Spatial distribution of an undergrowth palm in fragments of the Brazilian Atlantic Forest

The occurrence of disturbed sectors may be as important as microscale edge effects in tropical forests fragments. We considered the spatial distribution dynamics of life stages (youngs, immatures, and adults) of the acaulescent, endemic palm Attalea humilis Mart. ex. Spreng. in fire-prone fragments of the Brazilian Atlantic forest to inves-tigate population responses to fragment size and fire occurrence. From 1996 to 1999, we recorded the number of individuals in different life stages in adjacent 10×10-m plots in two perpendicular transects across each of three fragments of different sizes (1.6, 6.4, and 9.9 ha) in the Reserva Nacional de Poço das Antas, Southeastern Bra-zil. A fire burnt the fragments studied in 1997. Application of Morisita’s Index showed clumping at most scales, with a marked reduction in clumping degree from youngs to adults, a pattern not influenced by fragment size. After fire, clumping degree increased temporarily among the youngs. No association between life stages was detected using presence/absence data. Palm density concentrated in the most disturbed transect arms, a pattern very little affected by fragment size or fire. No consistent relationship between palm density and distance from fragment edge was detected for any stage, fragment, or year. We hypothesize that short-distance seed dispersal by scatterhoarding rodents results in discrete, low-density clumps of youngs dissociated from reproductive plants. The spatial pattern of later stages is probably conditioned by the distribution of canopy gaps in the largest, mor