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Crown-Width Models for Parkia biglobosa Plantation in Wasangare, Oyo State

P.O. Ige


Information on tree growth variables is an important factor during an inventory exercise. This information is beneficial in sustaining proper forest stocking, thinning, pruning, economic evaluation of trees, making aesthetic choices, and in selecting appropriate growth measurements to monitor individual tree growth, wildlife habitat suitability, and in assessing forest health. In this study, crown-width models were developed for Parkia biglobosa plantations (seeds of this species were from Cameroon, Egypt, Guinea, Nigeria, and Tunisia and planted separately) in Wasangare, Oyo State, Nigeria. The diameter at breast height and Crown ratio were used as independent variables for developing the models. Four models were developed and tested in predicting the crown-width of the tree stands of this species. The 'R' programming statistical package was used to fit the models. To consider the best model, Akaike Information Criterion (AIC), Root Mean Square Error (RMSE) and the Welch two-sample test were used for evaluating the models. The summary of the assessment criteria for CW-DBH indicates that the AIC values are 250.07, 206.56, 171.43, 187.82, and 370.03 for Cameroon, Egypt, Guinea, Nigeria and Tunisia accessions respectively with power model function, saturation growth rate, simple linear function, and exponential model performed better.