DistribuiÃÃo espacial e efeito de borda em briÃfitas epÃfitas e epifilas em um remanescente de floresta atlÃntica nordestina

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

Bryophytes work like a key group to elucidate answers to the environmental variations because his elevated sensibility to microclimate and especific microhabitats. This study aimed to deepen the knowledge on the ecology of epiphyte and epiphyllous bryophyte communities in relation to fragmentation in an Atlantic Forest remanant (2.628ha) of the Ecological Station of Murici, Alagoas (09Â11â05â-09Â16â48âS / 35Â45â20â-35Â55â12âW), Northeast of Brazil. So, the composition, richness, diversity and stratification of epiphyte bryophytes were analysed in the vertical gradient in 15 phorophytes subdivided in five height zones; and epiphyte and epiphyllous of understorey were investigated from the edge up to the centre of the remnant regarding five concentric belts of 200m of width each and for collection site. 78 species were registered in the vertical gradient and 93 species in the understorey, being 75 epiphyte and 34 epiphyllous. It was stimated to be necessary the triple of the effort of collection suggested in the literature for representative sampling in the vertical zonation in Tropical Forests. Standard was not observed in the horizontal and vertical distribution of species, being the inferior strata a significant contribution for the bryophyte flora. These results demonstrate that the environmental heterogeneity of the remnant per se can be an important factor of the lack of differentiation in the vertical gradient and between the edge and the interior. These facts to do reference to processes of canopy simplification resulting from the structural alterations of the forest fragmentation and from the selective logging. Epiphytes and epiphyllous of understorey did not answer the distance of the edge up to the centre of the remnant, 1.084m, being the notable effects of edge in the whole his extension. Microenvironmental specific and scattered conditions in the remnant, like greater degree of canopy opening and altitude, elucidated the distribution, principally, of sensitive species, like epiphytes and shade-typical. The presence of area nucleus was not detected, which is alarming, because that remnant is one of the biggest of the Atlantic Forest above the SÃo Francisco River. Being so, there is still unlikely the detection of effect of edge for bryophytes in the existent remnants in this biogeographic region of the Atlantic Forest, which reinforces his urgency of conservation

ASSUNTO(S)

efeito de borda conservaÃÃo gradiente vertical conservation floresta tropical tropical rain forest microhabitat vertical gradient bryophyte flora microhabitat edge effect botanica brioflora

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