A new nonlinear model applied to the height-DBH relationship in Gmelina arborea

- Application of new models to DBH-height relationship.
- Favorable comparison of new models with traditional Schnute and Richards models.
- Consideration of allometric based models in comparison with sigmoidal models.
- Applications of multi-variable form of models to improve representation of data.

Modeling of the relationship between diameter and height of trees generally employs one of several possible nonlinear growth models, with Richards and Schnute among the most commonly used in the literature. The recently defined hyperbolastic models are nonlinear models of sigmoidal growth noted for their flexibility in representation of biological phenomena. We apply these models to a set of data representing the relationship between diameter and height for a stand of Gmelina arborea in Ibadan, Nigeria and compare the performance with several other nonlinear models. We also compare these nonlinear models with a standard allometric relation, as well as an expanded version. In addition we display the use of the multivariable form of these hyperbolastic models for use in models representing height as a function of diameter as well as other additional explanatory variables.