Original article Spatial variation in post-dispersal seed removal in an Atlantic forest: Effects of habitat, location and guilds of seed predators Alexander V. Christianini a, *, Mauro Galetti b a Departamento de Bota ˆnica, Plant Phenology and Seed Dispersal Research Group, Instituto de Biocie ˆncias, Universidade Estadual Paulista (UNESP), CP 199, 13506-900 Rio Claro, SP, Brazil b Laborato ´rio de Biologia da Conservac ¸a ˜o, Departamento de Ecologia, Plant Phenology and Seed Dispersal Research Group, Instituto de Biocie ˆncias, Universidade Estadual Paulista (UNESP), CP 199, 13506-900 Rio Claro, SP, Brazil article info Article history: Received 19 November 2005 Accepted 20 June 2007 Published online 17 August 2007 Keywords: Birds Edge effect Granivory Habitat fragmentation Rodents Seed predation abstract Studies of post-dispersal seed removal in the Neotropics have rarely examined the magni- tude of seed removal by different types of granivores. The relative impact of invertebrates, small rodents, and birds on seed removal was investigated in a 2,178 ha Atlantic forest frag- ment in southeastern Brazil. We used popcorn kernels (Zea maysdPoaceae) to investigate seed removal in a series of selective exclosure treatments in a replicated, paired design experiment that included forest understory, gaps, and forest edge sites. We recorded the vegetation around the experimental seed stations in detail in order to evaluate the influence of microhabitat traits on seed removal. Vertebrate granivores (rodents and birds) were sur- veyed to determine whether granivore abundance was correlated with seed removal levels. Seed removal varied spatially and in unpredictable ways at the study site. Seed encounter and seed use varied with treatments, but not with habitat type. However, seed removal by invertebrates was negatively correlated with gap-related traits, which suggested an avoidance of large gaps by granivorous ants. The abundance of small mammals was re- markably low, but granivorous birds (tinamous and doves) were abundant at the study site. Birds were the main seed consumers in open treatments, but there was no correlation between local granivorous bird abundance and seed removal. These results emphasize the stochastic spatial pattern of seed removal, and, contrary to previous studies, highlight the importance of birds as seed predators in forest habitats. ª 2007 Elsevier Masson SAS. All rights reserved. 1. Introduction In tropical forests, many plant species are absent from sites ap- parently suitable for recruitment (Nathan and Muller-Landau, 2000, and references therein). Since seeds are subject to heavy mortality after dispersal from the mother tree (Janzen, 1971; Wenny, 2000), it is possible that seed predators have a great in- fluence on spatial patterns of plant recruitment (but see Andersen, 1989), although there is also great natural variation in seed rain (Nathan and Muller-Landau, 2000). Indeed, seed * Corresponding author. Present address: Programa de Po ´ s-graduac ¸a ˜ o em Ecologia, Instituto de Biologia, Departamento de Zoologia, Universidade Estadual de Campinas (UNICAMP), CP 6109, 13083-970 Campinas, SP, Brazil.: Fax: þ55 19 3289 3124. E-mail address: avchristianini@yahoo.com.br (A.V. Christianini). available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/actoec 1146-609X/$ – see front matter ª 2007 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.actao.2007.06.004 acta oecologica 32 (2007) 328–336