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Chapter 54: Ecosystems

Chapter 54: Ecosystems. Ecosystem. All the organisms and abiotic factors in a community. 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. Trophic Levels.

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Chapter 54: Ecosystems

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  1. Chapter 54: 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). 1. Primary Producers 2. Primary Consumers 3. Secondary Consumers 4. Detritivores

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

  6. Consumers • Primary Consumers • Organisms that feed on the producers. • Ex: Herbivores • Secondary Consumers • Organisms that feed on the Primary Consumers. • Ex: Carnivores • Comment • There may be several layers of Secondary Consumers in an ecosystem.

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

  8. Linear pathway of who eats who in an ecosystem. Food Chain

  9. Network showing all the feeding relationships in an ecosystem. Food Webs

  10. Primary Productivity • The rate at which light energy is captured by autotrophs or primary producers. • NPP = GPP - Rs • NPP = Net Primary Productivity • GPP = Gross Primary Productivity • Rs = Respiration

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

  12. 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.

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

  14. Energy Transfers • Not 100% efficient. • Why? • Second law of thermodynamics. • Waste. • Materials that can’t be digested etc. • Averages 10% with each Trophic Level change.

  15. Question ? • Why do most ecosystems have only 3 - 4 trophic levels? • There isn’t enough energy passed up through the food web to support more levels.

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

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

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

  19. Chemical Cycling • Matter is recycled through ecosystems. • Ex: Biogeochemical Cycles • Matter Reservoirs 1. Organic Materials 2. Inorganic Materials • Available  Unavailable

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

  21. Energy vs Matter • Energy - flows through ecosystems and is mostly lost as heat. • Matter - cycles in ecosystems. • Question? • What is Man's influence on Ecosystems ? • Humans have had many negative impacts.

  22. Hubbard Brook

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

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

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

  26. Greenhouse Effects • Causes • Industrialization. • Burning of fossil fuels. • Loss of forests. • Results • Earth will heat up. • Ice caps melt and sea levels will rise. • Climate shifts. • Increased Ps (?)

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

  28. Exotic Species • When transplanted species are too successful and upset the ecosystem in new areas. • Ex: Starlings Fire Ants Carp

  29. Habitat Destruction • Worst problem threatening most species today.

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

  31. 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.

  32. 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.

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