Carrying-capacity is perhaps the key concept for the protection of our fragile planet. Carrying capacity is the measure of a ecosystem to support life. It is dependent upon the balance between animal and plant populations that take up and use the resources of the eco-system and the waste that the produce, and the amount of available resources of an eco-system. An ecosystem where its carry-capacity is said to be in balance is a sustainable ecosystem. An unbalanced ecosystem, however, is not sustainable over the long term.