Usually, 40% or less of the energy ingested is stored by growth. An invertebrate typically uses about a a quarter of this 40% for growth; in other words, about 10% of the food, an invertebrate eats is turned into its own body and thus into potential food for its predators. Although the the comparable figure varies from approximately 5% in carnivores to nearly 20% for herbivores, 10% is a good average value for the amount of organic matter that reaches the next trophic level.

1. ENERGY FLOW IN
AN ECOSYSTEM
Presented by:
S. Esakkiammal,
II M.Sc. Botany,
Department of Plant Science,
M. S University.

2. Energy :
The property of matter
and radiation which is
manifest as a capacity
to perform work

3. Laws ofThermodynamics:
•It states that the amount of energy in
the universe is constant. It may change
from one form to another, but it can
neither be created nor destroyed.
•The change of energy from one form to
another takes place in such a way that a
part of energy assumes waste form.

4. Energy loss:

5. Energy flow in Ecosystems:
•Living organisms can use energy in two
forms radiant and fixed energy.
•Radiant energy - electromagnetic
waves, such as light.
•Fixed energy - potential chemical
energy bound in various organic
substances which can be broken down
in order to release their energy content.

7. Primary Productivity:
•As the amount of biomass or organic
matter produced per unit area over a
time period by plants during
photosynthesis.
•It is expressed in terms of
weight (g–2) or energy (kcal m–2).
•The rate of biomass production is
called productivity.

8. Primary
productivity
Gross primary
productivity
(GPP)
Net primary
productivity

9. •Gross primary productivity of an
ecosystem is the rate of production of
organic matter during photosynthesis.
•A considerable amount of GPP is utilised
by plants in respiration.
•Gross primary productivity minus
respiration losses (R),is the net primary
productivity (NPP).
GPP – R = NPP

10. Secondary productivity
•The rate of formation
of new organic matter
by consumers.

11. Photosynthetically active radiation
(PAR):
• Plants capture only 2-10 per cent of the PAR and
this small amount of energy sustains the entire living
world.
• So, it is very important to know how the solar energy
captured by plants flows through different organisms
of and ecosystem.
• All organisms are dependent for their food on
producers, either directly or indirectly.
• So you find unidirectional flow of energy from the
sun to producers and then to consumers.

12. How does energy move
between tropic levels?
Energy can pass
from one tropic
level to the next
level
organic
molecules
Organism’s
body eaten by
another
organism

14. •No energy that is trapped into an
organism remains in it for ever.
•The energy trapped by the
producer, hence, is either passed on
to a consumer or the organism dies.
•Death of organism is the beginning
of the detritus food chain/web.

15. 1o %
loss

16. Main source of energy is sun
57% of sun energy is absorbed in the
atmosphere and scattered in the
space
35% is spent to heat water and
land areas and to evaporate
water.
8% of light energy
striking plant surface,
10% to 15% is reflected
2% (0.5 to 3.5%) of the total
light energy used in
photosynthesis

17. Usually 40% or less of the energy ingested is
stored by growth. An invertebrate typically uses about a
quarter of this 40% for growth; in other words, about 10%
of the food an invertebrate eats is turned into its own body
and thus into potential food for its predators. Although the
comparable figure varies from approximately 5% in
carnivores
to nearly 20% for herbivores, 10% is a good average
value for the amount of organic matter that reaches the
next trophic level.

18. Aquatic ecosystem:
Primary
producers
– 7618
kcal/m2/yr
Primary
consumer
s- 1103
kcal/m2/yr
Secondary
consumers
– 111
kcal/m2/yr
Tertiary
consumer
s – 5
kcal/m2/yr