The propagation and some implifications of environmental noise in ecological food webs

Jörgen Ripa

Dept of Theoretical Ecology, University of Lund, Sweden

Abstract

I have studied the effects of environmental noise in ecological food webs through linear analysis. My main interests were on spectral characteristics of population dynamics and the propagation of environmental disturbances through food webs. My results show that a simple linear analysis of a stochastic food web model can tell a great deal about the models dynamic behaviour and the relative responses to noise, entering the foodwebs at different trophic levels. These results turned out to be general and robust, even when I analysed a linear approximation of a nonlinear model. One interesting feature of stochastic food web models is the possibility of sustained oscillations, even though the deterministic equivalent model has a stable equilibrium. I also found a general and very simple rule concerning two-species food webs and their responses to external noise.