Distinct responses of terrestrial and epiphytic ferns and lycophytes along an elevational gradient in Southern Brazil

Questions What are the drivers that govern fern and lycophyte community composition across different elevation zones in the South Brazilian Atlantic Forest? Does explanatory power of the models increase when we consider substrate-based life forms separately? Do terrestrial and epiphytic species respond similarly to environmental drivers? Study site Four distinct elevation zones of the Atlantic Rain Forest sensu stricto in northeastern Rio Grande do Sul, Brazil. Method Variation partitioning was used to investigate the role of climatic, edaphic and spatial variation on species composition at different spatial scales. We considered both the entire community and subsets with either only epiphytic or terrestrial species. Results On the broad scale, environmental variables were the most important in shaping the fern and lycophyte community composition. Edaphic filters had a more important role for the terrestrial community, and climatic filters for epiphytic species. Considering epiphytic and terrestrial species separately increased the explanatory power of the models. Conclusions Changes in community composition of ferns and lycophytes along an elevational gradient in the South Brazilian Atlantic Forest are primarily driven by niche processes. Ferns and lycophytes found on different substrates (epiphytic vs terrestrial species) show distinct responses to environmental factors and thus should be considered separately in ecological studies.