chapter8.ppt
- 1. ENVIRONMENTAL SCIENCE CHAPTER 8: Ecosystems: What Are They and How Do They Work?
- 2. Core Case Study: Tropical Rainforests Are Disappearing (1) • Found near the equator • 2% land surface • ~50% world’s known terrestrial plant and animal species • ≥50% destroyed or disturbed by humans – Cutting trees – Growing crops – Grazing cattle – Building settlements
- 3. Core Case Study: Tropical Rainforests Are Disappearing (2) • Consequences of disappearing tropical rainforests 1. Decreased biodiversity as species become extinct 2. Accelerated global warming: fewer trees to remove carbon dioxide from the atmosphere 3. Changes regional weather patterns: can lead to increase in tropical grasslands
- 4. Fig. 3-1, p. 39
- 5. 3-1 What Keeps Us and Other Organisms Alive? • Concept 3-1A The four major components of the earth’s life-support system are the atmosphere (air), the hydrosphere (water), the geosphere (rock, soil, sediment), and the biosphere (living things). • Concept 3-1B Life is sustained by the flow of energy from the sun through the biosphere, the cycling of nutrients within the biosphere, and gravity.
- 6. Earth Has Four Major Life- Support Components • Atmosphere • Hydrosphere • Geosphere • Biosphere
- 7. Fig. 3-2, p. 41
- 8. Fig. 3-2, p. 41 Rock Crust Atmosphere Vegetation and animals Biosphere Mantle Lithosphere Soil Geosphere (crust, mantle, core) Mantle Core Crust (soil and rock) Biosphere (living organisms) Atmosphere (air) Hydrosphere (water)
- 9. Three Factors Sustain Life on Earth • One-way flow of high-quality energy from the sun • Cycling of matter or nutrients through parts of the biosphere • Gravity
- 10. Solar Energy Reaching the Earth • Electromagnetic waves –Visible light –UV radiation –Heat • Natural greenhouse effect • Energy in = energy out • Human-enhanced global warming
- 11. Fig. 3-3, p. 41
- 12. Solar radiation Radiated by atmosphere as heat Reflected by atmosphere Most absorbed by ozone Absorbed by the earth Greenhouse effect Visible light UV radiation Heat radiated by the earth Heat Troposphere Lower Stratosphere (ozone layer) Fig. 3-3, p. 41
- 13. 3-2 What Are the Major Components of an Ecosystem? • Concept 3-2 Some organisms produce the nutrients they need, others get the nutrients they need by consuming other organisms, and some recycle nutrients back to producers by decomposing the wastes and remains of organisms.
- 14. Ecology • How organisms interact with biotic and abiotic environment • Focuses on specific levels of matter: –Organisms –Populations –Communities –Ecosystems –Biosphere
- 15. Fig. 3-4, p. 42
- 16. Smallest unit of a chemical element that exhibits its chemical properties Biosphere Ecosystem Community Population Organism Cell Molecule Atom Parts of the earth's air,water, and soil where life is found A community of different species interacting with one another and with their nonliving environment of matter and energy Populations of different species living in a particular place, and potentially interacting with each other A group of individuals of the same species living in a particular place An individual living being The fundamental structural and functional unit of life Chemical combination of two or more atoms of the same or different elements Fig. 3-4, p. 42 Water Hydrogen Oxygen
- 17. Smallest unit of a chemical element that exhibits its chemical properties Atom Molecule Chemical combination of two or more atoms of the same or different elements Cell The fundamental structural and functional unit of life Organism An individual living being Population A group of individuals of the same species living in a particular place Community Populations of different species living in a particular place, and potentially interacting with each other Stepped Art Ecosystem A community of different species interacting with one another and with their nonliving environment of matter and energy Biosphere Parts of the earth's air,water, and soil where life is found Fig. 3-4, p. 42
- 18. Living and Nonliving Components (1) • Abiotic –Water –Air –Nutrients –Solar energy –Rocks –Heat
- 19. Living and Nonliving Components (2) • Biotic –Plants –Animals –Microbes –Dead organisms –Waste products of dead organisms
- 20. Fig. 3-5, p. 43
- 21. Soluble mineral nutrients Producers Decomposers Secondary consumer (fox) Carbon dioxide (CO2) Primary consumer (rabbit) Producer Oxygen (O2) Precipitation Water Fig. 3-5, p. 43
- 22. Trophic Levels (1) • Producers – autotrophs –Photosynthesis • Consumers – heterotrophs –Primary - herbivores –Secondary - carnivores –Third-level • Omnivores
- 23. Trophic Levels (2) • Decomposers –Release nutrients from the dead bodies of plants and animals • Detrivores –Feed on the waste or dead bodies of organisms
- 24. Fig. 3-6, p. 44
- 25. Time progression Powder broken down by decomposers into plant nutrients in soil Mushroom Wood reduced to powder Dry rot fungus Termite and carpenter ant work Decomposers Detritus feeders Carpenter ant galleries Bark beetle engraving Long-horned beetle holes Fig. 3-6, p. 44
- 26. Production and Consumption of Energy • Photosynthesis • Carbon dioxide + water + solar energy glucose + oxygen • Aerobic respiration • Glucose + oxygen carbon dioxide + water + energy
- 27. Energy Flow and Nutrient Recycling • Ecosystems sustained through: –One-way energy flow from the sun –Nutrient recycling
- 28. Fig. 3-7, p. 45
- 29. Abiotic chemicals (carbon dioxide, oxygen, nitrogen, minerals) Decomposers (bacteria, fungi) Consumers (herbivores, carnivores) Producers (plants) Solar energy Heat Heat Heat Heat Heat Fig. 3-7, p. 45
- 30. Science Focus: Invisible Organisms (1) • Microorganisms/Microbes –Bacteria –Protozoa –Fungi –Phytoplankton
- 31. Science Focus: Invisible Organisms (2) • Microbes can cause disease –Malaria –Athlete’s foot • Microbes are also beneficial –Intestinal flora –Purify water –Phytoplankton remove carbon dioxide from the atmosphere
- 32. 3-3 What Happens to Energy in an Ecosystem? • Concept 3-3 As energy flows through ecosystems in food chains and webs, the amount of chemical energy available to organisms at each succeeding feeding level decreases.
- 33. Energy Flow in Ecosystems • Trophic levels • Food chain –Sequence of organisms, each of which serves as a source of food for the next • Food web –Network of interconnected food chains –More complex than a food chain
- 34. Fig. 3-8, p. 46
- 35. Fourth Trophic Level Third Trophic Level Second Trophic Level First Trophic Level Heat Heat Heat Heat Heat Tertiary consumers (top carnivores) Secondary consumers (carnivores) Primary consumers (herbivores) Producers (plants) Solar energy Heat Heat Decomposers and detritus feeders Fig. 3-8, p. 46
- 36. Fig. 3-9, p. 46
- 38. Usable Energy by Trophic Level • Energy flow follows the second law of thermodynamics – energy lost as heat • Biomass decreases with increasing trophic level • Ecological efficiency – typically 10% • Pyramid of energy flow
- 39. Fig. 3-10, p. 47
- 40. Tertiary consumers (human) Secondary consumers (perch) Producers (phytoplankton) Primary consumers (zooplankton) Usable energy available at each trophic level (in kilocalories) Heat Decomposers 10 100 1,000 10,000 Heat Heat Heat Heat Fig. 3-10, p. 47
- 41. 10 Heat Tertiary consumers (human) Usable energy available at each trophic level (in kilocalories) Heat Secondary consumers (perch) 100 Heat Decomposers Heat Primary consumers (zooplankton) 1,000 Heat Producers (phytoplankton) 10,000 Stepped Art Fig. 3-10, p. 47
- 42. Two Kinds of Primary Productivity • Gross primary productivity (GPP) • Net primary productivity (NPP) • Planet’s NPP limits number of consumers • Humans use, waste, or destroy 10- 55% of earth’s total potential NPP • Human population is less than 1% of total biomass of earth’s consumers
- 43. Fig. 3-11, p. 48
- 44. Temperate forest Aquatic Ecosystems Open ocean Continental shelf Lakes and streams Estuaries Terrestrial Ecosystems Extreme desert Desert scrub Tundra (arctic and alpine) Temperate grassland Woodland and shrubland Agricultural land Savanna Northern coniferous forest (taiga) Swamps and marshes Tropical rain forest Fig. 3-11, p. 48 Average net primary productivity (kcal/m2/yr) 800 1,600 2,400 3,200 4,000 4,800 5,600 6,400 7,200 8,000 8,800 9,600
- 45. 3-4 What Happens to Matter in an Ecosystem? • Concept 3-4 Matter, in the form of nutrients, cycles within and among ecosystems and in the biosphere, and human activities are altering these chemical cycles.
- 46. Biogeochemical Cycles • Nutrient cycles • Reservoirs • Connect all organisms through time
- 47. Hydrologic Cycle • Water cycle is powered by the sun 1. Evaporation 2. Precipitation 3. Transpiration - evaporates from plant surfaces • Water vapor in the atmosphere comes from the oceans – 84% • Over land, ~90% of water reaching the atmosphere comes from transpiration
- 48. Fig. 3-12, p. 49
- 49. Increased flooding from wetland destruction Condensation Evaporation from ocean Climate change Infiltration and percolation into aquifer Condensation Ocean Lakes and reservoirs Ice and snow Surface runoff Surface runoff Aquifer depletion from overpumping Point source pollution Reduced recharge of aquifers and flooding from covering land with crops and buildings Groundwater movement (slow) Runoff Precipitation to land Precipitation to ocean Transpiration from plants Evaporation from land Fig. 3-12, p. 49 Processes Processes affected by humans Reservoir Pathway affected by humans Natural pathway
- 50. Science Focus: Water’s Unique Properties (1) • Holds water molecules together – hydrogen bonding • Liquid over a wide temperature range • Changes temperature slowly • Requires large amounts of energy to evaporate
- 51. Science Focus: Water’s Unique Properties (2) • Dissolves a variety of compounds • Filters out UV light from the sun • Adheres to a solid surface – allows capillary action in plants • Expands as it freezes
- 52. Carbon Cycle • Based on carbon dioxide (CO2) • CO2 makes up 0.038% of atmosphere volume • Major cycle processes – Aerobic respiration – Photosynthesis – Fossil fuel combustion and deforestation • Fossil fuels add CO2 to the atmosphere and contribute to global warming
- 53. Fig. 3-13, p. 51
- 54. Respiration Forest fires Deforestation Diffusion Carbon dioxide dissolved in ocean Carbon in limestone or dolomite sediments Marine food webs Producers, consumers, decomposers Transportation Carbon dioxide in atmosphere Carbon in animals (consumers) Plants (producers) Animals (consumers) Decomposition Respiration Compaction Carbon in fossil fuels Carbon in plants (producers) Burning fossil fuels Photosynthesis Fig. 3-13, p. 51 Processes Reservoir Pathway affected by humans Natural pathway
- 55. Nitrogen Cycle • Multicellular plants and animals cannot utilize atmospheric nitrogen (N2) • Nitrogen fixation • Nitrification • Ammonification • Denitrification
- 56. Fig. 3-14, p. 52
- 57. Nitrogen in atmosphere Nitrogen loss to deep ocean sediments Nitrogen oxides from burning fuel Nitrates from fertilizer runoff and decomposition Nitrogen in ocean sediments Ammonia in soil Volcanic activity Electrical storms Nitrogen in animals (consumers) Bacteria Nitrate in soil Nitrogen in plants (producers) Nitrification by bacteria Denitrification by bacteria Uptake by plants Decomposition Fig. 3-14, p. 52 Processes Reservoir Pathway affected by humans Natural pathway
- 58. Phosphorus Cycle • Does not cycle through the atmosphere • Obtained from terrestrial rock formations • Limiting factor on land and in freshwater ecosystems • Biologically important for producers and consumers
- 59. Fig. 3-15, p. 53
- 60. Sea birds Phosphate in shallow ocean sediments Bacteria Animals (consumers) Plants (producers) Runoff Runoff Runoff Phosphates in fertilizer Phosphates in mining waste Phosphates in sewage Phosphate dissolved in water Erosion Phosphate in deep ocean sediments Ocean food chain Plate tectonics Phosphate in rock (fossil bones, guano) Fig. 3-15, p. 53 Processes Reservoir Pathway affected by humans Natural pathway
- 61. Sulfur Cycle • Most sulfur stored in rocks and minerals • Enters atmosphere through: –Volcanic eruptions and processes –Anaerobic decomposition in swamps, bogs, and tidal flats –Sea spray –Dust storms –Forest fires
- 62. Fig. 3-16, p. 54
- 63. Fig. 3-16, p. 54 Refining fossil fuels Sulfur in animals (consumers) Sulfur in plants (producers) Sulfur dioxide in atmosphere Sulfur in soil, rock and fossil fuels Sulfur in ocean sediments Dimethyl sulfide a bacteria byproduct Processes Reservoir Pathway affected by humans Natural pathway Decay Sulfuric acid and Sulfate deposited as acid rain Uptake by plants Decay Mining and extraction Burning coal Smelting
- 64. 3-5 How Do Scientists Study Ecosystems? • Concept 3-5 Scientists use field research, laboratory research, and mathematical and other models to learn about ecosystems.
- 65. Field Research • Collecting data in the field by scientists • Remote sensing devices • Geographic information systems (GIS)
- 66. Laboratory Research • Simplified model ecosystems – Culture tubes – Bottles – Aquariums – Greenhouses – Chambers with controllable abiotic factors • How well do lab experiments correspond with the greater complexity of real ecosystems?
- 67. Scientific Studies of Ecosystems • Models –Mathematical –Computer simulations • Models need to be fed real data collected in the field- baseline data • Models must determine relationships among key variables
- 68. Baseline Data to Measure Earth’s Health • Needed to measure changes over time • Lacking for many ecosystems • Call for massive program to develop baseline data
- 71. Animation: Feedback Control of Temperature
- 72. Animation: Diet of a Red Fox
- 75. Animation: Energy Flow in Silver Springs
- 77. Animation: Prairie Food Web
- 81. Animation: Roles of Organisms in an Ecosystem
- 82. Animation: Matter Recycling and Energy Flow
- 83. Animation: Current and Projected Population Sizes by Region
- 86. Animation: Species Diversity By Latitude
- 87. Animation: Area and Distance Effects
- 89. Animation: Categories of Food Webs
- 96. Video: Owl with Mouse PLAY VIDEO