Ecosystems and Human Interferences

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Ecosystems and Human Interferences

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1. Ecosystems and Human Interferences Chapter 48

2. Mader: Biology, 9th Ed. Biosphere

3. Mader: Biology, 9th Ed. Nature of Ecosystems Biosphere is part of the atmosphere, hydrosphere, and lithosphere that contains living organisms Ecosystem – where organisms interact among themselves and with physical and chemical environment Ecosystems characterized by: One-Way flow of energy Cycle of materials from abiotic environment through biotic community

4. Mader: Biology, 9th Ed. Ecosystems

5. Mader: Biology, 9th Ed. Biotic Components Autotrophs Require only inorganic nutrients and an outside energy source to produce organic nutrients Producers Photoautotrophs Chemoautrophs

6. Mader: Biology, 9th Ed. Heterotrophs Heterotrophs Need a preformed source of organic nutrients Consumers Herbivores - Feed on plants Carnivores - Feed on other animals Omnivores - Feed on plants and animals

7. Mader: Biology, 9th Ed. Heterotrophs Decomposers Heterotrophic bacteria and fungi Break down dead organic matter Detritus – decomposing products of organisms

8. Mader: Biology, 9th Ed. Energy Flow and Chemical Cycling Energy flows as nutrients pass from one population to another Each level retains some energy Remaining energy converted to heat, which dissipates into the environment Thermodynamics First Law – energy cannot be created or destroyed, it can only be changed from one form to another Second Law – when energy is transformed from one state to another there is a loss of energy from the system usually in the form of heat

9. Mader: Biology, 9th Ed. Nature of an ecosystem

10. Mader: Biology, 9th Ed. Energy Flow and Chemical Cycling Chemicals cycle as organic nutrients are returned to the producers Excretion Death Cellular Respiration

11. Mader: Biology, 9th Ed. Energy Balances

12. Mader: Biology, 9th Ed. Energy Flow Food Web - Interconnecting paths of energy flow describing trophic relationships Food Chain – represents a single path sequence of organisms that form links

13. Mader: Biology, 9th Ed. Food Web

14. Mader: Biology, 9th Ed. Ecological Pyramids A trophic level is composed of all the organisms that feed at the same level of the food chain In general, only about 10% of the energy of one trophic level is available to the next trophic level Explains why few carnivores can be supported in a food web Biomass – number of organisms multiplied by their weight; eliminates size as a factor

15. Mader: Biology, 9th Ed. Ecological Pyramid

16. 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 move along food chains, perhaps never entering a pool

17. Mader: Biology, 9th Ed.

18. Mader: Biology, 9th Ed. 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

19. Mader: Biology, 9th Ed.

20. Mader: Biology, 9th Ed. Carbon Cycle Atmosphere is an exchange pool for carbon dioxide Total amount of carbon dioxide the atmosphere has been increasing every year Thought to be due to fossil fuel combustion Transfer Rate – amount of a nutrient that moves from one component of the environment to another within a specified period of time

21. Mader: Biology, 9th Ed.

22. Mader: Biology, 9th Ed. Greenhouse Effect Greenhouse gases Carbon dioxide, nitrous oxide, methane Allow solar radiation to pass through atmosphere but trap heat (infrared radiation) from escaping If Earth’s temperature rises More water will evaporate More clouds will form Setting up a potential positive feedback loop

23. Mader: Biology, 9th Ed. Earth’s Radiation Balances

24. Mader: Biology, 9th Ed. Nitrogen Cycle Nitrogen fixation – nitrogen is converted to a form that plants can use Atmospheric nitrogen is fixed by bacteria in order to 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

25. Mader: Biology, 9th Ed.

26. Mader: Biology, 9th Ed. 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 water in some areas Causes heavy metals to leak out of rocks, poisoning aquatic animals Kills plants and causes fish to be unfit for consumption

27. Mader: Biology, 9th Ed. Thermal Inversion

28. Mader: Biology, 9th Ed. 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 – enrichment of water by inorganic nutrients used by phytoplankton; can lead to overgrowth of bacteria and O2 depletion Biomagnification – process by which substances become more concentrated in organisms in the higher trophic levels of a food web

29. Mader: Biology, 9th Ed.

30. Mader: Biology, 9th Ed. Sources of Water Pollution

31. Mader: Biology, 9th Ed.

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