The heterogeneity of characteristics observed in the pith-bark direction within a log causes sawn pieces of wood have different behaviors during water removal. Understanding these differences is important for the industry regarding the possibility of classification of the lumber into juvenile wood and mature wood, facilitating the drying in separate loads. Thus, this study aimed to evaluate the behavior of juvenile and mature wood samples of Eucalyptus saligna when subjected to drastic drying. In order to do this, test specimens were submitted to drastic drying at 100°C to obtain the drying times, drying rates and dimensions of end checks. These data were applied in equations to obtain the parameters initial temperature, final temperature and drying potential, used in the elaboration of drying schedules. In juvenile wood we observed that the basic density was lower and the initial moisture content was higher. Mature wood showed a lower drying rate. Drying schedules were developed separately for juvenile and mature wood, the drying schedule for the latter considered milder than the drying schedule developed for juvenile wood.

The objective of this study was to establish the correlation between the size of the wood knots and the modulus of elasticity (MOE) and the compressive strength (Fc) in Eucalyptus wood. 156 Eucalyptus urophylla samples with knots were separated into 3 classes (small, medium and large knots), and samples were selected from the same tree and submitted to the parallel fiber compression test for MOE and Fc determination. There was a significant difference between the MOE and Fc of the smaller knot class (Class 1) and the other classes with larger knots (Classes 2 and 3). In general, the larger the knot, the greater the difference between the MOE and Fc. Wood with small knots (8.31 mm 2 ) presents stiffness and strength statistically equal to wood free of defects. Eucalyptus wood stiffness is more sensitive to the presence of knots than the strength when compared to clear wood samples.

Currently, there is a little and sparse information about how the growing conditions influence the spatial variation of wood along the stem. Thus, the aim of this study was to compile the knowledge from literature in a manuscript for better understanding to what extent the growing conditions influence the spatial variation of wood properties in Eucalyptus plantations. The wood characteristics may present variations in their properties and can be caused by both genetic and environmental factors. However, how genetic and environmental factor acts on wood variation along the trunk is still unclear. Another point is that even with new genetic breeding programs, the mechanical properties of wood have not been considered in these programs, since the selection of new material is always based on the growing rate, cellulose and lignin content and wood density.

Esse trabalho teve como objetivo delimitar a idade de transição entre o lenho juvenil e o adulto de Eucalyptus pilularis, Eucalyptus saligna, Eucalyptus cloeziana e Corymbia maculata com 37 anos de idade, a partir da análise das variações no sentido medula-casca do comprimento das fibras e do ângulo microfibrilar. Duas árvores de cada espécie foram selecionadas, abatidas e tiveram discos cortados na base do tronco. Amostras foram retiradas do disco no sentido medula-casca para a determinação do ângulo das microfibrilas e do comprimento das fibras. O E. saligna apresentou o maior comprimento médio das fibras e a menor média do ângulo microfibrilar. As idades de transição estimadas pela análise da variação do comprimento das fibras foram menores do que aquelas estimadas pela análise da variação do ângulo microfibrilar. A análise de regressão linear response plateau permitiu estimar o ponto em que ocorre a estabilização do comprimento das fibras e do ângulo microfibrilar para as espécies avaliadas.

This study aimed to evaluate the behavior of samples of juvenile and mature Eucalyptus cloeziana wood when subjected to the drying process, and the influence of the anatomy on that behavior. In order to do this, saturated specimens from this woods measuring 10 × 5 × 1 cm were subjected to drastic drying at 100 °C, where the drying rates and the end check scores in different steps of the process were obtained. The fibers and vessels morphology, initial moisture and basic density were analyzed to help understanding the data obtained in the drying test. The juvenile wood presented 26% higher drying rate and 21% smaller drying time, also 53% higher end check score. Smaller fibers length and fibers wall thickness, higher vessels frequency and smaller vessels diameter were associated with higher total drying rate and water adsorption, as well as with the higher end check score.