Ecosystem – Components and Charavteristics

Components of an Ecosystem

The living part of the ecosystem is called its biotic component while the non-living parts are called the biotic component.

(a) Biotic component: This includes all living things/organisms in an environment. It is also called the biotic community. It is made up of;

(i) Food producer’s e.g. autotrophs (green plants), chemosynthetic bacteria and protophyta.

(ii) Food consumer’s i.e. heterotrophs such as animals, protozoa and some bacteria.

(iii) Decomposer’s i.e. saprophytes like fungi and some bacteria.

(b) Abiotic component: This consists of abiotic resources and abiotic conditions

Abiotic resources: These are what organisms need so as to stay alive. E.g. sunlight (a source of energy) and inorganic nutrients like water, nitrogen, carbon dioxide, phosphorus etc.

Abiotic conditions: These are those factors that determine the kind of organisms that are found in a particular ecosystem. These factors affect the behaviour, growth and breeding patterns of organisms, they include;

(i) Climatic factors such as temperature, wind, light intensity, humidity, water currents, turbidity, rainfall, e.t.c.

(ii) Edaphic factors such as soils, rocks, topography, etc.

Other factors include air, water, storms, etc.

Characteristics of an Ecosystem

The following are the characteristics of an ecosystem:

(i) There is a flow of energy

(ii) There is recycling of inorganic nutrients.

The major interaction between the biotic and abiotic components involves feeding. Food producers like plants, trap sun-light energy and nutrients (e.g. carbon dioxide, nitrogen) etc. from the abiotic environment to make food. The energy and nutrients in the food is passed on to heterotrophs (consumers) such as animals which feed on plants or on one another. The animals and plants  eventually die and decomposers feed on them thereby obtaining their own energy. However in the process, the decomposers release the nutrients in the animals and plants back into the abiotic environment (i.e. the soil). These  nutrients can be re-used again by the food producer’s. Plants also give out oxygen during photosynthesis and this is used by animals for respiration. Animals give off carbon dioxide during respiration which plants take up.

NB: As the energy in food is passed from one organism to another it eventually escapes into the environment and cannot be re-used.


  1. Define (a) biotic factor (b) abiotic factor
  2. Give two examples each of the concepts defined above
  3. What characteristics make an ecosystem a self- supporting unit.

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