Population Uncertainty in Model Ecosystem: Analysis by Stochastic   Differential Equation
  Perturbation experiments are carried out by contact process and its mean-field version. Here, the mortality rate is increased or decreased suddenly. It is known that the fluctuation enhancement (FE) occurs after the perturbation, where FE means a population uncertainty. In the present paper, we develop a new theory of stochastic differential equation. The agreement between the theory and the mean-field simulation is almost perfect. This theory enables us to find much stronger FE than reported previously. We discuss the population uncertainty in the recovering process of endangered species. 
Satoru Morita, Kei-ichi Tainaka, Hiroyasu Nagata, and Jin Yoshimura