Woody Plants Species Composition and Diversity in West Bank Forest of International Institute of Tropical Agriculture (IITA) Ibadan, Oyo State, Nigeria

Abstract

Woody plants species composition, richness, dominance and diversity in west bank forest of International Institute of Tropical Agriculture (IITA) was undertaken to understand the status of the forest. The analysis of tree species composition, richness and diversity in the forest was carried out with the aim of developing efficient management plan that will ensure biodiversity conservation. Vegetation survey using transects and plot sampling techniques were used to collect data for the study. Three transects of 500 m long each {A (270°W), B (90°E) and C (180°S)} were constructed with the aid of prismatic compass in the forest. 10 sampling plots of 10 m by 10 m each were demarcated along each transect making a total number of 30 sampling plots. In each plot, all woody plant species (trees and shrubs) with girth at breast height (gbh) greater than or equal to 10 cm (gbh ≥ 10 cm) were identified, enumerated and measured. The results showed that 581 woody plants belonging to 65 species and 28 families were encountered in the forest. The most abundant family in the forest was Fabaceae sub families of Caesalpinioidea, Mimosoideae and Palpilinoideae. The forest had Simpson diversity index (D), Shannon-Wiener (H) and Evenness index of 0.012, 0.354 and 0.195 respectively. The total density and basal area of woody plants species in the forest was 1,936.67 individuals’ ha-1 and 98.23 m2 ha−1. Newbouldia laevis had the highest density of 190 ha-1 and relative frequency of 9.811% while Milicia excelsa had the highest basal area of 40.34 m2 ha−1, relative dominance of 41.07% and Importance value index of 14.04%. The study concludes that the forest has a reasonably good tree and shrub species composition and richness, dominated by trees and a repository of many indigenous tropical woody plant species. The study recommends in-depth forest inventory, preparation of management plan and promotion of good governance in management of the forest. Also, further studies on regeneration, structure, soil seed bank, seed physiology and herbaceous plant should be carried out in the forest.