No abstract

No abstract

The production of eucalyptus for the cellulose and paper industry is based on the cultivation of clones, which are obtained by crossing species with desirable characteristics. However, clones that were considered to have great potential have presented serious problems because of permanent bending and breakage, which are caused mainly by wind forces during the early years of growth. Wave propagation methods have shown great potential in applications related to predicting the stiffness of logs and lumber. Based on the premise that the stiffness of the stem is a major contributor to a tree's resistance to the wind, the objective of the present study was to determine whether an ultrasound wave propagation test performed directly on trees would have the sensitivity within a sample group to differentiate between clones and whether this differentiation would be consistent with the differences in stiffness between them. The stem was used to evaluate the stiffness of clones rather than logs, pieces of a structural size, or specimens. A cantilever static scheme and the application of a load near the top of the stem were intended to simulate field conditions. A total of 189 trees were tested from 21 different clones. To differentiate the clones, the ultrasound wave propagation velocity was obtained directly from the trees. The velocity differences among the trees were consistent with the results obtained using the stem stiffness of the same trees.

Early selection of trees allows acceleration of genetic improvement, as well as processes related to forest management, to improve the quality of the wood produced; however, to reach this objective, it is necessary to know which parameters can be used as predictors of a tree’s aged condition. The objective of this research was to study parameters that are measurable in nursery seedlings and that could be used in prediction models of basic density (BDt), modulus of elasticity (EMt), and strength (fmt) of wood from trees. The tests were performed in 240 seedlings (3 and 6 months old) and in 52 trees (72 months old) from seven genetic units of two species: three Eucalyptus clones and four Pinus pinaster progenies. In the seedlings, measurements of longitudinal velocity of ultrasonic waves (VLs), basic density (BDs), height (Hs), diameter (Ds), strength (fts), and modulus of elasticity (Ets) in tension parallel to the grain were obtained. The EMt and fmt can be predicted by parameters obtained in seedlings of the same genetic unit. Thus, the use of these parameters, in association with others already used in selection programs, may increase the positive results of the early selection, with economic gains and time reductions in forest management.

O conhecimento das propriedades da madeira é de extrema importância para o setor florestal e para o estudo da arborização urbana. Entre essas propriedades, a densidade se destaca por apresentar correlação com diversas outras propriedades do material. Ensaios não destrutivos são cada vez mais utilizados pelo setor florestal para determinação das propriedades da madeira sem a necessidade do corte da árvore. O trado de Pressler é um equipamento comumente utilizado na retirada de amostragem de árvores para a determinação de densidade. Em parceria com Universidades da Espanha, foi desenvolvido um dispositivo extrator de madeira, para ser acoplado a uma furadeira comercial, que gera amostragem, a partir de material coletado na árvore viva, capaz de ser utilizada na determinação da densidade do material. O objetivo dessa pesquisa foi avaliar a eficiência do WoodEx (Wood Extractor) na determinação da densidade de árvores. Para isso foram coletadas amostras provenientes de 6 espécies encontradas na arborização urbana utilizando Trado de Pressler e o WoodEx, que foram utilizadas para a determinação das densidades básicas médias de cada uma das espécies. Os resultados obtidos pela amostragem do WoodEx foram comparados aos resultados obtidos pela amostragem do trado. Embora os dados obtidos a partir do WoodEx tenham se apresentado numericamente menores do que os dados provenientes das amostras do Trado de Pressler, houve forte correlação entre as amostragens.