Evaluation of soil seed bank-vegetation and regeneration potential of Tectona grandis L. f. plantation (Taungya farm) in Akure forest reserve, Ondo State, Nigeria

Abstract

The study investigated the germinable soil seed bank along three soil depths in a Tectona grandis plantation (Taungya farm) in Akure forest reserve, Ondo State, Nigeria. Three sampling plots of 50 by 50 m using systematic line transect were laid. Composition of the established plantation was assessed by taking fifteen different soil samples (0–3, 3–6 and 6–9 cm depth) at each plot and the seed banks composition was determined by greenhouse germination over a period of 3 months. In the soil seed bank seedling, the Shannon-Wienner index had 2.8. The result of other biodiversity indices were; 2.8 for species evenness value. For Margaref’s index of species richness, Taungya farm had value of 123.9. Species abundance in seedlings germinated from soil seed bank was observed as 349 species from Taungya farm. On the other hand, sapling densities, the common tree saplings in this plantation were Baphia nitida, Ficus exasperata and Rauvolfia vomitoria. The species abundance from the sapling was also observed in Taungya farm with the total of 27 seedling m.The value in the other biodiversity indices; Margalef’s index of species richness (4.19), Pielou’s species evenness index (0.9) and Shannon Weiner index (2.97). The similarity between the composition of the seed bank flora and that of the above vegetation (sapling) and established plantation was low throughout the study. The seed bank density and diversity for most species in this study were found to be greatly influenced by environmental factors. At low soil depth layer, richness is greater and herbaceous species dominate while at higher soil depth layer (0–9 cm) species richness diminishes and less dominates.