Spacing effect on growth and yeld of fast rotation Eucalyptus at 24 months of age

The objective of this study was to evaluate the growth in height, diameter and volume production of a eucalyptus clone at 24 months of age planted at different spacing. Values of circumference at soil height, circumference at chest height and the heights of all plants in the plots were collected at 6, 12, 18 and 24 months after planting. Using the collected data, the diameter values at ground and chest height and the mean height at each age were calculated. Rigorous cubing of the average tree in each plot was performed 24 months after planting to obtain the wood volume per tree and per hectare. The spacing did not present a clear pattern of influence on the total height of the plants. The final height was not affected by spacing. The effect of planting spacing on growth in diameter at soil height intensified from the first year after planting. Tree mean diameter increased with planting spacing, as well as the wood volume per tree. Wood volume per hectare was higher in the denser spacing.

EQUAÇÕES VOLUMÉTRICAS PARA UM CLONE JOVEM DE EUCALIPTO NO SUL DO TOCANTINS

Este trabalho teve como objetivo avaliar um total de 26 modelos volumétricos para um clone do híbrido entre Eucalyptus urophylla e Eucalyptus grandis. Foram utilizados dados da cubagem rigorosa de 25 árvores, distribuídas em cinco classes diamétricas com amplitude de 2 cm cada. Para a avaliação dos modelos volumétricos, adotou-se os critérios: coeficiente de determinação ajustado, erro padrão residual, análise da distribuição de resíduos, soma dos quadrados dos resíduos relativos, erro médio e raiz do quadrado médio. O modelo logarítmo: , um dos mais utilizados no Brasil, teve o oitavo lugar como a melhor colocação dentre os 26 modelos volumétricos avaliados. O modelo que mais se destacou foi: que, ajustado com a inclusão da variável binária Tx, permitiu o ajuste de uma única equação para quantificar, tanto o volume com casca como sem casca, para o clone estudado. A equação obtida foi: .Palavras-chave: inventário florestal, modelos volumétricos, eucalipto. VOLUMETRIC EQUATIONS FOR A YOUNG EUCALYPTUS CLONE IN THE SOUTH OF TOCANTINS ABSTRACT:This work aimed to evaluate a total of 26 volumetric models for clone of the hybrid between Eucalyptus urophylla and Eucalyptus grandis. We used data from the rigorous cubing of 25 trees distributed in five diameter classes with amplitude of 2 cm each. For the evaluation of the volumetric models, the following criteria were adopted: adjusted coefficient of determination, residual standard error, residue distribution analysis, sum of squares of relative residues, mean error and root mean square. The logarithm model: , one of the most used in Brazil, ranked eighth as the best placement among the 26 volumetric models evaluated. The best that most stood out was: which, adjusted with the inclusion of the binary variable Tx, allowed the adjustment of a single equation to quantify both the shell and shelled volume for the studied clone. The equation obtained was: .Keywords: forest inventory, volumetric models, eucalyptus.

INFLUENCE OF PLANT SPACING ON THE BARK PROPERTIES OF A Eucalyptus CLONE

ABSTRACT For several wood uses, such as pulp, paper and charcoal, the presence of the bark is undesirable, compromising production. Thus, this study aimed to evaluate the influence of different plant spacings on the properties of the bark of a clone of Eucalyptus grandis x E. camaldulensis at seven years of age at five different plant spacings. The wood discs were removed from the trees at 0, 25, 50, 75 and 100% of the commercial height; then we performed thickness, basic density, gross calorific value and mineral content analysis of bark. There were no significant differences among treatments for the bark gross calorific value and thickness. For the bark basic density, the highest values were found in trees planted in wider plant spacings and considering the mineral content, there was a significant difference only for P, Mn and Zn.