In the past environmental management practices have been based on disparate analysis of the impacts of pollutants on selected components of ecosystems. The world we live in is composed of many, many different ecosystems, all interacting and playing off one another. Each of these ecosystems has parts, or components, which also interact within the ecosystem to produce the effects we observe and draw conclusions from. Although the components of ecosystems vary greatly from one place to another, in general we can categorize them to help better understand how they interrelate and what commonalities exist from one ecosystem to another.
A basic division that is made when considering the components of any ecosystem is between the living, or “biotic,” parts and the non-living, or “abiotic”. The amount of sunlight a particular area receives, the temperature and climate over an extended period of time, and the amount of rainfall received are all examples of abiotic components of an ecosystem. For ecosystems that exist in water, the type of water (freshwater or salt) and the strength of water current are ecosystem-specific components.
Biotic Components of Ecosystems
The biotic components of ecosystems can be further broken down into subcategories based on the feeding characteristics of a given animal. The most basic level of biotic components are the primary producers, or “autotrophs,” which produce their own food usually using the chemical process known as photosynthesis. In a land ecosystem, these organisms would be the green plants, trees, bushes and the like, in a sea ecosystem, the primary producers are phytoplankton.
Above the level of autotrophs are the “heterotrophs,” animals which feed on other animals to get their necessary nutrients. Within this category there can be countless divisions again, depending on which level in the food chain a particular animal preys upon for its food. However, there are four subcategories which must be present in any ecosystem, which are:
- Herbivores, which feed only on plants
- Carnivores, which feed only on other animals
- Omnivores, which feed on plants and animals, and
- Detritivores, which feed on dead things.
Now we must look briefly at how the components of ecosystems interact with and affect one another. Take, for example, a pond. The sunlight shines down into the water, and if the pond is relatively stagnant and nutrient-rich, tiny green algae will utilize the abiotic components to manufacture their own food. At the edge of the pond, the same sunlight is taken in by other plants, such as reeds and marshland plant life, to produce their food. Inside the pond, microscopic animals feed on the algae. Insects, such as water beetles and their young, will in turn feed on the microscopic animals, and become food for larger animals such as fish and birds. At the top of the chain lie the animals that only eat other animals, such as herons, which feed only on fish. The final step in the chain occurs when the animal dies, and is fed on by bacteria as part of the decomposition process.