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Outline

Outline. The Nature of Ecosystems Biotic Components Autotrophs Heterotrophs Energy Flow Ecological Pyramids Global Biogeochemical Cycles Hydrologic Cycle Carbon Cycle Nitrogen Cycle Phosphorus Cycle. Nature of Ecosystems. Biosphere is the organism-containing part of the Atmosphere

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Outline

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  1. Ecosystems & Human Interferences

  2. 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. Nature of Ecosystems • 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

  4. Ecosystems

  5. Biotic Components:Autotrophs • Producers are autotrophs • Require only inorganic nutrients and an outside energy source to produce organic nutrients • Photoautotrophs • Chemoautrophs

  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 andChemical 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

  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. Ecological Pyramid

  14. GlobalBiogeochemical 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. Hydrologic Cycle • Fresh water evaporates from bodies of water • Precipitation on land enters the ground, surface waters, or aquifers • Water eventually returns to the oceans

  17. The Hydrologic (Water) Cycle

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

  31. Ecosystems & Human Interferences

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