The b-value was constant with DBH in each tree of A. mangium and A. auricuriformis (Fig. 5(a)), and also in P. falcataria, both Java origin and Solomon origin (Fig. 5(c)). Conversely, a negative correlation was observed between the bvalue and DBH at the 1% significance level in E. globulus and E. grandis (Fig. 5(b)).