Communities & Ecosystems


Primary Productivity
Population Dynamics
Biome Project

Ecology Information

Trophic Levels
Predator & Prey

Community/ Ecosystem Sites


Henderson's Dictionary of Biological Terms, by Eleanor Lawrence. 10th Ed.


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Communities & Ecosystems



The study of ecosystems looks at how the physical environment shapes communities, how communities interact with the physical environment. Examples of ecosystems are forest, rivers, meadows, soil, mountains, the surface waters of the ocean, the oceans' bottom, and the intertidal zone lying between the oceans and land. It is within these ecosystems, the life has its dance with the environment. Nutrient cycles, such as the carbon cycle, nitrogen cycle, and phosphorus cycle marks the path of these essential atoms from the environment and through the communities via their trophic levels. Essential elements that organisms use to make proteins, carbohydrates, lipids, and nucleic acids, the building blocks and engines that life is based upon.

Ecosystems are defined by an area that has a very similar environment. Still, the size of the ecosystem studied can be a large as a mountain range, or a small as a fallen log. An island, or a pond on the island may be studied as an ecosystem. What ecologists chooses to study as an ecosystem depends solely upon their interest, and the scope of their study. But an important component in any ecological study is the fact that no ecosystem is isolated from other ecosystems. Nutrients flow through several ecosystems, as water tumbles over rocks and boulders at the head of a stream, then swiftly moves downhill, joining other streams until they form rivers. Water, eroding rocks, brings phosphorus into an ecosystem. So just one stream can be examined as an ecosystem, with nutrients and immigrants coming downstream into this stream ecosystem. But this stream ecosystem losses nutrients, as the water flows through, then away from this stream ecosystem where the stream joins other streams, creating new physical conditions for its inhabitants. Individuals in the streams populations may emigrant downstream, to the river, or even to the ocean at the end of the water course.