Abstract
The use of form factors is a practical alternative for estimating tree volume. However, only a few studies in this topic are relevant to Tectona grandis, and only few to those that evaluate the effect of spacing on it. The goal of this study was to generate form factor equations and evaluate spacing influence on it in teak plantations. Samples were taking in 3 × 2 m, 4 × 3 m, 5 × 2 m, and 6 × 2 m plots. The database consisted of rigorous cubage of 120 trees, 30 of which were utilised in spacing for the calculation of the artificial form factor models; these were compared using statistical indicators and graphic analyses. In order to assess possible differences among the equations, the identity test of models at the p < 0.05 significance level was utilised. The results of the identity test of models show that it is possible to utilise a single equation (the reduced model) to estimate the form factor for all spacings, indicating that the factor was not influenced by plantation spacing. It was found that with increasing diameter, teak tree trunks became more cylindrical. Stabilisation occurs starting at a diameter of 27 cm and a height of 25 m, with a form factor of 0.47. Key words: Teak, volumetric, plantation density.
Highlights
Tectona grandis L.f., originally from Asia, produces wood of excellent quality and is considered unequalled for shipbuilding; it is utilised in the production of fine furniture in luxurious ambients (Lamprecht, 1990)
We aimed to evaluate the influence of spacing on the form factor and to develop artificial form factor equations, with bark, for non-thinning stands of teak in different spacings
From the identity test of models, it was observed that the equation derived from the reduced model was not significant, showing an F value (1.023) lower than its tabled value (2.025), indicating that this model is flexible, because it enable to estimate the form factor using one single equation, for spacings 3 × 2 m, 4 × 2 m, 5 × 2 m and 6 × 2 m
Summary
Tectona grandis L.f. (teak), originally from Asia, produces wood of excellent quality and is considered unequalled for shipbuilding; it is utilised in the production of fine furniture in luxurious ambients (Lamprecht, 1990). The natural form factor is obtained by measuring the diameter at a relative height (10% of total height). In some cases diameters are not measured at the relative height. The DBH is measured at 1.30 m above ground level, but 1.37 is used in the USA and 1.2 m is used in Japan and Korea (Van and Akça, 2007)
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