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.
