Search

Lichens are widely used to assess the consequences of human activities, including urbanization, which has strong influence on the structure of their communities. Our hypothesis is that increasing human population density and modifying land use and cover cause structural and functional changes in lichen communities. The main objective of this study was to evaluate changes in lichen species composition and functional patterns along a gradient of urbanization in southern Brazil. The study was carried out in nine sites, classified a priori according to the matrix where they were inserted, as rural, suburban and urban, in which the lichen community was sampled in 10 phorophytes using the rubber band method. Several environmental variables and lichen functional traits were quantified. The sites inserted in the rural matrix were characterized by phorophytes with higher bark pH, higher percentage of agriculture areas in the vicinity of the sampling sites, and by the following functional groups: loosely attached crustose thalli, Trentepohlia photobiont, reproduction by thallus fragmentation and apothecia. The sites located in the urban matrix showed greater demographic density, vehicular fleet, percentage of urban and open fields coverage, foliose narrow lobed thalli, photobiont Chlorococcoid algae and reproduction by soredia. Regarding lichen functional patterns, sites located in the rural matrix presented higher species richness, functional richness, evenness and diversity. Based on our results, we showed that urbanization has a strong influence on lichen communities, since it has affected both species composition and functional patterns, besides species richness. The combined use of species composition, richness, functional composition and functional indexes proved to be effective in obtaining detailed information on the changes suffered by lichen communities and can be used as a tool to evaluate the environmental quality in urban environments.

Understanding community assembly patterns with regard to functional traits, which may be common to different species, allows us to compare ecological communities in a wider range of environmental and phytogeographic conditions. Moreover, a functional approach may facilitate the comprehension of the relation between biotic changes and ecosystem functions in complex systems such as tropical forests. Considering the lack of information in relation to the influence of environmental conditions on lichen functional traits, on lichen functional patterns in tropical forests and the potential usage of this approach in bioindication studies, this paper aims at (i) determining the functional structure of the lichen communities along the forest succession gradient, (ii) assessing the relation of lichen functional traits to this gradient and (iii) verifying the potential of using lichen functional traits as indicators of successional stages in tropical rainforests. Lichens were sampled in 24 sampling units of three successional stages (6–10; 12–20; and 40–60 years of recovering). The results corroborated our main hypothesis that the functional structure of the lichen communities responds to structural changes along a forest regeneration gradient. Growth forms (foliose, fruticose and crustose) as well as some reproductive trait states (lirella, isidia and perithecia) were the most suitable lichen traits to be used as indicators of forest succession in the southern edge of the Atlantic Rainforest. Lirella, fruticose and foliose were more related to earlier successional stages; isidia was more related to intermediate stages, while perithecia and crustose were more related to older stages. These results reinforce the ability of lichens to be used as bioindicators of forest conditions.