Chapter 55 Dynamics of Ecosystems

1
Chapter 55 Dynamics of Ecosystems
2
Ecosystem

• All the organisms and abiotic factors in a
  community.

3
Ecosystem Studies

• 1. Energy Flow the movement of energy through
  trophic levels.
• 2. Chemical Cycling the movement of matter from
  one part of the ecosystem to another.

4
Trophic Levels

• Division of an ecosystem based on the source of
  nutrition (energy).

5
Trophic Levels

• 1. Primary Producers
• 2. Primary Consumers
• 3. Secondary Consumers
• 4. Detritivores

6

7
Primary Producers

• Usually plants, capture energy and store it in
  chemical bonds.
• Are the source of the energy available to an
  ecosystem.

8
Primary Consumers

• Organisms that feed on the producers.
• Ex Herbivores

9
Secondary Consumers

• Organisms that feed on the Primary Consumers.
• Ex Carnivores

10
Comment

• There may be several layers of Secondary
  Consumers in an ecosystem.

11
Detritivores

• Get their energy from the organic waste produced
  by all levels.
• Ex bacteria and fungi

12
Food Chain

• Linear pathway of who eats who in an ecosystem.

13
Food Webs

• Network showing all the feeding relationships in
  an ecosystem.

14
Primary Productivity

• The rate at which light energy is captured by
  autotrophs or primary producers.

15
(No Transcript)
16
Primary Productivity

• NPP GPP - Rs
• NPP Net Primary Productivity
• GPP Gross Primary Productivity
• Rs Respiration

17
Available Energy

• Daily - 1022 joules of solar radiation.
• 1 - captured by Ps.
• About 170 billion tons of organic matter is
  created each year.

18
Primary Producers

• 50 - 90 of GPP is lost to Rs by the primary
  producers.
• NPP 10 - 50
• Animals - use only NPP, which limits the food
  webs.

19
(No Transcript)
20
Limiting Factors

• Material or nutrient that is not present in
  sufficient quantity for the primary producers.
• Ex N, P, K, Mg Light, CO2

21
(No Transcript)
22
Energy Transfers

• Not 100 efficient.
• Why?
• Second law of thermodynamics.
• Waste.
• Materials that cant be digested etc.

23
(No Transcript)
24
Energy Transfer

• Averages 10 with each Trophic Level change.

25
Question ?

• Why do most ecosystems have only 3 - 4 trophic
  levels?
• There isnt enough energy passed up through the
  food web to support more levels.

26
Implications

• There has to be fewer high level consumers in a
  food web.
• The higher level consumers usually need a large
  geographical area.

27
Question

• Which would support more humans per area?
• Eating meat?
• Eating plants?

28

29
Pyramids

• Graphical representation of relationships in
  ecosystems.
• Ex
• 1. Productivity
• 2. Biomass
• 3. Numbers

30

31
(No Transcript)
32
Chemical Cycling

• Matter is recycled through ecosystems.
• Ex Biogeochemical Cycles

33
Matter Reservoirs

• 1. Organic Materials
• 2. Inorganic Materials
• Available ?? Unavailable

34

35
Representative Cycles

• Water
• Carbon
• Nitrogen
• Know one or more of these cycles for an essay
  question.

36

37
(No Transcript)
38

39
Energy vs Matter

• Energy - flows through ecosystems and is mostly
  lost as heat.
• Matter - cycles in ecosystems.

40
Question ?

• What is Man's influence on Ecosystems ?
• Humans have had many negative impacts.

41
Hubbard Brook
42
(No Transcript)
43
Biological Magnification

• The concentration of toxins in successive levels
  of a food web.
• Ex DDT Heavy metals
  (Hg, Cd Pb)

44
(No Transcript)
45
(No Transcript)
46
Causes

• Not broken down by digestion/decomposition.
• Lipophilic.
• Concentrates and effects the upper levels of the
  food web.

47
Greenhouse Effects

• The trapping of heat by the Earth's atmosphere.
  (CO2, H2O etc.).

48
Carbon Dioxide Levels

• Prior 1850 - 274 ppm 1958 - 316 ppm
  1992 - 351 ppm
• Point the levels of CO2 are rising. The cause
  is probably due to humans.

49
(No Transcript)
50
Causes

• Industrialization.
• Burning of fossil fuels.
• Loss of forests.

51
Result

• Earth will heat up.
• Ice caps melt and sea levels will rise.
• Climate shifts.
• Increased Ps (?)

52
Acid Rain

• Caused by air pollution.
• Lowers the pH of rainfall.
• Is seriously damaging many ecosystems.

53
(No Transcript)
54
(No Transcript)
55
Habitat Destruction

• Worst problem threatening most species today.

56
Comment

• Man has a major impact on the Biosphere.
• Man needs to learn how to work with the Biosphere.

57
Summary

• Know the tropic levels of ecosystems.
• Know an example of a food chain and a food web.
• Know how energy moves through an ecosystem.

58
Summary

• Know how matter moves through an ecosystem.
• Know one or more examples of matter cycling.
• Be able to discuss in detail a human impact
  problem on ecosystems.