Although the edge effect is a phenomenon much studied in tropical forests, the effects of edge creation in open ombrophilous forests of the Atlantic Forest of northeastern Brazil are little discussed. Plant communities with large canopy openness, including periods with partial loss of leaves may respond differently to the impacts of edge formation because species may be more light-tolerant. The matrix can have a direct influence on the edge effect. Most studies available examine the consequences of the interface between forest and agricultural areas or pasturelands. However, the effects of the creation of a water body have been little studied, despite being frequent in the last century. In this study, we analyze the edge effect in two faces of a fragment, the first edge in contact with sugarcane crop, and the second with a lake formed by a dam. To neutralize the effect of selective logging and avoid counting species established before the edge formation, we analyzed the composition and density of the juvenile layer (≤ 1m). The results pointed out that the construction of a dam (water body) has caused an edge effect in the forest fragment, which seems to be not relevant in the area adjacent to sugarcane cultivation.