[Nonlinear resistance in a diffuse trigger system. Biological barrier]

Mathematical model of antagonistic interrelations of biological species in which the migration is taken into account is considered. The ecological nish, occupied by one of the antagonistic species cannot be populated by the other if the initial quantity of the new species does not exceed the particular value. This is considered as the demonstration of the ecological barrier. The approach to the investigation of the nonlinear stability for spatially distributed systems can be applied to other biophysical problems.