A presentation to support the IB ESS course examining energy flow through and ecosystem. The presentation covers photosynthesis and respiration on ecosystems, productivity, and feeding relationships through the use of Arctic ecosystems as examples. Questions are included along the way to help students critically think about the relationships between energy, productivity and populations.

1. Energy in an ecosystem using Artic
Ecosystems as examples
Topic 2: Ecosystems and
Ecology

2. Ecosystems are linked together by energy and matter flows.
The Sun’s energy drives these flows, and humans are impacting the flows of energy and
matter both locally and globally.
Topic 2: Ecosystems and
Ecology
Energy in an ecosystem - The Artic Ecosystems
Main ideas 1

3. Topic 2: Ecosystems and
Ecology
Energy in an ecosystem - The Artic Ecosystems

4. The interactions of species with their environment result in energy and nutrient flows.
Photosynthesis and respiration play a significant role in the flow of energy in communities.
The feeding relationships of species in a system can be modelled using food chains, food
webs and ecological pyramids
Topic 2: Ecosystems and
Ecology
Main ideas 2
Energy in an ecosystem - The Artic Ecosystems

5. Topic 2: Ecosystems and
Ecology
The first part
Energy in an ecosystem - The Artic Ecosystems

6. Topic 2: Ecosystems and
Ecology
Energy in the ecosystem
Energy in an ecosystem - The Artic Ecosystems

7. Topic 2: Ecosystems and
Ecology
Pathway of energy through an ecosystem can be summarised as:
conversion of light energy to chemical energy
transfer of chemical energy from one trophic level to another with varying
efficiencies
overall conversion of ultraviolet and visible light to heat energy by an ecosystem
re-radiation of heat energy to the atmosphere.
The conversion of energy into biomass for a given period of time is
measured as productivity.
Energy in the ecosystem
Energy in an ecosystem - The Artic Ecosystems

8. The starting point of all energy in ecosystems is the sun.
But only organisms which photosynthesise can obtain energy directly from
the sun.
And as we have already seen not all of the planet receives the same
amount of solar energy
All other organisms obtain energy by eating
Energy in the Ecosystem
Topic 2: Ecosystems and
Ecology
At the Poles the suns energy
is spread over a large area
At the Equator
the suns energy
is spread over a
small area
Energy in an ecosystem - The Artic Ecosystems

9. Inputs of Water,Carbon Dioxide
and Sunlight
Light energy is trapped
by the chlorophyll
inside the chloroplasts
Energy is released,splitting
water into hydrogen and
oxygen
Oxygen is realesed
to the atmosphere
The hydrogen combines with
carbon dioxide to make glucose
Photosynthesis Involves
Inputs
Processes
Outputs
Photosynthesis and Respiration in Ecosystems
Topic 2: Ecosystems and
Ecology
Energy in an ecosystem - The Artic Ecosystems

10. Inputs
Sunlight
Carbon dioxide
Water
Carbon Dioxide
from the atmosphere
Water from
the soil
Sunlight
Photosynthesis and Respiration in Ecosystems
Topic 2: Ecosystems and
Ecology
Energy in an ecosystem - The Artic Ecosystems

11. Inputs
Sunlight
Carbon dioxide
Water
Carbon Dioxide
from the atmosphere
Water from
the soil
Sunlight
Photosynthesis and Respiration in Ecosystems
Topic 2: Ecosystems and
Ecology
Energy in an ecosystem - The Artic Ecosystems

12. Inputs
Sunlight
Carbon dioxide
Water
Carbon Dioxide
from the atmosphere
Water from
the soil
Sunlight
Photosynthesis and Respiration in Ecosystems
Topic 2: Ecosystems and
Ecology
Energy in an ecosystem - The Artic Ecosystems

13. Outputs
Glucose used as an energy source
by the plant
Oxygen released to the atmosphere Oxygen Released
Glucose produced
used as energy
source by whole plant
Photosynthesis and Respiration in Ecosystems
Topic 2: Ecosystems and
Ecology
Energy in an ecosystem - The Artic Ecosystems

14. Photosynthesis and Respiration in Ecosystems
Topic 2: Ecosystems and
Ecology
Glucose
Oxygen
Photosynthesis
Carbon dioxide
Sunlight
Water
Inputs Process Outputs
Energy in an ecosystem - The Artic Ecosystems

15. Photosynthesis and Respiration in Ecosystems
Transformations: Photosynthesis
•Light energy
•To
•Stored chemical energy
Topic 2: Ecosystems and
Ecology
Howard T. Odum, Systems Ecology: an Introduction, Wiley-Interscience, New York, 1983
System diagram for the transformation in photosynthesis based on Odum’s energese
Light energy
Photosynthesis
Biomass
Energy in an ecosystem - The Artic Ecosystems

16. What does it do?
Powers the whole ecosystem
Photosynthesis and Respiration in Ecosystems
Topic 2: Ecosystems and
Ecology
Energy in an ecosystem - The Artic Ecosystems

17. What does it do?
Provides the building blocks to
produce all other biological
molecules
Photosynthesis and Respiration in Ecosystems
Topic 2: Ecosystems and
Ecology
Energy in an ecosystem - The Artic Ecosystems

18. What does it do?
Provides the building blocks to
produce all other biological
molecules
Photosynthesis and Respiration in Ecosystems
Topic 2: Ecosystems and
Ecology
carbon dioxide + water. glucose + oxygen
Energy in an ecosystem - The Artic Ecosystems

19. What does it do?
Provides the building blocks to
produce all other biological
molecules
Photosynthesis and Respiration in Ecosystems
Topic 2: Ecosystems and
Ecology
carbon dioxide + water. glucose + oxygen
Energy in an ecosystem - The Artic Ecosystems

20. Photosynthesis produces the
raw material for producing
biomass. This becomes the
energy source for all other
organisms.
Photosynthesis and Respiration in Ecosystems
Topic 2: Ecosystems and
Ecology
carbon dioxide + water. glucose + oxygen
Energy in an ecosystem - The Artic Ecosystems

21. The total amount of energy
available to all other
organisms in any ecosystem
depends on the amount of
photosynthesis
Photosynthesis and Respiration in Ecosystems
Topic 2: Ecosystems and
Ecology
carbon dioxide + water. glucose + oxygen
Energy in an ecosystem - The Artic Ecosystems

22. Producers (plants) are
the starting point of all energy
available for an ecosystem
Producer
Primary Consumer
Secondary Consumer
Tertiary Consumer
Trophic Level 1
Trophic Level 3
Trophic Level 4
Trophic Level 2
Topic 2: Ecosystems and
Ecology
Photosynthesis and Respiration
in Ecosystems
Energy in an ecosystem - The Artic Ecosystems

23. Respiration
In plants Photosynthesis and
Respiration both occur
Animals depend on the
biomass produced by
photosynthesis as the energy
source for respiration
Photosynthesis and Respiration in Ecosystems
Topic 2: Ecosystems and
Ecology
Energy in an ecosystem - The Artic Ecosystems

24. Respiration
the release of energy from
glucose or other organic
substances inside living
cells
Glucose
Conversion
process
(respiration)
Energy Released
Oxygen Carbon Dioxide
and Water
Photosynthesis and Respiration in Ecosystems
Topic 2: Ecosystems and
Ecology
Energy in an ecosystem - The Artic Ecosystems

25. Respiration
Energy lost as Heat
Food in
Oxygen from
the atmosphere
Cellular respiration
Oxidation of Glucose
Releases energy to
drive life processes
Carbon dioxide
and water vapour released
Inputs of Glucose and Oxygen
Oxidation process in the cells
Release of energy for work and heat
Photosynthesis and Respiration in Ecosystems
Topic 2: Ecosystems and
Ecology
Energy in an ecosystem - The Artic Ecosystems

26. Respiration dissipates energy
as heat
Increases entropy in the
ecosystem
But this allows organisms to
maintain order and a relatively
low internal entropy
Photosynthesis and Respiration in Ecosystems
Topic 2: Ecosystems and
Ecology
Heat
Energy in an ecosystem - The Artic Ecosystems

27. Photosynthesis and Respiration in Ecosystems
Topic 2: Ecosystems and
Ecology
Chemical Energy
Stored in biomass
Kinetic Energy
Work
Heat
Energy in an ecosystem - The Artic Ecosystems

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Photosynthesis and Respiration in Ecosystems
Topic 2: Ecosystems and
Ecology
Chemical Energy
Stored in biomass
Kinetic Energy
Work
Heat
Energy in an ecosystem - The Artic Ecosystems

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Photosynthesis and Respiration in Ecosystems
Topic 2: Ecosystems and
Ecology
Chemical Energy
Stored in biomass
Kinetic Energy
Work
Heat
Energy in an ecosystem - The Artic Ecosystems

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Photosynthesis and Respiration in Ecosystems
Topic 2: Ecosystems and
Ecology
Chemical Energy
Stored in biomass
Kinetic Energy
Work
Heat
Energy in an ecosystem - The Artic Ecosystems

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Photosynthesis and Respiration in Ecosystems
Topic 2: Ecosystems and
Ecology
Chemical Energy
Stored in biomass
Kinetic Energy
Work
Heat
Energy in an ecosystem - The Artic Ecosystems

32. Transformations: Respiration
• Stored chemical energy
• To
• Kinetic energy and
• Heat
Photosynthesis and Respiration in Ecosystems
Topic 2: Ecosystems and
Ecology
Chemical Energy
Stored in biomass
Kinetic Energy
Work
Heat
Energy in an ecosystem - The Artic Ecosystems

33. Plants capture the suns energy and convert it to glucose,
herbivores eat plants and carnivores eat herbivores - different
feeding levels (Greek for food is trophe)
Topic 2: Ecosystems and
Ecology
Energy in an ecosystem - The Artic Ecosystems

34. Plants capture the suns energy and convert it to glucose,
herbivores eat plants and carnivores eat herbivores - different
feeding levels (Greek for food is trophe)
Trophic level 1
Trophic level 2
Trophic level 3
Topic 2: Ecosystems and
Ecology
Energy in an ecosystem - The Artic Ecosystems

35. Plants capture the suns energy and convert it to glucose,
herbivores eat plants and carnivores eat herbivores - different
feeding levels (Greek for food is trophe)
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Trophic level 1
Trophic level 2
Trophic level 3
Topic 2: Ecosystems and
Ecology
Energy in an ecosystem - The Artic Ecosystems

36. Plants capture the suns energy and convert it to glucose,
herbivores eat plants and carnivores eat herbivores - different
feeding levels (Greek for food is trophe)
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Trophic level 1
Trophic level 2
Trophic level 3
Topic 2: Ecosystems and
Ecology
Energy in an ecosystem - The Artic Ecosystems

37. Plants capture the suns energy and convert it to glucose,
herbivores eat plants and carnivores eat herbivores - different
feeding levels (Greek for food is trophe)
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Trophic level 1
Trophic level 2
Trophic level 3
Topic 2: Ecosystems and
Ecology
Energy in an ecosystem - The Artic Ecosystems

38. Plants capture the suns energy and convert it to glucose,
herbivores eat plants and carnivores eat herbivores - different
feeding levels (Greek for food is trophe)
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Trophic level 1
Trophic level 2
Trophic level 3
Topic 2: Ecosystems and
Ecology
Energy in an ecosystem - The Artic Ecosystems

39. Plants capture the suns energy and convert it to glucose,
herbivores eat plants and carnivores eat herbivores - different
feeding levels (Greek for food is trophe)
Trophic level 1 - producer
Trophic level 2 - herbivore (primary consumers)
Trophic level 3 - carnivore (secondary consumers)
Trophic level 4 - carnivore (tertiary consumer)
The first trophic level, the autotrophs supports the energy
requirements of all the other trophic levels above.
Trophic level 1
Trophic level 2
Trophic level 3
Topic 2: Ecosystems and
Ecology
Energy in an ecosystem - The Artic Ecosystems

40. Trophic level:The position that an organism occupies in a food
chain, or a group of organisms in a community that occupy the
same position in food chains.
Topic 2: Ecosystems and
Ecology
Topic 2.2: Communities and Ecosystems

41. Trophic level:The position that an organism occupies in a food
chain, or a group of organisms in a community that occupy the
same position in food chains.
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Topic 2: Ecosystems and
Ecology
Topic 2.2: Communities and Ecosystems

42. Trophic level:The position that an organism occupies in a food
chain, or a group of organisms in a community that occupy the
same position in food chains.
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Topic 2: Ecosystems and
Ecology
Topic 2.2: Communities and Ecosystems

43. Trophic level:The position that an organism occupies in a food
chain, or a group of organisms in a community that occupy the
same position in food chains.
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Topic 2: Ecosystems and
Ecology
Topic 2.2: Communities and Ecosystems

44. Trophic level:The position that an organism occupies in a food
chain, or a group of organisms in a community that occupy the
same position in food chains.
It is possible to classify the way organisms obtain energy
into two categories.
Producers or Autotrophs: These manufacture their own
food from simple inorganic substances (plants)
Consumers or Heterotrophs: Feed on autotrophs or
other heterotrophs to obtain energy (herbivores,
carnivores, omnivores, detrivores and decomposers
But within the consumers their is a feeding hierarchy of
feeding
Topic 2: Ecosystems and
Ecology
Topic 2.2: Communities and Ecosystems

45. Topic 2: Ecosystems and
Ecology
Feeding relationships in ecosystems
Energy in an ecosystem - The Artic Ecosystems

46. Producer
Primary Consumer
Secondary Consumer
Tertiary Consumer
Trophic Level 1
Trophic Level 3
Trophic Level 4
Trophic Level 2
Topic 2: Ecosystems and
Ecology
Feeding relationships in ecosystems
Energy in an ecosystem - The Artic Ecosystems

47. E
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Producer
Primary Consumer
Secondary Consumer
Tertiary Consumer
Trophic Level 1
Trophic Level 3
Trophic Level 4
Trophic Level 2
Topic 2: Ecosystems and
Ecology
Feeding relationships in ecosystems
Energy in an ecosystem - The Artic Ecosystems

48. E
E
E
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Producer
Primary Consumer
Secondary Consumer
Tertiary Consumer
Trophic Level 1
Trophic Level 3
Trophic Level 4
Trophic Level 2
Topic 2: Ecosystems and
Ecology
Feeding relationships in ecosystems
Energy in an ecosystem - The Artic Ecosystems

49. Ecosystems have an hierarchy of
feeding relationships .
The energy flow in the ecosystem
can be illustrated as a Food chain.
The arrows show the direction
that energy flows
Producer
Primary Consumer
Secondary Consumer
Tertiary Consumer
Trophic Level 1
Trophic Level 3
Trophic Level 4
Trophic Level 2
Topic 2: Ecosystems and
Ecology
Feeding relationships in ecosystems
Energy in an ecosystem - The Artic Ecosystems

50. Ecosystems have an hierarchy of
feeding relationships .
The energy flow in the ecosystem
can be illustrated as a Food chain.
The arrows show the direction
that energy flows
Producer
Primary Consumer
Secondary Consumer
Tertiary Consumer
Trophic Level 1
Trophic Level 3
Trophic Level 4
Trophic Level 2
Topic 2: Ecosystems and
Ecology
Feeding relationships in ecosystems
Energy in an ecosystem - The Artic Ecosystems

51. Ecosystems have an hierarchy of
feeding relationships .
The energy flow in the ecosystem
can be illustrated as a Food chain.
The arrows show the direction
that energy flows
Producer
Primary Consumer
Secondary Consumer
Tertiary Consumer
Trophic Level 1
Trophic Level 3
Trophic Level 4
Trophic Level 2
Topic 2: Ecosystems and
Ecology
Feeding relationships in ecosystems
Energy in an ecosystem - The Artic Ecosystems

52. Ecosystems have an hierarchy of
feeding relationships .
The energy flow in the ecosystem
can be illustrated as a Food chain.
The arrows show the direction
that energy flows
Producer
Primary Consumer
Secondary Consumer
Tertiary Consumer
Trophic Level 1
Trophic Level 3
Trophic Level 4
Trophic Level 2
Topic 2: Ecosystems and
Ecology
Feeding relationships in ecosystems
Energy in an ecosystem - The Artic Ecosystems

53. Energy Pathways in the Sub-arctic
(Tundra and a bit of Tiaga)
Topic 2: Ecosystems -
Case Study
S
c
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e
n
cebitz.
c
o
m

54. Limited Solar Energy
Topic 2: Ecosystems
What makes the Tundra biome
S
c
i
e
n
cebitz.
c
o
m

55. Limited Solar Energy
Topic 2: Ecosystems
What makes the Tundra biome
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At the Poles the suns energy
is spread over a large area
At the Equator
the suns energy
is spread over a
small area
S
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cebitz.
c
o
m

56. Limited Solar Energy
Topic 2: Ecosystems
What makes the Tundra biome
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p
p
p
a
a
a
a
a
a
a
a
a
a
a
a
At the Poles the suns energy
is spread over a large area
At the Equator
the suns energy
is spread over a
small area
S
c
i
e
n
cebitz.
c
o
m

57. Limited Solar Energy
Topic 2: Ecosystems
What makes the Tundra biome
At higher latitudes light required for
photosynthesis is spread over a
greater area
This means the rate of
photosynthesis is much lower than
at the equator
Therefore GPP is also lower
At the Poles the suns energy
is spread over a large area
At the Equator
the suns energy
is spread over a
small area
S
c
i
e
n
cebitz.
c
o
m

58. Limited Solar Energy
Topic 2: Ecosystems
S
c
i
e
n
cebitz.
c
o
m
What makes the Tundra biome

59. Limited Solar Energy
Topic 2: Ecosystems
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
23.5˚
Tilt
Southern Hemisphere
Summer
Northern Hemisphere
Winter
S
c
i
e
n
cebitz.
c
o
m
What makes the Tundra biome

60. Limited Solar Energy
Topic 2: Ecosystems
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
h
h
h
h
h
h
h
h
h
h
23.5˚
Tilt
Southern Hemisphere
Summer
Northern Hemisphere
Winter
S
c
i
e
n
cebitz.
c
o
m
What makes the Tundra biome

61. Limited Solar Energy
Topic 2: Ecosystems
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
h
h
h
h
h
h
h
h
h
h
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
D
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
s
23.5˚
Tilt
Southern Hemisphere
Summer
Northern Hemisphere
Winter
S
c
i
e
n
cebitz.
c
o
m
What makes the Tundra biome

62. Limited Solar Energy
Topic 2: Ecosystems
The Earth also tilts at an angle of 23.5˚
Creating summer and winter in each
hemisphere
During the Northern Winter almost no
solar energy reaches the high arctic
This again reduces productivity at the
poles
23.5˚
Tilt
Southern Hemisphere
Summer
Northern Hemisphere
Winter
S
c
i
e
n
cebitz.
c
o
m
What makes the Tundra biome

63. Extreme seasonality
Topic 2: Ecosystems
S
c
i
e
n
cebitz.
c
o
m
What makes the Tundra biome

64. Extreme seasonality
Topic 2: Ecosystems
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
“
“
“
“
“
“
“
“
“
“
“
“
“
“
“
“
“
“
“
“
“
“
“
“
“
“
“
“
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
-40
-30
-20
-10
0
10
20
30
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Temperature (˚c) Precipitation (mm)
S
c
i
e
n
cebitz.
c
o
m
What makes the Tundra biome

65. Extreme seasonality
Topic 2: Ecosystems
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
T
“
“
“
“
“
“
“
“
“
“
“
“
“
“
“
“
“
“
“
“
“
“
“
“
“
“
“
“
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
-40
-30
-20
-10
0
10
20
30
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Temperature (˚c) Precipitation (mm)
S
c
i
e
n
cebitz.
c
o
m
What makes the Tundra biome

66. Extreme seasonality
Topic 2: Ecosystems
Tundra experiences very little
“rainfall” - making it the driest
terrestrial biome
Limited solar energy and
excessive albedo effect lead to
extreme winter temperatures
Summers are short but long hours
of daylight help to compensate
and slightly extend the “actual”
growing season
-40
-30
-20
-10
0
10
20
30
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Temperature (˚c) Precipitation (mm)
S
c
i
e
n
cebitz.
c
o
m
What makes the Tundra biome

67. Topic 2: Ecosystems
Survival of the fittest!
S
c
i
e
n
cebitz.
c
o
m
What makes the Tundra biome

68. Topic 2: Ecosystems
Survival of the fittest!
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
S
c
i
e
n
cebitz.
c
o
m
What makes the Tundra biome

69. Topic 2: Ecosystems
Survival of the fittest!
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
S
c
i
e
n
cebitz.
c
o
m
What makes the Tundra biome

70. Topic 2: Ecosystems
Survival of the fittest!
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
F
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
m
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
f
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
a
S
c
i
e
n
cebitz.
c
o
m
What makes the Tundra biome

71. Topic 2: Ecosystems
Survival of the fittest!
Few plants can survive the extreme conditions
found in the tundra
All need adaptations to survive conditions that
would freeze the cells of most plants while
managing with very little moisture
Lichens - a symbiotic associating between a
fungus and a photosynthesising algae are the only
available “plant” biomass during the winter
Hard tough species like cotton grass manage to
grow during the summer
S
c
i
e
n
cebitz.
c
o
m
What makes the Tundra biome

72. Topic 2: Ecosystems and
Ecology
Suggest the impact of extreme seasonality and solar
spread on photosynthesis in the Arctic regions
Define albedo Effect
Suggest in relation to respiration why many arctic
consumer species either hibernate or reduce their activity
during the winter months (be careful this is not a question
about limited food supply directly)
Energy in an ecosystem - The Artic Ecosystems

73. Topic 2: Ecosystems and
Ecology
Part 2 - productivity
Energy in an ecosystem - The Artic Ecosystems

74. Topic 2: Ecosystems and
Ecology
Productivity
Carbon Dioxide
from the atmosphere
Water from
the soil
Sunlight
Oxygen Released
Glucose produced
used as energy
source by whole plant
Energy in an ecosystem - The Artic Ecosystems

75. Topic 2: Ecosystems and
Ecology
Productivity
All the energy fixed by plants is converted to
sugars
This is Gross Primary Production (GPP)
By the plant:
GPP can be converted into biomass
GPP can be used as an energy source
Carbon Dioxide
from the atmosphere
Water from
the soil
Sunlight
Oxygen Released
Glucose produced
used as energy
source by whole plant
Energy in an ecosystem - The Artic Ecosystems

76. Topic 2: Ecosystems and
Ecology
Productivity
All the energy fixed by plants is converted to
sugars
This is Gross Primary Production (GPP)
By the plant:
GPP can be converted into biomass
GPP can be used as an energy source
GPP forms the starting point (primary). Of
production in all other trophic levels
Carbon Dioxide
from the atmosphere
Water from
the soil
Sunlight
Oxygen Released
Glucose produced
used as energy
source by whole plant
Energy in an ecosystem - The Artic Ecosystems

77. Topic 2: Ecosystems and
Ecology
Productivity
It is the production that is left after plants have
carried out their own “work” which is available
to the rest of the ecosystem
Glucose produced
during photosynthesis
(Gross Primary Production)
Some glucose used to
supply energy to drive cellular
processes
(Respiration)
Remaining glucose available
to be laid down as
new material - biomass
(Net Primary Production)
NPP = GPP - R
Energy in an ecosystem - The Artic Ecosystems

78. Topic 2: Ecosystems and
Ecology
Productivity
It is the production that is left after plants have
carried out their own “work” which is available
to the rest of the ecosystem
Net Primary Production - NPP represents the
difference between the rate at which plants
photosynthesize (GPP) and the rate, which
they respire (R)
Glucose produced
during photosynthesis
(Gross Primary Production)
Some glucose used to
supply energy to drive cellular
processes
(Respiration)
Remaining glucose available
to be laid down as
new material - biomass
(Net Primary Production)
NPP = GPP - R
Energy in an ecosystem - The Artic Ecosystems

79. Topic 2: Ecosystems and
Ecology
Productivity
It is the production that is left after plants have
carried out their own “work” which is available
to the rest of the ecosystem
Net Primary Production - NPP represents the
difference between the rate at which plants
photosynthesize (GPP) and the rate, which
they respire (R)
NPP is the rate at which plants accumulate
dry mass, usually measured in kg,m-2,yr-1, or
as the energy value gained per unit time
kJ,m-2,yr-1
Glucose produced
during photosynthesis
(Gross Primary Production)
Some glucose used to
supply energy to drive cellular
processes
(Respiration)
Remaining glucose available
to be laid down as
new material - biomass
(Net Primary Production)
NPP = GPP - R
Energy in an ecosystem - The Artic Ecosystems

80. Topic 2: Ecosystems and
Ecology
Productivity
Glucose produced
during photosynthesis
(Gross Primary Production)
Some glucose used to
supply energy to drive cellular
processes
(Respiration)
Remaining glucose available
to be laid down as
new material - biomass
(Net Primary Production)
NPP = GPP - R
Energy in an ecosystem - The Artic Ecosystems

81. Topic 2: Ecosystems and
Ecology
Productivity
Glucose produced in photosynthesis has
two main fates.
Glucose produced
during photosynthesis
(Gross Primary Production)
Some glucose used to
supply energy to drive cellular
processes
(Respiration)
Remaining glucose available
to be laid down as
new material - biomass
(Net Primary Production)
NPP = GPP - R
Energy in an ecosystem - The Artic Ecosystems

82. Topic 2: Ecosystems and
Ecology
Productivity
Glucose produced in photosynthesis has
two main fates.
Some provides for growth, maintenance
and reproduction with energy being lost as
heat during processes such as respiration.
Glucose produced
during photosynthesis
(Gross Primary Production)
Some glucose used to
supply energy to drive cellular
processes
(Respiration)
Remaining glucose available
to be laid down as
new material - biomass
(Net Primary Production)
NPP = GPP - R
Energy in an ecosystem - The Artic Ecosystems

83. Topic 2: Ecosystems and
Ecology
Productivity
Glucose produced in photosynthesis has
two main fates.
Some provides for growth, maintenance
and reproduction with energy being lost as
heat during processes such as respiration.
The remainder is deposited in and around
cells represents the stored biomass
(NPP=GPP-R).
Glucose produced
during photosynthesis
(Gross Primary Production)
Some glucose used to
supply energy to drive cellular
processes
(Respiration)
Remaining glucose available
to be laid down as
new material - biomass
(Net Primary Production)
NPP = GPP - R
Energy in an ecosystem - The Artic Ecosystems

84. Topic 2: Ecosystems and
Ecology
Productivity
Total energy
taken in
(food eaten)
Usable energy
(Assimilation)
Waste
(faeces)
Gross Secondary Production = Energy assimilated
Food eaten - faeces
Energy in an ecosystem - The Artic Ecosystems

85. Topic 2: Ecosystems and
Ecology
Productivity
Biological communities include more than just
plants, they also include herbivores, carnivores
and detritivores.
Production also occurs in animals as
Secondary Production.
Importantly though animals do not use all the
biomass they consume.
Some passes through to become feces.
Gross production in animals equals the amount
of biomass or energy assimilated or biomass
eaten less faeces.
Total energy
taken in
(food eaten)
Usable energy
(Assimilation)
Waste
(faeces)
Gross Secondary Production = Energy assimilated
Food eaten - faeces
Energy in an ecosystem - The Artic Ecosystems

86. Total energy
taken in
(food eaten)
Energy to drive cellular
processes
(Respiration)
New
Biomass
Waste
(faeces)
NSP = GSP - R
(Food eaten - Energy in faeces) - Respiration
Topic 2: Ecosystems and
Ecology
Productivity
Energy in an ecosystem - The Artic Ecosystems

87. Total energy
taken in
(food eaten)
Energy to drive cellular
processes
(Respiration)
New
Biomass
Waste
(faeces)
NSP = GSP - R
(Food eaten - Energy in faeces) - Respiration
Topic 2: Ecosystems and
Ecology
Productivity
As with plants some of the energy
assimilated by animals is used to drive cellular
processes - respiration
The remainder is available to be laid down as
new biomass.
This is Net Secondary Production.
Net secondary productivity (NSP ) = food eaten -
faeces - respiration energy
so NSP = GSP- R (just like plants)
Energy in an ecosystem - The Artic Ecosystems

88. Calculating Net Secondary production
If Net secondary productivity (NSP
) = (food eaten - faeces) -
respiration energy
So NSP = GSP- R (just like plants)
Then Food eaten = 90, Faeces =
58, Respiration = 30
But what about Urine?
Topic 2: Ecosystems and
Ecology
Energy in an ecosystem - The Artic Ecosystems

89. Calculating Net Secondary production
If Net secondary productivity (NSP )
= (food eaten - faeces) - respiration
energy
So NSP = GSP- R (just like plants)
Then Food eaten = 90, Faeces = 58,
Respiration = 30
But what about Urine? Urine is treated
as a waste from the system.
Therefore
GSP: 90.00 - 58.00 = 32.00
R: 30.00 + 0.05 = 30.05
GSP
32.00 - 30.05 = 1.95 kJ x 106 year -1
Topic 2: Ecosystems and
Ecology
Energy in an ecosystem - The Artic Ecosystems

90. Calculating efficiency of transfer production
Efficiency = (energy in new form /
Original energy form) x 100
So original energy form = 90, New
energy form = 1.95
Therefore Efficiency:
(1.95 / 90) x 100 = 2.17%
Topic 2: Ecosystems and
Ecology
Topic 2.2: Communities and Ecosystems

91. Topic 2: Ecosystems
Tundra Productivity
S
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Energy in an ecosystem - The Artic Ecosystems

92. Topic 2: Ecosystems
Tundra Productivity
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e e
e
e
e
e
e e
e
e
e
e
e
e
e
e
0
500
1000
1500
2000
2500
Tropical
rain
forest
Temperate
deciduous
forest
Savanna
Boreal
Forest
Temperate
grassland
Tundra
Biomass
(g
m
-2
yr
-1
)
Based on a table from: Whittaker, R.H. and Likens, G.E. 1975. The biosphere and man. In: Leith, H. and Whittaker, R.H. (Eds.),
Primary Productivity and the Biosphere, Ecological Studies 14, Springer-Verlag, Berlin, Germany, pp. 305-328.
Comparison of Net productivity in different Biomes
S
c
i
e
n
cebitz.
c
o
m
Energy in an ecosystem - The Artic Ecosystems

93. Topic 2: Ecosystems
Tundra Productivity
Plant biomass can the thought of as the
energy store for the entire ecosystem
With the extreme climate and limited
light Tundra biomass is very low
0
500
1000
1500
2000
2500
Tropical
rain
forest
Temperate
deciduous
forest
Savanna
Boreal
Forest
Temperate
grassland
Tundra
Biomass
(g
m
-2
yr
-1
)
Based on a table from: Whittaker, R.H. and Likens, G.E. 1975. The biosphere and man. In: Leith, H. and Whittaker, R.H. (Eds.),
Primary Productivity and the Biosphere, Ecological Studies 14, Springer-Verlag, Berlin, Germany, pp. 305-328.
Comparison of Net productivity in different Biomes
S
c
i
e
n
cebitz.
c
o
m
Energy in an ecosystem - The Artic Ecosystems

94. Topic 2: Ecosystems
Tundra Productivity
Plant biomass can the thought of as the
energy store for the entire ecosystem
With the extreme climate and limited
light Tundra biomass is very low
Relationship of biomes to temperature and rainfall
S
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n
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c
o
m
Energy in an ecosystem - The Artic Ecosystems

95. Topic 2: Ecosystems
Tundra Productivity
Plant biomass can the thought of as the
energy store for the entire ecosystem
With the extreme climate and limited
light Tundra biomass is very low
Based on a table from: Whittaker, R.H. and Likens, G.E. 1975. The biosphere and man. In: Leith, H. and Whittaker, R.H. (Eds.),
Primary Productivity and the Biosphere, Ecological Studies 14, Springer-Verlag, Berlin, Germany, pp. 305-328.
Relationship of biomes to temperature and rainfall
S
c
i
e
n
cebitz.
c
o
m
Energy in an ecosystem - The Artic Ecosystems

96. Topic 2: Ecosystems
Tundra Foodchain
S
c
i
e
n
cebitz.
c
o
m
Energy in an ecosystem - The Artic Ecosystems

97. Topic 2: Ecosystems
Solar energy
Primary Consumer
Reindeer
Secondary Consumer
Grey Wolf
Primary Producer
Reindeer moss
Winter Foodchain
Tundra Foodchain
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l
l
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C
C
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Energy in an ecosystem - The Artic Ecosystems

98. Topic 2: Ecosystems
Solar energy
Primary Consumer
Reindeer
Secondary Consumer
Grey Wolf
Primary Producer
Cotton grass
Summer Foodchain
Tundra Foodchain
In winter reindeer survive eating
lichen, in particular Cadonia
rangiferina (Reindeer moss)
In the summer there is a greater
choice of plants - though all with
relatively low NPP
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Energy in an ecosystem - The Artic Ecosystems

99. Primary Producer
Cotton grass
Summer Foodchain
Topic 2: Ecosystems
2.1.3: Food chains - Tundra food system
Solar energy
Primary Consumer
Reindeer
Secondary Consumer
Grey Wolf
Tundra Foodchain
S
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100. Primary Producer
Cotton grass
Summer Foodchain
The tundra food chain can be thought
of as individual units - interlinked to
create an entire system
Topic 2: Ecosystems
2.1.3: Food chains - Tundra food system
Solar energy
Primary Consumer
Reindeer
Secondary Consumer
Grey Wolf
Tundra Foodchain
Input Process Output
S
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101. Primary Producer
Cotton grass
Summer Foodchain
The tundra food chain can be thought
of as individual units - interlinked to
create an entire system
Topic 2: Ecosystems
2.1.3: Food chains - Tundra food system
Solar energy
Primary Consumer
Reindeer
Secondary Consumer
Grey Wolf
Tundra Foodchain
Input Process Output
S
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102. Primary Producer
Cotton grass
Summer Foodchain
The tundra food chain can be thought
of as individual units - interlinked to
create an entire system
Topic 2: Ecosystems
2.1.3: Food chains - Tundra food system
Solar energy
Primary Consumer
Reindeer
Secondary Consumer
Grey Wolf
Tundra Foodchain
Input Process Output
Each trophic level in the foodchain is
an individual system inside a bigger
system
S
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103. Primary Producer
Cotton grass
Summer Foodchain
The tundra food chain can be thought
of as individual units - interlinked to
create an entire system
Topic 2: Ecosystems
2.1.3: Food chains - Tundra food system
Solar energy
Primary Consumer
Reindeer
Secondary Consumer
Grey Wolf
Tundra Foodchain
S
c
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c
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m

104. Primary Producer
Cotton grass
Summer Foodchain
The tundra food chain can be thought
of as individual units - interlinked to
create an entire system
Topic 2: Ecosystems
2.1.3: Food chains - Tundra food system
Solar energy
Primary Consumer
Reindeer
Secondary Consumer
Grey Wolf
Tundra Foodchain
Inputs of Water,Carbon Dioxide
and Sunlight
Light energy is trapped
by the chlorophyll
inside the chloroplasts
Energy is released,splitting
water into hydrogen and
oxygen
Oxygen is realesed
to the atmosphere
The hydrogen combines with
carbon dioxide to make glucose
Autotrophs are the first unit in the foodchain
system - but that itself is a system with
inputs, processes and outputs
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105. Primary Producer
Cotton grass
Topic 2: Ecosystems
2.1.3: Food chains - Tundra food system
Solar energy
Primary Consumer
Reindeer
Secondary Consumer
Grey Wolf
Tundra Foodchain and Energy
S
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c
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106. Primary Producer
Cotton grass
Energy is neither created
nor destroyed..
Energy can only change
from one form to another
Often called: The Law of
Conservation of energy or
the FIRST LAW OF
THERMODYNAMICS
Topic 2: Ecosystems
2.1.3: Food chains - Tundra food system
Solar energy
Primary Consumer
Reindeer
Secondary Consumer
Grey Wolf
Tundra Foodchain and Energy
I
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c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
c
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c
c
c
c
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107. Primary Producer
Cotton grass
Energy is neither created
nor destroyed..
Energy can only change
from one form to another
Often called: The Law of
Conservation of energy or
the FIRST LAW OF
THERMODYNAMICS
Topic 2: Ecosystems
2.1.3: Food chains - Tundra food system
Solar energy
Primary Consumer
Reindeer
Secondary Consumer
Grey Wolf
Tundra Foodchain and Energy
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p
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108. Primary Producer
Cotton grass
Energy is neither created
nor destroyed..
Energy can only change
from one form to another
Often called: The Law of
Conservation of energy or
the FIRST LAW OF
THERMODYNAMICS
Topic 2: Ecosystems
2.1.3: Food chains - Tundra food system
Solar energy
Primary Consumer
Reindeer
Secondary Consumer
Grey Wolf
Tundra Foodchain and Energy
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
c
c
c
c
c
c
c
c
c
c
c
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109. Primary Producer
Cotton grass
Energy is neither created
nor destroyed..
Energy can only change
from one form to another
Often called: The Law of
Conservation of energy or
the FIRST LAW OF
THERMODYNAMICS
Topic 2: Ecosystems
2.1.3: Food chains - Tundra food system
Solar energy
Primary Consumer
Reindeer
Secondary Consumer
Grey Wolf
Tundra Foodchain and Energy
S
c
i
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n
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c
o
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110. Primary Producer
Cotton grass
Topic 2: Ecosystems
2.1.3: Food chains - Tundra food system
Solar energy
Primary Consumer
Reindeer
Secondary Consumer
Grey Wolf
Tundra Foodchain and Energy
S
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111. Primary Producer
Cotton grass
TH
H
E
E
E
E
E
A
A
T
T
T
T
T
:
Topic 2: Ecosystems
2.1.3: Food chains - Tundra food system
Solar energy
Primary Consumer
Reindeer
Secondary Consumer
Grey Wolf
Tundra Foodchain and Energy
S
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112. Primary Producer
Cotton grass
TH
H
E
E
E
E
E
A
A
T
T
T
T
T
:
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
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e
e
e
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i
Topic 2: Ecosystems
2.1.3: Food chains - Tundra food system
Solar energy
Primary Consumer
Reindeer
Secondary Consumer
Grey Wolf
Tundra Foodchain and Energy
S
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113. Primary Producer
Cotton grass
THE SECOND LAW STATES:
Energy conversions are never
efficient and the more conversions
in a system the greater the total
inefficiency
So in an ecosystem not all the
energy at any Trophic level can
ever be passed on to the next as
some is lost as heat in respiration
Topic 2: Ecosystems
2.1.3: Food chains - Tundra food system
Solar energy
Primary Consumer
Reindeer
Secondary Consumer
Grey Wolf
Tundra Foodchain and Energy
S
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114. Primary Producer
Cotton grass
THE SECOND LAW STATES:
Energy conversions are never
efficient and the more conversions
in a system the greater the total
inefficiency
So in an ecosystem not all the
energy at any Trophic level can
ever be passed on to the next as
some is lost as heat in respiration
Topic 2: Ecosystems
2.1.3: Food chains - Tundra food system
Solar energy
Primary Consumer
Reindeer
Secondary Consumer
Grey Wolf
Tundra Foodchain and Energy
Heat generated
during work
e.g.respiration
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115. Primary Producer
Cotton grass
THE SECOND LAW STATES:
Energy conversions are never
efficient and the more conversions
in a system the greater the total
inefficiency
So in an ecosystem not all the
energy at any Trophic level can
ever be passed on to the next as
some is lost as heat in respiration
Topic 2: Ecosystems
2.1.3: Food chains - Tundra food system
Solar energy
Primary Consumer
Reindeer
Secondary Consumer
Grey Wolf
Tundra Foodchain and Energy
Heat generated
during work
e.g.respiration
Heat generated
during work
e.g.respiration
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116. Primary Producer
Cotton grass
THE SECOND LAW STATES:
Energy conversions are never
efficient and the more conversions
in a system the greater the total
inefficiency
So in an ecosystem not all the
energy at any Trophic level can
ever be passed on to the next as
some is lost as heat in respiration
Topic 2: Ecosystems
2.1.3: Food chains - Tundra food system
Solar energy
Primary Consumer
Reindeer
Secondary Consumer
Grey Wolf
Tundra Foodchain and Energy
Heat generated
during work
e.g.respiration
Heat generated
during work
e.g.respiration
Heat generated
during work
e.g.respiration
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117. Topic 2: Ecosystems
2.6: Changes in Ecosystems - Tundra carrying capacity
Tundra Populations
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118. Topic 2: Ecosystems
2.6: Changes in Ecosystems - Tundra carrying capacity
Tundra Populations
Tundra populations are therefore dependent
on the amount of energy that is passed on
from one trophic level to the next
The wolf population can only gain energy that
has been passed on from the Reindeer, who
can only gain whatever energy is passed on
from the plant community
This means there will always be fewer
organisms at the top of the foodchain than at
the bottom
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Lichen population
Reindeer
population
Wolf
population

119. Topic 2: Ecosystems and
Ecology
Referring to the laws of thermodynamics explain why
herds of zebra on the Serengeti can be much larger than
herds of Reindeer in Arctic ecosystems
Energy in an ecosystem - The Artic Ecosystems

120. Topic 2: Ecosystems and
Ecology
Calculate the values for GPP
and Solar radiation not used
for Photosynthesis
Calculate the efficiency of the
conversion of absorbed
sunlight by plants to stored
biomass
Energy in an ecosystem - The Artic Ecosystems
Sunlight
36.64 x 107
Not used for
photosynthesis
?
GPP ?
NPP
0.09 x 107
Respiration
0.08 x 107
The fate of solar radiation on Alaskan Tundra after Johnson and
Kelly (1970) Values are in cal m-2

121. Ecosystems have a hierarchy of
feeding relationships .
The energy flow in the ecosystem
can be illustrated as a Food chain.
The arrows show the direction
that energy flows
Producer
Primary Consumer
Secondary Consumer
Tertiary Consumer
Trophic Level 1
Trophic Level 3
Trophic Level 4
Trophic Level 2
Topic 2: Ecosystems and
Ecology
Food chains, webs and pyramids
Energy in an ecosystem - The Artic Ecosystems

122. Food chains are an oversimplification
They only show direct feeding relationships within one hierarchy
Some organisms can be at different trophic levels in different food
chains
Topic 2: Ecosystems and
Ecology
Cotton
Grass
Lemming Wolf
Food chains, webs and pyramids
Energy in an ecosystem - The Artic Ecosystems

123. Food chains are an
oversimplification
They only show direct feeding
relationships within one hierarchy
Some organisms can be at
different trophic levels in different
food chains
Topic 2: Ecosystems and
Ecology
Food chains, webs and pyramids
Energy in an ecosystem - The Artic Ecosystems

124. Food chains are an
oversimplification
They only show direct feeding
relationships within one hierarchy
Some organisms can be at
different trophic levels in different
food chains
Topic 2: Ecosystems and
Ecology
Simplified Boreal Forest Food Web
Food chains, webs and pyramids
Energy in an ecosystem - The Artic Ecosystems

125. Many illustrations of food chains
found in textbooks do not take
account of decomposers and
parasites
Topic 2: Ecosystems and
Ecology
Simplified Boreal Forest Food Web
Food chains, webs and pyramids
Energy in an ecosystem - The Artic Ecosystems

126. Many illustrations of food chains
found in textbooks do not take
account of decomposers and
parasites
Topic 2: Ecosystems and
Ecology
Simplified Boreal Forest Food Web
Food chains, webs and pyramids
Why
?
Does that say anything
about problems with
food chains as a
model?
Energy in an ecosystem - The Artic Ecosystems

127. Topic 2: Ecosystems and
Ecology
Food chains, webs and pyramids
Simplified
Coral Reef Food Web
Descriptive models
Energy in an ecosystem - The Artic Ecosystems
Why might the coral
reef food web be more
complex than the last
one
?

128. Topic 2: Ecosystems and
Ecology
Food chains, webs and pyramids
Simplified
Coral Reef Food Web
Descriptive models
Simplification
Only qualitative
Energy in an ecosystem - The Artic Ecosystems

129. Topic 2: Ecosystems and
Ecology
Food chains, webs and pyramids
Simplified
Coral Reef Food Web
Food webs say nothing about the
numbers of organisms at each
tropic level
Or the amount of energy stored
and transferred between levels
Energy in an ecosystem - The Artic Ecosystems

130. Topic 2: Ecosystems and
Ecology
In terms of productivity suggest why coral reef food webs
are more complex than Boreal (arctic) food webs in the
previous slides
Energy in an ecosystem - The Artic Ecosystems

131. Topic 2: Ecosystems and
Ecology
Ecological pyramids
Pyramids of number show estimations of the number of organisms at
each trophic level
5,842,424
708,624
354,904
3
Trophic level 1
Trophic level 2
Trophic level 3
Trophic level 4
Redrawn based on: Odum, Eugene P. Fundamentals of Ecology. Philadelphia: Saunders, 1959. Print.
Pyramid of numbers for a grassland ecosystem (0.4ha)
Energy in an ecosystem - The Artic Ecosystems

132. Topic 2: Ecosystems and
Ecology
Ecological pyramids
However
Redrawn based on: Odum, Eugene P. Fundamentals of Ecology. Philadelphia: Saunders, 1959. Print.
Pyramid of numbers for a Temperate forest ecosystem (summer)
200
150,000
120,000
2
Trophic level 1
Trophic level 2
Trophic level 3
Trophic level 4
Energy in an ecosystem - The Artic Ecosystems

133. Topic 2: Ecosystems and
Ecology
Ecological pyramids
Pyramids of biomass use estimations of dry mass (gm-2) of all
organisms at each trophic level
Redrawn based on: Odum, Eugene P. Fundamentals of Ecology. Philadelphia: Saunders, 1959. Print.
Pyramid of biomass for a lake in the USA
96
11
2
gm-2
Trophic level 1
Trophic level 2
Trophic level 3
Energy in an ecosystem - The Artic Ecosystems

134. Topic 2: Ecosystems and
Ecology
Ecological pyramids
However
Redrawn based on: Odum, Eugene P. Fundamentals of Ecology. Philadelphia: Saunders, 1959. Print.
Pyramid of biomass for a lake in the USA
4
21
0
gm-2
Trophic level 1
Trophic level 2
Trophic level 3
Energy in an ecosystem - The Artic Ecosystems

135. Topic 2: Ecosystems and
Ecology
Ecological pyramids
Pyramids of energy are proportional to the total energy utilized at each
trophic level - usually gm-2yr-1 or Jm-2yr-1 and represent productivity
Redrawn based on: Odum, Eugene P. Fundamentals of Ecology. Philadelphia: Saunders, 1959. Print.
Pyramid of energy for the Silver Springs catchment USA
87,0692
3,368
383
KJm-2yr -1
Trophic level 1
Trophic level 2
Trophic level 3
Trophic level 4
D 5060
21
Energy in an ecosystem - The Artic Ecosystems

136. Topic 2: Ecosystems and
Ecology
Ecological pyramids and laws of thermodynamics
2nd Law of Thermodynamics
(Topic 1)
Numbers, biomass and energy
decrease along food chains.
So produce a PYRAMID
Redrawn based on: Odum, Eugene P. Fundamentals of Ecology. Philadelphia: Saunders, 1959. Print.
8
3
Trophic level 1
Trophic level 2
Trophic level 3
Trophic level 4
D 5060
96
11
2
gm-2
Trophic level 1
Trophic level 2
Trophic level 3
5,842,424
708,624
354,904
3
Trophic level 1
Trophic level 2
Trophic level 3
Trophic level 4
Number
Biomass Energy
Energy in an ecosystem - The Artic Ecosystems

137. Topic 2: Ecosystems and
Ecology
Ecological pyramids
Pyramids of number and
biomass often contain
anomalies
Pyramids of biomass resolve
these
Redrawn based on: Odum, Eugene P. Fundamentals of Ecology. Philadelphia: Saunders, 1959. Print.
8
3
Trophic level 1
Trophic level 2
Trophic level 3
Trophic level 4
D 5060
96
11
2
gm-2
Trophic level 1
Trophic level 2
Trophic level 3
5,842,424
708,624
354,904
3
Trophic level 1
Trophic level 2
Trophic level 3
Trophic level 4
Number
Biomass Energy
Energy in an ecosystem - The Artic Ecosystems

138. Topic 2: Ecosystems and
Ecology
Ecological pyramids
Pyramids of number:
Advantages
simple overview and can be good at comparing changes in population numbers with time or season.
Disadvantages
all organisms are included regardless of their size. A single tree counts the same as a grass plants
do not allow for juveniles or immature forms
numbers can be too great to represent accurately.
Redrawn based on: Odum, Eugene P. Fundamentals of Ecology. Philadelphia: Saunders, 1959. Print.
Energy in an ecosystem - The Artic Ecosystems

139. Topic 2: Ecosystems and
Ecology
Ecological pyramids
Pyramids of biomass:
Advantages
Overcome most of the problems of pyramids of number.
Disadvantages
uses samples from populations, so it is impossible to measure biomass exactly
time of the year that biomass is measured affects the result (fixed sample time)
Take no account of short lived highly productive organisms
Redrawn based on: Odum, Eugene P. Fundamentals of Ecology. Philadelphia: Saunders, 1959. Print.
Energy in an ecosystem - The Artic Ecosystems

140. Topic 2: Ecosystems and
Ecology
Ecological pyramids
Pyramids of energy:
Advantages
Most accurate system shows the actual energy transferred and allows for rate of production.
Disadvantages
difficult and complex to to collect energy data - often from “representative” samples of similar organisms
or estimates
Redrawn based on: Odum, Eugene P. Fundamentals of Ecology. Philadelphia: Saunders, 1959. Print.
Energy in an ecosystem - The Artic Ecosystems

141. Work cited:
Johnson, P. L. and Kelley,J.J., Jr. Dynamics ofcarbondioxide in an arc-tic biosphere. Ecology,51: pp. 73-80, 1970,
Odum, Eugene P. Fundamentals of Ecology. Philadelphia: Saunders, 1959. Print.
Whittaker, Robert.H. and Likens, G.E. The biosphere and man. In: Leith, H. and Whittaker, R.H. (Eds.), Primary Productivity and the Biosphere,
Ecological Studies 14, Springer-Verlag, Berlin, Germany, pp. 305-328, 1975.
NB* Unless stated in the presentation all illustrations, figures and images are the property and copyright of N Gardner. Four Corners Education
Topic 2: Ecosystems and
Ecology
Energy in an ecosystem - The Artic Ecosystems

142. Work cited:
NB* Unless stated in the presentation all illustrations, figures and images are the property and copyright of N Gardner. sciencebitz.com
Topic 2: Ecosystems and
Ecology
Energy in an ecosystem - The Artic Ecosystems