RESUMO: "Variação sazonal dos teores de taninos em cascas de espécies de barbatimão". A composição de taninos em cascas de espécies de barbatimão, Stryphnodendron adstringens (Mart.) Cov. and S. polyphyllum (Mart.), foi analisada mensalmente durante um ano. Os resultados foram correlacionados com as condições climáticas do período de coleta (precipitação, umidade e temperatura média) através de métodos quimiométricos. Análise de componentes principais dos dados mostrou uma tendência de maior produção de taninos na estação quente e chuvosa, sugerindo que os fatores ambientais podem afetar os teores de taninos nestas espécies.

ABSTRACT:This work aimed to analyze the pattern of variation in wave lengths in presence of wood holes and to develop a model capable of describing the process. To attain that end, wood pieces were used from species pequiá (Aspidosperma desmanthum), on which circular and linear artificial holes were made and gradually enlarged. Ultrasonic tests were performed using USLab equipment and 45 kHz transducers. Measurements were taken first on the intact piece and then after each stage of artificial hole enlargement. Results demonstrated that propagation velocities of ultrasonic waves are affected by presence of holes and also that reduction in velocity is caused by changes in wave path, since waves tend to deviate from empty space and travel through matter. The circular hole type had a slightly stronger influence on velocity reduction than the linear hole type. Variation in velocity as a function of increasing percentage of hollow space relative to the intact piece can be represented by a linear model.

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.

Errata-onde se lê: " ... obtenção do título de mestre em Enge nh ari a Agrícola.'• Leia-se: " ... obtenç ão do título de me stre em Enge nh aria Agrícola, na área de conc entração Construções Rurais e Ambiência.'' FICHA CATALOGRÁFICA ELABORADA PELA lll iv BIBLIOTECA DA ÁREA DE ENGENHARIA E ARQUITETURA BAE UNICAMP B32d