A number of renewable resources are limited in size, even in the absence of human exploitation. In presenting the model of the previous section we have assumed that either the resource level was far from this limit or else that the limit did not affect significantly the behavior of the system. Whatever the specific mechanisms involved in the actual limitation of a given resource, which might be food or space limitations or the existence of predators, the concept of a carrying capacity m [May, 1981] is easily introduced by a decrease of the renewal rate represented in the dynamics of the resource by replacing equation 3 with:
