Nonlinear Height-Diameter Models for Anthocephalus macrophyllus in Indonesia

Plantation of Anthocephalus macrophyllus (Roxb.)Havil. is relatively extensive in Indonesia.Reliable and updated height-diameter models are required to quantify the growth of A. macrophyllus.In this study, we developed the tree height-diameter at breast height (DBH) models for A. macrophyllus in Indonesia to better understand the developmental dynamics and management using twenty-seven models.A total of 2961 total height and DBH measurements were used and randomly split into two datasets.Eighty percent of the measurements were utilized for the initial parameter estimation of the twenty-seven models, while the remaining 20% were used for model validation.The quality of the models was assessed using the following metrics: Root Mean Square Error (RMSE), Mean Absolute Percentage Error (MAPE), coefficient of determination (R 2 ), adjusted coefficient of determination (R 2 -adj), Akaike Information Criterion (AIC), and Bayesian Information Criterion (BIC).The Mean Difference (MD) for each DBH class (5 cm interval) and the overall MD were calculated for model validation.The results of this research showed that three-parameter models of height-diameter metrics are slightly better than two-parameter models.The best model is the Chapman-Richards (R 2 : 0.937; MAPE: 9.98; RMSE: 1.1) and Huang model (R 2 : 0.937; MAPE: 9.96; RMSE: 1.1), which is reliable and has been applied in most of the three stands in the literature.Since correct height-diameter models can increase the efficiency of forest inventories, improve growth forecasts, and help to build sustainable management methods, these results have important consequences for forest management and policy-making.Moreover, the acceptance of these models can guide policy decisions on long-term planning for the preservation and use of A. macrophyllus plantations, resource allocation, and reforestation initiatives.