ABSTRACT Background: This article aims to provide information on the diameter distribution of naturally regenerated forests of Taurus cedar (Cedrus libani A. Rich), a tree species endemic in the mountains of the Eastern Mediterranean basin and assess their prediction ability with the Johnson SB distribution. Previous research attested to the flexibility of Johnson family distributions to mimic empirical diameter data for a large set of tree species, justifying its use for the case study. A set of 134 plots (400 m2) were sampled in the most represented areas of the distribution of the species in Türkiye and diameter at breast height was measured in all the living trees. The cedar forests displayed heterogeneous diameter structures with diameters range from 10 to 116 cm and irregular shapes (e.g. unimodal, bell-shaped, left- and right-skewed, and non-uniform). Over three-quarters of the empirical diameter distributions (104 sample plots) were classified as SB distribution. The remaining were classified as bounded at the lower end, SL (16) or unbounded, SU (14). The authors essayed the 3-parameter and 4-parameter recovery methods after Parresol and Fonseca and other´s fundamental studies. The 3-parameter recovery method outperformed the 4-parameter method in the convergence criterion and error index (EI) expressed in the basal area. Results: Results show that the Johnson SB distribution can adequately reproduce the high variability in diameter for most of the distributions observed in these natural forests, providing reliable estimates which can serve as a basis for decision support systems. Conclusion: The SB distribution can represent the diameter distributions of natural cedar forests, even if the empirical distributions are not in the region covered by this distribution.

ABSTRACT In Portugal, chestnut wood demand has increased in the last decades. Since chestnut plantations are usually established in low fertility soils, addition of N, P and K as fertilizers usually have a benefic effect in increasing wood productivity. The study aims to evaluate the effects of fertilization on growth of chestnut tree (Castanea sativa Mill.) cultivated for wood purposes. An experimental essay was established in a 3-year old chestnut tree stand with a planting spacing of 3.5 × 3.0 m. Four treatments were applied to randomized blocks with three repetitions: control (C), addition of phosphorus (P), addition of phosphorus and potassium (PK) and addition of nitrogen, phosphorus, and potassium (NPK). The chemical properties of the soil and the concentration of nutrients in the leaves were evaluated after the treatment, and measurements of tree diameter and stem height were made for a monitoring period of 4 years. Treatments did not affect soil properties or leaf nutrient concentrations. On the counterpart, the effect of the fertilizers was noticed for tree dimensions and growth. Gains of NPK in relation to the control were observed for the height variable, over the years. Seven years after application of the treatments, differences were also noticed for the diameter and the volume index variables. The NPK treatment has presented a significant effect on tree growth compared to the control, with noticeable gains in the stem height.

Neste trabalho conjuga-se a exploração sustentável de material lenhoso com a avaliação da capacidade de propagação de fogo em pinheiro bravo num conjunto de 5 áreas comunitárias (baldios), no Norte de Portugal, para o período de 2012 a 2016. Foram considerados dois cenários: ausência de intervenção versus implementação de um plano de exploração. Para obter o plano usou-se um modelo de otimização visando a maximização do material lenhoso removido, considerando um conjunto de restrições. As caraterísticas do fogo foram determinadas com recurso ao simulador PiroPinus. Para cada parcela, registou-se a capacidade de propagação do fogo ao nível de vegetação de sub-bosque (fogo de superfície) e a propagação do fogo às copas, distinguindo-se neste caso, fogo de copas passivo ou ativo, dependendo da velocidade da propagação do fogo. Em 2012 havendo deflagração, cerca de 1/3 da área é propensa a fogo de copas. Em 2016 verificou-se uma redução nessa proporção, quer se adote ou não o plano de exploração. Isto deve-se ao estado de desenvolvimento dos povoamentos (maturidade) e à sua evolução natural, cujo crescimento se traduz num aumento da altura média a que se encontram as copas com uma concomitante redução na possibilidade de propagação do estrato superficial às copas.

Cette étude combine une gestion durable des forêts pour la production de bois à l’évaluation de la propagation du feu, dans une forêt de pin maritime situé dans la région nord du Portugal, au cours de la période 2012-2016. La zone d’étude se réfère à 1393 ha, répartis entre cinq terres communes appelées zones Baldio. Deux scénarios ont été analysés: l’absence d’intervention contre l’éclaircie et coupe rase utilisant un plan de gestion forestière. Le plan a été obtenu par un modèle d’optimisation dont le but est de maximiser le bois prélevé étant donné un ensemble de contraintes. Les caractéristiques du feu ont été déterminées avec le simulateur PiroPinus. La sortie individualise le feu de surface des feux de canopée, en distinguant dans le cas de la canopée, un feu passif ou actif, en fonction de la vitesse de propagation du feu. En 2012, la proportion de la zone sujette aux feux de canopée est de 1/3 environ. En 2016, cette proportion diminue. Cela est dû à la phase de développement des peuplements étudiés (maturité) et à l’évolution naturelle de la forêt. La hauteur de la couronne augmente avec l’âge du peuplement avec une réduction simultanée de la possibilité de propagation du feu à la canopée.

This study combines a sustainable forest management for timber production with the assessment of the spread of fire, in a maritime pine forest located in the northern region of Portugal, during the period 2012-2016. The study area refers to 1393 ha, distributed among five common lands called baldio areas. Two scenarios were analyzed: absence of intervention versus thinning and clear-cutting scheduling using a timber management plan. The plan was obtained by an optimization model where the goal is to maximize the removed timber given a set of constraints. The characteristics of the fire were determined with the simulator PiroPinus. The output individualizes between surface fire and crown fire, distinguishing in the case of the canopy layer, a passive or active crown fire, depending on the speed of spread of fire. In 2012 the proportion of area prone to crown fire is around 1/3. In 2016 that proportion decreases. This is due to the stand development stage of the studied stands (maturity) and to the natural evolution of the forest. The crown height increases with stand age with a simultaneous reduction in the possibility of fire spreading to the canopy layer.