Influence of an invasive ant on grazing and detrital communities and nutrient fluxes in a tropical forest

Trophic interactions are important features of terrestrial ecosystems affecting grazing and detrital food webs and ecosystem processes (Lawrence & Wise, 2000; Schmitz et al., 2000; Wardle et al., 2005; Fukami et al., 2006; Dunham, 2008); however, pathways linking these subsystems have long been ignored. Detrital systems and their processes had been assumed to be primarily donor-controlled (via resource availability) (Begon et al., 1986; Strong, 1992), but empirical work has led to a growing awareness that drivers of this system are likely to be much more complex (Setälä et al., 1998) and that generalist predators may form an important link between aboveand below-ground terrestrial subsystems (Halaj & Wise, 2001; Scheu, 2001; Miyashita et al., 2003; Dunham, 2008). However, little attention has been paid to the trophic impacts of generalist predators as potential drivers of nutrient cycling or in altering linkages between grazing and detrital subsystems (i.e. communities based on plant versus detrital resources) (Wardle et al., 2005; Fukami et al., 2006). Thus, a better understanding of linkages between these subsystems has recently become a priority for further development of terrestrial ecology (Wardle et al., 2004). The invasion by a generalist predator creates a unique opportunity for studying the effects predation has across subsystem boundaries. Here, we examined the effects of the little red fire ant (Wasmannia auropunctata, Roger), on both grazing and detrital invertebrate communities and ecosystem processes in the rain forest understorey of Gabon. Ants that function as generalist predators often feed on consumers of Department of Ecology and Evolutionary Biology, Rice University, Houston, TX 77005; Monitoring and Assessment of Biodiversity Program, Smithsonian Conservation and Research Center, National Zoological Park, PO Box 37012, Washington, DC 20560, USA, Section of Integrative Biology, University of Texas, 1 University Station C0930, Austin, TX 78752, USA