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Understanding Ecosystems: Energy Flow, Chemical Cycling, and Trophic Levels

Explore the intricate relationships within ecosystems, focusing on energy flow and chemical cycling. This chapter discusses how energy moves through various trophic levels—starting with primary producers, then moving to primary and secondary consumers, and finally detritivores. Learn about primary productivity, the significance of nutrients, and the implications of energy transfer inefficiency. We also delve into the impact of human activity on ecosystems, including pollution, and discuss key biogeochemical cycles crucial for understanding the environment.

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Understanding Ecosystems: Energy Flow, Chemical Cycling, and Trophic Levels

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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).

  5. Trophic Levels 1. Primary Producers 2. Primary Consumers 3. Secondary Consumers 4. Detritivores

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

  7. Primary Consumers • Organisms that feed on the producers. • Ex: Herbivores

  8. Secondary Consumers • Organisms that feed on the Primary Consumers. • Ex: Carnivores

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

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

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

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

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

  14. Primary Productivity • NPP = GPP - Rs • NPP = Net Primary Productivity • GPP = Gross Primary Productivity • Rs = Respiration

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

  16. 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.

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

  18. Energy Transfers • Not 100% efficient. • Why? • Second law of thermodynamics. • Waste. • Materials that can’t be digested etc.

  19. Energy Transfer • Averages 10% with each Trophic Level change.

  20. 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.

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

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

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

  24. Chemical Cycling • Matter is recycled through ecosystems. • Ex: Biogeochemical Cycles

  25. Matter Reservoirs 1. Organic Materials 2. Inorganic Materials • Available  Unavailable

  26. Homework • Behavior Lab – Mon. 5/7 • Chapter 53 – today • Chapter 54, 55 – Mon. 5/7 for x-credit • Exam 4 – Mon. 5/7, 12:00 Burkhardt 100

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

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

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

  30. Hubbard Brook

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

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

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

  34. 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.

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