Species composition, diversity and structure of secondary tropical forests following selective logging in Huong Son, Ha Tinh Province, Vietnam

Abstract

Species composition, diversity and structure of Huong Son secondary forests post-logged 2 years (PL2), 12 years (PL12) and 22 years (PL22) were studied in May 2004. Percent composition of families and number of commercial species found in the plot PL2 were lower in comparison with those of the two other plots. The medium Sorensen similarity index, ranging from 29.55 to 40.25%, found for all tree size classes showed a slightly high dissimilarity between plots. Simpson's index for all tree size classes was quite similar among plots though only small difference was found for seedlings in the plot PL2. Shannon-Wiener index (H') in all plots exhibited relatively high, ranging from 1.76 to 3.48, for all size classes combined but revealed slightly low diversity indices for commercial species. Species richness and evenness (H) turned out to be the best indices for demonstrating diversity among plots. The size class distribution with Weibull model showed nearly a continuously inverse J-shaped curve. Except the plot PL2 and the plot PL12 followed a similarly exponential trend, the plot PL22 showed a left skewed shape. However, the result of basal area showed that the PL12 had lower basal area than others. All plots showed having some commercial species with relatively high importance value index along with a proportion contributed by other noncommercial ones, i.e. Syzygium cinereum and Diospyros apiculata.