We investigate a model of a dynamical system of a conflict triad that describes the interaction between the substances of the natural triad: biological populations (life), environment (living resources), and negative influences (infection). The main phases of coexistence of the substances of the triad are established: the equilibrium dynamical state (a stable fixed point), cyclic attractors, periodically oscillating trajectories, and evolutions close to chaotic ones. The existence of bifurcation points and thresholds of transitions between phases are shown for specific models.