This document summarizes energy flow within ecosystems. It explains that energy moves through different trophic levels in an ecosystem based on the cycling of energy and nutrients from external sources. Only about 1% of the sun's energy is captured by plants for distribution, but this is enough to support all life. Energy is degraded at each trophic transfer according to the 10% law, with 10-20% available to the next level. Photosynthesis converts solar energy to chemical energy stored in plants. Productivity refers to organic matter production, with net primary productivity equaling total productivity minus energy used for respiration. Food chains arrange organisms transferring energy through eating, and trophic levels designate organism positions. Ecological pyramids graphically represent parameters

1. PRESENTE
D
BY
RITU
KUMARI
MSc zoology
[final]
Energy flow
within
ecosystem

2. What is an ecosystem?
Abiotic biotic
Ecosystem is the smallest structural
and functional unit of nature or
environment. It is a self regulatory and
self sustaining unit.
Components of ecosystem :-
a) biotic component
b) abiotic component
Functional aspects of ecosystem :-
1. Energy flow
2. Nutrient cycling
3. Productivity
4. Decomposition

3. Energy flow in an ecosystem
Energy moves life. The cycle of energy is based
on the flow of energy through different trophic
levels in an ecosystem.
Our ecosystem is maintained by the cycling
energy and nutrients obtained from different
external sources.
The study of flow of energy through the
ecosystem is known as ecological energetics.
All the power utilized by living Organism is
ultimately derived from the sun.
Still ,as little as 1% of its total radiant energy is
captured by green plants for distribution
throughout the ecosystem.
This relatively small amount is nevertheless
sufficient to support all life on earth.

4. Energy flow in an ecosystem
 Animals can use energy in two forms, radiant and fixed energy. Radiant energy is
the framework of electromagnetic waves ,such as light. Fixed energy is potential
chemical energy tide up in different organic substances which can be injured in
order to discharge their energy content.
Organisms that can fix radiant energy can take advantage of inorganic substances
to produce organic molecules are called autotrophs.
Organisms that cannot obtain energy from an abiotic source but depend on energy
rich organic molecules synthesized by autotrophs are called heterotrophs.
Those who obtain energy from living organisms are called consumers ,and those
who obtain energy from dead animals are called decomposers.

5. Energy flow in an ecosystem
 When the light energy spill on the green surfaces of plants, a part of it is converted
into chemical energy which is kept in various organic products in the green plants .
When the herbivores eat plants as food and transform energy into chemical energy
accumulated in plant products into kinetic energy, degradation of energy will occur
through its conversion into hotness.
When herbivores are eaten up by carnivores of the foremost order [secondary
consumers], further degradation will occur.
Similarly when primary carnivores are fed by top carnivores, again energy will be
degraded.

6. Plants as producers
By performing
photosynthesis
they convert
solar energy
into chemical
energy.
PHOTOSYNTHESIS

7. Why is photosynthesis so important to
life?
It is estimated that 99% of the energy used by living cells comes from the
sun.
Incorporation of sunlight into chemical bonds occurs through the process of
photosynthesis
Oxygen is a waste product of photosynthesis. All oxygen in atmosphere is
believed to originate from photosynthesis.
Photosynthesis begins the carbon cycle by fixing CO2 in the atmosphere.
The oxygen released as a byproduct has a major impact on the biosphere.
Today’s atmosphere would not have 21% oxygen if not for photosynthesis.

8. Energy flow in an ecosystem based on two
laws of thermodynamics:
1st law: It states that energy can neither be
created nor destroyed hence it can only be
transferred from one system to another
from one form to another form.
2nd law: It states that during the
transformation ,a portion of the energy is
dissipated into the surroundings as heat
energy.
Thermody
namics of
energy
flow

9. Lindemann’s 10% law of energy flow
• Lindemann [1942] put forth 10% law for the transfer of energy
from one trophic level to the next.
• According to the law ,during the transfer of organic food from
one trophic level to the next ,only about 10% of the organic
matter is stored as flesh. The remaining is lost during transfer or
broken down in respiration.
• Plants utilize sun energy for primary production and can store
only 10% of the utilized energy as net production available for
the herbivores. When the plants are consumed by animals,
about 10% of the energy in the food is fixed into animal flesh
which is available for next trophic level[carnivores]. When a
carnivore consumes that animal, only about 10% of energy is
fixed in its flesh for the higher level.
• So at each transfer 80 to 90% of potential energy is dissipated
as heat [second law of thermodynamics] where only 10 to 20%
of energy is available to the next trophic level.

10. Productivity in
ecosystem
• The amount of organic matter produced as a
product via photosynthesis process is known
as productivity within an ecosystem.
• Gross primary productivity [GPP]= total
primary productivity
• Respiration [R]= metabolism
• Net primary productivity[NPP]= total primary
productivity less the energy used for
respiration.
NPP = GPP - R

11. Trophic level and food chain
• In ecosystem every Organism depends on other
organisms for food material and all organisms are[plants,
herbivores, carnivores] arranged in a series in which food
energy is transferred through repeated eating and being
eaten. It is called food chain. In food chain, energy flow is
in the form of food.
• Designation of Organism in every level is called trophic in
food chain that is what we call a trophic level.
• Top predators are sensitive to changes in the energy flow
of an ecosystem cannot have more than four or five levels
on a trophic pyramid, because level of energy decreases
during the flow of energy from one trophic to the another
trophic level.
• In food chain energy flow is unidirectional that is
from producers to top consumers. Shorter food
chains will provide greater energy.

12. Ecological pyramid (Elton pyramid)
 Graphical representation of
ecological parameters at different
trophic level in ecosystem is called
pyramids.
 Ecological Pyramid was formed by
Charles Elton.
 Called as Eltonian pyramids.
 In pyramids basal, mid and top tiers
shows the parameters values for
producer, herbivores and carnivores
in the ecosystem.
 These parameters are number
,biomass and energy.

13. THANK YOU