What happens when large numbers of plants and animals build up in the new habitats?
If you think about a natural habitat such as a pond or a wood, it stays the same for many years even though all the plants and animals are breeding. The reason for this is due to the way all the living things are linked together through feeding. Each plant and animal produces a large number of offspring because most of them will become the food of something else. If a kind of plant were to begin to increase greatly in number the animals that feed upon it would also increase greatly in number. They would reduce the numbers of the plant. In a similar way the predators of the plant-eating animal would increase in number too. If the numbers of the plant-eating animal fell, some of the predators would starve to death or move away to find other food. In this way the numbers of plants and animals in a habitat are controlled. It is done naturally and is sometimes called the balance of nature.
