Amostragem para avaliação da densidade básica da madeira de um híbrido de eucalyptus grandis w.hill ex maiden x eucalyptus urophylla s. t. bake

Abstract

The research aimed: i) to evaluate destructive and non destructive methods of sampling for to estimate the basic density of the wood; ii) to determine the longitudinal and radial variation of basic density in the stem in each method and diameter class; iii) to fit model of average basic density estimating along to stem and across the diameter; iv) to determine the optimum number of trees to be assessed to estimate the basic density; v) to determine an optimum sampling point within stem. For this, 50 trees of a hybrid clone of Eucalyptus grandis x Eucalyptus urophylla a 5.6 years-old from the Martinho Campos, Minas Gerais State, Brazil, were used. The trees were sorted in three diameter classes; discs being removed from a range of heights from the sampling methods: "traditional" (0%, 25%, 50%, 75% and 100% of the commercial height- Hc), "alternative" (2%, 10 %, 30% and 70% Hc) and "meter to meter" (each meter above breast height). Also three non destructive sampling methods were evaluated: Resistograph®, Pilodyn® and increment corer. For the radial sampling, small corer being removed from a two opposite sides of pit. It was observed that the "alternative" method showed the highest correlations with the "meter to meter" method. This was the more efficient method for estimate to basic density in stem. The density decreased initially up to 2.3 m of high, then increased to 9.3 m (8.1 cm class) and 13.3 m (11.4 and 14.2 cm class) then decreased from these points up to top. The pattern of radial variation showed a increase across diameter. It was possible to suggest the points of the 1.10 m and 1.50 m for use the Resistograph® and Pilodyn ®. The core underestimated the average density of the tree in 9.5%. The density measured at 1.10 and 1.50 m of stem presented the highest correlations with the three sampling methods considered