Comparative Evaluation of the Species Richness and Diversity of Three Parallel Forest Ecosystems in South-Eastern Nigeria

Abstract

The comparative evaluations of the species diversity of three parallel forest ecosystems were evaluated to ascertain and establish the differences in species diversity and abundance. The Point Center Quarter method of plotless sampling was employed while Shannon Wiener’s Index of diversity was used to analyze the accrued data. Results showed that Newbouldia laevis recorded the highest importance value index (28.80) while Datarium microcarpius has the least importance value index (2.77) in Ogugu-Nza Shrine forest. It was obvious that Ceiba pentandra had the highest importance value index (8.87) in Ukpor Community Forest while Rauvolfia vomitoria recorded the lowest importance value index (2.58). When compared to Osomari forest reserve, the importance value index proved that Gmelina arborea was the highest with (69.7), followed by Tectona grandis, (43.64) while the lowest was Borassus aetheopicum. It is crystal clear that there is no iota of relationship in the experimental forests when the observed abundances of different species in terms of importance value index were compared. This could be explained by the fact that the sampled forests were of different orientations, management motives etc (nature reserve, shrine, and community forests). Meanwhile, Ogugu- Nza shrine forest has species diversity of (0.949), with 31 plant species. The dominant species are Newbouldia laevis, Pterocarpus sp, Gambeya albida, among others (Table 4). Osomari forest Reserve had species diversity of (0.8), with 24 plant species. The dominant species are Tectona   grandis and Gmelina aborea (Table 5). Ukpor community forest had high species diversity (0.976), with 35 number of plant species recorded in the forest. In Ukpor community forest, the dominant species are Ceiba pentandra, Sarcocephalus latifolius and Pentaclethra macrophylla (Table 6). Comparatively, it is glaring that Ukpor community forest ranked highest in species diversity, followed by Ogugu-Nza Shrine forest. This goes a long way to confirm that species richness of a particular forest ecosystem is also a function of its species diversity. Management, mode of exploitation and environmental factors could actually account for the paucity of plant species as well as the low species diversity as observed in the Osomari forest reserve.