Abstract

Long-term effects on soil chemical properties and plant composition of a crude oil polluted site were assessed using random surface soil samples and quantitative vegetation data collection methods. Results showed that total hydrocarbon content (542.50±28.58 mg kg–1) and total organic carbon (1.06±0.18%) of polluted site were significantly (p = 0.05) higher than the unpolluted site of 27.90±22.10 mg kg–1 and 0.73±0.06%, respectively. Plant species composition showed that Aspillia busei and Heterotis rotundofolia were abundant at polluted site and absent in unpolluted site while Panicum maximum and chromolaena odoratum were absent in polluted site. Species diversities records were 0.37 (polluted site) and 0.64 (unpolluted). Aspillia busei recorded the highest frequency of occurrence (90%) and density (28.2 m–2) in the polluted site while Starchytarpheta jamaicensis recorded the highest frequency of occurrence (40%) and Andropogon tectorum the highest density (3.9 m–2) at the unpolluted site. It can be concluded that the effects of crude oil pollution persists for a long time and negatively affect soil chemical properties, plant species composition and species diversity.