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This paper examined the status of tree diversity in Idah Local Government Area of Kogi State, Nigeria. . The data for the study were collected from quadrants
laid within five forests which are: forest of the royal dead (Ojaina forest); Inachallo sacred forest; Ubi-egbe forest; forest of the warlords and river bank forest. A
total of twenty-one (21) quadrants of 20m × 20m in dimension were used for the assessment. Individual tree species in each of the quadrant were identified,
counted, and their diameter at breast height measured. Some of the indices computed are: basal area, species relative frequency, species relative density, species
relative dominance, Important Value Index (IVI); Shannon-Wiener diversity index (H?), species evenness and species richness. The results show that
Daniella oliverii, Raphia hookeri, Elaeis guineensis, Khaya senegalensis, Parkia biglobosa, Vitex doniana, and Adansonia digitata were the most important
species with the highest IVI values of 19.54, 18, 14.18, 11.98, 11.94, 11.88 and 9.62, respectively. Based on Shannon-Wiener diversity index, forest of the
royal dead (2.93) is most diverse followed by Inachallo sacred forest (2.9), Ubi-egbe forest (2.83), river bank forest (2.7) and forest of the warlords (2.59). The
results of species richness show that forest of the royal dead (10.97) is the richest, followed by Inachallo sacred forest (10.34); river bank forest (9.92); Ubiegbe
forest (9.77); and forest of the warlords (8.83). The evenness index shows that individual species in Inachallo sacred forest (2.27) are more evenly
distributed, followed by species in forest of the royal dead (2.26), Ubi-egbe forest (2.26), river bank forest (2.19) and: forest of the warlords (2.18). An
understanding of the current state of the resource is very important in identifying threats to species and ecological communities, and the strategies needed for the
preservation of species, habitats and ecosystem functioning.