Functional patterns and species diversity of epiphytic vascular spore-producing plants in riparian forests with different vegetation structure from southern Brazil

Background and aims – Functional patterns and the environmental influence over species traits are important tools for the conservation of riparian forests. Richness, diversity and functional structure of the epiphytic vascular spore-producing plant community (ferns and lycophytes) were studied and compared at the superior (site 1), middle (site 2) and inferior (site 3) parts of Sinos River, which is one of the most important and impacted rivers in southern Brazil. We tested the hypotheses that functional patterns of epiphytic vascular spore-producing plant assemblages differ among sites; that richness, canopy openness, density, and tree basal area influence the epiphytic functional structure and that functional traits that favor species tolerance to water deficit will be more abundant in areas with simplified surrounding vegetation structure.Methods – All ferns and lycophyte species were recorded on 120 phorophytes (forty at each site). In order to compare environmental differences among sites we used the vegetation parameters taken at each sampling unit. For the functional analyses we used traits related to the ecological category, life form, leaf dimorphism, leaf division, position of leaves, presence and amount of leaf trichomes or scales and the presence of succulent rhizome.Key results – A total of 32 epiphytic species of vascular spore-producing plants were surveyed. The majority of species recorded were holoepiphytes, had a creeping rhizome, and monomorphic, divided and erect leaves. Functional diversity, species diversity and functional redundancy were higher at site 1. The two other sites were statistically equivalent regarding these parameters. At site 1, phorophytes had the highest species richness and the vegetation as a whole showed a higher density and total basal area.Conclusions – We observed that functional structure and richness of epiphytic vascular spore-producing plants change according to the forest stand structure, highlighting the importance of preserving the riparian forest at site 1 and the need for restoration measures at sites 2 and 3