In biomechanical analyses, computational models are essential tools for simulating the behavior of a tree subjected to a load. However, such models allow only approximation of the actual behavior of the tree if the elastic parameters of the wood in different tree parts (stem, branches, and roots) and at least orthotropic behavior are not considered. In addition, as the wood is green, the parameters of strength and stiffness must be adequate for this level of moisture. However, even for stem wood, knowledge of elastic properties is not available for most species used in urban tree planting, and this scarcity of information is even greater for wood branches. The objective of this research was to evaluate methodology, based on wave propagation, in characterizing the 12 elastic constants of wood from branches. Complementarily, compression tests were performed to characterize the strength. The obtained elastic parameters using ultrasound tests were comparable with the values expected based on theoretical aspects related to the behavior of the wood. The results of the compression test complemented the ultrasound characterization, but the application of this method for the complete characterization of the elastic parameters is not feasible for tree branches because of their small size.

Wood-processing industries must be able to estimate the properties of wood to properly manage the wood production chain. For this estimation, changes in certain characteristics over time must be identified so that they can be used to rapidly differentiate a clone or species. Of interest are acoustical, geometrical, physical, and mechanical properties, all measurable in seedlings. Thus, the objective of this research was to analyze the evolution of the ultrasonic wave propagation velocity, diameter, height, basic density, strength, and stiffness starting in nursery seedlings at 3 months of age to trees at 6 years of age, which is the cutting age used by the pulp and paper industry in Brazil. The experiment was conducted in 121 seedlings and 270 trees of three Eucalyptus clones. Within the age range analyzed, the results indicated that all parameters have the potential to be used in a predictive model to estimate the future quality of clones, although the predictive value of these parameters varies. The ultrasonic wave propagation velocity was the only property that maintained the coherent differences among clones from the seedling to the cutting age (6 yr old). The strength, stiffness, diameter, and height maintained coherence from 12 months to the cutting age, whereas the basic density was maintained from the age of 24 months to the cutting age. We hope that these results will contribute to improving the methods to select clones.

The dimensional variables of trees play an important role in biomechanical studies that seek to estimate the risk of falls, since they influence their biomechanical behavior in relation to the forces to which they are subjected, and therefore, their safety factor. The aim of this research is to evaluate the effect of dimensional variables of trees on their mechanical behavior. A finite-element model was used to perform linear static analysis. The wood from the tree was considered clean, and the architectural model was based on dimensional variables of species commonly used in urban afforestation in São Paulo, Brazil. Different slenderness, tapering, height, and load level were used to analyze the tree mechanical behavior. The numerical-simulation model facilitates the evaluation of the influence of dimensional parameters of trees on deflections and stresses. The behavior of the deflections varies according to height, diameter, and loading level. Since the model considers the geometric variations of the section, the stresses show smooth variations along the trunk. The maximum module values of positive and negative stresses are not equal, and can undergo sudden variations in position along the trunk when local maximum stresses become global maximums.

In Spain, Eucalyptus nitens is distributed in the West of the Cantabrian Cornice, especially in the autonomous community of Galicia. Despite being mainly destined for paper pulp, in the last 15 years, eucalypts ( Eucalyptus globulus & E. nitens ) have been targeted as sawn timber for structural purposes in the country. In Europe, structural timber is graded according to the European standard EN 14081-1:2016+A1:CEN (2019). Timber structures – strength graded structural timber with rectangular cross section – part 1: general requirements (EN 14081-1), either visually or by machine, in order to determine the characteristic mechanical properties, as required by design standards. This study aimed to propose visual strength grading criteria for Spanish shining gum ( E. nitens ) and to assign its bending strength classes according to European Standards, based on four-point bending tests performed on full-size specimens. Considering the strength, stiffness, and density profile of the tested specimens – with characteristic values of 41.6 MPa for bending strength, 11.60 GPa for modulus of elasticity, and 453 kg/m ³ for density- the assignment of the strength class C35 was deemed adequate for the Spanish provenance shining gum timber graded to the “MEF” visual grade (structural timber from hardwood species). Furthermore, the relationship between global and local moduli of elasticity for the species was analyzed, and a formula was proposed to adjust the global to the local value.

In a global scenario of increasing the use of wood as a structure, the idea of making quality timber production compatible with other forestry activities, including resin extraction, has arisen. Implementing resin extraction practices can bring various socioeconomic benefits to forest communities during tree growing. However, the effects of resin extraction on wood quality are still unknown. Within this context, this research aimed to evaluate the quality of Pinus pinaster timber from resing trees. A total of 238 boards from resin-treated and control trees from two plots located in Galicia were evaluated. Non-destructive and bending tests were carried out according to European standards. The influence of the resin activity on the quality of wood was statistically analyzed. Statistically significant differences between samples of resin and control samples were analyzed for non-destructive, strength, modulus of elasticity, and density parameters. In general, it was observed that the resin activity did not affect the parameters analyzed.