ECOSYSTEM

The two components of nature, viz. organisms
and their environment are not only complex
and dynamic, but also interdependent,
mutually reactive and inter-related. Ecology
deals with the various principles which govern
such relationships between organisms and their
environment.
Professor Eugene P. Odum (1913-2002), is
widely recognized as the “Father of Ecosystem
Ecology”. His monumental book entitled Fundamentals
of Ecology (first published in 1953)
revolutionized teaching of ecology world over
as it presented a new framework of the subject.
Haeckel first used the term ecology. He regarded
the ecology of an organism as the knowledge of
the sum of the relations of organisms to the surrounding
outer world and to organic and inorganic
conditions of existence. After the introduction
of the term ecosystem in literature by A.
Tansley in 1935, started the era of ecosystem
approach to ecology.
The various communities of living organisms
(plants and animals) interact among themselves
as well as with their physical environment like
soil, air and water. The living organisms interact
with one another through their food chains
in which one organism consumes another organism.
The living organisms like plants interact
with soil to get essential nutrients like nitrogen,
phosphorus, etc, with air to get carbon dioxide
and also with water bodies for carrying out the
process of photosynthesis. Thus, the various
communities of living organisms like plants and
animals along with soil, air and water of that
region form a self-subsisting or functional ambit
of the living world. This functional unit or system
made up of living and non-living components
which is capable of independent existence
is called an ecosystem.
Definition: Tansley defined ecosystem as
“the system resulting from the integration of all
the living and non-living factors of the environment.”
He further stated that “ the whole system
includes not only the organism complex but
also the whole complex of physical factors forming
what we call the environment of the biomethe
habitat factors in the widest sense. "It is the
systems so formed which-are basic units of nature
on the face of the earth.”
Strahler has defined ecosystem as “the total
assemblage of components entering into the interactions
of a group of organism”. He further elaborated
that “to the geographer, ecosystems are the
part of the physical composition of the life layer.”
Ecosystem has also been defined as-“a unit
that includes all the organisms (biological factors)
in a given area interacting with the environment
(physical factors) so that a flow of energy
leads to a clearly defined trophic (nutrient
requiring) structure, biotic diversity, and material
cycles (i.e. exchange of materials between
living and non-living sectors).”
An ecosystem is an overall integration of
whole mosaics of interacting organisms and their
environment. It is normally an open system with
a continuous, but variable, influx and loss of
material and energy. It is a basic, functional unit
with no limits of boundaries, consisting of both
biotic and abiotic components interacting with
each other, both necessary for maintenance of
life upon earth. Thus an ecosystem represents
the highest level of ecological integration which
is energy-based and this functional unit is capable
of energy transformation, accumulation
and circulation. Its main function in ecological
sense is to emphasize obligatory relationships,
interdependence and causal relations.
KINDS OF ECOSYSTEM
Ecosystems may be categorized as follows:
1. Natural Ecosystems: These operate by
themselves under natural conditions without
any major interference by man. Based
upon the particular kind of habitat, these
are further divided as:
a) Terrestrial, as forest, grassland, desert, etc.
b) Aquatic, which may be further distinguished
as: