José Nivaldo Garcia

Estimates of genetic parameters of wood traits for sawn timber production in Eucalyptus grandis

In this study, the breeding perspectives of 41 open-pollinated progenies of Eucalyptus grandis were evaluated based on their wood traits. The progenies were distributed in two experiments in a randomized complete block design, with three replicates and linear plots containing six plants each. The traits were assessed at eight years of age. Two trees from each plot were selected for this assessment based on better growth, stem form and phytosanity. Significant differences in basic density, sapwood/heartwood ratio, bowing, specific gravity, parallel compression and static bending were detected among the progenies. These traits were potentially promising for breeding programs, with heritability coefficients that varied from 0.34 to 0.61 on a progeny mean basis. There was no genetic variation in the moisture content, board end-splitting, log volume under bark, log eccentricity, bark content, crooking, and shear strength of the progenies. Intermediate to highly significant genetic correlations were detected among the physical and mechanical properties, as well as between pairs of traits such as basic density and log end-splitting, basic density and bowing, specific gravity and bowing, sapwood/heartwood ratio and bowing, log volume and bowing, and log volume and log end-splitting. These results show that the levels of growth stress in trees can be reduced by selection using indirect traits such as the sapwood/heartwood ratio and bowing.

Propriedades de resistência e rigidez à flexão estática de painéis OSB e compensados

In a stuffed furniture industry, located in the Piracicaba, SP, Brazil, panel samples (plywood and OSB) were randomly collected to determine bending strength and stiffness properties (MOR and MOE) in order to compare them and evaluate the possibility of direct substitution of plywood, traditionally used in furniture structural parts, for OSB. The mechanical trials were conducted following NBR 9533 - Brazilian standard, similar to the ASTM D 1037 - American standard. MOR (parallel and perpendicular) and MOE (perpendicular) analyses revealed that the plywood results were significantly higher than the OSB ones. The panels showed to be equivalent with respect to stiffness (MOE parallel). In conclusion, the direct substitution of plywood for OSB is not recommendable, because although they can have similar physical properties (specific gravity) they differed on those important mechanical properties. This indicates that substitutions between those materials should be preceded with more elaborated studies taking into account the magnitude of the properties required by the products in use.In a stuffed furniture industry, located in the Piracicaba, SP, Brazil, panel samples (plywood and OSB) were randomly collected to determine bending strength and stiffness properties (MOR and MOE) in order to compare them and evaluate the possibility of direct substitution of plywood, traditionally used in furniture structural parts, for OSB. The mechanical trials were conducted following NBR 9533 Brazilian standard, similar to the ASTM D 1037 American standard. MOR (parallel and perpendicular) and MOE (perpendicular) analyses revealed that the plywood results were significantly higher than the OSB ones. The panels showed to be equivalent with respect to stiffness (MOE parallel). In conclusion, the direct substitution of plywood for OSB is not recommendable, because although they can have similar physical properties (specific gravity) they differed on those important mechanical properties. This indicates that substitutions between those materials should be preceded with more elaborated studies taking into account the magnitude of the properties required by the products in use.

Variação da densidade aparente e resistência à compressão paralela às fibras em função da intensidade de desbaste, adubação e posição radial em Eucalyptus grandis hill ex-maiden

The Eucalyptu grandis stands apart for its productivity and quality wood. The ideal forest management where a greater wood ratio and better quality are obtained is one of the questions to be considered in the research of the E. grandis. The present work had as its general objective the study of the variation of the specific gravity and the resistance to the compression as a function of the thinning intensity, fertilization and diameter classes in the radial position in trees of a 21-year old population of E. grandis, managed under the system of selective thinning, with the application of fertilizaers. The factors used in this study were: three intensities of selective thinning (37, 50 and 75%), presence or absence of fertilizers, three diameter classes and five radial positions. The influences of the factors and of their combinations were evaluated regarding specific gravity and compression strength. The specific gravity and compression strength of the wood were influenced by factors such as fertilizer and diameter class in almost all radial positions, increasing significantly from the pith to bark. A good positive relationship was found to exist among the specific mass, compression strength and radial position.

WOODFRAME: LIGHT FRAMING HOUSES FOR DEVELOPING COUNTRIES

The building technique of light wooden framing, or woodframe, represents a great innovative goal of construction, due to the very efficient levels of rationalization of material, operational flexibility and productive agility. In addition, excessive use of natural materials of renewable character in the woodframes, as the wood of planted forests, contributes to sustainability, a desired factor in most modern homes. In recent years, Latin American countries have suffered from the constant housing deficit, which destroys the possibilities of the first property by the neediest populations. Therefore, it is necessary to propagate studies, research and information on industrialized housing construction techniques, such as woodframe. This study focused on the exhibition of this innovative wooden building typology, emphasizing its advantages, importance, types, and its current panorama in countries in development stage, such as the countries of Latin America. Currently, woodframe is known as a modern wooden residential technique, and it is conquering the public of all kind of economic classes, because of its innovation, lightness, competitive costs, and also efficient levels of sustainability, cleanness, assembly time, and rationalization of raw materials.

EFFECT OF FERTILIZATION ON CELL SIZE IN WOOD OF Eucalyptus grandis HILL Ex Maiden

The use of fertilization in forest stands results in yield gains, yet little attention has been directed to its potential effects on the quality of wood produced. Information is scarce about the effect of fertilization on anatomical structures of older Eucalyptus wood. This work aims to study the effect of fertilization on tissue cell size of wood from a Eucalyptus grandis stand at age 21 years, the management system of which is based on selective thinning and fertilizer application at the start of the thinning season. Factors to consider include: presence or absence of fertilizers, two log positions and five radial (pith to bark) positions. Results led to the conclusion that fertilization significantly influenced only vessel frequency. Vessel element length was influenced by tree height. Fiber length, fiber diameter, fiber wall thickness, vessel element length, vessel diameter and vessel frequency were influenced by the radial position of the sample in relation to the log. A positive correlation was observed between fiber length, fiber diameter, fiber wall thickness, vessel element length, vessel diameter, ray width and radial position, while a negative correlation was observed between ray frequency and radial position.

Efeito da fertilização em propriedades mecânicas da madeira de Eucalyptus grandis

The effect of the fertilization in the amount and quality of the produced wood is one of the questions to be considered in the research of the Eucalyptus grandis. The present work aimed to evaluate the fertilization effect in the mechanical properties of Eucalyptus grandis. The population of Eucalyptus grandis was 21 years old and was managed under the system of selective thinning, with application of fertilizers. The factors used in this study were: presence or absence of fertilizers, two positions of log and five radial positions. The influences of the factors and of their combinations were evaluated regarding to compression strength, shear strength, modulus of rupture and modulus of elasticity in static banding. The compressive strength and the modulus of elasticity had been influenced by the factors: fertilizer and radial positions of the log. There was also an increase in the direction of the pith-bark in all studied properties. A good positive relationship was found to exist among the compression strength, the shear, the modulus of rupture and the modulus of elasticity with radial position.

Difficulties of wooden housing production sector in Brazil

ABSTRACT This research identified the central hindrances found in Brazilian wooden housing scenario in the fields of finished product, producer, and sector. Thus, a questionnaire with three qualitative questions based on multiple-choice answers allowed investigating the difficulties faced by these producers in Brazil. This sector still faces obstacles in the three observed fields, especially for the negative aspects of house financing, housing technique certification, skilled hand labour, general costs incurred in local production, tax exemptions, public policies, utilization of wooden houses in public works, and other factors. These obstacles in wooden housing sector have created limitations of production potential and restrictions of its market. A current panorama from these obstacles was formed, which could contribute with sectoral development. Actions such as creation and institution of incentives and specific policies should consolidate as the main direction to reduce these difficulties faced by the wooden housing producers.

Use of Hevea brasiliensis Rubberwood for Glulam Beam Production

In Brazil, Hevea brasiliensis plantations are principally destined for latex production. In the national literature however, there are few studies on the mechanical properties of rubberwood. This study aimed to evaluate the potential of rubberwood in the manufacture of glulam beams (VLC), through the use of pieces of sawn wood of H. brasiliensis clone RRIM 600 glued using mono-component polyurethane adhesive. The beams were subjected to destructive bending tests according to the procedures of standard NBR 7190/97. The results were correlated with the resistance to shearing in the solid wood and the glue line. The structural performance of VLCs manufactured from rubberwood was significant when the last layer was removed from the bending calculation. This layer presented problems in the finger joint. The bending strength of VLCs is highly dependent on the tensile strength of the finger joint, which proved to be the critical point in this study.

Relationships among wood anatomy, hydraulic conductivity, density and shear parallel to the grain in the wood of 24-year-old Handroanthus vellosoi (Bignoniaceae)

We studied the relationships among wood anatomy, hydraulic conductivity, density and shear parallel to the grain in the stem of Handroanthus vellosoi trees with the goal to identify possible trade-offs between hydraulic conductivity and mechanical properties. For this study we felled 12 trees with 24-year-old and cut 10-cm-thick disks at three heights: base of the trunk, one meter in height, and two meters in height. We propose that the relationship between hydraulic conductivity and mechanical resistance found along the H. vellosoi trunk indicates greater mechanical investment in the wood at the base of the trunk compared with the other two heights (1 and 2 meters). Anatomically, this would be represented by smaller diameter vessels and fibers with thicker walls. Consequently, strength investment implies lower water conductivity at the stem base. However, more studies are needed to determine whether this lower value with respect to 1 and 2 meters represents a significant effect on water transport along the stem.

Some Properties of Astronium graveolens Wood Along the Stem

We investigated the axial variation of specific gravity, shear parallel to the grain and anatomical features of Astronium graveolens wood and related these properties to the anatomy along the stem. We felled five 20-year-old trees and cut discs from four different stem heights, including stem base, 1 meter, 2 meters and 3 meters, for a total of 20 discs, and studied wood samples near the bark and at the base of trunk. Axial variations found appear to provide a balance between mechanical strength of the wood at stem base by the higher density and higher shear by the increase in ray frequency that contributes to locking the vertical cells and growth rings, thus preventing the stem from easily breaking when bent. For hydraulic conductivity, vessels with smaller diameter and frequency at the stem base help prevent the occurrence of embolisms that would reduce water flow along the main stem.