Composição floristica e estrutura fitossociologica do estrato herbaceo-subarbustivo em duas areas de floresta ombrofila densa, Parana, Brasil

AUTOR(ES)
DATA DE PUBLICAÇÃO

2001

RESUMO

A comparison of the floristic composition and structure of the herbaceous and small shrub layer in two Dense Ombrophilous Forests, Parana, Brazil. In two areas of Atlantic Coastal Wet F orest, the herbaceous and small shrub layers were compared tloristically and structurally from March 1999 to February 2000. The areas were located at mount Bento Alves (Ilha do Mel) and mount Facãozinho (Morretes), in the state of Paraná. The goal of the study was to identify and compare the Magnoliophyta and Pteridophyta and to study the structure of this vegetation layer, and determine whether this vegetation layer is indicative of this forest, or whether local variation is significant. Plants were identified to the species level, using literature, herbarium specimens, or authorities as necessary. Quadrats at Bento Alves (n=120) were compared with quadrats at Facãozinho (n=160), in which specie?s frequency, cover (absolute and relative), indexes of diversity (Shannon) and similarity (Jaccard) were estimated and compared. In Bento Alves 99 species, 71 genera in 36 families were found. The most speciose families were Dryopteridaceae (9), Orchidaceae (8) and Piperaceae (8). In Facãozinho, 108 species, 66 genera in 39 families were recorded. Here the most species rich families were Dryopteridaceae (15) and Araceae (7). In the quadrats, at Bento Alves, 59 species, 48 genera in 29 families were recorded while at Facãozinho, 57 species, 38 genera in 27 families were found. The most species rich families in both study sites were Dryopteridaceae, Araceae, Piperaceae and Acanthaceae. The average number of species per quadrant was 13 in Bento Alves, with 30,62% cover, and six species with 32,75% cover in Facãozinho. The difference in cover in the two areas was due to the size difference of plants in the two areas, which were larger in Facãozinho. The most important species were Cyathea corcovadensis, Monstera adansonii and Calathea sp. in Bento Alves, and Philodendron ochrostemon, Stigmatopteris heterocapa e Polybotrya cylindrica in Facãozinho. Similarity of the two sites was very low, as calculated by the J accord index, and so the two sites were considered to be very different in their herbaceous and shrub under story. The understory appears very different while the forest type remains constant, suggesting that factors that influence forest under story may be very different than those which influence the forest itself. However, the causal explanations for these differences remain unknown. This study is important in that it illustrates that the dynamics that influence plant community structure may vary widely, which suggests that an apparently very stable forest type may harbor a very dynamic and regionally variable under story community

ASSUNTO(S)

mata atlantica florestas mata atlantica - composição

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