It is hard to take seriously the idea that the way Mother Earth will strike back is with an arsenal of prehistoric monsters underground that it has that it will release as a result of nuclear tests. But the idea that Mother Earth might retaliate is still with us and taken fairly seriously by some. And, in fact, it has more than a grain of truth. It suggests that the eco-system actually has defense mechanisms to protect itself. But unlike a lot of mystical ideas, this one to some extent is true.
Nature breeds for stable equilibria, in a way.
The sort of thing that happens is that an increase in prey leads to an increase in predators. An increase in predators leads to a decrease in prey. A decrease in prey leads to a decrease in predators. A decrease in predators leads to an increase in prey, and the cycle begins again. If the effects become greater and greater then eventually the prey goes down to the point where it cannot continue the population, and it dies out and the predators die or go away.