Living beings which consume only plants are called herbivores. We sometimes call them vegetarians. Well-known herbivores are rabbits, deer, cows, sparrows, squirrels and honeybees. They have specially designed teeth and produce special enzymes to digest plant matter.
The four elements of an ecosystem are: (a) The non-living environment, (b) Producers (green plants), (c) Consumers and (d) Decomposers. The non-living environment of an ecosystem includes sunlight, water, oxygen, minerals, dead plants and animal matter. The producers of an ecosystem are green plants. Animals, both herbivorous and carnivorous are the consumers of an ecosystem. Decomposers are bacteria, fungi and insects that decompose dead plants and animals.
The ability of nature to remain unchanged is called the balance of nature or ecological balance. The whole earth is an ecosystem, a system of give and take among plants, animals and their surroundings. In theory the ecosystem is a closed cycle but in practice the ecosystem is seldom in a state of balance. Gradual readjustment to the composition of a balanced community is continuously taking place. Man is often responsible for causing sudden ecological imbalance through activities like deforestation, polluting the atmosphere, destroying habitats, seas, lake and by rapid industrialization or sometimes through the out break of new disease.
Ecosystem is a functional unit consisting of interacting organisms and all aspects of the environment in any area. It contains both the non-living (abiotic) and living (biotic) components.
Ecology is the branch of science that is concerned with the relationships of life forms with each other and with their surroundings. The word ecology was coined in 1866 by Ernst Haeckel. It is derived from two ancient Greek words meaning “study of the home”. The word ecology comes from the Greek word Oikos meaning ‘household’.