O conhecimento das relações existentes entre a estrutura anatômica da madeira com suas propriedades físicas ou mecânicas é importante para seu uso adequado. Este trabalho teve como objetivo caracterizar a anatomia microscópica e propriedades físicas da madeira de quatro diferentes espécies florestais. A madeira estudada foi proveniente das seguintes espécies: Cedrela fissilis (Cedro), Híbrido clonal Eucalyptus urophylla × Eucalyptus grandis (Eucalipto urograndis), Hovenia dulcis (Uva do Japão) e Gallesia integrifolia (Pau d'alho). Para a determinação da retratibilidade, utilizou-se a norma MB26/40 da ABNT (1940); as dimensões lineares foram obtidas com palmer, precisão de 0,001mm. O estudo da anatomia da madeira seguiu as recomendações da norma de procedimento em estudos de anatomia de madeira, da COPANT (1974) e também da IAWA (1989). Os caracteres anatômicos avaliados foram: diâmetro tangencial (µm) e frequência de vasos (n^omm^-2); comprimento de fibra (µm), diâmetro de lume (µm) e espessura de parede de fibra (µm); altura (µm), largura (µm) e frequência de raios (n^omm^-1). Os valores do coeficiente anisotrópico foram de 1,16; 1,77; 1,81 e 1,84 para a madeira de C. fissilis, H. dulcis, Híbrido clonal e G. integrifolia, respectivamente, demonstrando que a madeira de C. fissilis possui elevada estabilidade dimensional e as demais madeiras, valores aceitáveis para esse coeficiente.

A secagem natural é uma alternativa que pode ser empregada como pré-secagem ou secagem definitiva para diversas madeiras com baixo custo e condições simples de trabalho. O presente trabalho foi realizado com o objetivo de estudar o comportamento das curvas características de secagem ao ar livre de tábuas de Acacia mangium e Tectona grandis. Árvores de cada espécie com idade de 15 anos foram abatidas, com toras de aproximadamente 3 m. Essas foram desdobradas utilizando-se o sistema de cortes tangenciais para a obtenção das tábuas de 3,0 cm de espessura. Instalada a pilha de madeira para a secagem, a umidade inicial das amostras foi determinada e o acompanhamento foi realizado por meio de pesagens periódicas das amostras de controle. Observou-se que nas condições ambientais expostas, a madeira de Acacia mangium secou mais lentamente ao ar livre que a madeira de Tectona grandis. Recomenda-se a análise da curva de secagem para cada espécie separadamente.

Cuatro métodos de evaluación visual del riesgo se aplicaron en 30 árboles urbanos con niveles de riesgo en la ciudad de Talca (Chile). Los métodos utilizados fueron: “Avaliação de árvores de risco na arborização de vias públicas de Nova Olímpia” (método Sampaio), “Internation Society of Arboriculture (ISA) Matheny y Clark” (método ISA[A]), “Best Management Practice BMP/ISA” (método ISA[B]) y “Urban tree risk management USDA Forest Service” (método USF). Los resultados fueron estandarizados para su análisis estadístico, se encontraron diferencias significativas y variaciones en los métodos al aplicar el test no paramétrico de Kruskal-Wallis y de Duncan. Se conformaron tres grupos: los métodos Sampaio y USF, que presentaron evaluaciones con riesgo muy alto y alto, respectivamente; el segundo, conformado por USF e ISA(A), presentó evaluaciones de alto a medio riesgo; mientras que un tercer grupo lo conformó ISA(B), con evaluaciones de riesgo bajo. Ya que la ciudad de Talca no cuenta con una metodología propia, se sugiere usar en el área mediterránea de Chile el método ISA(A) o USF, ya que fueron los métodos que presentaron una mejor adecuación a las condiciones locales.

Understanding how thinning strategies impact wood quality and quantity for different purposes is of interest, given that plantation management is often based on parameters that require validation under varying growth conditions. Planted forests for solid purposes in the northern region of Urugay, western Argentina and South of Brazil are usually managed in initial stockings ranging from 800 to 1200 trees·ha⁻¹ depending on the use of clones or seeds. Subsequent thinnings are applied (at plantation ages varying from 3 to 11 years) up to final stockings of around 200 trees·ha⁻¹. This study evaluated contrasting thinning regimes applied early in the crop cycle, with an initial tree density of 840 trees·ha⁻¹. Two thinning treatments were applied at 1.5 and 7.3 years, reducing tree densities to 700–400 and 400–100 trees·ha⁻¹, respectively. Growth analyses were conducted from 1.5 to 20.8 years, considering total height, diameter at breast height, individual volume, total and commercial volume per hectare, mean annual increase, and current annual increase. At the final harvest, contrasting tree densities of 100, 250, and 400 trees·ha⁻¹ were sampled to assess wood density and mechanical properties (bending and compression on small-scale clear samples). Individual growth and wood properties were related to a Stand Density Index to understand the effect of competition on these values. The results identified thinning regimes that resulted in the most significant individual and per-hectare growth (both in thinning and clear felling) and the optimal harvest time under specific growth conditions. We assessed the proportions of commercial logs for sawmill and pulp uses, providing valuable inputs for subsequent economic analyses of thinning regimes aiming for the most convenient combination of wood products. Wood’s physical and mechanical properties were relatively little affected by contrasting levels of competition between trees; therefore, the choice of silvicultural system will depend on production and economic criteria.

In the last few years, the interest in keeping the city trees healthy has increased in order to improve their survival and minimize claims due to potential accidents. The pest and diseases, the pollution, and the climate change together with the little genetic diversity of trees in urban areas are some of the factors that contribute to increase the likelihood of death and/or failure of trees in the cities. This work is part of a sanitary and risk of failure assessment of plane street trees (Platanus x acerifolia) carried out between 2019 and 2020. A random sample of 10 city blocks and their 193 plane trees was selected. In these, the presence of cankers, abnormal bark colorations, deformations, and a series of structural attributes that determine likelihood of failure variables were registered. The proportion of individuals with each symptom and the severity main index (SMI) were calculated as a weighted average of the different severity (SEV) levels in the total of evaluated plants. The severity indices were determined according to trunk or branches circumference and the portion of the tree affected (1st, 2nd or 3rd portion from the base). Deformations presented the main incidence (0.6), SMI (1.68) and a correlation with the presence of damages and human injuries. The presence of cankers and reddish bark were the symptoms that most affected the density of the crowns.

The risk assessment of urban trees is a challenge that must be addressed by many cities, in consideration of their climatology, management and spatial heterogeneity. Since these trees are in stages of aging, added to bad practices, inadequate selection and establishment, amongst others, their early elimination, and hence the loss of the ecosystem services they provide, is being promoted. For this reason, two tree risk assessment methods were developed to be applied in a complementary manner in urban parks, one basic visual (BV) and the other detailed visual (DV), both structured with the components of likelihood of failure, likelihood of impact, consequence and risk rating, being analyzed qualitatively and semi quantitatively. The methods were applied in 24 trees of Eucalyptus and Tipuana genus by two groups of assessors, experienced and inexperienced, totaling 192 assessments. Results were analyzed with a linear mixed model (LMM), which showed differences between both methods for the likelihood of failure, where the assessment of branches turned out to be the attribute with the highest impact. The methods proved to be suitable to be used in a complementary manner, since BV turns out to be efficient when it is necessary to assess a large number of trees. DV turned out to be more effective, since it was able to identify more precisely the attributes of the tree that must be considered for adequate risk mitigation and management. Therefore, their combined use is recommended for risk assessment in trees established in parks.