Application of diameter distribution model for volume estimation in Tectona grandis L.f. stands in the Oluwa forest reserve, Nigeria

Abstract

The ability to predict the distribution of diameters in a stand is essential for forest managers to make informed management decisions such as prescription of silvicultural treatments and harvesting regimes. Such information is preferably derived from suitable distribution model. This study evaluated the performance of four distribution models in describing the structure of the teak stands in Oluwa Forest Reserve, Nigeria. Data were collected from 12 temporary sample plots of 20 × 20 m size in the teak stand. Maximum likelihood estimator was used to fit the distribution models: beta, gamma, Johnson SB, and Weibull to the diameter data from the teak stand. Relative rank-sum derived from four indices was used to conclude on the most suitable distribution for the stand. The results showed that the Weibull distribution was the most suitable function for the teak stand with a relative rank-sum of 4.0. Application of Weibull distribution together with suitable height-diameter and volume models estimated yield of 136.281 m ha within timber size class (diameter ≥30 cm). And a total of 309.640 m ha was estimated for the stand. Other product specifications were also provided. This would help in the routine management of the stand.