Ecosystems: How do they work?


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  • Figure 3.2 Natural capital: levels of organization of matter in nature. Ecology focuses on five of these levels.
  • Figure 3.3 Natural capital: breakdown of the earth ’ s 1.4 million known species. Scientists estimate that there are 4 million to 100 million species.
  • Figure 3.6 Natural capital: general structure of the earth.
  • Figure 3.7 Natural capital: life on the earth depends on the flow of energy (wavy arrows) from the sun through the biosphere and back into space, the cycling of crucial elements (solid arrows around ovals), and gravity , which keeps atmospheric gases from escaping into space and helps recycle nutrients through air, water, soil, and organisms. This simplified model depicts only a few of the many cycling elements.
  • Figure 3.8 Solar capital: flow of energy to and from the earth.
  • Figure 3.9 Natural capital: major biomes found along the 39th parallel across the United States. The differences reflect changes in climate, mainly differences in average annual precipitation and temperature.
  • Figure 3.10 Natural capital: major components of an ecosystem in a field.
  • Figure 3.11 Natural capital: range of tolerance for a population of organisms, such as fish, to an abiotic environmental factor—in this case, temperature. These restrictions keep particular species from taking over an ecosystem by keeping their population size in check.
  • Figure 3.12 The physical conditions of the environment can limit the distribution of a species. The green area shows the current range of sugar maple trees in eastern North America. (Data from U.S. Department of Agriculture)
  • Figure 3 .A Simplified overview of photosynthesis. In this process, chlorophyll molecules in the chloroplasts of plant cells absorb solar energy. This initiates a complex series of chemical reactions in which carbon dioxide and water are converted to sugars, such as glucose, and oxygen.
  • Figure 3.13 Natural capital: various scavengers (detritivores) and decomposers (mostly fungi and bacteria) can “ feed on ” or digest parts of a log and eventually convert its complex organic chemicals into simpler inorganic nutrients that can be taken up by producers.
  • Figure 3.14 Natural capital: the main structural components of an ecosystem (energy, chemicals, and organisms). Matter recycling and the flow of energy—first from the sun, then through organisms, and finally into the environment as low-quality heat—links these components.
  • Figure 3.16 Solutions: goals, strategies, and tactics for protecting biodiversity.
  • Figure 3.17 Natural capital: a food chain. The arrows show how chemical energy in food flows through various trophic levels in energy transfers; most of the energy is degraded to heat, in accordance with the second law of thermodynamics.
  • Figure 3.18 Natural capital: a greatly simplified food web in the Antarctic. Many more participants in the web, including an array of decomposer organisms, are not depicted here.
  • Figure 3.19 Natural capital: generalized pyramid of energy flow showing the decrease in usable energy available at each succeeding trophic level in a food chain or web. In nature, ecological efficiency varies from 2% to 40%, with 10% efficiency being common. This model assumes a 10% ecological efficiency (90% loss in usable energy to the environment, in the form of low-quality heat) with each transfer from one trophic level to another. QUESTION: Why is it a scientific error to call this a pyramid of energy?
  • Figure 3.20 Natural capital: gross primary productivity across the continental United States based on remote satellite data. The differences roughly correlate with variations in moisture and soil types. (NASA ’ s Earth Observatory)
  • Figure 3.21 Natural capital: distinction between gross primary productivity and net primary productivity. A plant uses some of its gross primary productivity to survive through respiration. The remaining energy is available to consumers.
  • Figure 3.22 Natural capital: estimated annual average net primary productivity per unit of area in major life zones and ecosystems, expressed as kilocalories of energy produced per square meter per year (kcal/m 2 /yr). QUESTION: What are nature ’ s three most productive and three least productive systems? (Data from Communities and Ecosystems, 2nd ed., by R. H. Whittaker, 1975. New York: Macmillan)
  • Figure 3.23 Natural capital: soil formation and generalized soil profile. Horizons, or layers, vary in number, composition, and thickness, depending on the type of soil. (Used by permission of Macmillan Publishing Company from Derek Elsom, Earth, New York: Macmillan, 1992. Copyright © 1992 by Marshall Editions Developments Limited)
  • Figure 3.24 Natural capital: soil profiles of the principal soil types typically found in five types of terrestrial ecosystems.
  • Figure 3.24 Natural capital: soil profiles of the principal soil types typically found in five types of terrestrial ecosystems.
  • Figure 3.24 Natural capital: soil profiles of the principal soil types typically found in five types of terrestrial ecosystems.
  • Figure 3.24 Natural capital: soil profiles of the principal soil types typically found in five types of terrestrial ecosystems.
  • Figure 3.25 Natural capital: the size, shape, and degree of clumping of soil particles determine the number and volume of spaces for air and water within a soil. Soils with more pore spaces (left) contain more air and are more permeable to water than soils with fewer pores (right).
  • Figure 3.26 Natural capital: simplified model of the hydrologic cycle.
  • Figure 3.27 Natural capital: simplified model of the global carbon cycle. Carbon moves through both marine ecosystems (left side) and terrestrial ecosystems (right side). Carbon reservoirs are shown as boxes; processes that change one form of carbon to another are shown in unboxed print. QUESTION: What are three ways in which your lifestyle directly or indirectly affects the carbon cycle? (From Cecie Starr, Biology: Concepts and Applications, 4th ed., Pacific Grove, Calif.: Brooks/Cole, © 2000)
  • Figure 3.28 Natural capital degradation: human interference in the global carbon cycle from carbon dioxide emissions when fossil fuels are burned and forests are cleared, 1850 to 2006 and projections to 2030 (dashed lines). (Data from UN Environment Programme, British Petroleum, International Energy Agency, and U.S. Department of Energy)
  • Figure 3.29 Natural capital: simplified model of the nitrogen cycle in a terrestrial ecosystem. Nitrogen reservoirs are shown as boxes; processes changing one form of nitrogen to another are shown in unboxed print. QUESTION: What are three ways in which your lifestyle directly or indirectly affects the nitrogen cycle? (Adapted from Cecie Starr, Biology: Today and Tomorrow, Brooks/Cole © 2005)
  • Figure 3.30 Natural capital degradation: human interference in the global nitrogen cycle. Human activities such as production of fertilizers now fix more nitrogen than all natural sources combined. (Data from UN Environment Programme, UN Food and Agriculture Organization, and U.S. Department of Agriculture)
  • Figure 3.31 Natural capital: simplified model of the phosphorus cycle. Phosphorus reservoirs are shown as boxes; processes that change one form of phosphorus to another are shown in unboxed print. QUESTION: What are three ways in which your lifestyle directly or indirectly affects the phosphorus cycle? (From Cecie Starr and Ralph Taggart, Biology: The Unity and Diversity of Life, 9th ed., Belmont, Calif.: Wadsworth © 2001)
  • Figure 3.32 Natural capital: simplified model of the sulfur cycle. The movement of sulfur compounds in living organisms is shown in green, blue in aquatic systems, and orange in the atmosphere. QUESTION: What are three ways in which your lifestyle directly or indirectly affects the sulfur cycle?
  • Figure 3.33 Geographic information systems (GISs) provide the computer technology for organizing, storing, and analyzing complex data collected over broad geographic areas. They enable scientists to overlay many layers of data (such as soils, topography, distribution of endangered populations, and land protection status).
  • Figure 3.34 Major stages of systems analysis. (Modified data from Charles Southwick)
  • Ecosystems: How do they work?

    1. 1. Chapter 3 Ecosystems: Connections in Nature
    2. 2. Chapter Overview Questions <ul><li>What is ecology? </li></ul><ul><li>What basic processes keep us and other organisms alive? </li></ul><ul><li>What are the major components of an ecosystem? </li></ul><ul><li>What happens to energy in an ecosystem? </li></ul><ul><li>What are soils and how are they formed? </li></ul><ul><li>What happens to matter in an ecosystem? </li></ul><ul><li>How do scientists study ecosystems? </li></ul>
    3. 3. Core Case Study: Have You Thanked the Insects Today? <ul><li>Many plant species depend on insects for pollination. </li></ul><ul><li>Insect can control other pest insects by eating them </li></ul>
    4. 4. Core Case Study: Have You Thanked the Insects Today? <ul><li>… if all insects disappeared, humanity probably could not last more than a few months [E.O. Wilson, Biodiversity expert]. </li></ul><ul><ul><li>Insect ’s role in nature is part of the larger biological community in which they live. </li></ul></ul>
    5. 5. THE NATURE OF ECOLOGY <ul><li>Ecology is a study of connections in nature. </li></ul><ul><ul><li>How organisms interact with one another and with their nonliving environment. </li></ul></ul>
    6. 6. Communities Subatomic Particles Atoms Molecules Protoplasm Cells Tissues Organs Organ systems Organisms Populations Populations Communities Ecosystems Biosphere Earth Planets Solar systems Galaxies Universe Organisms Realm of ecology Ecosystems Biosphere
    7. 7. Animation: Levels of Organization PLAY ANIMATION
    8. 8. Organisms and Species <ul><li>Organisms, the different forms of life on earth, can be classified into different species based on certain characteristics. </li></ul>
    9. 9. Insects 751,000 Other animals 281,000 Fungi 69,000 Prokaryotes 4,800 Plants 248,400 Protists 57,700 Known species 1,412,000
    10. 10. Case Study: Which Species Run the World? <ul><li>Multitudes of tiny microbes such as bacteria, protozoa, fungi, and yeast help keep us alive. </li></ul><ul><ul><li>Harmful microbes are the minority. </li></ul></ul><ul><ul><li>Soil bacteria convert nitrogen gas to a usable form for plants. </li></ul></ul><ul><ul><li>They help produce foods (bread, cheese, yogurt, beer, wine). </li></ul></ul><ul><ul><li>90% of all living mass. </li></ul></ul><ul><ul><li>Helps purify water, provide oxygen, breakdown waste. </li></ul></ul><ul><ul><li>Lives beneficially in your body (intestines, nose). </li></ul></ul>
    11. 11. Populations, Communities, and Ecosystems <ul><li>Members of a species interact in groups called populations. </li></ul><ul><li>Populations of different species living and interacting in an area form a community. </li></ul><ul><li>A community interacting with its physical environment of matter and energy is an ecosystem. </li></ul>
    12. 12. Populations <ul><li>A population is a group of interacting individuals of the same species occupying a specific area. </li></ul><ul><ul><li>The space an individual or population normally occupies is its habitat. </li></ul></ul>
    13. 13. Populations <ul><li>Genetic diversity </li></ul><ul><ul><li>In most natural populations individuals vary slightly in their genetic makeup. </li></ul></ul>
    14. 14. THE EARTH ’S LIFE SUPPORT SYSTEMS <ul><li>The biosphere consists of several physical layers that contain: </li></ul><ul><ul><li>Air </li></ul></ul><ul><ul><li>Water </li></ul></ul><ul><ul><li>Soil </li></ul></ul><ul><ul><li>Minerals </li></ul></ul><ul><ul><li>Life </li></ul></ul>
    15. 15. Biosphere <ul><li>Atmosphere </li></ul><ul><ul><li>Membrane of air around the planet. </li></ul></ul><ul><li>Stratosphere </li></ul><ul><ul><li>Lower portion contains ozone to filter out most of the sun ’s harmful UV radiation. </li></ul></ul><ul><li>Hydrosphere </li></ul><ul><ul><li>All the earth ’s water: liquid, ice, water vapor </li></ul></ul><ul><li>Lithosphere </li></ul><ul><ul><li>The earth ’s crust and upper mantle. </li></ul></ul>
    16. 16. Lithosphere (crust, top of upper mantle) Rock Soil Vegetation and animals Atmosphere Oceanic Crust Continental Crust Lithosphere Upper mantle Asthenosphere Lower mantle Mantle Core Biosphere Crust Crust (soil and rock) Biosphere (living and dead organisms) Hydrosphere (water) Atmosphere (air)
    17. 17. What Sustains Life on Earth? <ul><li>Solar energy, the cycling of matter, and gravity sustain the earth ’s life. </li></ul>
    18. 18. Nitrogen cycle Biosphere Heat in the environment Heat Heat Heat Phosphorus cycle Carbon cycle Oxygen cycle Water cycle
    19. 19. What Happens to Solar Energy Reaching the Earth? <ul><li>Solar energy flowing through the biosphere warms the atmosphere, evaporates and recycles water, generates winds and supports plant growth. </li></ul>
    20. 20. Absorbed by ozone Visible Light Absorbed by the earth Greenhouse effect UV radiation Solar radiation Energy in = Energy out Reflected by atmosphere (34% ) Radiated by atmosphere as heat (66%) Heat radiated by the earth Heat Troposphere Lower Stratosphere (ozone layer)
    21. 21. Animation: Sun to Earth PLAY ANIMATION
    22. 22. ECOSYSTEM COMPONENTS <ul><li>Life exists on land systems called biomes and in freshwater and ocean aquatic life zones. </li></ul>
    23. 23. 100–125 cm (40–50 in.) Coastal mountain ranges Sierra Nevada Mountains Great American Desert Coastal chaparral and scrub Coniferous forest Desert Coniferous forest Prairie grassland Deciduous forest 1,500 m (5,000 ft.) 3,000 m (10,000 ft.) 4,600 m (15,000 ft.) Average annual precipitation Mississippi River Valley Appalachian Mountains Great Plains Rocky Mountains below 25 cm (0–10 in.) 25–50 cm (10–20 in.) 50–75 cm (20–30 in.) 75–100 cm (30–40 in.)
    24. 24. Nonliving and Living Components of Ecosystems <ul><li>Ecosystems consist of nonliving (abiotic) and living (biotic) components. </li></ul>
    25. 25. Sun Oxygen (O 2 ) Carbon dioxide (CO 2 ) Secondary consumer (fox) Soil decomposers Primary consumer (rabbit) Precipitation Falling leaves and twigs Producer Producers Soluble mineral nutrients Water
    26. 26. Animation: Roles of Organisms in an Ecosystem PLAY ANIMATION
    27. 27. Animation: Diet of a Red Fox PLAY ANIMATION
    28. 28. Factors That Limit Population Growth <ul><li>Availability of matter and energy resources can limit the number of organisms in a population. </li></ul>
    29. 29. Zone of intolerance Optimum range Zone of physiological stress Zone of physiological stress Zone of intolerance Temperature Low High No organisms Few organisms Upper limit of tolerance Population size Abundance of organisms Few organisms No organisms Lower limit of tolerance
    30. 30. Factors That Limit Population Growth <ul><li>The physical conditions of the environment can limit the distribution of a species. </li></ul>
    31. 31. Sugar Maple
    32. 32. Producers: Basic Source of All Food <ul><li>Most producers capture sunlight to produce carbohydrates by photosynthesis: </li></ul>
    33. 33. Producers: Basic Source of All Food <ul><li>Chemosynthesis: </li></ul><ul><ul><li>Some organisms such as deep ocean bacteria draw energy from hydrothermal vents and produce carbohydrates from hydrogen sulfide (H 2 S) gas . </li></ul></ul>
    34. 34. Photosynthesis: A Closer Look <ul><li>Chlorophyll molecules in the chloroplasts of plant cells absorb solar energy. </li></ul><ul><li>This initiates a complex series of chemical reactions in which carbon dioxide and water are converted to sugars and oxygen. </li></ul>
    35. 35. Sun Chloroplast in leaf cell Light-dependent Reaction Light-independent reaction Chlorophyll Energy storage and release (ATP/ADP) Glucose H 2 O Sunlight O 2 CO 2 6CO 2 + 6 H 2 O C 6 H 12 O 6 + 6 O 2
    36. 36. Consumers: Eating and Recycling to Survive <ul><li>Consumers (heterotrophs) get their food by eating or breaking down all or parts of other organisms or their remains. </li></ul><ul><ul><li>Herbivores </li></ul></ul><ul><ul><ul><li>Primary consumers that eat producers </li></ul></ul></ul><ul><ul><li>Carnivores </li></ul></ul><ul><ul><ul><li>Primary consumers eat primary consumers </li></ul></ul></ul><ul><ul><ul><li>Third and higher level consumers: carnivores that eat carnivores. </li></ul></ul></ul><ul><ul><li>Omnivores </li></ul></ul><ul><ul><ul><li>Feed on both plant and animals. </li></ul></ul></ul>
    37. 37. Decomposers and Detrivores <ul><ul><li>Decomposers: Recycle nutrients in ecosystems. </li></ul></ul><ul><ul><li>Detrivores: Insects or other scavengers that feed on wastes or dead bodies. </li></ul></ul>
    38. 38. Scavengers Powder broken down by decomposers into plant nutrients in soil Bark beetle engraving Decomposers Long-horned beetle holes Carpenter ant galleries Termite and carpenter ant work Dry rot fungus Wood reduced to powder Mushroom Time progression
    39. 39. Aerobic and Anaerobic Respiration: Getting Energy for Survival <ul><li>Organisms break down carbohydrates and other organic compounds in their cells to obtain the energy they need. </li></ul><ul><li>This is usually done through aerobic respiration . </li></ul><ul><ul><li>The opposite of photosynthesis </li></ul></ul>
    40. 40. Animation: Linked Processes PLAY ANIMATION
    41. 41. Aerobic and Anaerobic Respiration: Getting Energy for Survival <ul><li>Anaerobic respiration or fermentation: </li></ul><ul><ul><li>Some decomposers get energy by breaking down glucose (or other organic compounds) in the absence of oxygen. </li></ul></ul><ul><ul><li>The end products vary based on the chemical reaction: </li></ul></ul><ul><ul><ul><li>Methane gas </li></ul></ul></ul><ul><ul><ul><li>Ethyl alcohol </li></ul></ul></ul><ul><ul><ul><li>Acetic acid </li></ul></ul></ul><ul><ul><ul><li>Hydrogen sulfide </li></ul></ul></ul>
    42. 42. Two Secrets of Survival: Energy Flow and Matter Recycle <ul><li>An ecosystem survives by a combination of energy flow and matter recycling. </li></ul>
    43. 43. Abiotic chemicals (carbon dioxide, oxygen, nitrogen, minerals) Heat Heat Heat Heat Heat Solar energy Consumers (herbivores, carnivores) Producers (plants) Decomposers (bacteria, fungi)
    44. 44. Animation: Matter Recycling and Energy Flow PLAY ANIMATION
    45. 45. BIODIVERSITY
    46. 46. Biodiversity Loss and Species Extinction: Remember HIPPO <ul><li>H for habitat destruction and degradation </li></ul><ul><li>I for invasive species </li></ul><ul><li>P for pollution </li></ul><ul><li>P for human population growth </li></ul><ul><li>O for overexploitation </li></ul>
    47. 47. Why Should We Care About Biodiversity? <ul><li>Biodiversity provides us with: </li></ul><ul><ul><li>Natural Resources (food water, wood, energy, and medicines) </li></ul></ul><ul><ul><li>Natural Services (air and water purification, soil fertility, waste disposal, pest control) </li></ul></ul><ul><ul><li>Aesthetic pleasure </li></ul></ul>
    48. 48. Solutions <ul><li>Goals, strategies and tactics for protecting biodiversity. </li></ul>
    49. 49. The Ecosystem Approach Protect populations of species in their natural habitats Goal The Species Approach Goal Protect species from premature extinction Preserve sufficient areas of habitats in different biomes and aquatic systems Strategy Tactics <ul><li>Protect habitat areas </li></ul><ul><li>through private purchase or government action </li></ul><ul><li>Eliminate or reduce </li></ul><ul><li>populations of nonnative species </li></ul><ul><li>from protected areas </li></ul><ul><li>Manage protected areas to sustain native species </li></ul><ul><li>Restore degraded </li></ul><ul><li>ecosystems </li></ul>Tactics <ul><li>Legally protect </li></ul><ul><li>endangered species </li></ul><ul><li>Manage habitat </li></ul><ul><li>Propagate endangered </li></ul><ul><li>species in captivity </li></ul><ul><li>Reintroduce species into </li></ul><ul><li>suitable habitats </li></ul>Strategies <ul><li>Identify endangered </li></ul><ul><li>species </li></ul><ul><li>Protect their critical </li></ul><ul><li>habitats </li></ul>
    50. 50. ENERGY FLOW IN ECOSYSTEMS <ul><li>Food chains and webs show how eaters, the eaten, and the decomposed are connected to one another in an ecosystem. </li></ul>
    51. 51. Heat Heat Heat Heat Heat Heat Heat Heat Detritivores (decomposers and detritus feeders) First Trophic Level Second Trophic Level Third Trophic Level Fourth Trophic Level Solar energy Producers (plants) Primary consumers (herbivores) Secondary consumers (carnivores) Tertiary consumers (top carnivores)
    52. 52. Animation: Energy Flow PLAY ANIMATION
    53. 53. Animation: Prairie Trophic Levels PLAY ANIMATION
    54. 54. Food Webs <ul><li>Trophic levels are interconnected within a more complicated food web. </li></ul>
    55. 55. Humans Blue whale Sperm whale Crabeater seal Elephant seal Killer whale Leopard seal Adelie penguins Emperor penguin Petrel Fish Squid Carnivorous plankton Krill Herbivorous plankton Phytoplankton
    56. 56. Animation: Categories of Food Webs PLAY ANIMATION
    57. 57. Animation: Rainforest Food Web PLAY ANIMATION
    58. 58. Animation: Prairie Food Web PLAY ANIMATION
    59. 59. Energy Flow in an Ecosystem: Losing Energy in Food Chains and Webs <ul><li>In accordance with the 2 nd law of thermodynamics, there is a decrease in the amount of energy available to each succeeding organism in a food chain or web. </li></ul>
    60. 60. Energy Flow in an Ecosystem: Losing Energy in Food Chains and Webs <ul><li>Ecological efficiency : percentage of useable energy transferred as biomass from one trophic level to the next. </li></ul>
    61. 61. Heat Heat Heat Heat Heat Decomposers Tertiary consumers (human) Producers (phytoplankton) Secondary consumers (perch) Primary consumers (zooplankton) 10 100 1,000 10,000 Usable energy Available at Each tropic level (in kilocalories)
    62. 62. Animation: Energy Flow in Silver Springs PLAY ANIMATION
    63. 63. Productivity of Producers: The Rate Is Crucial <ul><li>Gross primary production (GPP) </li></ul><ul><ul><li>Rate at which an ecosystem ’s producers convert solar energy into chemical energy as biomass. </li></ul></ul>
    64. 64. Gross primary productivity (grams of carbon per square meter)
    65. 65. Net Primary Production (NPP) <ul><li>NPP = GPP – R </li></ul><ul><ul><li>Rate at which producers use photosynthesis to store energy minus the rate at which they use some of this energy through respiration (R). </li></ul></ul>
    66. 66. Photosynthesis Sun Net primary production (energy available to consumers) Growth and reproduction Respiration Energy lost and unavailable to consumers Gross primary production
    67. 67. <ul><li>What are nature ’s three most productive and three least productive systems? </li></ul>
    68. 68. Average net primary productivity (kcal/m 2 /yr) Open ocean Continental shelf Lakes and streams Estuaries Aquatic Ecosystems Extreme desert Desert scrub Tundra (arctic and alpine) Temperate grassland Woodland and shrubland Agricultural land Savanna North. coniferous forest Temperate forest Terrestrial Ecosystems Tropical rain forest Swamps and marshes
    69. 69. SOIL: A RENEWABLE RESOURCE <ul><li>Soil is a slowly renewed resource that provides most of the nutrients needed for plant growth and also helps purify water. </li></ul><ul><ul><li>Soil formation begins when bedrock is broken down by physical, chemical and biological processes called weathering . </li></ul></ul><ul><li>Mature soils , or soils that have developed over a long time are arranged in a series of horizontal layers called soil horizons . </li></ul>
    70. 70. Fern Mature soil Honey fungus Root system Oak tree Bacteria Lords and ladies Fungus Actinomycetes Nematode Pseudoscorpion Mite Regolith Young soil Immature soil Bedrock Rock fragments Moss and lichen Organic debris builds up Grasses and small shrubs Mole Dog violet Wood sorrel Earthworm Millipede O horizon Leaf litter A horizon Topsoil B horizon Subsoil C horizon Parent material Springtail Red Earth Mite
    71. 71. Animation: Soil Profile PLAY ANIMATION
    72. 72. Layers in Mature Soils <ul><li>Infiltration: the downward movement of water through soil. </li></ul><ul><li>Leaching: dissolving of minerals and organic matter in upper layers carrying them to lower layers. </li></ul><ul><li>The soil type determines the degree of infiltration and leaching. </li></ul>
    73. 73. Soil Profiles of the Principal Terrestrial Soil Types
    74. 74. Mosaic of closely packed pebbles, boulders Weak humus-mineral mixture Dry, brown to reddish-brown with variable accumulations of clay, calcium and carbonate, and soluble salts Alkaline, dark, and rich in humus Clay, calcium compounds Desert Soil (hot, dry climate) Grassland Soil semiarid climate)
    75. 75. Tropical Rain Forest Soil (humid, tropical climate) Acidic light-colored humus Iron and aluminum compounds mixed with clay
    76. 76. Deciduous Forest Soil (humid, mild climate) Forest litter leaf mold Humus-mineral mixture Light, grayish-brown, silt loam Dark brown firm clay
    77. 77. Coniferous Forest Soil (humid, cold climate) Light-colored and acidic Acid litter and humus Humus and iron and aluminum compounds
    78. 78. Some Soil Properties <ul><li>Soils vary in the size of the particles they contain, the amount of space between these particles, and how rapidly water flows through them. </li></ul>
    79. 79. 0.05–2 mm diameter High permeability Low permeability Water Water Clay less than 0.002 mm Diameter Silt 0.002–0.05 mm diameter Sand
    80. 80. MATTER CYCLING IN ECOSYSTEMS <ul><li>Nutrient Cycles: Global Recycling </li></ul><ul><ul><li>Global Cycles recycle nutrients through the earth ’s air, land, water, and living organisms. </li></ul></ul><ul><ul><li>Nutrients are the elements and compounds that organisms need to live, grow, and reproduce. </li></ul></ul><ul><ul><li>Biogeochemical cycles move these substances through air, water, soil, rock and living organisms. </li></ul></ul>
    81. 81. The Water Cycle
    82. 82. Precipitation Precipitation Transpiration Condensation Evaporation Ocean storage Transpiration from plants Precipitation to land Groundwater movement (slow) Evaporation from land Evaporation from ocean Precipitation to ocean Infiltration and Percolation Rain clouds Runoff Surface runoff (rapid) Surface runoff (rapid)
    83. 83. Animation: Hydrologic Cycle PLAY ANIMATION
    84. 84. Water ’ Unique Properties <ul><li>There are strong forces of attraction between molecules of water. </li></ul><ul><li>Water exists as a liquid over a wide temperature range. </li></ul><ul><li>Liquid water changes temperature slowly. </li></ul><ul><li>It takes a large amount of energy for water to evaporate. </li></ul><ul><li>Liquid water can dissolve a variety of compounds. </li></ul><ul><li>Water expands when it freezes. </li></ul>
    85. 85. Effects of Human Activities on Water Cycle <ul><li>We alter the water cycle by: </li></ul><ul><ul><li>Withdrawing large amounts of freshwater. </li></ul></ul><ul><ul><li>Clearing vegetation and eroding soils. </li></ul></ul><ul><ul><li>Polluting surface and underground water. </li></ul></ul><ul><ul><li>Contributing to climate change. </li></ul></ul>
    86. 86. The Carbon Cycle: Part of Nature ’s Thermostat
    87. 88. Animation: Carbon Cycle PLAY ANIMATION
    88. 89. Effects of Human Activities on Carbon Cycle <ul><li>We alter the carbon cycle by adding excess CO 2 to the atmosphere through: </li></ul><ul><ul><li>Burning fossil fuels. </li></ul></ul><ul><ul><li>Clearing vegetation faster than it is replaced. </li></ul></ul>
    89. 90. CO 2 emissions from fossil fuels (billion metric tons of carbon equivalent) Year Low projection High projection
    90. 91. The Nitrogen Cycle: Bacteria in Action
    91. 92. Gaseous nitrogen (N 2 ) in atmosphere Ammonia, ammonium in soil Nitrogen-rich wastes, remains in soil Nitrate in soil Loss by leaching Loss by leaching Nitrite in soil Nitrification Nitrification Ammonification Uptake by autotrophs Uptake by autotrophs Excretion, death, decomposition Loss by denitrification Food webs on land Fertilizers Nitrogen fixation
    92. 93. Animation: Nitrogen Cycle PLAY ANIMATION
    93. 94. Effects of Human Activities on the Nitrogen Cycle <ul><li>We alter the nitrogen cycle by: </li></ul><ul><ul><li>Adding gases that contribute to acid rain. </li></ul></ul><ul><ul><li>Adding nitrous oxide to the atmosphere through farming practices which can warm the atmosphere and deplete ozone. </li></ul></ul><ul><ul><li>Contaminating ground water from nitrate ions in inorganic fertilizers. </li></ul></ul><ul><ul><li>Releasing nitrogen into the troposphere through deforestation. </li></ul></ul>
    94. 95. Effects of Human Activities on the Nitrogen Cycle <ul><li>Human activities such as production of fertilizers now fix more nitrogen than all natural sources combined. </li></ul>
    95. 96. Nitrogen fixation by natural processes Global nitrogen (N) fixation (trillion grams) Nitrogen fixation by human processes Year
    96. 97. The Phosphorous Cycle
    97. 98. Dissolved in Ocean Water Marine Sediments Rocks uplifting over geologic time settling out weathering sedimentation Land Food Webs Dissolved in Soil Water, Lakes, Rivers death, decomposition uptake by autotrophs agriculture leaching, runoff uptake by autotrophs excretion death, decomposition mining Fertilizer weathering Guano Marine Food Webs
    98. 99. Animation: Phosphorous Cycle PLAY ANIMATION
    99. 100. Effects of Human Activities on the Phosphorous Cycle <ul><li>We remove large amounts of phosphate from the earth to make fertilizer. </li></ul><ul><li>We reduce phosphorous in tropical soils by clearing forests. </li></ul><ul><li>We add excess phosphates to aquatic systems from runoff of animal wastes and fertilizers. </li></ul>
    100. 101. The Sulfur Cycle
    101. 102. Hydrogen sulfide Sulfur Sulfate salts Decaying matter Animals Plants Ocean Industries Volcano Hydrogen sulfide Oxygen Dimethyl sulfide Ammonium sulfate Ammonia Acidic fog and precipitation Sulfuric acid Water Sulfur trioxide Sulfur dioxide Metallic sulfide deposits
    102. 103. Animation: Sulfur Cycle PLAY ANIMATION
    103. 104. Effects of Human Activities on the Sulfur Cycle <ul><li>We add sulfur dioxide to the atmosphere by: </li></ul><ul><ul><li>Burning coal and oil </li></ul></ul><ul><ul><li>Refining sulfur containing petroleum. </li></ul></ul><ul><ul><li>Convert sulfur-containing metallic ores into free metals such as copper, lead, and zinc releasing sulfur dioxide into the environment. </li></ul></ul>
    104. 105. The Gaia Hypothesis: Is the Earth Alive? <ul><li>Some have proposed that the earth ’s various forms of life control or at least influence its chemical cycles and other earth-sustaining processes. </li></ul><ul><ul><li>The strong Gaia hypothesis: life controls the earth ’s life-sustaining processes. </li></ul></ul><ul><ul><li>The weak Gaia hypothesis: life influences the earth ’s life-sustaining processes. </li></ul></ul>
    105. 106. HOW DO ECOLOGISTS LEARN ABOUT ECOSYSTEMS? <ul><li>Ecologist go into ecosystems to observe, but also use remote sensors on aircraft and satellites to collect data and analyze geographic data in large databases. </li></ul><ul><ul><li>Geographic Information Systems </li></ul></ul><ul><ul><li>Remote Sensing </li></ul></ul><ul><li>Ecologists also use controlled indoor and outdoor chambers to study ecosystems </li></ul>
    106. 107. Geographic Information Systems (GIS) <ul><li>A GIS organizes, stores, and analyzes complex data collected over broad geographic areas. </li></ul><ul><li>Allows the simultaneous overlay of many layers of data. </li></ul>
    107. 108. Critical nesting site locations USDA Forest Service USDA Forest Service Private owner 1 Private owner 2 Topography Habitat type Lake Wetland Forest Grassland Real world
    108. 109. Systems Analysis <ul><li>Ecologists develop mathematical and other models to simulate the behavior of ecosystems. </li></ul>
    109. 110. Systems Measurement Define objectives Identify and inventory variables Obtain baseline data on variables Make statistical analysis of relationships among variables Determine significant interactions Objectives Construct mathematical model describing interactions among variables Run the model on a computer, with values entered for different Variables Evaluate best ways to achieve objectives Data Analysis System Modeling System Simulation System Optimization
    110. 111. Importance of Baseline Ecological Data <ul><li>We need baseline data on the world ’s ecosystems so we can see how they are changing and develop effective strategies for preventing or slowing their degradation. </li></ul><ul><ul><li>Scientists have less than half of the basic ecological data needed to evaluate the status of ecosystems in the United Sates (Heinz Foundation 2002; Millennium Assessment 2005). </li></ul></ul>