concept

Carrying capacity

The largest population of a species an environment can sustain indefinitely, set by the limits of food, space and resources. A population grows fast when sparse, then slows and levels off as it nears this ceiling - the very ceiling the simplest predator-prey model forgot, letting its prey breed to infinity. Put the ceiling back and the predator-prey wheel finally behaves like something that could survive in a real forest, returning toward balance after a shock instead of careering off the edge.