Ecosystem introduction

-A complete interacting self sufficient ecological unit is called ecosystem.
-The term ecosystem was introduced by A.G. Tansley in 1935.

Structure of ecosystem:
-Structure of an ecosystem has abiotic and biotic components 
-The abiotic components of an ecosystem are made up of different climatic, edaphic and topographical factors 
-The biotic components of an ecosystem are made up of producers, consumers and decomposers.

Functions of ecosystem:
The functionsof ecosystem is due to flow of energy and nutrients cycle.

I. Flow of energy:
-It involves process of transfer of energy from producers to decomposers. 
- In each step of transfer 90% energy is lost.
Thus the flow of energy is irreversible process.
II. Nutrients cycle:
-It involves the transfer of inorganic chemical of environment into plant.
- The organic chemical synthesizes in plants from inorganic chemical then transfers into consumers and decomposers.
-Finally the comlex organic chemicals in dead body of producers and consumers and their excretory products  are decomposed into simple inorganic chemical and returns back in to the environment by decomposers. 
- Thus nutrient cycling is reversible process.

Types of ecosystem:
-There are mainly two types of ecosystem i.e. artificial and natural ecosystem.
-Crop field, garden etc. are artificial ecosystem whereas pond, grass land etc. are natural ecosystem.
- Natural ecosystems may be aquatic or terrestrial.
- Aquatic ecosystem may be running water (lotic) ecosystem or standing  water (lentic) ecosystem.
- Terrestrial ecosystem occurs on land it may be forest, desert or grassland ecosystem.