1013 Seed predators limit plant recruitment in Neotropical savannas Alana Vaz Ferreira, Emilio M. Bruna and Heraldo L. Vasconcelos A. Vaz Ferreira and H. L. Vasconcelos, Inst. de Biologia, Univ. Federal de Uberlândia, CP 593, 38400-902, Uberlândia, MG, Brazil. – E. M. Bruna (embruna@ufl.edu), Wildlife Ecology and Conservation, and Center for Latin American Studies, Univ. of Florida, PO Box 110430, Gainesville, FL 32611-0430, USA. Despite the well-documented impacts of consumers on seed abundance the link between seed predation and plant popula- tion dynamics remains poorly understood because experimental studies linking patterns of predation with seedling estab- lishment are rare. We used experimental manipulations with six woody plant species to elucidate the effects of seed predator type, habitat, and plant species identity on rates of seed predation and seedling recruitment in the Neotropical savannas known as the Cerrado. We found that seed predation rates are consistently high across a diversity of local habitat types, with important inter-habitat variation in seed predation for three of the six species used in our experiments. We also found that seed predation has a clear demographic signal – experimentally excluding predators resulted in higher rates of seedling establishment over the course of two seasons. Because the intensity of seed predation varied between species and habitats, it may play a role in structuring local patterns of plant abundance and community composition. Finally, our results lend support to the recent hypothesis that herbivores have major and underappreciated impacts in Neotropical savannas, and that top–down factors can influence the demography of plants in this extensive and biodiversity-rich biome in previously unexplored ways. heoretical models suggest seed predation plays a key role in structuring plant populations and ultimately communi- ties, and empirical studies conducted in a diversity of eco- systems have shown that post-dispersal seed predators can cause extensive seed loss (sensu Andersen 1989, Curran and Webb 2000). Seedling establishment may be limited by fac- tors other than seed availability, however, such as the pres- ence of suitable microsites in which seedlings can become established. If so, even extensive seed predation may have a negligible effect on plant recruitment – predators would only be removing seeds which would have failed to germi- nate anyway (reviewed by Crawley 2000). Furthermore, many perennial plants are buffered against predation by seed banks, which help ensure the saturation of safe sites and further divorce seed availability from seedling establishment (Maron and Simms 1997). Despite the well-documented impacts of consumers on seed abundance, however, the link between seed predation and plant population dynam- ics remains unclear. his is because experimental stud- ies directly linking predation with seedling establishment (sensu Bricker et al. 2010) are rare, even in habitats where consumers exert large effects on seed availability and plant community composition (Brown and Heske 1990, Valone and Schutzenhofer 2007). It is also difficult to generalize about how consumers influ- ence plant recruitment because of the often striking interspe- cific variation in seed traits (e.g. size, strength, the presence of arils or elaiosomes) that can influence the susceptibility of seeds to predation. Furthermore, many ecological communi- ties include a diversity of seed predators ranging from insects to mammals whose body mass can vary over 20-fold (Paine and Beck 2007). hese different consumer guilds can vary in their preference for seeds based on size or other traits, often in unexpected ways (Kelt et al. 2004, Munoz and Cavieres 2006). Such preferences can alter the diversity of seedlings in a site (Paine and Beck 2007), and ultimately drive shifts in community structure (Brown and Heske 1990). Finally, the demographic consequences of granivory will also be influenced by the potentially modulating effects of environmental heterogeneity on seed predation (reviewed by Turnbull et al. 2000). he abundance and impacts of consumers can vary with habitat type, and as a result popu- lations of the same plant species may experience markedly different patterns of seed predation (Maron and Kauffman 2006). However, relatively few studies have evaluated how the predation of seeds from plant species representing a wide range of seed traits varies among habitat types. Delineat- ing interspecific variation in predation pressure – and how it varies among habitats – is critical to resolving the long- standing question of whether differences in plant recruit- ment result from habitat-specific patterns of granivory or other forms of biotic and abiotic heterogeneity (Kauffman and Maron 2006). In this study we elucidate the effect of seed predators on seedling establishment by experimentally evaluating the interactive effects of seed predator type, habitat, and plant Oikos 120: 1013–1022, 2011 doi: 10.1111/j.1600-0706.2010.19052.x © 2011 he Authors. Oikos © 2011 Nordic Society Oikos Subject Editor: Robin Pakeman. Accepted 10 November 2010