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An ecosystem is a community of living organisms (plants, animals and microbes) at a particular place or area. The living and physical components are linked together through nutrient cycles and energy flows. Ecosystems can be of any size, but usually they are in particular places.
Each ecosystem has its own community. A terrarium community, for example, can have small animals. A desert community may have cacti, small snakes, and scorpions. A pond community can have frogs, insects, snakes, and plants, and a forest community may have rabbits, foxes and pine trees. Communities are also divided into populations. A population is composed of species.
Ecosystems are stable, but not rigid. They react to major changes in the environment, especially climate changes. For example, the major rainforests have lasted for a long time (perhaps 50 million years or more in some cases). As the rainfall and temperature changes, they change. We know that the Amazon rainforest shrank in size during ice ages, and expanded in the warmer periods.
What drives all ecosystems is the primary production. Primary production is the production of organic matter from inorganic carbon sources. This happens through photosynthesis. It drives the carbon cycle, which influences global climate via the greenhouse effect.
Through the process of photosynthesis, plants capture energy from light and use it to combine carbon dioxide and water to produce carbohydrates and oxygen. The photosynthesis carried out by all the plants in an ecosystem is called the gross primary production (GPP). About 48–60% of the GPP is consumed in plant respiration. The rest is known as the net primary production (NPP). Total photosynthesis is limited by a range of environmental factors. These include the amount of light available, the amount of leaf area a plant has to capture light (shading by other plants limits photosynthesis), the supply of carbon dioxide and water, and suitable temperatures for carrying out photosynthesis.
Some of the many types of ecosystem:
- Hatcher, Bruce Gordon (1990). "Coral reef primary productivity: a hierarchy of pattern and process". Trends in Ecology and Evolution 5 (5): 149–155. . .
- Molles, Manuel C. 1999. Ecology: concepts and applications. Boston: WCB/McGraw-HIll. ISBN 0-07-042716-X
- Odum E.P. 1971. Fundamentals of ecology. 3rd ed, New York: Saunders. ISBN 0534420664
- Chapin F.S; Matson P.A. & Mooney H.A. 2002. Principles of terrestrial ecosystem ecology. New York: Springer, 97–104. ISBN 0-387-95443-0