Impact of longevity and wettability of fern leaves on epiphyll colonization in a Mexican lowland rainforest

Questions: Leaf traits play an important role in the epiphyll colonization of leaves. Although ferns are common in forest understories, they have been widely ignored as possible host plants. We asked: How does epiphyll colonization (cover, richness, and composition) differ among fern species depending on their leaf longevity and surface wettability? Location: Tropical Biological Station of "Los Tuxtlas", Veracruz (Mexico). Methods: Epiphyll cover was monitored on leaves of six individuals per species after 2, 5, 12, 16.5, and 26 months. Leaf longevity was calculated from leaf turnover rates over 24 months. Leaf wettability was determined through the contact angle technique. Results: All studied fern species had hydrophilic leaf surfaces. Fern species with shorter leaf longevity (14.4-17.8 months) were colonized faster by epiphylls than species with longer leaf life spans (33.9-38.8 months). The area of the oldest leaves was covered to 1.2%-26.1% by foliicolous lichens and to 0.3%-2.2% by green algae. Foliicolous lichens were more species-rich on Danaea nodosa (27 spp.) than on the other fern species (1-9 lichen spp.). Foliose liverworts thrived on the only riparian fern (3.57%). Only 0.04%-1.1% of the area of plastic substrates was colonized by epiphylls. Conclusions: The hydrophilic leaf surfaces of ferns facilitated the colonization of epiphylls, especially of foliicolous lichens. The speed of epiphyll colonization was faster in ferns with shorter leaf longevity but increased in all species with leaf age. However, the relatively low epiphyll cover on fern leaves and artificial substrates in our study might be related to unfavorable microclimatic parameters.