On-Off Intermittency in a Three-Species Food Chain

The environment affects population dynamics through multiple drivers. Here we explore
a simplified version of such influence in a three-species food chain, making use of the Hastings-
Powell model. This represents an idealized resource-consumer-predator chain, or equivalently, a
vegetation-host-parasitoid system. By stochastically perturbing the value of some parameters in
this dynamical system, we observe dramatic modifications in the system behavior. In particular,
we show the emergence of on-off intermittency, i.e., an irregular alternation between stable phases
and sudden bursts in population size, which hints towards a possible conceptual description of
population outbursts grounded into an environment-driven mechanism.