Biodiversity Assessment of Lichens as Bioindicators of Air Quality in Jos Metropolis, Plateau State

Lichens are well-established bioindicators of atmospheric quality because of their sensitivity to sulphur dioxide, nitrogen oxides, and particulate matter, and their diversity assessment in Jos metropolis, Plateau State, provides an ecological audit of air quality in this North Central Nigerian city. This study assessed lichen species diversity, abundance, and substrate preferences on tree bark at 12 sites distributed across Jos metropolis, representing industrial, high-traffic, residential, and peri-urban zones. Belt transects (15m x 5m) were surveyed at each site, and all lichen thalli on bark substrates were counted, identified, and mapped. An index of atmospheric purity was calculated for each site using species frequency and sensitivity weightings. Forty-one lichen species from 22 genera were identified. Species richness ranged from 5 species at an industrial zone site to 28 species at a peri-urban site. Crustose lichens dominated all urban sites, while foliose and fruticose forms were more prevalent in peri-urban areas. The index of atmospheric purity was significantly negatively correlated with traffic density (r = -0.82, p < 0.01) and proximity to industrial areas (r = -0.74, p < 0.01). The Sele and Terminus areas of Jos had the lowest lichen diversity, indicating the poorest air quality. The study concludes that lichen diversity mapping is a cost-effective air quality monitoring tool for Jos metropolis, and recommends its integration into the Plateau State Environmental Protection Agency's environmental monitoring programme. Keywords: lichens, bioindicators, air quality, index of atmospheric purity, Jos metropolis