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Ecosystems: Components, Energy Flow, and Nutrient Cycles

Understand the components of ecosystems, how energy flows through food chains and webs, and the cycling of nutrients in the biosphere.

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Ecosystems: Components, Energy Flow, and Nutrient Cycles

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  1. CHAPTER THREE ECOSYSTEMS: WHAT ARE THEY & HOW DO THEY WORK?

  2. Natural Capital Degradation: Satellite Image of the Loss of Tropical Rain Forest 28 YEARS LATER Fig. 3-1a, p. 54

  3. Four Major Components Support Life on Earth • Atmosphere • Troposphere: where weather happens • Stratosphere: contains ozone layer • Hydrosphere • Geosphere • Biosphere

  4. Three Factors Sustain Life on Earth • One-way flow of high-quality energy: • Sun → plants → living things → environment as heat → radiation to space • Cycling of nutrients through parts of the biosphere • Gravity holds earths atmosphere

  5. Sun, Earth, Life, & Climate • Sun: UV, visible, and IR (Infra-red) energy • Radiation • Absorbed by ozone and other atmosphere gases • Absorbed by the earth • Reflected by the earth • Radiated by the atmosphere as heat Natural greenhouse effect

  6. Flow of Energy to and from the Earth Fig. 3-4, p. 57

  7. Levels of Organization in Nature Communities & Abiotic Factors Many species In same place Group of Organisms of Same species In same place

  8. Major Biotic and Abiotic Components of an Ecosystem • Abiotic • Water • Air • Nutrients • Rocks • Heat • Solar energy • Biotic • Living and once living Fig. 3-6, p. 59

  9. Organisms Are Either Producers or Consumers, Not Both (with a few exceptions) • Producers autotrophs • Photosynthesis: • 6CO2 + 6H2O + sunlight → C6H12O6 + 6O2 • Chemosynthesis 12H2S + 6CO2 → C6H12O6+ 6H2O + 12S (simplified) • Consumers heterotrophs • Primary consumers herbivores • Secondary consumers • Tertiary consumers Omnivores & Carnivores Omnivores & Carnivores

  10. Producers Fig. 3-7a, p. 59

  11. Consumers Fig. 3-8a, p. 60

  12. Specialized Consumers • Decomposers • Consumers that release nutrients • Bacteria • Fungi • Detritivores • Feed on dead bodies of other organisms • Earthworms • Vultures

  13. Ecosystem Components Fig. 3-11, p. 62

  14. Energy Flows Through Ecosystems in Food Chains and Food Webs • Food chain • Movement of energy and nutrients from one trophic level to the next (always one-directional) • Photosynthesis → feeding → decomposition • Food web • Network of interconnected food chains

  15. A Food Web Fig. 3-13, p. 64

  16. Usable Energy Decreases with Each Link in a Food Chain or Web • Biomass • Dry weight of all organic matter of a given trophic level in a food chain or food web • Decreases at each higher trophic level due to heat loss • Pyramid of energy flow • 90% of energy lost with each transfer • Less chemical energy for higher trophic levels

  17. Some Ecosystems Produce Plant Matter Faster Than Others Do • Gross primary productivity (GPP) • Rate at which an ecosystem’s producers convert solar energy to chemical energy and biomass • Kcal/m2/year • Net primary productivity (NPP) • Rate at which an ecosystem’s producers convert solar energy to chemical energy, minus the rate at which producers use energy for aerobic respiration • Ecosystems and life zones differ in their NPP

  18. Estimated Annual Average NPP in Major Life Zones and Ecosystems Fig. 3-15, p. 66

  19. Nutrients Cycle in the Biosphere • Biogeochemical cycles (nutrient cycles) • Hydrologic • Carbon • Nitrogen • Phosphorus • Sulfur • Nutrients may remain in a reservoir for a period of time

  20. Sulfur Cycles through the Biosphere • Sulfur found in organisms, ocean sediments, soil, rocks, and fossil fuels • Like carbon, nitrogen and phosphorus; sulfur is taken up by plants (in the form of SO4) • These four elements move into the ecosystem as the plants are consumed and then the consumers are consumed 2 amino acids: Cysteine and Methionine (what is Met?)

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