Height diameter model for selected trees within University of Ibadan, Oyo State, Nigeria

Abstract

For growth and yield prediction models, tree height and diameter at breast height (Dbh) are essential input variables. The relationship between the two  tree characteristics at the stand level is satisfactorily explained by height-diameter models. This study was carried out to model the heightdiameter  relationship of Terminalia radii Plantation at Heritage Park and Tectonagrandis at Teak Plantation, University of Ibadan. Ten non-linear growth functions  were chosen as potential base models, and they were then fitted to the height-diameter information for each individual tree. Complete enumeration was  carried out at Heritage Park while stratified sampling technique was employed using two transect lines at 50 meters apart with 10 sample plots. A total  number of 277 trees were identified and measured with 146 trees from Heritage Park and 131 trees from Teak plantation. The ten (10) non-linear model  parameters for trees in the study area were estimated using the sampled trees. Among the ten models, Curtis demonstrated the best model with  smallest RMSE, AIC, BIC, high R² and small sum rank of 5.356499, 815.4638, 824.0894, 0.3800086, and 7 respectively; Logistic showed the best model with  smallest RMSE, AIC, BIC, highest R² and small sum rank of 2.884578, 728.6374, 740.5718, 0.1058006, and 10 respectively with other h-d models for  Teak plantation and Heritage Park respectively. For estimating tree height in the study locations, the two models are recommended.