The term environment has been derived from the word environ, which means around. In other words, we can say that everything which surrounds us may collectively be termed as environment.
In a general way environment can be defined as the aggregate of all the physical and the biological world (both abiotic and biotic) and their influences affecting the life and development of an organism in it’s natural habitat.
No organism can exist without an environment. An ecosystem is the basic functional unit in ecology. Living organisms and their non living environment are interrelated to each other.
An ecosystem may be defined as a specific unit of all the organisms occupying a given area which interact with physical environment producing distinct trophic structure and material cycling.
There are two basic processes involved in an ecosystem:
· Cycling of material: it is a cycle of materials between living things and environment.
· Flow of energy: The energy trapped by given plants from the sun is passed on to the other organism.
Types of Ecosystem
On the basis of the nature ecosystem may be of the following two types:
· Natural ecosystem: It is a self regulating ecosystem without any major interference by man. Forests Lakes rivers etc are examples of natural ecosystem.
· Artificial ecosystem: It is a man made and is maintained artificially by planned manipulation
The pond as an ecosystem:
The pond is a classical example of ecosystem. The pond ecosystem comprises of the following four components:
Abiotic substances: These include water and the physical and chemical environment of water. Physical environment of water include temperature , light intensity, pH etcWhile the chemical environment includes the basic elements, the minerals dissolved gases, organic and inorganic compounds.
Producers (Autotrophs): These include rooted and floating plants as well as phytoplanktons.
Consumers: These include the hetertotrophs mainly the animals that feed upon other organisms The primary consumers are minute floating fauna(Zooplanktons), water fleas and larvae of insects. Consumers of second order are crustaceans ratifiers, small fish and frogs. The tertiary consumers are large fish and water birds.
Decomposers: These include aquatic bacteria, fungi, flagellate protozoan and actinomycetes. Although they are distributed throughout the pond, they are abundantantly present in mud at the bottom of the pond.
Producers receive solar energy in the form of organic material through photosynthesis. Producers are eaten by primary consumers (insects larvae, ratifiers, mollusks), which in turn are eaten by secondary consumers (insects fish, frog). The secondary consumers become the prey of
Tertiary consumers (large fish, Frog, snakes water birds). At some stage or the other, producers and the different grades of consumers die. Their dead bodies are acted upon by the decomposers who are responsible for breaking the complex organic substances into simple substances to be utilized again by the producers. In this way pond is an ideal example of an ecosystem.