1. Biology, 9th ed, Sylvia Mader
Chapter 48
Chapter 48
Ecosystems & Human Interferences
Ecosystems & Human Interferences

2. The Nature of Ecosystems
Outline
The Nature of Ecosystems
Biotic Components
Autotrophs
Heterotrophs
Energy Flow
Ecological Pyramids
Global Biogeochemical Cycles
Hydrologic Cycle
Carbon Cycle
Nitrogen Cycle
Phosphorus Cycle

3. Biology, 9th ed, Sylvia Mader
Nature of Ecosystems
Chapter 48
Ecosystems & Human Interferences
Biosphere is the organism-containing part of the
Atmosphere
Hydrosphere, and
Lithosphere
An ecosystem is a place where organisms interact with the physical environment
Ecosystems characterized by:
Cyclical flow of materials from abiotic environment through biotic community and back
One-way flow of energy
2.D.1: Water and nutrient availability, temperature, salinity, pH

4. Ecosystems

5. Biotic Components: Autotrophs
Biology, 9th ed, Sylvia Mader
Biotic Components: Autotrophs
Chapter 48
Ecosystems & Human Interferences
Producers are autotrophs
Require only inorganic nutrients and an outside energy source to produce organic nutrients
Photoautotrophs
Chemoautrophs
2.A.1: Change in the producer level can affect the number and size of other trophic levels.

6. Biotic Components: Heterotrophs
Consumers are heterotrophs
Require a source of preformed organic nutrients
Herbivores - Feed on plants
Carnivores - Feed on other animals
Omnivores - Feed on plants and animals
Decomposers are also heterotrophs
Bacteria and fungi
Break down dead organic matter

7. Biotic Components

8. Energy Flow and Chemical Cycling
Nutrients pass one-way through food chain from one level to another
Each level retains some energy
The rest is converted to heat, which dissipates into the environment
Chemicals cycle as organic nutrients
Once used, they are returned back to the producers by
Excretion
Death
Cellular Respiration

9. Nature of an Ecosystem

10. Energy Balances

11. Grazing & Detrital Food Webs
Biology, 9th ed, Sylvia Mader
Grazing & Detrital Food Webs
Chapter 48
Ecosystems & Human Interferences
2.A.1: Food chains and food webs

12. Ecological Pyramids A trophic level
Composed of all the organisms that feed at the same level in a food chain
Only about 10% of the energy of one trophic level is useable to the next trophic level
Explains why few top carnivores can be supported in a food web

13. Biology, 9th ed, Sylvia Mader
Ecological Pyramid
Chapter 48
Ecosystems & Human Interferences
2.A.1: Change in energy resources levels such as sunlight can affect the number and size of the trophic levels.

14. Global Biogeochemical Cycles
Chemical cycling may involve:
Reservoir - Source normally unavailable to producers
Fossil Fuels
Minerals
Sediments
Exchange Pool - Source from which organisms generally take chemicals
Atmosphere
Soil
Water
Biotic Community - Chemicals remain in food chains, perhaps never entering a pool

15. Model for Chemical Cycling

16. Biology, 9th ed, Sylvia Mader
Hydrologic Cycle
Chapter 48
Ecosystems & Human Interferences
Fresh water evaporates from bodies of water
Precipitation on land enters the ground, surface waters, or aquifers
Water eventually returns to the oceans
2.D.1: Water availability
Fresh water makes up about 3% of the world’s supply of water; considered renewable because water cycle produces new supply but it is possible to run out of fresh water.

17. The Hydrologic (Water) Cycle

18. Atmosphere is an exchange pool for carbon dioxide
Carbon Cycle
Atmosphere is an exchange pool for carbon dioxide
The total amount of carbon dioxide in the atmosphere has been increasing every year
Thought to be due to fossil fuel combustion
Transfer Rate

19. The Carbon Cycle

20. Greenhouse Effect Greenhouse gases If Earth’s temperature rises
Carbon dioxide, nitrous oxide, methane
Allow sunlight to pass through atmosphere
Reflect infrared back to earth
Trap heat in atmosphere
If Earth’s temperature rises
More water will evaporate
More clouds will form, and
Setting up a potential positive feedback loop

21. Earth’s Radiation Balances

22. Atmospheric nitrogen is fixed by bacteria
Nitrogen Cycle
Atmospheric nitrogen is fixed by bacteria
Make it available to plants
Nodules on legume roots
Nitrification - Production of nitrates
Denitrification - Conversion of nitrate to nitrous oxide and nitrogen gas
Balances nitrogen fixation

23. The Nitrogen Cycle

24. Nitrogen and Air Pollution
Acid Deposition
Nitrogen oxides and sulfur dioxide are converted to acids when they combine with water vapor
Acid rain dramatically reduces pH of surface waters in some areas
Causes heavy metals to leach out of rocks, poisoning aquatic organisms
Kills plants and causes fish to be unfit for human consumption
Smog

25. Acid Deposition

26. Thermal Inversion

27. Phosphorus does not enter the atmosphere
Phosphorus Cycle
Phosphorus does not enter the atmosphere
Sedimentary cycle
Phosphate taken up by producers incorporated into a variety of organic molecules
Can lead to water eutrophication
Biomagnification

28. The Phosphorus Cycle

29. Sources of Water Pollution

30. Biology, 9th ed, Sylvia Mader
Global Climate Change
Chapter 48
Ecosystems & Human Interferences
The average temperature in the U.S. has risen since The warmest decade on record was With the increase in temperature, there have also been increases in drought conditions in some areas, and increased precipitation in other areas, increase in sea level. U.S. produced greenhouse gas emissions have increased by 14 percent from Since global climate change effects the entire world population, global cooperation is required in order to solve the problems at hand.
4.A.5: Global climate change models

31. Global Climate Change
The Kyoto Protocol, which has been enforced since 2005, has the goal to achieve stabilization and reduction of greenhouse gas concentrations. The United States has not ratified the agreement. The Copenhagen conference in 2009 did not create any binding agreement for long term action against climate change. One of the outcomes of this conference was the commitment to raise money to help poor countries cope with the effects of climate change. The Cancun summit in 2010 solidified the agreement to raise funds to help poor countries defend against climate change

32. Biology, 9th ed, Sylvia Mader
Chapter 48
Ending Slide Chapter 48
Ecosystems & Human Interferences
Ecosystems & Human Interferences