Tamanho amostral para a estimativa da densidade básica em um clone híbrido de Eucalyptus sp.

Abstract

There are several methods of collecting wood samples for the study of their properties, which consider the accuracy, time and cost of collecting and processing the material. However, often the variation pattern of ownership in the tree is neglected. Depending on the shape and size of the sample in the study the variability of the properties of the wood cannot be properly captured. The aim of this study was to estimate the number of trees needed to estimate the average basic density of the tree in a Eucalyptus urophylla x Eucalyptus grandis hybrid clone, considering different longitudinal sampling and diameter classes. For this, 50 trees were used to hybrid from clone with 5.6 years. The trees were divided into three diameter classes and sampled in the form of discs, three ways: traditional (0%, 25%, 50%, 75% and 100% of the commercial height Hc); alternative (2%, 10%, 30% and 70% Hc) and every meter from DAP. There was no difference between the number of trees required to estimate the density of the clone regardless sampling form, assuming an error of 5% and a confidence interval of 95%. Alternative sampling was considered most effective, considering the sample size along the stem and the coefficient of variation. Classification by diameter resulted in a greater number of trees to estimate the average density due to greater property variation within diameter classes than within the sampling method.