Epiphytic ferns in swamp forest remnants of the coastal plain of southern Brazil: latitudinal effects on the plant community

ABSTRACT

Community structure and spatial distribution of epiphytic ferns in swamp forest remnants along the coastal plain of the state of Rio Grande do Sul were analyzed. A total of 440 trees were sampled in fifty-seven 10 x 10 m plots. Each phorophyte was divided into five ecological zones (strata), where all species of epiphytic ferns were recorded. A total of 34 species representing 18 genera in six families were recorded. Polypodiaceae was the most represented family with 17 species, and Microgramma vacciniifolia had the highest epiphytic importance value. Characteristic holoepiphyte was the predominant ecological category, representing 70 % of the species. Ordination analysis showed a gradual change in floristic composition between ecological zones with richness differing significantly between strata. We observed that with increasing latitude there was a decrease in mean temperature and total rainfall, but an increase in frosts. These climatic and phytogeography changes result in a reduction in species richness and a change in the structure of epiphytic fern communities in a north-to-south direction. The importance of swamp forest remnants of the coastal plain to the diversity of epiphytic ferns is discussed.

Keywords
community structure; conservation; environmental factors; epiphytism; spatial distribution