Development of a Taper Equation for Teak (Tectona grandis L.f.) Growing in Western Thailand
Teak is an important and valuable tropical hardwood species. In this study, we developed and evaluated suitable taper equations for teak growing in Western Thailand using a formulation of Goodwin cubic polynomial model combined with a bark thickness model. The best taper model calibration was sel...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Mahidol University
2021-04-01
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| Series: | Environment and Natural Resources Journal |
| Subjects: | |
| Online Access: | https://ph02.tci-thaijo.org/index.php/ennrj/article/view/241591 |
| Summary: | Teak is an important and valuable tropical hardwood species. In this study, we
developed and evaluated suitable taper equations for teak growing in Western
Thailand using a formulation of Goodwin cubic polynomial model combined
with a bark thickness model. The best taper model calibration was selected
based on goodness-of-fit and leave-one-out cross validation statistical testing.
In total, 12 different model calibrations were tested, with Thong Pha Phum
(TPP) 2 being the most suitable for teak in Western Thailand. The mean
prediction error of three validation statistics: (prediction of diameter under bark
given height; prediction of height given diameter under bark; and prediction of
under bark volume given log length) were within 10% and the overall validation
index was 5.454, which was the lowest when compared to other calibrations. A
comparison of TPP 2 with a teak taper equation developed for Northern
Thailand, using a graphical analysis of the stem shape and bark thickness,
indicated that the teak trees growing in the two regions have similar stem
shapes, but the trees in Western Thailand tend to have a thicker bark. These
results will also help in further work as they indicate that bark thickness
equations are particularly important. |
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| ISSN: | 1686-5456 2408-2384 |