Abstract Based on the need to monitor air pollution and on the importance of doing it with biological organisms, the present work had as main objective to assess air quality in urban areas through lichen transplants. Besides, we also tested whether there were differences among the studied sites, aiming to point out the main pollution characteristics of the areas. The monitoring was carried out in seven cities, which varied from mainly rural to mainly industrial, in Rio Grande do Sul, southern Brazil. The foliose lichen Parmotrema tinctorum was used as the biomonitor species. Physiological tests and contents of sulphur and heavy metals were measured in the lichen thalli. Other pollutants assessed through air samplers were available for some cities, and modeled concentrations of fine particulate matter and nitrogen oxides for all sites. The effect of air pollution negatively reflected on the physiology parameters of the lichen and the concentration of all heavy metals increased after exposure, especially in the industrial sites. We generated a profile of air pollutants and pointed out that Charqueadas and Esteio had the worst air quality. Since they have high demographic densities, the results are of great public health concern and could be guidelines for future studies.

Resumo Liquens são mundialmente conhecidos como indicadores de qualidade ambiental porque são sensíveis às modificações do ambiente, especialmente as de origem antrópica. Neste estudo foram avaliadas a riqueza, a composição e a cobertura de comunidades de liquens corticícolas em nove municípios com diferentes graus de urbanização e verificadas as principais semelhanças na composição das espécies entre as comunidades. Os locais amostrados estavam distribuídos em uma matriz rural, rural/urbana ou urbana/ industrial. Dez forófitos foram amostrados em cada área, utilizando o método do elástico. Ao total, foram identificadas 215 espécies de liquens, das quais nove são novas ocorrências, sendo quatro para o Brasil e cinco para o Rio Grande do Sul. Com o aumento da urbanização, observou-se uma simplificação da estrutura da comunidade de liquens, com diminuição da riqueza e mudanças na composição das espécies. Além disso, na matriz urbana/industrial poucas espécies apresentaram alta porcentagem de cobertura e, em conjunto, somaram grande importância na comunidade. Maior homogeneidade da composição de espécies foi encontrada em áreas mais próximas e inseridas na matriz urbano/industrial. Este estudo demonstrou que a arborização urbana é um fator importante para o estabelecimento das espécies de liquens, ao longo de um gradiente de urbanização.

Abstract Lichens are known worldwide as indicators of environmental quality because they are sensitive to environmental changes, specially the ones with anthropogenic origin. In this study, we analyzed species composition, richness and coverage of corticolous lichen communities in nine municipalities with diferente urbanization levels, and evaluated their similarities considering lichen species composition. The studied sites were distributed in rural, rural/urban and urban/industrial matrices. Ten phorophytes were sampled in each area using the rubber band method. A total of 215 lichen species were identified, of which nine species are new records: four are being cited for Brazil for the first time, and five for Rio Grande do Sul. As urbanization increased, a simplification of the lichen community structure was observed, as well as a decrease in species richness and changes on species composition. Besides, in the urban/industrial matrix, few species had high coverage percentage and together added great importance to the community. We found higher homogeneity on species composition in closer areas and in the ones that were inserted in the urban/industrial matrix. This study showed that urban tree vegetation is an important factor for lichen species establishment along an urbanization gradient.

RESUMO Com o objetivo de caracterizar a estrutura da comunidade arbórea de um remanescente de floresta ribeirinha do rio Taquari, foram estabelecidas 42 unidades amostrais de 100 m2 (10 × 10 m) e calculados os parâmetros fitossociológicos e índices de diversidade de Shannon (H') e Equabilidade de Pielou (J). Foram amostradas 39 espécies, 21 famílias, 2,83 para H' e 0,77 para J. Dentre as espécies Callisthene inundata O.L. Bueno, A.D. Nilson & R.G. Magalh. é endêmica, estando, junto com Picrasma crenata (Vell.) Engl., na lista das espécies ameaçadas de extinção. A densidade encontrada foi de 1.557,14 ind. ha-1. Luehea divaricata Mart. e Lonchocarpus nitidus Benth. apresentaram os maiores índices de valores de importância. Além de contribuir para o conhecimento da distribuição das espécies e estrutura da comunidade, este estudo alerta para a necessidade de conservação dos remanescentes florestais nativos existentes.

ABSTRACT Aiming to characterize the structure of the arboreal community in a riverine forest remnant of the Taquari river, State of Rio Grande do Sul, 42 sampling units of 100 m2 (10 × 10 m) were located. Phytosociological parameters were also assessed and the indexes of Shannon diversity (H') and Pielou evenness (J) were evaluated. A total of 39 species, 21 families, 2.83 nats ind-1 for H' and 0.77 for J were recorded. Among the species found, the endemic Callisthene inundata O.L. Bueno, A.D. Nilson & R.G. Magalh. and Picrasma crenata (Vell.) Engl. are included in the list of endangered species. The density found was of 1,557.14 ind ha-1. Luehea divaricata Mart. and Lonchocarpus nitidus Benth. showed the highest indexes of importance values. Besides contributing to the knowledge of species distribution and community structure, this study points out the need for conservation of existing native forest remnants.