Efeito de borda e reduÃÃo de diversidade vegetal: o papel da Attalea oleifera Barb. Rodr. (Arecaceae)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

Due to dispersion lack, germination failure and increased mortality rates, the seedling bank in forest edges is impoverished and scarce. To understand how habitat fragmentation and edge creation affects recruitment is crucial to identify threats to tree population maintenance in a fragmented landscape. The present work aims to evaluate if Attalea oleifera, a canopy palm species that becomes superabundant in hyper-disturbed remnants of northeastern Atlantic forest, has a negative effect on seedling recruitment. We analyzed the seedling bank and seed rain richness and abundance beneath adult palm canopies, and in its vicinity, in forest edge areas. Seedling and seed rain richness were 23% and 50% lower under A. oleifera canopy than in its vicinity. The abundance was also 40% and 65% lower under the palm tree for seedling and seed rain, respectively. Small seeds (<6 mm) represented ca. 98% of all seeds collected. Seed larger than 6 mm and smaller than 30 mm were less frequent beneath the palm (1,38%). A negative correlation between the palm adult individuals density and seedling density was found. We also observed that the presence of leaves of A. oleifera reduces germination rates (160%) and increases mortality (180%). About 16% of the understory area in which A. oleifera clusters occur, the seedling bank is direct impacted by itÂs presence. The vast occurrence of A. oleifera may be acting as a "filter", disabling seedling recruitment of some species more susceptible to physical damage and reducing seedling density in forest edge areas. Our results suggests that unexpected modifications, such as the demonstrated, may be acting to reduce fragments capacity to retain species due to the awkwardness of forest edges in advance through successive regenerations stages

ASSUNTO(S)

attalea oleifera habitat fragmentation seedling recruitment atlantic forest recrutamento de plÃntulas fragmentaÃÃo de habitats floresta atlÃntica attalea oleifera botanica

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