Bioindicator potential of mosses and lichens for metal deposition and nutrient status in a Regrowth Forest, Southwestern Nigeria

Abstract Mosses and lichens are effective bioindicators because they absorb nutrients and pollutants directly from the atmosphere, allowing them to accumulate metals and nutrients. This study evaluated mosses and lichens as bioindicators of heavy metals and nutrients in a regrowth forest at Obafemi Awolowo University, Southwestern Nigeria. Vegetation assessment was conducted using 16 plots of 25 m × 25 m, and 111 moss and 383 lichen samples were collected between November and December, where total enumeration and tree species identification were done in the regrowth forest. The diameter at breast height (DBH) of all tree species was measured at breast height for trees above > 3 m and at the mid-point for trees < 3 m in height. Result showed that dominant trees with lichen presence on their bark were Azadirachta indica, Dracaena manii, while, Dracaena manii had highest number of occurrence of mosses with lowest number mosses occurrences in Azadirachta indica and Annona reticulate. The lowest values of lichen characterized with host trees with smooth bark while the distribution and number of mosses were equally distributed on both rough and smooth bark. Nutrients concentration across the mosses and lichens species is in this order: C > Ca > K > Mg > P > Na. The level of heavy metals such as Zn, Fe and Cu in mosses and lichen was found to be significantly different (P < 0.05). Conversely, the level heavy metals (Pb and Cd) found in the species were not significantly different but highest in Hyophila involute and lower in Lecanoral expallens. The order of heavy metals concentration in mosses and lichens is in order: Fe > Zn > Cu > Pb > Cd. Mosses absorb more Zn, Fe and Cu in forest ecosystems compared to lichen, and factors such as DBH. and bark texture contributed to structural changes in mosses and lichen community.