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Chapter 4

Chapter 4. Ecosystems: What Are They and How Do They Work?. ECOLOGY. Ecology is the study of the connection between organisms and their living and non-living environments. The average number of organisms that can be sustained in an ecosystem is known as carrying capacity .

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Chapter 4

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  1. Chapter 4 Ecosystems: What Are They and How Do They Work?

  2. ECOLOGY • Ecology is the studyof the connection between organisms and their living and non-living environments. • The average number of organisms that can be sustained in an ecosystem is known as carrying capacity. • Food, water, and shelter are known as limiting factors.

  3. L E V E L S of O R G A N I Z A T I O N F O C U S E D on in E C O L O G Y Biosphere Biosphere Ecosystems Communities Populations Organisms

  4. Population Species Community Biome Biosphere Ecosystem Species is the lowest on this hierarchy and Biosphere is the largest.

  5. homeostasis

  6. Oceanic crust Continental crust Biosphere Vegetation and animals Lithosphere Upper mantle Soil Crust Asthenosphere Rock Lower mantle core Mantle Crust (soil and rock) Biosphere (Living and dead organisms) Atmosphere (troposphere, stratosphere) (air) Lithosphere (crust, top of upper mantle) Hydrosphere (water)

  7. Solar Capital Solar radiation Energy in = Energy out Reflected by atmosphere (34%) Radiated by atmosphere as heat (66%) UV radiation Lower stratosphere (ozone layer) Visible light Greenhouse effect Troposphere Absorbed by ozone Heat Absorbed by the earth Heat radiated by the earth Earth

  8. ECOLOGY • Abiotic – All of the non-livingelements in an ecosystem like air, water, and temperature. • Biotic – All of the living elements in an ecosystem.

  9. Biotic Factors in an Aquatic Ecosystem

  10. Abiotic Factors in Terrestrial and Aquatic Ecosystems • Sunlight • Temperature • Precipitation • Wind • Latitude (distance from equator) • Altitude (distance above sea level) • Fire frequency • Soil • Light penetration • Water currents • Dissolved nutrient concentrations (especially N and P) • Suspended solids • Salinity

  11. Ecotones: Ecosystem Boundaries

  12. Tolerance • Range of Tolerance: range of chemical and physical conditions that must be maintained for populations of a particular species to stay alive and grow, develop, and function normally. • Law of Tolerance: the existence, abundance, and distribution of a species in an ecosystem are determined by whether the levels of one or more physical or chemical factors fall within the range tolerated by the species.

  13. Lower limit of tolerance Upper limit of tolerance No organisms Few organisms Few organisms No organisms Abundance of organisms Population Size Zone of intolerance Zone of physiological stress Optimum range Zone of physiological stress Zone of intolerance Low Temperature High Range of tolerance for a population of organisms, such as fish, to an abiotic environmental factor—in this case, temperature.

  14. Ecology Biodiversity is the number and variety of organisms found within a certain region. Extinction is when a species is no longer in existence. Endangered means a species is in danger of extinction throughout all of a significant portion of its range.

  15. ECOLOGY Food Chain – A chain illustrating the organisms and their food source. Grass grasshopper bird

  16. A food chain illustrates the transfer of energy from one trophiclevel to the next.

  17. ECOLOGY Food Web – multiplechains assembled into one large web.

  18. ECOLOGY Ecological Pyramid A food chain that shows the relationship between the organisms in each trophic level.

  19. Ecological Pyramid of Numbers The figures represent number of individuals counted at each trophic level.

  20. The total dry weight of organisms in a particular trophic level is referenced as biomass. Ecological Pyramid of Biomass BIOMASS = # of organisms x the weight of an average individual biomass

  21. Ecological Pyramid of Energy • Energy in ecosystems flows from producers to consumers. • Energy is depicted in kilocalories. • Ecological efficiency: % of usable • energy transferred from one trophic level to the next. (Average is about 10%.)

  22. Ecological Pyramid of Energy

  23. Nutrient Cycles Cycling of materials between the environment and organisms. Chemical and biological processes. Examples: Water cycle Carbon cycle Nitrogen cycle Phosphorus cycle Sulfur cycle Oxygen cycle

  24. Water (Hydrologic) Cycle Runoff Runoff Surface runoff (rapid) Surface runoff (rapid) Condensation Rain clouds Precipitation Transpiration from plants Precipitation Precipitation to ocean Transpiration Evaporation Evaporation From ocean Infiltration and percolation Surface runoff (rapid) Groundwater movement (slow) Ocean storage Groundwater movement (slow)

  25. Carbon Cycle

  26. Nitrogen Cycle

  27. Nitrogen Cycle • Nitrogen Fixation: bacteria convert nitrogen to ammonia • Nitrification: bacteria convert ammonia to nitrite and nitrate, which are used by plants • Assimilation: plant roots absorb ammonia and nitrate • Ammonification: decomposers convert dead organisms and waste to simpler compounds • Denitrification: bacteria convert ammonia back into nitrite and nitrate, which are released into the air (cycle begins again)

  28. Phosphorus Cycle Phosphate Rock Phosphate Mining Erosion Fertilizer containing phosphates Animal waste Uplifting into rocks Animal Excretion Dissolved Phosphates

  29. The Sulfur Cycle

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