An ecosystem is a place where plants and animals live and support each other's lives. All organisms in an ecosystem need energy and are therefore either producers, consumers or decomposers.

Ecosystems exhibit a state of equilibrium^*. The processes at work in the environment and in the living residents support each other. Energy is constantly^* transferred so that a natural balance is maintained.

The plants and animals in an ecosystem must work together in order to maintain the balance of the ecosystem.

• One way we can represent this balance is by a food web. A food web shows specific interactions^* among the inhabitants^* of an ecosystem.
• The maturing of a forest is an example of this balance at work.
• Sometimes people maintain an ecosystem for their own purposes. Farms are an example of this type of ecosystem.

All the organisms of one species make up a population.

An ecosystem can be thrown completely out of balance by natural disasters or by human activities. Disruption of an ecosystem can threaten or endanger the species that inhabit the ecosystem. This is because changes to the ecosystem can change the natural cycles in which natural resources are used and re-used.