Survival without Dispersers: Seedling Recruitment under Parents

Abstract

to the cutting of trees, however, subsistence and commercial hunting have affected large tracks of forest but have left their physical structure relatively unaltered (Redford 1992). For example, subsistence hunting by 230 inhabitants of three Waorani villages in Ecuador kills an estimated 3165 mammals, birds, and reptiles annually (Yost & Kelley 1983). Unfortunately, there is little understanding of how these hunting activities alter the processes governing the maintenance and long-term sustainability of forest ecosystems. For example, large animals are the preferred species for hunters, and it may be that these species play particularly significant roles in the dispersal of large, seeded tropical trees (Terborgh 1988; Wrangham et al. 1994). Wrangham et al. (1994) demonstrated that, although chimpanzees (Pan troglodytes) constitute only 1.4% of the primate frugivore populations and 14.2% of the primate frugivore biomass, they are responsible for an estimated 45.3% of the seeds defecated by the frugivorous primates. Such findings support the idea that seed dispersal by frugivores is vital to the survival of fruiting tree populations because the survival of fallen fruit does not appear to be sufficient to maintain populations of many tropical tree species (Howe 1984; Pannell 1989; Chapman et al. 1992). A number of species-specific studies examining seedling survival under parent trees have found little or no recruitment under parent trees (Augspurger 1984). For example, Howe et al. (1985) found that 99.96% of Virola surinamensis fruit that drop un-