Allometric equations for three members of Olacaceae (R. Br.) family in a tropical rainforest of Nigeria

Abstract

Sustainable forest management requires accurate measurements of tree growth variables. Foresters and ecologists have long observed regularities in tree growing processes, where every aspect has its own role. These aspects are inter-linked and are usually explained by allometric equations. Allometric relationships for estimating tree-level parameters are important for managing forest resources. This study establishes height-diameter and stem volume allometries for Coula edulis (Baillon), Strombosia grandifolia (Hook.f. ex Benth) and Strombosia postulata (Oliv.) of Olacaceae family in Oban Hill region of the Cross River National Park. Systematic sampling technique was adopted for plot locations. Fortyeight 50m~50m plots were used. In all the plots, tree growth variables were measured for the three species with dbh.10.00cm. The data were analyzed using descriptive  statistics, ANOVA and regression. The result showed that Strombosia postulata was the most abundant of the three members in the stand (42.8% of the total). Height-diameter equations produced poor results for the three species with R2-values of between 0.20 and 0.50. The stem volume equations were rather good. For the quadratic models, Strombosia grandifolia produced the best result (R2 = 0.97; SEE = 0.21) while  Strombosia postulata produced the best result for the transformed models (R2 = 0.98; SEE = 0.13).

Key words: species abundance, quadratic, transformed, relationship, conservation.