Edge effects on fern community in an Atlantic Forest remnant of Rio Formoso, PE, Brazil/ Efeitos de borda na comunidade de samambaias em um remanescente de Floresta Atlantica de Rio Formoso, PE, Brasil

We have investigated how edge effects influence the fern community of Jaguarao Forest (08°35' 49"S and 35° 15' 39"W), located in the district of Rio Formoso, Pernambuco, Brazil. A comparative analysis was made of the interior and edge of the fragment of forest, regarding the richness, abundance and diversity of ferns in the two areas. Six plots of 10 x 20 m were chosen, three in each area. A total of 381 ferns were recorded, which were distributed among 25 species, 17 genera and 12 families. The two areas (edge and interior) were found to differ, with distinct relative air humidities and temperatures (p = 0.00254 and p = 0.00019, respectively). The interior showed higher diversity (t = 7.251 and p = 0.018) and richness (t = 6.379 and p = 0.023) than the edge area, but the same abundance (t = 1.728; p = 0.226) as the edge. Regarding the composition of the flora, it was clear that the interior is a habitat completely distinct from the edge with regard to the fern community, given that only one species, Adiantum petiolatum Desv., was common to both environments. It was concluded that the edge effect causes a decrease in richness and abundance of the fern species found in Jaguarao Forest, where the more sensitive species are being replaced by species that are tolerant to the disturbance caused by the creation of an edge.