POLLINATOR FUNCTIONAL-RESPONSE AND PLANT-POPULATION DYNAMICS - POLLINATORS AS A LIMITING RESOURCE

During recent years, much work has focused on which factors limit the reproductive success in plants. Several studies show a strong influenc e of either resource limitation, pollen limitation or a combined effec t of both. The theoretical arguments for resource limitation are abund ant, but there has been very little work done concerning the effect of pollinator availability. In this paper we construct a model to study how the reproductive success in plants is influenced by the foraging b ehaviour of the pollinators. The pollinator population is assumed to h ave a constant population density. A functional response function for the pollinators is derived. It is similar to a Holling type II functio nal response. It is shown that, since the pollinators are regulated by factors not included in the model and their capability to pollinate i s limited by the functional response, this is sufficient for regulatin g the plant population. There also exists a threshold condition for th e persistence of the plant population that depended on the search rate of the pollinators and the demographic parameters of the plant popula tion. If this threshold condition is not satisfied the plant populatio n cannot persist and will become extinct. If the condition is satisfie d the plant population grows until it is limited at the equilibrium me ntioned above.