Rômulo Trevisan

Efeito da intensidade de desbaste nas características dendrométricas e tecnológicas da madeira de Eucalyptus grandis

This study aimed at evaluating the effect of different thinning intensities in the dendrometric and technological characteristics of 14 years-old Eucalyptus grandis W. Hill ex Maiden wood sited in the northern coast of Rio Grande do Sul. Randomized blocks experiment, with four treatments (T1 = 1638 trees/ha; T2 = 1150 trees/ha; T4 = 589 trees/ha and T8 = 192 trees/ha) and four repetitions was analyzed. The trees were selected on the basis of the dominant and average diameter of each treatment. After cutting down, trees were measured and the volume was determined by the Smalian method, disks were taken at the base 0, 25, 50, 75 and 100% of the commercial height, and at the DBH (diameter at breast height), for basic density, dry mass and radial shrinkage determination. In relation to the dendrometric characteristics, results indicate that the application of more severe thinning caused significant gain in diameter at breast height, height and volume in average trees, not influencing the dominant ones. Concerning the technological characteristics, results indicate that the basic density of the average trees was influenced by thinning; however, without presenting clear trend regarding the intensity of the intervention. The production of dry mass of the average trees increased with the thinning intensity and did not affect the production of the dominant trees. The radial shrinkage of the dominant and average trees grew up in the pith-to-bark direction, not being modified by thinning intensity. Results allow concluding that the silvicultural interventions applied in the forest influence wood quality.

Interceptação da radiação luminosa pelo dossel de espécies florestais e sua relação com o manejo das plantas daninhas

The energy of solar radiation absorbed by the plants is a decisive factor of the photosynthesis tax and it can limit the production, the biomass accumulation and the development of the plants. The objective of the research was to evaluate the interception of the luminous radiation and her relationship with the need of handling undesirable plants through crowning and mowing, in the forest species: Acacia mearnsii De Wild, Eucalyptus grandis W. Hill ex Maiden, Mimosa scabrella Benth e Ateleia glazioviana Baill, submitted at levels spacing: 2,0x1,0m; 2,0x1,5m; 3,0x1,0m and 3,0x1,5m. The measurement of the luminous radiation was accomplished monthly during the period from 0 to 360 days after the planting. The points of samplings were among the plants in the line and in the planting among-line. The crowning and mowing were not necessary when the levels of interception of radiation photosynthesis activate were larger than 60%. However, they became necessary starting from the second month after the planting and with a frequency of 60 days for all the species until the first 180 days. The crowning was spared for the species E. grandis starting from the 210 days and for A. mearnsii and M. scabrella after the 240 days after the transplant. Cleared was given only for the species E. grandis in the spacings 2,0x1,0m and 2,0x1,5m starting from the 210 and 240 days after the planting, respectively.

Propriedades de flexão estática da madeira úmida e a 12% de umidade de um clone de Eucalyptus saligna Smith sob o efeito do espaçamento e da adubação.

The bending properties of a Eucalyptus saligna Smith clone were studied. Thirty trees, with age of approximately ten years, coming from Klabin-Riocell forests were used in the tests. The specimens, manufactured following ASTM D143-94 (1995), were tested in two series: after conditioning in standard room (20 0 C and 65% relative humidity) or after water soaking. The results indicated values 1,296 and 1,4 times larger for air-dried when compared to moist wood, for bending stiffness and strength, respectively. Wood density, modulus of rupture and elasticity increased with fertilization and tree spacing.

Influência do espaçamento nas características energéticas de espécies arbóreas em plantios de curta rotação

This study aimed to determine the higher heating value (PCS) of trees and basic density weighted (ρb pond) of wood of Acacia mearnsii De Wild, Eucalyptus grandis W. Hill ex Maiden, Mimosa scabrella Benth and Ateleia glazioviana Baill distributed in different spacings in planting: 2.0 x 1.0 m, 2.0 x 1.5 m, 3.0 x 1.0 m and 3.0 x 1.5 m, at ages of 1 and 3 years. The study was conducted in an experiment in the city of Frederico Westphalen, State of RS, in experimental design of randomized complete block design with three replications in a split plots. The determination of the PCS of the trees was made from the weighting of the values obtained in each compartment (wood, bark, twig and leaf) using calorimeter bomb. The determination of ρb pond was performed from the weighting of the values recorded on discs collected at different positions along the stem, using the method of hydrostatic balance and dry mass. The PCS of all species in the first year after planting was higher than the third year, highlighting the Acacia mearnsii with the highest averages. The ρb pond had no systematic trend of increase or decrease over time, and the species Acacia mearnsii and Ateleia glazioviana showed the highest values. The different planting spacings did not induce the change in PCS and ρb pond in the species studied and it was not verified a positive or negative systematic trend in relation to the living space provided by the spacing.

Eficiência de conversão da radiação fotossinteticamente ativa interceptada em fitomassa de mudas de eucalipto

The biomass production is function of the conversion efficiency of the photosynthetically active radiation intercepted (PARi), varying according to the conditions in which plants are cultivated. Therefore the objective of this work was to quantify the function of the efficiency of conversion of the photosynthetically active radiation intercepted (PARi) in dry biomass - eb - , of seedlings of Eucalyptus grandis W. Hill ex Maiden (eucalyptus) when submitted to different sizes of tubes and densities of plants. Therefore, an experiment was conducted in randomized blocks to study seedlings production in two sizes of tubes (small and medium) and two densities of plants in the tray (high with 100% of occupation of the tray and average with 50% of occupation), where PARi, the index of foliar area and the total dry biomass of the seedlings were evaluated. The volume of the tube did not interfere in the efficiency values, but, the density of plants did because the index of foliar area is the one which determines such value. The ab was of 7.33 g.MJ-1 for medium and small tube in high density and of 3.26 g.MJ-1 for medium and small tube in medium density.

Resistência ao impacto da madeira de açoita-cavalo em diferentes condições de umidade

Neste estudo, objetivou-se comparar a resistencia ao impacto da madeira de acoita-cavalo (Luehea divaricata Mart. et Zucc Mart.) ensaiada em condicoes de equilibrio a 12% de umidade e saturada em agua. Para tanto, foram utilizadas arvores procedentes de duas regioes fisiograficas do estado do Rio Grande do Sul. Os corpos-de-prova foram submetidos ao impacto, utilizando-se pendulo de Charpy e avaliados quanto a resistencia oferecida a aplicacao da carga nos planos radial e tangencial e nas posicoes de retirada (medula -casca) das toras, para as duas regioes fisiograficas em cada condicao de umidade. Para auxiliar na interpretacao dos dados determinou-se a densidade aparente a 12% e saturada, teor de umidade, trabalho absorvido, resistencia ao impacto, coeficiente de resiliencia e a cota dinâmica. Os resultados evidenciaram que a madeira de acoita-cavalo testada na condicao saturada apresentou maior resistencia, indicando que a especie e mais resistente ao impacto quando verde, absorvendo grande parte da forca aplicada sobre ela, quando comparada a resistencia a 12% de umidade.

Variação axial e efeito do desbaste na massa específica das árvores centrais de Eucalyptus grandis

This study was undertaken to evaluate the axial variation and the effect of thinning on the basic density of Eucalyptus grandis central diameter trees with 18 years of age. A thinning experiment, located in the northern coast of Rio Grande do Sul, installed in random blocks with four repetitions was evaluated. The treatments were defined according to the number of interventions applied that ranged from zero to six. The trees were selected, in each treatment, on the basis of the central diameter. After cutting down, the trees were measured and the volume determined by Smalian method. Afterwards, disks were taken at the base, 25, 50, 75 and 100% of the commercial height, and at the breast height (DBH), for basic density determination. The results indicated that basic density showed a decrease up to DBH, followed by an increase, without a clear tendency to stabilize with the height in all treatments analyzed. The thinning caused variation in basic density of the central trees; however, there was no positive or negative precise trend related to the beneficial space provided by thinning.

Qualidade da madeira serrada proveniente de árvores dominantes e médias de Eucalyptus grandis submetidas à secagem

Neste estudo, objetivou-se verificar, em arvores de diâmetro dominante e medio, a influencia da secagem ao ar livre e secagem convencional na qualidade da madeira serrada de um povoamento de Eucalyptus grandis W. Hill ex Maiden, aos 14 anos de idade, situado no municipio de Capivari do Sul, Rio Grande do Sul. Para tanto, a amostragem das arvores foi realizada apos um inventario piloto, tendo como base o diâmetro a altura do peito (DAP) dominante e medio. Apos a derrubada, foi retirada a tora localizada entre as posicoes DAP e 25% da altura comercial. As toras foram desdobradas em tabuas para serem submetidas a secagem ao ar livre ate 18% do teor de umidade, e a secagem convencional foi conduzida ate 13% de umidade. Rachaduras de topo e arqueamento das tabuas foram avaliadas apos o desdobro, na secagem ao ar livre e na secagem convencional. Os resultados mostraram que, tanto para as arvores dominantes quanto para as medias, o indice de rachaduras de topo e a flecha de arqueamento das tabuas nao diferem significativamente nas diferentes fases de processamento da madeira. No entanto, a comparacao entre esses dois estratos evidencia que a magnitude desse defeito e mais pronunciada nas arvores medias.

Estimativa da idade de segregação do lenho juvenil a adulto de Carya illinoinensis (Wangenh) K. Koch por meio de parâmetros anatômicos da madeira

Knowledge of the demarcation of juvenile and mature wood is essential both for wood technology and forest management. Thinning, in most cases, must take into account this parameter, as the juvenile wood has inferior characteristics compared to mature wood, and different proportions of each type of wood will affect the quality and the use of the wood. Thus, this study aimed to determine the age of maturation of the wood using anatomical characteristics of Carya illinoinensis (Wangenh) K. Koch wood, through the segregation of juvenile and mature wood. Three adult trees, of good trunk, with diameter greater than 30 cm DBH, were chosen from the region Encosta Superior do Nordeste in the State of the Rio Grande do Sul. From each tree, one disc was removed, with approximately 2 cm in thickness, at 0.10 m in height of the trunk. From each disc was removed a central portion of 2 cm in width, well oriented in the radial direction, including the pith in the center, and this central portion was divided into samples “A” and “B”. One of these two samples was selected for separation of the initial wood of each growth ring for maceration (Jeffrey method ). First, the length, width and diameter of the lumen of one hundred fibers were measured in the first ring (next to the bark) and later, thirty fibers were defined per growth ring as statistically sufficient for the assay. The thickness of the walls of the fiber was taken as the half of the difference of the diameter of the fiber and the lumen. The segregation of the two types of wood was defined by the radial variation (pith-bark) of the anatomical characteristics (length, diameter, width of the lumen and thickness of the wall of fibers), through two simple linear regressions. The results indicate that the fiber length is the best characteristic for the definition of the year of segregation. The age of segregation of juvenile-mature wood was defined as 16 years. In their turn, the anatomical parameters, diameter of fibers, width of the lumen and thickness of the wall of fibers were shown to be inadequate for estimating the age of segregation.

EFFECT OF PLANTING AGE AND SPACING ON ENERGY PROPERTIES OF Eucalyptus grandis W. Hill EX Maiden

This study aimed to determine the effect of planting age and spacing on energy properties of different compartments of the biomass of Eucalyptus grandis W. Hill ex Maiden, disseminated in different spacings: 2.0 x 1.0 m, 2.0 x 1.5 m, 3.0 x 1.0 m e 3.0 x 1.5 m, in the 1st, 3rd and 5th year after the planting. The present study was carried out as an experiment installed in an experimental design of randomized complete blocks in three replications. Variables determined were Biomass (BIO), Gross Calorific Value (GCV), Basic Density (BD), Energy Productivity (EP), Energy Density (ED), Fixed Carbon Content (FCC), Volatile Material Content (VMC), and Ash Content (AC). Ages have an effect on all studied variables, and in the 5th year after planting, the largest BIO, EP, BD, ED and FCC values are checked. The planting spacings induce different productions of BIO and EP, with a trend towards lower values with increasing planting spacing in all assessed periods. The compartments of trees influence BIO, GCV, FCC, VMC and AC variables. Regarding to energy, the higher the age and lower the planting spacing, the better the energy properties of biomass.