This paper presents of the results of floristic composition, abundance and phytossociological aspects of pteridophytic flora in three environments of the Ecological Research of Rio Guamá Area (APEG), located in Belém, Pará State, Brazil. The studied environments were a dense amazonian lowland, called "terra firme" forest (Mocambo Reserve), a swamp forest, called "igapó" (Catu Reserve) and a transitional area in these two ecosystems. Each of the three environmental sites were divided into six plots of 5 x 10, for a total of 18. In each plot species ocurrence was recorded, and all individual plants and life forms counted. The life forms were discriminated into hemi-epiphytes, holo-epiphytes and terrestrial. The inventoried pteridophytic flora encompassed 12 species distributed into 11 genera and 9 botanical families. The largest diversity was found in the "igapó", followed by transition ecotone and the "terra firme" forest, although the "terra firme" showed more plant abundance. Some species showed high frequency and abundance in more than one habitat, while anothers were locally rare and restricted to only one environment. The "igapó" forest plots present smaller internal similarity when compared with "terra firme" and the transition forest plots. The true epiphytes or holoepiphytes prevailed in all three studied environments, however they were more representative in the igapó forest, where the permanent soil flooding may have inhibited the terrestrial forms. Protection strategies for this plant group should be directed to implementines units of conservation that includes environmental variation, because even those near as well as interlinked areas, may include considerable number of exclusive or restricted species.
pteridophytes; Brazilian Amazonia; floristic composition; abundance of ferns
