a) Food chain
b) Food web
c) Energy flow
d) Trophic level or Ecological pyramid
a) Food chain - Food chain is defined as the transfer of energy and nutrients through the continuous process of " eating and being eaten" .
The plants and animals of an ecosystem are linked link is known as food chain.
Food chain divided into 3types
I) Terrestrial Food Chain
II) Grass Food Chain
III) Aquatic Food Chain
b) Food web
In an ecosystem the various food chain are inter-connected with each other and it is called as food web.
In an ecosystem , normally the food chain never separate as isolated unit but are inter-connected with one another to form network of food chain called food web.
A particular organisms may not occupied the same trophic level in every food chain , it may behave as secondary , tertiary consumer.
Hence food chain are inter-connected with another through different types of organisms at different trophic level.
Food web maintain the stability of an ecosystem . More complex the food web , more stable in the ecosystem .
Example:
c)Energy flow
Sun is the ultimate source of energy.
Flow of energy takes place from the producer to the decomposed.
Thus energy flow in an ecosystem is always unidirectional .
It is based on two important laws of thermodynamics.
#) First law of thermodynamics : It state that energy can neither be created nor be destroyed but can be converted from one form to another form.
#) Second law of thermodynamics : It state that energy can't be transferred 10% from one form to other form.
During tranfer from one form of energy to another form a part of concentrated enery is converted into degraded energy and the rest amount is lost during transfer.
Example: In our domestic electric supply electric energy in converted into light energy through illumination of electric bulb.
The total electric energy spent for illustration is not converted 10% into light energy .
Apart of it is converted into light energy and rest is lost as heat energy produced by electric bulb .
10% Rule of energy flow :
Lindemann in 1942 proposed the 10% rules of energy flow and according to him , about 10% of energy is transferred from one trophic level to the next trophic level.
If in an ecosystem the net primary production is 100cal the secondary production at herbivores leave would be 10cal ,at primary carnivorous would be 1cal ,at secondary carnivorous would be 0.1 cal
d) Ecological pyramid
An ecological pyramid is a graphic representation of an ecological parameters , like biomass energy or number of individuals present in different trophic level of a food chain .
Ecological pyramid were first prepared by Elton in 1927 . Hence they are also called as eltonian pyramid.
In a pyramid , the various steps of a food chain are represented by the sequence . The producers are placed at the base of the pyramid and the top of the pyramid and primary carnivorous are placed between the top and base level of the pyramid.
An ecological pyramid may be upright or inverted .
Depending upon different parameters the ecological pyramid is 3 types
#) Pyramid of number
#) Pyramid of biomass
#) Pyramid of energy
#) Pyramid of number
It is a graphic representation of the no of individuals per unit area of various trophic level i.e. number of producer herbivores and carnivorous .
The base of the pyramid contain the number of producer where as the number of carnivorous are occupied at the top of the pyramid.
The pyramid of numbers may be upright or inverted .
In grass land ecosystem the pyramid of numbers is upright . Because the number of grass or the producer is large as compared to herbivores and carnivorous the top of the pyramid include a small or few number of carnivorous
But in case of parasitic food chain the pyramid of number.
#) Pyramid of biomass
Biomass is the total mass of the organisms.
It is measured both as fresh and dry weight .
Pyramid of biomass is a graphic representation of biomass is present per unit area of different trophic level comparision produser at the base and top carnivorous at the top of pyramid .
Pyramid of biomass is more real than the pyramid of number .
Pyramid of biomass is upright in grass land ecosystem and inverted in the Ponds or aquatic ecosystems.
In grass land or forest maximum biomass occure in producer and it gradually decreases from the base to the top.
The herbivores and carnivorous has very low amount of biomass.
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