DENDROCHRONOLOGICAL STUDY OF Brosimum utile (Kunth) Oken FROM TIMBIQUÍ, CAUCA, COLOMBIA

Brosimum utile (Kunth) Oken is a timber-yielding high-potential species with elevated rates of forest harvest at large-scale commercial transport in Colombia. In order to provide silvicultural management elements for natural forests, this study applied dendrochronological technique in a manner that promoted sustainable methods to manage the species. In this study, ten timber dicks using wood-sampling logs from Timbiquí-Cauca were used. The logs’ surfaces were observed and prepared, and their growth rings were marked. By developing cross-dating and x-ray densitometry value analysis, accomplished in ESALQ-USP, Brazil, the study established the chronologies; and as a direct consequence, it obtained a correlation of 0.692. Afterwards, the standard chronology was correlated with rainfalls in a 44-year series. The growth was modeled using the Von Bertalanffy equation, and the current annual increment (CAI) and mean annual increment (MAI) were calculated, whose results were classified into five age-categories, obtaining 6.336 and 5.683 mm.year-1 as final values, respectively

Technological evaluation of Eucalyptus grandis wood mdf panels manufactured in laboratory and industrial production line

Chapas MDF de fibras da madeira de Eucalyptus grandis foram confeccionadas em laborat\uf3rio e em linha de produ\ue7\ue3o industrial e determinadas suas propriedades anat\uf4micas, f\uedsicas e mec\ue2nicas. O desfibramento da madeira provocou o rompimento transversal da parede das fibras. Os pain\ue9is MDF obtidos em linha de produ\ue7\ue3o apresentaram menores valores de inchamento e de absor\ue7\ue3o e melhores propriedades mec\ue2nicas para m\uf3dulo de ruptura, m\uf3dulo de elasticidade e resist\ueancia \ue0 tra\ue7\ue3o superficial. Para os pain\ue9is MDF confeccionados em laborat\uf3rio, verificou-se correla\ue7\ue3o estatisticamente significativa entre m\uf3dulo de ruptura e de elasticidade, densidade m\ue9dia e resist\ueancia \ue0 tra\ue7\ue3o perpendicular e inchamento e absor\ue7\ue3o. Para os pain\ue9is MDF confeccionados em linha de produ\ue7\ue3o industrial, verificaram-se as mesmas tend\ueancias, sem signific\ue2ncia estat\uedstica. A avalia\ue7\ue3o dos par\ue2metros de qualidade de pain\ue9is MDF de eucalipto confeccionados em laborat\uf3rio e em linha de produ\ue7\ue3o visa a calibrar as vari\ue1veis para a obten\ue7\ue3o de chapas MDF em pequena escala e melhorar a precis\ue3o das an\ue1lises de rotina de controle de qualidade bem como nas informa\ue7\uf5es apresentadas em publica\ue7\uf5es cient\uedficas.MDF panels of Eucalyptus grandis wood fibers were made in either experimentally in a laboratory or on an industrial production line. In order to analyze the influence of the production condition, the anatomical, physical and mechanical properties of the panels were determined. The wood refining induced the transversal rupture of the transversal fiber wall. The MDF panels obtained from the industrial production line presented less swelling in thickness and absorption values and improved mechanical properties in the requirements of bending strength, module of elasticity and surface resistance. For laboratory MDF panels, it was possible to verify a statistically significant correlation between bending strength and module of elasticity, medium density and internal bond and swelling in thickness and absorption. This tendency was also true for the MDF panels obtained in real conditions of production, however without statistical significance. By comparing the quality properties of MDF panels produced in the laboratory with those obtained in real conditions of production, it was sought to standardize the established variables for obtaining panels on a small scale, as well to make possible the safe transfer and divulgation of information obtained in the laboratory

Evaluation of the retratibility in seven eucalypt species

As variações na retratibilidade no lenho das árvores são as principais causas dos defeitos de secagem, como o empenamento e fendilhamento das peças de madeira. Os tipos de madeira presentes em um tronco estão relacionados com as variações dessa importante propriedade física. Este trabalho teve como objetivo estudar a retratibilidade da madeira de sete espécies de eucaliptos. Os parâmetros de retratibilidade, bem como a sua variação na direção radial da medula em direção à periferia do tronco de sete espécies de eucaliptos, foram avaliados de acordo com a Norma brasileira. De modo geral, os resultados indicaram que as espécies de eucaliptos estudados possuíam madeira com elevada retratibilidade. À exceção das madeiras de Eucalyptus tereticornis e E. pilularis, as demais espécies estudadas apresentaram valores menores de retratibilidade na região próxima da medula.The variation of the retratibility in lumber is the main cause of the occurrence of drying defects, especially those characterized by warped and split wood. The different wood types present in the stem are related to the variation of these important physical properties. This work aimed to study the retratibily of seven eucalypt species. The retratibility parameters such as the variation in the pith to bark direction in the peripheral of the trunk were studied according the Brazilian Standard for the seven eucalypts. In general the results showed that the species of eucalypts studied have a high retratibility. Except for Eucalyptus tereticornis and E. pilularis the others species studied showed lower values of retratibility in the pith region