Self-sustaining community comprised of interdependent organisms (plants, insects, animals) and their natural environment. It provides the food chain through which energy flows, and the biological cycles that recycle. An ecosystem is a complete community of living organisms and the nonliving materials of their surroundings. Thus, its components include plants, animals, and microorganisms; soil, rocks, and minerals; as well as surrounding water sources and the local atmosphere. The size of ecosystems varies tremendously. An ecosystem could be an entire rain forest, covering a geographical area larger than many nations, or it could be a puddle or a backyard garden. Even the body of an animal could be considered an ecosystem, since it is home to numerous microorganisms. On a much larger scale, the history of various human societies provides an instructive illustration as to the ways that ecosystems have influenced civilizations.
Components of the Ecosystem
1. Primary consumers (herbivores) feed directly on plants or other producers. 2. Secondary consumers (carnivores) feed only on primary consumers. 3. Tertiary or higher level consumers feed only on animal-eating animals. 4. Omnivores can eat both plants and animals. Examples are pigs, rats, cockroaches, and humans. 5. Detrtivores (decomposers and detritus feeders) live off of detritus, parts of dead organisms and castoff fragments and waste of living organisms. 6. Decomposers digest detritus by breaking down the complex organic molecules in these materials into simpler, inorganic compounds. Decomposers consist of various bacteria and fungi.
Types of Species Found in Ecosystems
1. Native species-which normally live and thrive in a particular ecosystem. 2. Immigrant species-which migrates into an ecosystem or which are deliberately or accidently introduced into an ecosystem by humans. 3. Indicator species-which serves as a early warning that a community or an ecosystem is being degraded. 4. Keystone species-which plays a role affecting many other organisms in an ecosystem. The loss of a keystone species can lead to sharp population drops and extinction of other species that depend on it for certain services.
Principal Ways Species Interact
1. Interspecific competition-competition from one or more species for one or more to the limited resources it needs. 2. Predation-an individual organism of one species, know as a predator, feeds on parts or all of a organism of another species, the prey, but does not live in or on the prey. 3. Parasitism-A parasite is a consumer that feeds on another living organism (its host) by living on or in its host organism for all or most of the host's life. 4. Mutualism-is a type of interaction in which both participating species generally benefit. 5. Commensalism-one specie benefits, while the other is neither helped nor harmed to any great degree.
How It Works
Earth itself could be considered a massive ecosystem, in which the living and nonliving worlds interact through four major subsystems: the atmosphere, hydrosphere (all the planet's waters, except for moisture in the atmosphere), geosphere (the soil and the extreme upper portion of the continental crust), and biosphere. The biosphere includes all living things: plants (from algae and lichen to shrubs and trees), mammals, birds, reptiles, amphibians, aquatic life, insects, and all manner of microscopic forms, including bacteria and viruses. In addition, the biosphere draws together all formerly living things that have not yet decomposed.
Several characteristics unite the biosphere. One is the obvious fact that everything in it is either living or recently living. Then there are the food webs that connect organisms on the basis of energy flow from one species to another. A food web is similar to the more familiar concept food chain, but in scientific terms a food chain—a series of singular organisms in which...
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