The diversity of foliicolous lichens on ferns in two Brazilian tropical forests

Abstract

A more complete picture of the function of plants in ecosystems results from understanding biotic interactions and this study examined the interactions between ferns and foliicolous lichens. A sampling method involving 15-h walks in each of two tropical forests in Brazil was employed to assess foliicolous lichen diversity on ferns. The nature of foliicolous lichen-fern interactions, and their relationship with forest types (lowland and submontane) and leaf traits (hairs and leaf area), was investigated. Eleven fern species were found to be hosts to 30 foliicolous lichen taxa. Telmatoblechnum serrulatum and Meniscium longifolium were considered the key hosts harboring a greater number (18 and 12) of lichen taxa, of which five taxa were restricted to these two ferns. Approximately 55% of the foliicolous lichens were found on a single fern host. Thicharia sp. A and Gyalectidium filicinum were the more interactive taxa, occurring on seven and ten host ferns, respectively. The forest type had no influence on the interactions. The foliicolous lichen-host fern network differed significantly from null expectations, and there was no sign of specialization. There was also no variation related to the presence of hairs on the sampled ferns (80% had glabrous leaves) and leaf hairs had no significant influence on lichen diversity. Furthermore, leaf area had no influence on the diversity of lichen species. Our results provide a first picture of diversity of foliicolous lichens on fern assemblages in tropical forests. However, there are uncertainties about the mechanisms driving these interactions so more research is needed.