Tree diversity status and abundance in Ehor tropical rainforest reserve in Edo state, Nigeria
This study assessed the status of biodiversity and the tree abundance investigated in BC areas 12/1, 15/1 and 16/1 of Ehor Forest Reserve, Edo State, Nigeria. Systemic line transect was employed for laying of plots. Two transects with a distance of 500m between them were laid at the centre of each of the three BC areas. Four sample plots (20m x 20m) per transect were laid. Within each plot, woody plant species with diameter at breast height (dbh) ≥ 5 cm were identified and their dbh and height measured. A total of 541 individual trees were measured within the sample plots. The results indicated that 206, 809 and 675 average number of trees per hectare were encountered in BC areas 12/1, 15/1 and 16/1 respectively. The mean basal area per hectare were 1.82 m2 ha-1 for BC 12/1 area, 26.66 m2 ha-1 for BC 15/1 area and 28.24 m2 ha-1 for BC 16/1 area. The species richness indices computed were 6.92, 8.64 and 8.19 for BC areas 12/1, 15/1 and 16/1 respectively and the values of Shannon-Wiener diversity Index (HꞋ) for BC areas 12/1, 15/1 and 16/1 were 3.19, 3.54 and 3.40 respectively. These indices were very high, indicating that the forest is a potential biodiversity hotspot. The indices compared favourably with several protected tropical rainforest areas that are biodiversity hotspots. The most abundant tree species were Ceiba pentandra (19 stems/ha) and Mansonia altissima (19 stems/ha) found in BC 12/1. In BC 15/1, out of 49 tree species, Berlina coriacea, Celtis zenkeri, and Brachystegia kennedyi had the highest density with 75 stems, 63 stems and 50 stems per hectare respectively while in BC 16/1, the species with the highest density were Trichilia welwitschii (69 stems/ha), Celtis zenkeri (63 stems/ha) and Blighia sapida (47stems/ha). This research revealed the rich status of tree species diversity. Therefore, there is need to ensure sustainable management of the reserve in order to maintained and improved on its present status.
Keywords: Biodiversity status, tree species abundance, tropical rainforest, Ehor Forest Reserve