Ecosystem

An ecosystem is, therefore, defines as a natural functional ecological unit comprising of living organisms (biotic community) and their non-living (abiotic or physio chemical) environment that interact to form a stable self-supporting system. A pond, lake, desert, grassland, meadow, forest etc. are common examples of ecosystem.

Structure & Function of Ecosystem
(1) Abiotic Components
The non living factors or the physical environment prevailing in an ecosystem form the abiotic components. They have a strong influence on the structure, distribution, behavior and inter-relationship of organisms.

Abiotic components are two types
(a) Climatic Factors: Which includes rain, temperature, light, wind, humidity etc.
(b) Edaphic Factors: Which include soil, pH, torography mineral etc.

(2) Biotic Components
The living organisms including plants, animals and micro-organisms (Bacteria and Fungi) that are present in ecosystem form the biotic components.

On the basis of their role in the ecosystem the biotic components can be classified fied into three main groups:

(A) Producers: Photosynthesizing organisms

Producers are any kind of green plant. Green plants make their food by taking sunlight and using the energy to make sugar. The plant uses this sugar, also called glucose to make many things, such as wood, leaves, roots, and bark. Trees, such as they mighty Oak, and the grand American Beech, are examples of producers.

(B) Consumers

The animals lack chlorophyll and are unable to synthesis their own food. Therefore, they depend on the producers for their food. They are known as heterotrophs
(i.e. heteros = other, trophos = feeder)


The consumers are of four types

(a) Primary Consumers or First Order Consumer or Herbivores:
These are the animals which feed on plants or the producers. They re called herbivores. Examples are rabbit, deer, goat, cattle etc.




































(b) Secondary Consumers or Second Order Consumers or Primary Carnivores:
The animals which feed on the herbivores are called the primary carnivores. Examples are cats, foxes, snakes etc.

(c) Tertiary Consumers or Third Order Consumers:
These are the large carnivores which feed on the secondary consumers. Examples are Wolves.

(d) Quaternary Consumers or Fourth Order Consumers or Omnivores:
these are the largest carnivores which feed on the tertiary consumers and are not eaten up by any other animal. Examples are lions and tigers.