Abstract

Ekpa, N. E., Akindele, S. O. and Udofia, S. I.

The diameter distribution of growing stock is an essential starting point in many forest management planning problems. The three-parameter Weibull distribution model was used to grade the diameter classes of Gmelina arborea plantation in Oluwa Forest Reserve located in the tropical rainforest area of Nigeria. Data used for the study were diameter at breast height (dbh) taken at five years interval. The interval ranging from 11,16, 21, 26, and 31 years of plantation establishment. Quadratic mean dbh exhibited a strong linear relationship with Weibull parameters ‘a’ and ‘b’ and mean height exhibited a strong linear relationship with parameter ‘c’. Validation test carried out on the quadratic dbh and Weibull parameter relationship further proved that the models were consistent and efficient and were therefore recommended for predicting the diameter distribution of the stand.