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Com base em dados recolhidos em parcelas de amostragem instaladas na região do Vale do Tâmega, procedeu-se ao desenvolvimento de tabelas de produção para o pinheiro bravo. As variáveis de controlo do modelo de produção dizem respeito ao índice de qualidade e ao factor de espaçamento de Wilson. O diâmetro médio e o volume do povoamento antes do desbaste são determinados através de equações com estrutura semelhante às propostas por HALL e MARTINS (1986) para a região Centro Litoral. O diâmetro médio do povoamento secundário é estimado a partir do diâmetro médio do povoamento antes do desbaste, do número de árvores removidas e da razão entre o número de árvores removidas e o número de árvores em pé. A equação estabelecida para avaliação do volume retirado em desbaste é função do diâmetro médio e do número de árvores removidas. A produção total é calculada a partir do conhecimento do volume dos povoamentos principal e secundário e, com base naquele valor, são determinados os acréscimos corrente e médio anual. Os resultados encontram-se discriminados em três tabelas, de acordo com o nível de qualidade considerado (inferior, médio e superior). Data collected on sampling plots located in the Tâmega valley were used to develop yield tables for maritime pine. The control variables of this model refer to the site quality index and the Wilson spacing index. Mean diameters and stand volume before thinning are determined by modified versions of the equations proposed by HALL and MARTINS (1986) for the central coastal region of Portugal. The mean diameter of removed trees is estimated according to the mean diameter before thinning, the number of removed trees and the ratio between removed trees and the number of trees before thinning. The equation established for the prediction of the volume removed by thinning is a function of the mean diameter and the number of removed trees. Predicted removed and remaining volumes allow the calculation of the total production and, thereafter, the determination of current and mean annual increments. The results are indicated in three tables, according to the site quality level (low, medium and high). À partir des données récoltées au sein des placettes d'échantillon situées dans la vallée du Tâmega, on a développé des tables de production pour le pin maritime. Les variables déterminantes dans ce modèle de production concernent la classe de fertilité et le facteur d'espacement de Wilson. Le diamètre quadratique moyen et le volume du peuplement avant éclaircie sont determinés à partir des équations qui ressemblent à celles proposées par HALL et MARTINS (1986) pour la région du centre-littoral. Le diamètre moyen des arbres prélevés en éclaircie est estimé à partir du diamètre moyen des arbres du peuplement avant éclaircie, du nombre de tiges enlevées dans l'éclaircie et du rapport qui existe entre le nombre de tiges enlevées et le nombre de tiges du peuplement avant éclaircie. L'équation établie pour déterminer le volume de l'éclaircie dépend du diamètre quadratique moyen et du nombre d'arbres prélevé dans l'éclaircie. Après avoir estimé le volume du peuplement principal et les volumes enlevés par les éclaircies, on peut calculer la production totale en volume. Ensuite, à l'aide de cette information on peut déterminer les accroissements courant et moyen annuel. Les resultats sont presentés dans trois tableaux selon le niveau de qualité de la station (inférieur, moyen et supérieur).

Natural disturbances play a key role in ecosystem dynamics and are important factors for sustainable forest ecosystem management. Quantitative models are frequently employed to tackle the complexities associated with disturbance processes. Here we review the wide variety of approaches to modelling natural disturbances in forest ecosystems, addressing the full spectrum of disturbance modelling from single events to integrated disturbance regimes. We applied a general, process-based framework founded in disturbance ecology to analyze modelling approaches for drought, wind, forest fires, insect pests and ungulate browsing. Modelling approaches were reviewed by disturbance agent and mechanism, and a set of general disturbance modelling concepts was deduced. We found that although the number of disturbance modelling approaches emerging over the last 15 years has increased strongly, statistical concepts for descriptive modelling are still largely prevalent over mechanistic concepts for explanatory and predictive applications. Yet, considering the increasing importance of disturbances for forest dynamics and ecosystem stewardship under anthropogenic climate change, the latter concepts are crucial tool for understanding and coping with change in forest ecosystems. Current challenges for disturbance modelling in forest ecosystems are thus (i) to overcome remaining limits in process understanding, (ii) to further a mechanistic foundation in disturbance modelling, (iii) to integrate multiple disturbance processes in dynamic ecosystem models for decision support in forest management, and (iv) to bring together scaling capabilities across several levels of organization with a representation of system complexity that captures the emergent behaviour of disturbance regimes. (C) 2010 Elsevier B.V. All rights reserved.

Roundwood scaling requires measuring dimensions and determining a wood quality class. That can be done at the different time intervals from tree cutting, in which some wood faults can appear, for example fissures and insect attack, etc. This research aims to determine how insect attacks can influence the determination of the wood quality class regarding the fact that the roundwood scaling was done in different time intervals from cutting. The research was conducted in the summer period of 2021 during selection cutting of Silver fir (Abies alba Mill.) and Norway spruce (Picea abies (L.) Karst.) trees. In that period, ambrosia beetles (Pityokteines sp.) were not determined and insect attacks on Silver fir were not found. The buck-to-quality method was applied, and the roundwood scaling was done according to the European HRN EN 1927-1 standard. Data collecting (diameter, length, quality class, wood faults, and insect presence) was done by a newly designed computer module. According to the standard, damages caused by insects are not allowed in the first (A) and the second (B) quality class. The damage caused by bark beetles (< 2 mm) i. e. Ips typographus (L ; ), are only in the bark without decreasing log's utilization, so they were not considered in the initial quality class determination, but they were recorded. Data analysis and quality class modification with damage from insect attacks (< 2 mm), resulted in a reduction of A class assortments by 1.2% and B class assortments by 3.1% increasing the share of C class assortments by 4.4%. Based on the research results the modification of the classification standard should be considered in order to more clearly define the type and the intensity of the insect attack not permitted in the higher quality classes.