Nutrient Cycling in an Ecosystem
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In addition to energy, all organisms need certain elements in order to survive. There are a variety of basic elements found in living things of which 6 comprise 99% of the matter of life. These elements are sulfur, phosphorus, oxygen, nitrogen, carbon and hydrogen (SPONCH). These elements make up chemicals in the bodies of organisms such as proteins, carbohydrates, lipids and DNA. Since there is only a finite (in contrast to infinite) amount of these elements in the Biosphere, they have to be reused over and over. Technically, we call the circular movement of elements biogeochemical cycles since these chemicals, over a period of time, move through the living and nonliving environment. The term “nutrient cycle” is really a generalized designation for the various biogeochemical cycles of many different elements. It could, for example, be the water cycle (hydrogen and oxygen as H2O), the oxygen cycle, the carbon cycle, the sulfur cycle, the phosphorus cycle or the nitrogen cycle.
Group 2 - The Decomposers These are bacteria and fungi. Unlike the detritivores, the decomposers release chemicals from their bodies that break apart the dead matter. They then are able to acquire their needed energy and nutrients. Nutrients that remain behind in the soil or in the water (for aquatic ecosystems) are taken up by the producers living on land or in the water.
In our tropical rain forest, there are many detritivores and decomposers. The constant high temperature and moisture levels promote continual decomposition of dead matter (detritus). In fact, it occurs so rapidly that tropical soil is nutrient poor since the abundant diversity of plant life quickly extracts the nutrients in the soil.
The discovery of how nutrients are recycled in the Biosphere's ecosystems further helps us to understand how nature works.
The discovery of how nutrients are recycled in the Biosphere's ecosystems further helps us to understand how nature works.
If elements are located inside living matter then how are they extracted in order to be reused? All organisms eventually die. The world would quickly fill up with the dead bodies of all living things if there weren't some way to remove them, as well as extract the nutrients that are tied up inside of them. In the different ecosystems that comprise the Biosphere, there are two groups of organisms that accomplish these two major goals. First, they remove dead bodies, thereby functioning like trash collectors. Secondly, some of them (not all) are able to break apart dead matter (detritus) so that the nutrients can be released and recycled back to the producers.
Group 1 - The Detritivores These are organisms that eat detritus. This dead matter has two vital ingredients - energy and nutrients. So by eating detritus - the bodies of plants and animals, feces, cast away skin, leaves, etc. - detritivores acquire their needed energy and nutrients. Detritivores are highly adapted at finding and then chopping up the dead matter. Here are three detritivores:
Water Cycle
This biogeochemical cycle illustration shows the circular movement of water from land and water to the atmosphere. It eventually returns to land or water as precipitation.
This biogeochemical cycle illustration shows the circular movement of water from land and water to the atmosphere. It eventually returns to land or water as precipitation.
Dung Beetles
Hyenas
Vultures
Fungi - Mushrooms are fungi that grow on dead organisms especially plants
Bacteria - While some species of bacteria cause disease, most are harmless to humans and indeed are ecologically important since they recycle nutrients
The following Resources Articles may also be helpful:
Credits: Water Cycle, Dung Beetle, Hyena, Vulture (Dorling Kindersley) / Mushrooms (Algol | Dreamstime) / Bacteria (Sebastian Kaulitzk|Dreamstime)