1. Ecosystems
Chapter 54

2. I. Energy Flow Trophic Structures Energy Budget Secondary Productivity
Global EB
GPP & NPP
Biomass
Limits of PP- aquatic, terrestrial
Secondary Productivity
Energy Efficiency
Pyramids-production, #s, biomass
Biological Magnification

3. II. Biogeochemical Cycles
Water
Carbon
Nitrogen
Phosphorous

4. III. Human Impact
Chemical Cycles
Acid precipitation
Toxins & biological Magnification
Climate change-CO2 & O3

5. A. Trophic Structures- Energy Flow
Energy flow one way- sun is inflow
Food chains & webs are short b/c trophic energy level loses 90%

6. Energy Transfer Energy in Energy moves through from the Sun
captured by autotrophs = producers
Energy moves through
food chain
transfer of energy from autotrophs to heterotrophs (herbivores to carnivores)
heterotrophs = consumers

7. Energy Transfer
Primary producers primary consumers secondary consumers tertiary consumers
Detrivores/Decomposers get energy from detritus most important part in an ecosystem connects all levels

8. B. Energy Budget Primary Production
Producers determine the energy budget for an ecosystem
GPP amount of solar energy converted into chemical energy all photsynthesis
NPP = GPP- Respiration (cost of staying alive)
PP  J/m2/y or biomass

9. Primary Production
Aquatic Systems light & nutrients are limiting factors for PP
Terrestrial Systems  temperature, moisture, nutrients

10. C. Secondary Production
The mount of chemical energy in consumers’ food that is converted into their

11. Energy Inefficiency
incomplete digestion
metabolism

12. Pyramids of Production
represent the loss of energy from a food chain
how much energy is turned into biomass

13. Pyramid of Numbers
levels in pyramids of production are proportional to number of individuals present in each trophic level

14. Implications
Dynamics of energy through ecosystems have important implications for human populations
what food would be more ecologically sound?
We consume more than just food: water, energy, space/habitat

15. D. Biological Magnification
Toxins can become concentrated in successive trophic levels of food webs
Humans produce many toxic chemicals that are dumped into ecosystems.
These substances are ingested and metabolized by the organisms in the ecosystems and can accumulate in the fatty tissues of animals.
These toxins become more concentrated in successive trophic levels of a food web, a process called biological magnification.

16. The pesticide DDT, before it was banned, showed this affect.
Fig
The pesticide DDT, before it was banned, showed this affect.
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

17. Fig
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

18. Biogeochemical Cycles
Nutrient cycles
Gases cycle on a global level
Solids cycle slowly and locally

19. Fig
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

20. The water cycle is more of a physical process than a chemical one.
Fig
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

21. The carbon cycle fits the generalized scheme of biogeochemical cycles better than water.
Fig
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

22. The Nitrogen Cycle
Nitrogen enters ecosystems through two natural pathways.
Atmospheric deposition, where usable nitrogen is added to the soil by rain or dust.
Nitrogen fixation, where certain prokaryotes convert N2 to minerals that can be used to synthesize nitrogenous organic compounds like amino acids.

23. Fig
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

24. Fig
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

25. III. Human Impact Rising atmospheric CO2.
Since the Industrial Revolution, the concentration of CO2 in the atmosphere has increased greatly as a result of burning fossil fuels.

26. Measurements in 1958 read 316 ppm and increased to 370 ppm today
Fig
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

27. The Greenhouse Effect
Rising levels of atmospheric CO2 may have an impact on Earth’s heat budget.
When light energy hits the Earth, much of it is reflected off the surface.
CO2 causes the Earth to retain some of the energy that would ordinarily escape the atmosphere.
This phenomenon is called the greenhouse effect.
The Earth needs this heat, but too much could be disastrous.

28. Global Warming
Scientists continue to construct models to predict how increasing levels of CO2 in the atmosphere will affect Earth.
Several studies predict a doubling of CO2 in the atmosphere will cause a 2º C increase in the average temperature of Earth.
Rising temperatures could cause polar ice cap melting, which could flood coastal areas.
It is important that humans attempt to stabilize their use of fossil fuels.

29. Ozone Depletion
Life on earth is protected from the damaging affects of ultraviolet radiation (UV) by a layer of O3, or ozone.
Studies suggest that the ozone layer has been gradually “thinning” since 1975.

30. Fig b
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

31. Ozone Depletion
Probably results from the accumulation of chlorofluorocarbons, chemicals used in refrigeration and aerosol cans, and in certain manufacturing processes.
The result of a reduction in the ozone layer may be increased levels of UV radiation that reach the surface of the Earth.
This radiation has been linked to skin cancer and cataracts.

32. The impact of human activity on the ozone layer is one more example of how much we are able to disrupt ecosystems and the entire biosphere.