Ecosystem, Habitats, & Ecological Niches

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Density-dependent factors

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Density-independent factors

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Ecosystem, Habitats, and Ecological Niches

Ecosystems, habitats and ecological niches all intertwine in a complex network in nature. An ecosystem is a biological community of organisms interacting with one another and/or their physical environment. As a part of a larger ecosystem, a habitat is the area in which a specific species lives and thrives. An ecological niche is the role a species fills in its habitat or ecosystem.


shutterstock_506936800An ecological system, or ecosystem, is the all-encompassing term to describe an environment and all of the organisms living in it. It also describes how the organisms interact with one another and with the environment.

For example, a pond could be an ecosystem that supports the life of various fish, frogs, algae, weeds, microorganisms, insects and so on. It can support both land-based organisms and aquatic organisms. The fish will consume the insects and frog eggs, the frogs will consume various insects, and the insects will consume microorganisms, algae, animal waste and more. The pond is also affected by climate and sun exposure.


A habitat is a place where a plant, animal, or organism lives and thrives. Typically for animals, this means having access to water, food, shelter, air, and a place to raise its offspring within a given area. In the pond example, the pond (and general surrounding area) would be the habitat for the plants, animals, and organisms living in and around the pond. However, some animals (example: a bird) may come by the pond for water or food, but have a much more expansive habitat that the pond itself. The pond may not be the bird's habitat, but the bird is still a part of the pond ecosystem.

Some habitats can be as big and expansive as a forest or desert, while other habitats can be as small as a burrow near a water source. The key to determining a habitat is figuring out where a living thing’s shelter is, how far it travels for food, how far it travels for water (or how it gets water), how it gets air, and whether or not it can successfully raise offspring. A habitat can be as large or small as it needs to be to fulfill these necessities of survival!

Ecological Niches

An ecological niche can be described as a role or position a particular species has within its environment, how it fulfills its needs for food and shelter, ultimately how it survives (as predator or prey), and how it reproduces. The niche of a species includes all biotic (living) and abiotic (non-living) factors of the environment. Ecological niches also describe how a plant, animal, organism, or population thereof responds to how resources and competitors are distributed as well as how their adaptations also affect their environment or ecosystem.

Imagine once again the pond ecosystem. It is the habitat of many fish, as well as the food for these fish. Imagine that there are a number of birds that reside in a nearby grove of trees. These birds fly by the pond and catch and eat any fish at the surface. The fish fill the ecological niche of providing these birds food, and the birds fill the ecological niche of controlling the population of the fish through predation.

Now imagine that the grove of trees is cut down. The birds simply move and fine another source of food. The fish, however, have lost a natural predator. The ecological niche of limiting the fish population has been deserted. As a result, the fish population grows and consumes more insects and eggs from frogs and other fish. The additional effect of diminished insects and frog eggs will eventually affect the frog and insect population, and the food source for the increased fish population will decline. Once the fish don't have enough to eat, their population will be “corrected” by food scarcity. While the ecosystem does try - often successfully - to balance itself, any upset in these ecological niches can cause ecosystem failure should the balancing fail.  Because of ecological niches, something as small as erecting a building near a bird shelter can affect a pond miles away!


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