Definition of a Closed Ecosystem

A closed ecosystem cycles all nutrients within the ecosystem with no flow of nutrients into or out of the ecosystem. An open ecosystem differs by having a flow of nutrients into or out of the ecosystem.

Composition

An ecosystem is composed of all the living organisms (biotic factors) and their physical environment (abiotic factors) in a given area.

Biogeochemical Cycling

Nutrients such as carbon, nitrogen, phosphorous and sulfur are cycled from the environment into living organisms and back into the environment. This cycling is referred to as biogeochemical cycling. In a closed ecosystem these nutrients continually remain in the ecosystem.

Energy Input

While nutrients are cycled through the ecosystem, energy is lost through each step--energy that must continually be put back into the ecosystem. Often times, this energy is gained from the sun, but there are a number of ecosystems that gain their energy from other sources--for example, deep sea vents.

Reservoirs

In a closed ecosystem, reservoirs--areas where nutrients reside for extended periods of time--must be located within the ecosystem. One example of a reservoir is the carbon in coal located under ground.

Example

The biosphere, composed of the Earth and all the living organisms within it, is often considered a closed ecosystem, though a relatively small amount of material is gained from and lost into space.

References

• Marietta Collage: Environmental Biology--Ecosystems
• University of Colorado Department of Geological Sciences: Systems and Feedbacks
• The Habitable Planet: Ecosystems--Energy Flow through Ecosystems