To predict the yield of teak plantations in Northeastern Thailand, the new site index function was developed for predicting dominant tree height in teak stands. The Gompertz function was applied as the site index curve to improve the existing yield model. From the model, we computed the stem volume, stand basal area, stand volume, and stand density of the test plots were using site index values derived using the new site index function. These stand aggregates were compared to the previous model.
The results revealed that the statistical indicators used to evaluate the performance of the two models provided smaller values in the present model than in the previous model. This confirmed that the improved yield model had greater accuracy and precision than the previous model. The improved yield model could be applied to generate a new yield prediction table for teak plantations in Northeastern Thailand.