Abstract
Bella, Staeber, Hegi and tree crown volume formulas were used to calculate the corresponding competition index through three different search radius to search for the competitors for each subject tree. These indexes can be used to reflect the competition stress status for each tree in the stand. Based on the increment data obtained from each tree, evaluation on the effects of incorporating competition index was assessed. The correlation test showed the consistency between growth and competition index. The preliminary results indicated the reduction of MSE by introducing the competition index in the growth regressions. The bigger in search radius used, the larger in MSE reduction.