Comparison of post-fire planted and natural dry semi-deciduous forest communities in Ghana

Abstract

The planting of mixed indigenous tree species for reforestation has gained attention in conservation biology, because they allow the recruitment of other woody species to a site. This study compared the differences in tree species diversity, structure, and composition between secondary dry semi-deciduous forests on two previously burned sites; one site had been planted ten-years prior with mixed mahogany species, while the other naturally regenerated after the fire. Density, dominance, frequency and importance value index (IVI) as well as family important values index (FIV) were computed to evaluate the floristic composition. A variety of diversity measures were also employed to examine heterogeneity in each forest type. For both sites, the most abundant diameter-class was 5-10 cm and the most abundant height-class was 1- 10 m. The study recorded significant differences between the two sites with respect to nearly all the indices of species diversity (Simpson, P = 0.037; Shannon, P = 0.003 and species richness, P = 0.003) employed, with the exception of Pielou’s index of evenness (P = 0.06).The planted site recorded highest values for all the measures of species diversity. However, Sorensen’s similarity index between planted and natural regeneration sites was 0.703. Seventeen and five species respectively were found to be solely associated with the planted and natural regeneration sites. At both sites the four most dominant and abundant tree species which recorded highest importance value index (IVI) were Ficus exasperate, Terminalia superba, Morida lucida, and Antiaris toxicaria. The greatest family importance values (FVI) for both sites were for Moraceae and Fabaceae, especially its sub-family Mimosaceae. The paper concludes that, use of mixed indigenous tree species in restoration facilitate the recruitment of a diverse group of other native tree species. Key words: Native species, diversity index, restoration, African mahoganies, stand structure.