Combined fire and grazing of surrounding grassland does not prevent saxicolous lichens growth

Background and aims – The use of fire as a managing tool influences and maintains many types of vegetation and may determine landscape physiognomy and species composition. Fire has a strong effect on lichens but studies about their recolonization or resistance are rare. Considering this, the objectives of this study are to investigate how fire impacts the structure of saxicolous lichen communities on rocks in grassland, considering richness, cover and lichen taxa composition and to verify if there are changes on functional diversity and redundancy among sites with different fire events. Methods – The study was undertaken in an area composed of mosaics of native Araucaria forests and grasslands, in southern Brazil, where two sites were sampled. One of them experienced a recent intense fire episode, after being fifteen years without fire or grazing influence, and the other was regularly subjected to grazing and annual fire episodes. Key results – The sites differed in lichen cover, lichen taxa richness and composition. Regarding the environmental and structural variables of the surrounding vegetation, significant influence on saxicolous lichen communities was also observed, with taller vegetation and greater vegetation cover on the rocky outcrops from the site with only one and intense recent fire event. Functional diversity and functional redundancy was also significantly different between both sites. Conclusion – Based on these results it is possible to affirm that managing southern Brazilian natural grasslands with annual fire and grazing, unless it is not too intense, does not prevent the development of saxicolous lichen communities. The effect of fire on abandoned grasslands, with a high quantity of organic matter and taller vegetation, is importantly negative to saxicolous lichen community. Lichens take more time to grow and occupy the rock than the surrounding vegetation recovers, which can cause microclimate changes. The recolonization of these rocky outcrops can therefore take a long time and the new lichen community will probably never be the same as the former one