FlorÃstica e associaÃÃes de espÃcies de pteridÃfitas ocorrentes em remanescentes da Floresta AtlÃntica Nordestina, Brasil

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

The pteridophytes are considered to be a cosmopolitan group that exhibits a series of adaptations for different substrates types, life forms and habitats, influenced principally by climate and relief. Taking into consideration these ecological adaptations of the group, two areas were selected for vegetation surveys (âÃgua Azulâ forest fragment in the Usina Cruangi, municipality of TimbaÃba, Pernambuco, and âMaria Maiorâ forest fragment in the municipality of SÃo Josà da Laje, Alagoas, Brazil, both surviving remnants of the Brazilian Atlantic forest.). The objects of the study were to survey the different fern floras of the two study areas, to observe the life forms of the ferns, their substrates, and their habitats, to make a comparative analysis of these fern floras from the two areas, and to document these ecological associations of the fern species with these determinant factors. Standard botanical survey methods were employed. Data from the literature and from field observations were used for ecological aspects. Floristic similarity between the two study areas was determined with the Jaccard Index, the NTSys PC 2.1 computer program was used for multivariate analysis, and the Jaccard Simularity Index for ecological comparisons between the two study areas. In the Ãgua Azul forest fragment, 16 fern families, 42 genera and 85 species are found, and in the Maria Maior forest fragment 16 families, 38 genera and 76 species are found. In both areas, the families with the greatest number of species were Pteridaceae, Polypodiaceae, Thelypteridaceae and Dryopteridaceae, and the most species-rich genera were Adiantum and Thelypteris. The most common habitat types in the two study areas were stream banks in Ãgua Azul and steep slopes in Maria Maior, but neither habitat type harbored restricted species. The predominant habitats were the species found in stream banks, in rocky blooming, in the steep slopes, in the borders of trails inside the forest, in the border of the forest and in flooded places (non exclusive species). Eighty-eight species were recorded as new for the state of Alagoas and one, Thelypteris jamesonii (Hooker) R.M. Tryon, for the Brazilian Northeast. Danaea bipinnata H. Tuomisto was recorded for the first time from Brazil, as were 12 genera new to the fern flora of Alagoas that now includes 144 species. Among the 112 species recorded for the Ãgua Azul and Maria Maior forest fragments, 36 are restricted to the former area, 27 are restricted to the latter area, and 49 occur in both areas. In the two study areas, most species are terrestrial, hemicryptophytic, roseate, and reptant, occurring in the forest interior on stream banks or rocky outcrops. The floristic similarity of the two forest fragments is high (J= 43,75%). Five groups of associated species were determined for the Ãgua Azul forest fragment and six groups for the Maria Maior forest fragment. In general, the ecological factors that determined the species associations were habitat and substrate types

ASSUNTO(S)

pteridÃfitas agrupamento e similaridade botanica botÃnica floresta atlÃntica brasil (ne) pteridoflora botÃnica sistemÃtica ambiente de ocorrÃncia

ACESSO AO ARTIGO

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