Resumo As funções de afilamento são ferramentas úteis para estimar diâmetros de toras e volumes comerciais de madeira a quaisquer alturas, sendo de grande importância para os empreendimentos florestais que buscam a otimização do uso de suas florestas. Este trabalho teve como objetivo avaliar modelos de afilamento segmentados, não segmentados e modelos de forma variável para estudo do afilamento do tronco de árvores de Eucalyptus sp. Com uma base de dados proveniente de um plantio de Eucalyptus sp. localizado no sul do estado de São Paulo aos 6,3 anos de idade, os modelos de afilamento testados foram: os modelos não segmentados de Ormerod (1973) e de Schöepfer (1966), o modelo segmentado de Max e Burkhart (1976), e os modelos de forma variável de Muhairwe (1999), Methol (2001) apud Rachid et al. (2014) e de Kozak (2004). Os volumes reais foram calculados utilizando-se o método de Smalian. O modelo de Kozak (2004) obteve as melhores medidas de precisão para estimativa dos diâmetros, já a equação de Muhairwe (1999) demonstrou os melhores resultados gráficos de dispersão de resíduos para a mesma estimativa. Para a estimativa volumétrica, a equação que obteve os melhores resultados foi a proposta por Methol (2001) apud Rachid et al. (2014), com as melhores medidas de precisão e melhor comportamento gráfico, com menores tendências e dispersão mais concentrada dos resíduos.

Abstract Taper functions are useful tools for estimating log diameters and commercial wood volumes at any height, being of great importance to forestry enterprises that aim to optimize the use of their forests. Thus, the aim of this work was to evaluate segmented, non-segmented and variable-exponent taper models for studying the trunk taper of Eucalyptus sp. With a database from a 6.3-year-old Eucalyptus sp. planted forest, in the south of the state of São Paulo, the taper models tested were: the non-segmented models of Schöepfer (1966) and Ormerod (1973) the segmented model of Max and Burkhart (1976), and the variable-exponent models of Muhairwe (1999), Methol (2001) apud Rachid et al. (2014) and Kozak (2004). Real volumes were calculated using the Smalian formula. The equation proposed by Kozak (2004) obtained the best accuracy to estimate the diameters, whereas the Muhairwe (1999) equation showed the best graphic dispersion results for the same estimate. For volume estimation, the equation that obtained the best results was that proposed by Methol (2001) apudRachid et al. (2014), with the best measures of precision and better graphical behavior, with smaller trends and more concentrated dispersion of the residues.

ABSTRACT The aim of this study was to apply geostatistics to predict the spatial pattern of variations in moisture content of eucalyptus wood chip piles to generate subsidies for adequate sampling and material handling. Wood chip piles were installed in three different storage cycles using newly cut material for 7, 30, and 60 days. Sampling was performed in axial (top, middle, and base) and lateral positions, so that all samples were georeferenced in relation to the distance from the ground and the center of the pile. Moisture values were submitted to geostatistical analysis and kriging. The results confirmed the spatial dependence of moisture content over the piles stored at 7 and 30 days; however, the effect of rainfall was crucial to reduce the spatial dependence of moisture content. The results showed that geostatistics is a useful tool for the creation of reliable sampling protocols.