Diversity Indices of Crude Oil Impacted Vegetation

Abstract

Understanding of diversity indices helps measurable description and vegetation communities’ comparison, laying the ground work for reliable strategies for conservation and management. This study assessed the diversity indices of vegetation in crude oil-impacted plots and an uncontaminated control site in K-Dere community, Gokana Local Government. Using 40 m × 40 m quadrats, plant species composition was recorded in three oil-impacted plots (Plots 1–3) and one control plot. Diversity was evaluated using taxa richness index, Shannon–Wiener index, Simpson’s index, dominance, and Pielou’s evenness. A total of 41 plant taxa from 21 families were recorded across all plots. Taxa richness ranged from 38 (Plots 1 and 2) to 40 (control). Dominance values were consistently low (0.03283–0.04577), indicating no single species monopolised community resources. Simpson’s diversity ranged from 0.9542 (Plot 1) to 0.9672 (Plot 3); the Shannon–Weaver index increased progressively from 3.316 in Plot 1 to 3.54 in Plot 3, with the control recording 3.502. Evenness values (0.7248–0.8836) indicated broadly uniform species representation. These results showed that both contaminated and uncontaminated (control) areas are within a narrow margin, indicating a relatively similar level of species richness and evenness across all sites