Species composition (DBH ≥ 4.5 cm) of deciduous dipterocarp forest in Sakaerat during the 16-year period exhibit changes contemporaneously by adding new tree species and losing some initial tree species in the 4 stands as the result of tree death and recruitment. Losses of the initial tree species permanently are 5, 3, 1 and 1 species while new tree species having DBH reaching 4.5 cm add to the stands are 10, 20, 27 and 6 species in stands 1-4 respectively. These gaining and losing in tree species make the IVI of each tree species in the stand change subsequently by some tree species increase and some decline in their IVI. The initial dominant tree species demonstrate their declining IVI differently in each stand. Stand 1 demonstrates its association type change clearly as other 3 stands maintain the same association type as has been initially classified in the initial period. The most notable change in IVI is the shift of IVI of most legume tree species from a lower rank in the stands to be a higher IVI rank apparently. Final results of the 16-year investigation demonstrate that there are 19, 17, 16 and 23 tree species increased their IVI and 19, 16, 16 and 14 tree species decreased their IVI in stands 1-4 respectively. Each stand of deciduous dipterocarp forest community in Sakaerat (SDDF) exhibits the dynamic equilibrium in gaining and losing IVI differently by those having prominent gain are most of legume tree species for the 4 stands together with some relatively fast growing tree species newly recruited into the stands to compensate for IVI declining in some initial leading tree species.
Key words: Deciduous dipterocarp forest, Dynamic equilibrium, Species composition change, Sakaerat