Effect of host tree traits on the abundance of epiphytic lichens in a tropical Atlantic rainforest

Lichens, formed through symbiosis between mycobionts and photobionts, exhibit distinct growth forms, including crustose and foliose types, impacting their selection for various substrates and microclimates. In this sense, host tree traits are pivotal in shaping the colonization patterns of epiphytic lichens. This study assessed how host tree structure influences the abundance of lichen growth forms in a lowland Atlantic rainforest. We selected trees in six forest sites at the União Biological Reserve, Brazil, quantifying the abundance of crustose and foliose lichen growth forms on each tree. Host trait data such as trunk texture and diameter at breast height (DBH) were collected. Our findings revealed that trunk texture favored significantly foliose lichens on rougher trunks than smooth ones, but crustose lichens outnumbered these in both tree substrates. Overall, crustose lichens predominated on trunks in this particular lowland rainforest. Older trees with larger DBH did not consistently correlate with higher lichen abundance, likely due to the presence of numerous trees with smaller DBH. This study emphasizes the importance of preserving host trees with diverse habitat and structural characteristics to safeguard local lichen diversity within forest ecosystems. It also emphasizes the importance of considering functional groups such as growth forms and their particularities when evaluating the influence of host traits on lichen communities, given their close relationship to forest structure and disturbance. Limited knowledge of lichen ecology and increasing threats such as canopy disruption and host species loss make conservation efforts crucial, especially in highly fragmented ecosystems such as the Atlantic forest.