Crown stratification ratio models for Tectona grandis L. f in Oluwa Forest reserve, Nigeria

Abstract

This research investigated crown ratio models for Tectona grandis plantation in Oluwa Forest reserve (Ondo State, Nigeria) using variables of slenderness coefficient and merchantable height. With three non-linear regression functions - logistic, Chapman-Richard and exponential we showed that basal area, tree stem volume and mean tree height per hectare were of high significance. In the same vein, there were fewer tree species in the class of higher diameter and height than there were in lower class. There were also more trees in the co-dominant and intermediate classes than in the dominant and suppressed layers. The lack of emergence in the plantation reflected the past disturbance of the ecosystem. Most of the tree growth variables were significantly different in different canopy layers in the study area. Based on the evaluation models, the three functions investigated for tree crown ratio modeling gaveconstant and reliable results in all canopy layers considering their indices. Especially, Chapman-Richard and exponential functions gave consistent trends and good fits for crown ratio models. It is recommended to put strict measures in place to avert any level of illegalities that may likely disrupt the delicate equilibrium of the ecosystem. It is also recommended that complexity revealed in this study is sustained in the region, and encouraged in other parts of Nigeria.