Allometric Models for Estimating Site Index of Teak (Tectona grandis Linn F.) in Kanya Forest Plantation, Kebbi State, Nigeria

Abstract

This study aims to develop site index for Teak (Tectona grandis) in Kanya Forest Plantation, Nigeria. Site index is defined as the total height of the dominant or co-dominant trees at an arbitrary index age, it is a method used for quantifying site quality for pure even-aged stands which is essential in growth and yield modelling. The data used in this study were obtained from six different age classes. Five sample plots each were selected across all age classes in which a total of 712 trees were measured, variables measured include total height, diameter at the base, middle, top, and diameter at the breast height were taken from 30 temporary sampled plots of 25x25m approximately from the centre, 180 dominant trees were selected from 712 trees. Basal area and volume of sampled trees were computed. Yield values obtained from the dominant trees are (B = 249.312 m3/ha, D = 196.128 m3/ha, F = 134.976 m3/ha, C = 119.328 m3/ha, E = 100.320 m3/ ha and A = 86.976 m3/ha). The results showed that B was the best and A was the poorest. Seventeen models were generated and paired sampled t-test was used for model validation, comparing the actual and predicted height. Two out of 17 were rejected (significant P<0.05). The first model Hd=12075.346-354.809(Age)+3.448(Age)2-135193.126(1/Age) is the recommended height estimation of Teak in Kanya Forest plantation for its best performance.