All living and non-living things that occur naturally on the earth constitute the natural environment. All living organisms are dependent on the environment for their survival. Their life is regulated by the environment and in turn they influence the environment.
Living organisms draw their nutrition and oxygen for survival from the environment. In the process, plants and animals interact with each other and also their physical environment.
An ecosystem is defined as a biological environment consisting of all organisms living in a particular area, as well as the non-living physical components of the environment with which the organisms interact.
A.G.Tansley in 1935 put forward the concept of ecosystem. The word ecosystem is derived from the Greek word "oikos" meaning home and "systema" meaning system.
An ecosystem can either be natural or human-designed. All ecosystems that exist in nature are Natural ecosystem. They can either be terrestrial or aquatic. Grasslands and deserts constitute the terrestrial ecosystem while rivers, ponds and oceans form the aquatic ecosystem. On the other hand, man-made or human-designed ecosystem is an artificial ecosystem. For example, gardens, aquarium, crop fields.
Both, non-living and living things constitute an ecosystem. They are termed as abiotic and biotic components. All of these components vary over space and time.
Abiotic components are the non-living physical and chemical factors in the environment of an ecosystem.
Examples: Sunlight, Temperature, Precipitation, Water or moisture, Soil, Air.
Biotic components are the organisms which include plants, animals and micro-organisms in an ecosystem.
Examples: Primary producers, Herbivores, Carnivores, Omnivores, Detritivores.
All of these components vary over space and time. Plants of coastal regions, hilly areas and deserts are distinctly different from each other. It is because each one has different abiotic components like temperature, soil and moisture. Thus, the abiotic components affect the various organisms in the environment.
All living beings are totally dependent on the abiotic components of the environment. The green plants manufacture their food with the help of sunlight, CO2 and chlorophyll (the green pigment present in the leaves of the plants). The herbivores and carnivores including humans are dependent on the food produced by the plants. Plants, animals and other organisms release back carbon dioxide, oxygen, water and other nutrients into the environment. This not only enriches the soil but also replenishes the atmosphere.