The role of the seed predator guild in a tropical deciduous forest, with some reflections on tropical biological control

Abstract

What effect does the array of animals that kill seeds (and seedlings), henceforth termed the seed predator guild, have on the community structure of the plants in a forest? In north temperate forests, one of the major impacts of the seed predator guild appears to be in the generation of mast year cycles in seed production; this occurs through the mechanism of natural selection against those individual trees that are not synchronized in their fruiting with the majority of their conspecifics or even other unrelated members of the community (Janzen 1971a). I have also argued that it is the generation of mast year behaviour on a population and community-wide basis that prevents the seed predator guild from lowering the density of the dominant tree species to a level where other tree species may invade and thereby increase the richness and diversity of tree species in the forest (Janzen 197oa, 1971a). These arguments, as well as those discussed in the remainder of this presentation, can be applied to foliage-eating animals as well, but will not be discussed further here in that context.