Growth in world demand for wood implies a search for new fast growing species with silvicultural potential, and in this scenario for native species such as Paricá . Thus, the objective of this study was determining the physical and mechanical wood properties of the Schizolobium amazonicum species (known as Paricá in Brazil). Trees were collected from commercial plantations located in the north of Brazil with ages of 5, 7, 9 and 11 years. Four logs from trees of each age in the longitudinal direction of the trees were obtained, and later a diametrical plank of each log was taken to manufacture the specimens which were used to evaluate some physical and mechanical properties of the wood. The basic density of Paricá was reduced in the basetop direction and no difference between the radial positions was observed, while the average basic density of this wood was characterized as low. The region close to the bark showed less longitudinal contraction and also greater homogeneity of this property along the trunk, while for tangential contraction the smallest variation was found in the region near the pith. Paricá wood contraction was characterized as low. Age influenced most of the mechanical properties, where logs from the base had the highest values of mechanical strength.

RESUMO Considerando as atividades de colheita florestal mecanizada, este estudo teve como objetivo avaliar o sistema homem-máquina a fim de verificar a influência dos fatores ergonômicos na produtividade do conjunto. Foram selecionados três modelos de harvesters e três de forwarders, atuando em uma empresa florestal no Brasil. Os dados de produtividade das máquinas foram compilados a partir dos relatórios operacionais mensais das atividades da empresa, de janeiro a dezembro de 2018. As máquinas foram avaliadas de acordo com as orientações contidas no manual de classificação ergonômica Ergonomic Guidelines for Forest Machines do Instituto de Pesquisa Florestal da Suécia. Para avaliar o risco ergonômico das atividades para os operadores de máquina, foi utilizado o Índice TOR-TOM, o qual considera as taxas de ocupação real (TOR) e a taxa de ocupação máxima (TOM) durante o desenvolvimento de suas atividades. No período avaliado, os resultados mostraram que a produtividade média dos conjuntos de máquinas ficou abaixo do planejado, embora as taxas de utilização dessas máquinas tenham ficado acima das expectativas. Foi constatada forte correlação negativa entre a produtividade do sistema e os parâmetros ergonômicos das máquinas e das atividades, sem interferência das variáveis idade das máquinas e tempo de experiência dos operadores. As máquinas avaliadas apresentaram padrões ergonômicos deficientes em quase todos os aspectos avaliados, indicando que, ao operar em condições de solo e clima desfavoráveis, apresentam riscos ergonômicos aos seus operadores. O resultado do Índice TOR-TOM para as atividades de operação de ambas as máquinas indica claramente uma situação de trabalho com risco ergonômico presente, sem aproveitamento ótimo da força de trabalho, resultando em perdas de produtividade do sistema. Conclui-se que existe forte influência negativa dos fatores ergonômicos na produtividade do sistema homem-máquina nas atividades de colheita florestal, contribuindo para perdas operacionais e adoecimento do trabalhador.

The objective of this study was to determine the effects of tree age and of pith-bark and base-top positions on anatomical characteristics, and the effect of age on the chemical components of Schizolobium amazonicum (Paricá wood). The material was obtained from commercial plantations in the states of Maranhão and Pará with ages of 5, 7, 9 and 11 years. The first three logs (2.7 m length each) were obtained from the trees of each age. Only the effect of age was analyzed for the chemical characterization of the wood. The dimensions of the fibers increased along the pith-bark direction, while wall thickness decreased and the length of the fibers increased with aging. The width of the fibers and the lume diameter increased in the base-top direction. Paricá wood presented low extractive and hemicellulose content, and high cellulose content. The anatomical characteristics were more affected by the factors under study than the chemical composition, evidencing that the chemical elements of the wood are more stable with aging in relation to the anatomical characteristics.

In the wood processing industry, working with machines exposes workers to occupational risks. This study evaluates the biomechanics of work activities carried out in a wood processing operation in tropical forest regions in order to identify risks associated with the development of musculoskeletal injuries. Data were collected in a wood processing industry from tropical forest region in Midwest Brazil. Forty forest workers were evaluated, equivalent to 100% of the population of the company participating in the study. Biomechanical movements were measured using the Three-Dimensional Biomechanical Model for Predicting Stances and Static Forces (3DSSPPTM). There was a risk of injury to the joints of the upper limbs (wrists and shoulders), as well as to the torso. When splitting and manually stacking of wood, a risk of spinal injury was identified. All workers had a high risk of developing injuries in all joints evaluated in addition to risk of serious spinal injury. In this way, the development of these activities without any ergonomic interventions, makes the risk of developing musculoskeletal injuries in the workers involved imminent, with consequent early professional incapacity.