurs mainly in plantations. Forest fires are the main threat to forest plantations, affecting optimal stand management. The aim of this study was to develop management prescriptions for P. pinaster based on growth and yield models and optimisations. The objective function was soil expectation value, calculated taking the expected fire losses into account. Fire risk was assumed to consist of two components, probability of occurrence and damage. As the main cause of forest fires in Galicia is arson, the manager cannot significantly influence fire occurrence, which was assumed to be exogenous. Salvage was treated as an endogenous factor depending on the management schedule followed in the stand. Optimisations were done for different initial stands, timber assortments, discount rates and probabilities of fire occurrence. Based on the optimisation results, regression models were developed for the optimal rotation length as well as the timing and intensity of thinnings. The results show that when fire risk is partly endogenous, optimal rotation lengths become shorter with increasing probability of fire occurrence, and optimal thinning becomes heavier and earlier. However, without a price reduction for burned timber, the optimal rotation length increases with increasing probability of fire.

Optimising the management of even-aged Pinus sylvestris L. stands in Galicia, north-western Spain

The study developed management instructions for even-aged Pinus sylvestris stands in Galicia (north-western Spain). Although these stands are highly productive, no silvicultural management schedules have been proposed so far for them on the basis of systematic analyses. This study used data from 2160 optimisation runs to develop the management instructions. Land expectation value was used as the objective function. Different prices of timber assortments were considered and the discounting rate was varied from 0.5 to 5%. The method employed to find the optimal management schedules of stands was the combination of a stand simulator and an optimisation algorithm. The simulator uses an earlier growth and yield model for Pinus sylvestris in Galicia to predict the future development of the stand with a given management schedule while the optimisation algorithm seeks the best management schedule among all the possible alternatives. The results show that optimal rotation lengths vary widely between 42 and 170 years, high discounting rates and good site quality resulting in the shortest rotations. Four thinnings were found to be suitable for all sites and discounting rates. With discounting rates higher than 1% the commercial thinnings should gradually decrease the stand basal area towards the end of the rotation.RésuméCette étude développe des instructions de gestion pour des peuplements de Pinus sylvestris en Galice (Nord-ouest de l’Espagne). Bien que ces peuplements soient hautement productifs, aucun plan de gestion sylvicole basé sur des analyses sytématiques, n’a jusqu’ici été proposé. Cette étude utilise les données de 2 160 séquences d’optimisation pour développer des instructions de gestion. Une attente de valeur foncière a été utilisée comme fonction-objectif. Différents prix de lots de bois ont été pris en compte et le taux d’escompte a varié de 0,5 à 5 %. La méthode employée pour évaluer le programme optimal de gestion a été la combinaison d’un simulateur de croissance de peuplement et d’un algorithme d’optimisation. Le simulateur utilise un modèle existant de croissance et de production de Pinus sylvestris en Galice pour prédire le développement du peuplement pour un plan de gestion tandis que l’algorithme d’optimisation recherche le meilleur plan gestion parmi toutes les alternatives possibles. Les résultas montrent que la durée optimale de rotation varie entre 42 et 170 ans. Des taux d’escompte élevés et des stations de bonne qualité permettent les révolutions les plus rapides. Quatre éclaircies semblent appropriées pour toute les stations et tous les taux d’escompte. Avec des taux d’escompte plus élevés que 1 % les éclaircies commerciales doivent abaisser graduellement la surface terrière des peuplements vers la fin de la rotation.

The Importance of Industrial Forest Plantations

The first chapter of the book initially addresses the definition of planted forests, industrial forests and industrial forest plantations. It also contextualizes historically the evolution of the term forest plantations, citing the several international organizations involved and different attempts to satisfy many actors and opinions. Facts and figures are also presented to illustrate the evolving roles that forest plantations have undertaken over the years. Some comprehensive statistics are included to emphasize the importance and benefits of its expansion. The chapter also presents some important future trends that guide the need for the forest planning and forest management techniques discussed in the book. These tools may overcome the challenges brought by the more complex and conflicting social, economic and environmental goals confronted by the forest sector. Although regularly challenged by new technological advances, it is important to realize that trees are still one of the most efficient ways to produce highly demanded materials, with minimal collateral negative impacts. The argument stands in the principle that, being a renewable organism that synthesizes carbon fueled by sun light, the sustainable use of planted forests reduces the impact over other natural resources and fossil fuels. Furthermore, the antagonism between planted forests and natural forests has diminished, as well as its complementary and compatible coexistence with wild land native forests in many different landscapes and regional contexts.

Evaluation of tree biomass carbon stock changes in Andalusian forests: comparison of two methodologies

ABSTRACT Carbon sequestration has become an important issue in forest management in the light of concerns about global warming. The two methods proposed by IPCC to quantify the net carbon sequestered by trees are based either on the estimation of annual gains and losses of carbon due to the growth of trees and their removals (default method), or on the difference in carbon stocks between two consecutive inventories (stock-change method). The objectives of this study are to compare the net carbon sequestered by the tree layer of forest ecosystems in Andalusia estimated by the two methods, and to identify what measured variables contribute the most to the differences in the estimations. Multivariate analysis was performed in order to identify the causes of these variations. The results revealed differences of up to 200% in the estimated net carbon sequestration depending on the methodology employed, and changes in the direction of the capture/emission in some areas. The net carbon sequestration ranged between 0.08 ± 0.01 and 1.93 ± 0.52 Mg C ha−1 year−1 depending on the method used and on the tree species analyzed. In global terms, net carbon sequestration at the regional level reaches 2,101,715 ± 560,906 Mg C according to the default method and 1,693,412 ± 272,529 Mg C using the stock-change method.