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The effectiveness of tree species as bioindicators/biomonitors depends on appropriate selection based on their tolerance and sensitivity to air pollution, which is usually evaluated by the air pollution tolerance index (APTI). Despite the importance of the APTI in screening tree species for biomonitoring, there are still limitations to its usefulness in green belt establishment/management. Therefore, this study combined the APTI and anticipated performance index (API) to evaluate the potential of some tree species commonly growing on the campus of the University of Ilorin, north-central Nigeria, for green belt development. The study revealed that the APTI alone is not adequate for determining the suitability of tree species for green belt development, although it can be employed to identify sensitive plants for biomonitoring. The combination of the APTI and API in this study is a practical approach to developing a sink for air pollution control. The API indicated that Vitellaria paradoxa (API = 4) is a good performer in green belt development, while Terminalia catappa, Acacia nilotica and Prosopis africana (API = 3) are moderate performers. The present study suggests that integration of both the plant tolerance and performance indices for selection of tree species is very useful for the development of a green belt. [ABSTRACT FROM AUTHOR]

The essential oils from the leaves and stem-bark of Vitellaria paradoxa C. F. Gaertn. obtained by hydrodistillation were analyzed by GC/GC-MS. A total of 68 and 33 compounds representing 90.1% and 95.1% of the total oils were identified in the leaves and stem bark, respectively. The major constituent in the two oils was linalool (12.2 to 15.0%). The essential oil has LC50 value between 160.098 and 171.240 μg/ml indicating moderate toxicity. [ABSTRACT FROM AUTHOR]