Efeito de borda na dinâmica do dossel e sub-bosque em um fragmento de Floresta Atlântica em Igarassu, PE, Brasil

Abstract

Based on hypothesis that the edge habitat has higher rates of dynamic than interior habitat, this study aims to quantify the influence of edge effect in the dynamics (2005 and 2008) of canopy and woody understory in a gradient edge – interior in a fragment of Atlantic Forest in Igarassu, Pernambuco. The external edge, formed about 35 years, was defined the forestry bound to 50 m, the internal edge between 50 and 100 m and the interior a 150 m. To sample the canopy (individuals with stem diameter at 1.30 m> 4.77 cm) were allocated 10 plots of 10 × 10 m for the environment and the woody understory (individuals with stem diameter at soil level between 0, 96 and 4.77 cm) in sub-plots of 5 × 5 m installed in the top corner and left side portions of the canopy. The physiognomy of canopy in the habitats were similar, although it is noted decreased of basal area and diameter towards the interior forest. In the understory, the edges are statistically similar, differing from the interior. In the canopy the highest recruitment occurred in the habitat interior, while growth was similar in the three environments. IIn the understory the highest recruitment occurred at the edges while the mortality was more pronounced in the interior. In the canopy the major values of richness, diversity and evenness were recorded in the external edge, while in the understory had major richness in interior and diversity and evenness in the internal edge. The spatial distribution of populations in the canopy and understory was correlated with different soil variables in the two strata, separating the two edges of the interior. The results point out that the canopy is already sealed and that the greatest richness, density and mortality rate of the understory in the habitat interior may be related to localized disturbances.