How to Describe the Parts of an Ecosystem

by Kari Norborg Carter, Demand Media

http://everydaylife.globalpost.com/describe-parts-ecosystem-36131.html

The body of a higher animal, such as a mammal, consists of interrelated systems and organs that all depend upon each other to function properly. Similarly, an ecosystem, all the living and nonliving things in an ecological community, can function very much like a single organism. As with a mammal’s body, if one member or part of an ecosystem is damaged, becomes ill or dies, many or all of the other parts can be adversely affected. All parts of an ecosystem are interacting and interdependent.

Abiotic Factors

Many people first think of animals and plants when they hear the word “ecosystem,” but an ecosystem actually begins with the non-living or abiotic features of an environment: heat, light, water, atmosphere, chemicals, rocks, soil, latitude, altitude and other topographical factors. Most living things on Earth evolved over thousands or millions of years to adapt to their niche in their particular ecosystem. The organisms that have evolved to live in the low solar radiation of polar regions are very different from those that live near the equator. The kind of life that exists around alkali flats is a far cry from the life you find in a lush temperate rainforest. The water, air, inorganic nutrients and other chemicals in the abiotic part of an ecosystem are constantly being exchanged and recycled among the members of an ecosystem and the environment.

Autotrophs or Producers

For a living or biotic component to exist, all ecosystems must have autotrophs, producer organisms that can create organic molecules from inorganic substances. On Earth, the vast majority of autotrophs are plants. From carbon dioxide and water, plants can forge carbon bonds to produce sugars such as glucose. They do this using the energy of sunlight in a process called photosynthesis. Algae, which may be unicellular or multicellular, are also common autotrophs, using photosynthesis like plants. In the 1970s, scientists discovered that in the deepest trenches of the ocean where no sunlight penetrates, the abundant life found there depends not on plants and photosynthesis but on bacteria and a process called chemosynthesis: the bacteria make organic molecules from chemicals, including hydrogen sulfide, dissolved in magma-heated water surging from hydrothermal vents on the ocean floor. Even more recently, autotrophic bacteria that derive their energy from rocks and water, also through chemical reactions, were discovered deep underground.

Heterotrophs or Consumers

Heterotrophs or consumers are organisms that depend on the energy in organic molecules produced by autotrophs; they could not live without it. Herbivores, the primary consumers in an ecosystem, eat only producers or plants. They include such animals as butterflies, rabbits, koalas and elephants. They are specially adapted to collecting, processing and digesting particular kinds of plant foods. Carnivores, which play the role of secondary, tertiary, or higher consumers depending on where they lie in a food chain, eat other animals and possess adaptations for capturing and consuming those animals. They include preying mantises, polar bears and lions. Omnivores will eat a variety of plants and animals and include mice, raccoons, grizzly bears and humans. The venus flytrap and other carnivorous plants, which trap and digest insects, can be seen as both producers and carnivores.

Scavengers, Detrivores and Decomposers

Scavengers, detrivores and decomposers are heterotrophs that play a special role in an ecosystem. They all consume dead organic matter and thus derive the last bit of energy from those organisms. Often the names are used interchangeably. Scavengers consume mostly carrion, or dead animals, but some carnivores and omnivores will also scavenge on occasion. Blowflies, crabs and vultures are all scavengers. Detrivores consume detritus, or decomposing organic matter, including dead plants, dead animals and the droppings of animals. Dung beetles, millipedes, woodlice, terrestrial and fiddler crabs all act as detrivores. Decomposers further break down organic wastes on the molecular scale, turning them into nutrients in the soil in forms that autotrophs can use. They include many kinds of fungi, bacteria and protists. All play a vital role in cleaning up waste and helping recycle nutrients in an ecosystem. Interestingly, scientists believe that during the Carboniferous period, fungi and bacteria had not yet evolved the ability to digest lignin in wood. The extensive deposits of coal found deep underground resulted from the accumulation of dead plant matter from this period.