energy flow in ecosystem

1. Energy flow in ecosystem
Unit 2.2
Environmental Science

2. Types of Flow models….
1. Single channel Models
2. Double channel Models (also called Y shaped Models.)
Grazing
Detritus

3. Single-channel energy models
• This model explains the unidirectional flow of energy.
• Whatever the energy captured by the autotrophs does
not revert back to solar input. As it moves progressively
through the various trophic levels, it is no longer
available to the previous level.
• the system would collapse if the primary source, the
sun, were cut off.
• there is a progressive decrease in energy level at each
trophic level. So, shorter the food chain, greater would
be the available food energy.

4. Photosynthesis
• It is a chemical process that converts carbon dioxide into
organic compounds, especially sugars, using the energy
from sunlight
The process occurs in two steps:
• First light energy is absorbed by chlorophyll to split a
molecule of water releasing hydrogen and oxygen.
• The second step uses the energy to convert carbon
dioxide to carbohydrates.
6CO2 + 12H2O ---> C6H12O6 + 6O2 + 6H2O

5. Respiration
While photosynthesis builds stored chemical energy in a
plant,
Respiration is the process of "burning" stored chemical
energy basically through oxidation, for maintaining plant
metabolism.
During plant respiration,
C6H12O6+6O2--->6CO2+6H2O+2830 kj

6. Autotrophs
(111 g/cm2/yr.)
Herbivores
(15 g/cm2/yr.)
Carnivores
(3 g/cm2/yr.)
Solar radiation(118,872 g/cm2/yr.)
Autotrophs
(111 g/cm2/yr.)
Herbivores
(15 g/cm2/yr.)
Decomposition-D(3)
Not utilized-NU(70)
Respiration-R(23)
D (0.5)
NU (7.0)
R (4.5)
D (trace)
NU (1.2)
R (1.8)

7. 1

8. Y- shaped or 2-channel model
It is applicable to both terrestrial and aquatic ecosystems. In
this energy model, one arm represents herbivore food chain
and the other arm represents the decomposer (detritus)
food chain.
The primary producers are entirely different for each arms.
This model also indicates that two food chains are infact,
under natural conditions, not completely isolated from one
another.
(i) it confirms to the basic stratified structure of ecosystem.
(ii) it separates the grazing and detritus food chains in both
time and space, and
(iii) micro consumers and macro consumers differ greatly in
size and metabolic relations.

9. Sunlight
Plants
Herbivore
Detritus Consumer
Predator
Predator
2

10. Universal Model

11. • Proposed by Odum. It is applicable to any living
component whether a plant, animal
/microorganisms or individual/population or a trophic
group.
• These models depict the basic pattern of energy
flow in ecosystem. Under natural conditions, these
organisms are inter related in a way that several
food chains become interlocked this results into a
complex food web.
• Complexity of food web depends on the length of
the food chain.
Thus in nature, there operate multi channel energy
flows. But in these the channels belong to either of
the two basic food chains - Grazing or Detritus.

12. I
A
NU
S
E
GP
R
B
3

13. 4

14. References/Sources
1. https://lh5.ggpht.com/2SZXkoyviYm84vNry1cdicBBu9US_EVYPfbQtr9Aes2YvshYG0Ks7
Oofi54ieKITVSFmZLg=s139
2. https://lh4.ggpht.com/bgEnwIiNJwJIXDAoFgAjOKgNFuemonldH6FtEf0KSBnSDyJVbXNq
bG6ZbUuqSUxybdckens=s170
3. https://lh4.ggpht.com/KOJi8OsE1nofIJ6oo6xFCn6ny2JND3Z-
CWtjGXX_sRDUAFfzGxLz6SHGkQ-B14-cInb0yA=s122
4. https://lh5.ggpht.com/_TATKuvaEDDGRmnIO81eKJG4FNXEjD0-e4DY_zw8yT8gq9ECTrI-
ybUnP1T0luBwbKXlmA=s90
Book/Web Resources
http://www.docstoc.com/docs/172268724/ecosystemppt