Biomonitoring of air pollution: a dichotomous key for lichen species identification

Abstract

Biomonitoring has been seen as complementary analysis to physicochemical methods and as a low-cost alternative, mainly for regions lacking air pollution control programs. Despite being the most widely used bioindicator for this type of pollution, lichens are not easily identified and this methodology is restricted to groups of expert researchers. Accordingly, the aim of the present study was to analyze lichen diversity in urban and industrial areas, in order to elaborate a dichotomous key to identify the listed species, based on easily visualized features. Lichens with leaf stalks belonging to family Parmeliaceae and genus Parmotrema were the most abundant, which are known for their resistance to air pollution. The study sites generally presented low lichen diversity, which may also have been influenced by the degree of vegetation around them. This result reinforces the importance of green areas for mitigating air pollution in urban environment. The dichotomous key elaborated for the lichen species found aims to support research, environmental education and management activities, and may expand the use of lichens as air-quality bioindicators.