Comparison of floristic composition in four sites of a tropical lowland forest on the North-Central Coast of Vietnam

Natural regeneration, floristic composition, forest structure, and diversity of all tree species with a DBH ≥ 10 cm were investigated in four sites of a tropical lowland limestone and non-limestone forest in Ben En National Park, Vietnam. Four one-ha plots (twenty-five 20 m x 20 m plots each) were established in disturbed/undisturbed tropical lowland limestone (DLF/ULF) and non-limestone forests (DNLF/UNLF). All trees with ≥ 10 cm DBH along with poles ≥ 5 cm DBH and under 10 cm DBH were measured in a total of one hundred 20 m x 20 m sample plots, while twenty-five 2 m x 20 m strip-plots were established to sample the regeneration of tree species. A total of 2265 stems representing 177 species and 43 families were recorded in all sites. Tree abundance was highest (626 stems ha -1 ) in the DNLF and lowest in the UNLF and ULF sites. The greatest species richness was found in the UNLF (114 species ha -1 ), the lowest (63) in the DLF. Species richness in the two non-limestone forest sites (150 species) was higher than that of the two limestone forest sites (85). There were no significant differences in the species richness of seedlings among the four forest types; however, the observed differences in the species richness of regeneration among the four forest sites showed a lower observed species number in the two disturbed forest sites than in their undisturbed counterparts. Most species had a low abundance of tree seedlings and saplings. Journal of Nature and Science, 1(8):e144, 2015