Lichen diversity, substrate preference and environmental dynamics as indicators of air quality

Abstract

This study assessed the lichen diversity, and substrate growth preferences in a bid to determine the air quality in Ikot Oyoro, Akwa Ibom State, Nigeria. A total of eight (8) lichen species were found in the survey area, the species includes; Candelaria concolor and Hypogymnia physodes which had the highest number of occurrences, while Phlyctic argena was the most common species found in the survey area throughout the survey period (May – July 2023). The rest of the species (Graphis scripta, Hyperphyscia adglutinata, Cladionia ochrochlora, Flavopermelia caperata and Cladonia ochrochlora) were found in at least two (2) trees. For May; Nitrogen-sensitive species found were 43, while Nitrogen-tolerant had 262. In June, N-sensitive (41) and N-tolerant (1966). July recorded N-sensitive (74) and N-tolerant (1803). Elaeis guinensis was the predominant tree in the study area and the growth substrate for the lichen species found. Substrate pH ranged from 3.83 – 5.98 (acidic) while PM2.5 ranged from 8.10 – 32.2 for the 3 months of the survey. Lichen Indicator Score (LIS) shows the level of pollution in the survey area and at the end of the study period, LIS for May was 27.00, 235.00 for June and 218.25 for July which is greater than 1.25 in the Nitrogen Air Quality Index (NAQI) chart showing that the area is very N-polluted. In this study, lichens were used as reliable indicators to trace air pollution and it could be useful to combat the increasing anthropogenic disturbances in the study area.