Structure And Functions Of Biosphere

The biosphere can be studied from lower to higher levels of organisation starting from population, biotic community, ecosystem and biome.

A population comprises of individuals of same species. Various population constitute a biotic community.

When biotic communities and abiotic components interact with each other, an ecosystem is formed. Various ecosystems in a given geographical area form a biome.

The various components of biosphere can be discussed under the following heads :

POPULATION

A group of individuals of the same species in a given area constitute a population. It has a definite organisation and structure and exhibits various characteristics. The population may be deemed as the starting point of higher level (supraorganismal) organisation.

BIOTIC COMMUNITY

A group of populations of different species in a given area is referred to as biotic community. It includes several populations of plants and animals of a particular area which associate with each other e.g., a human being lives in a particular area and interacts with other members of the family. He domesticates some animals and also interacts with plants for various uses. Thus, it can be said that he is living in a biotic community.

ECOSYSTEM

A system resulting from the integration of living and non-living components of the environment is called ecosystem.According to Odum (1962), “A basic functional unit of organisms and their environment, interacting with each other and with their own components is termed as ecosystem”.

Ecosystem is a self contained structural and functional unit of biosphere which consists of distinct biotic community and the physical environment, both interacting and exchanging materials between them.There is a frequent exchange of energy and materials between adjoining ecosystems.It is an open system and depends upon solar energy from outside as ita energy source. An ecosystem can be temporary (e.g., rain water, pond, lake) or permanent; natural (terrestrial-a forest, a meadow, grass land, a desert or a hillside; aquatic-a pond, a lake, a river, a sea coast and an ocean) or artificial i.e. man made (e.g., cropland (agro-ecosystem) a garden, a park, a kitchen garden, or an aquarium); small (e.g., edge of a pond, a drop of pond water) or large (e.g., ocean).

Note:

•  The term Ecosystem was coined by Tansley. According to him Ecosystem is a symbol of structure and function of nature.
•  The term Ecology was coined by Reiter.
•  The term Ecology was first of all described by E.Haeckel.
•  Father of Indian Ecology-Prof.Ramdas Mishra.
•  The boundaries of ecosystem are indistinct and have an overlapping character with each others
•  "The total group of living things and environment of factors present in a particular place is called as ecosystem."
•  It means any structural and functional unit of the environment that can be identified and studied is called as ecosystem.
•  Ecosystem may be natural or artificial, permanent or temporary. Large ecosystem is called as biome such as desert, forest etc.

HOMEOSTASIS AND CYBERNETICS:

•  Homeostasis: Self maintainable characteristic is found in ecosystem. It means an ecosystem maintains the balance between the different trophic levels. Each trophic level controls the other trophic level in an ecosystem.
•  Cybernetics: A science of self control [homeostasis] in an ecosystem is called as "cybernetics".