Epiphytic Cryptogams as Bioindicators of Air Quality in a Tropical Andean City

Air pollution is one of the main environmental problems in developed and developing countries. Epiphytic cryptogams (bryophytes and lichens) are proposed as a reliable indicator to detect environmental changes, given to their sensitivity to pollutants. In this study we evaluated air quality in the city of Ambato using bryophytes and epiphytic lichens on three land uses (urban, peri-urban and control). In each zone we selected ten trees (a total of 90 trees) for each station (a total of nine stations), where we recorded the frequency and cover of epiphytic cryptogams in a quadrat of 10 × 50 cm that was divided into 5 × 5 cm squares. Differences in richness, index of atmospheric purity (IAP) and diversity were analyzed using a generalized linear model (GLM) and changes in species composition using multivariate analysis. We recorded 39 species of cryptogams (25 lichens and 14 bryophytes). Richness, diversity and index of atmospheric purity were higher in the control zone compared to the urbanized zones. Community composition changed between the different zones, with increasing differences between the control and urban zones. The urban areas of the city of Ambato were identified with high levels of air pollution due to their lower diversity related to higher vehicular traffic and industrial activities (e.g., footwear and textile factories, tanneries). Thus, epiphytic cryptogams are a fast and low-cost method for air quality assessment in tropical areas.