1. Chapter 3 Ecosystems: What Are They and How Do They Work?

2. Chapter Overview Questions  What is ecology?  What basic processes keep us and other organisms alive?  What are the major components of an ecosystem?  What happens to energy in an ecosystem?  What are soils and how are they formed?  What happens to matter in an ecosystem?  How do scientists study ecosystems?

3. Core Case Study: Have You Thanked the Insects Today?  Many plant species depend on insects for pollination.  Insect can control other pest insects by eating them Figure 3-1

4. Core Case Study: Have You Thanked the Insects Today?  …if all insects disappeared, humanity probably could not last more than a few months [E.O. Wilson, Biodiversity expert]. Insect’s role in nature is part of the larger biological community in which they live. Insect’s role in nature is part of the larger biological community in which they live.

5. Fig. 3-2, p. 51 Communities Subatomic Particles Atoms Molecules Protoplasm Cells Tissues Organs Organ systems Organisms Populations Communities Ecosystems Biosphere Earth Planets Solar systems Galaxies Universe Organisms Realm of ecology Ecosystems Biosphere

6. Organisms and Species  Organisms, the different forms of life on earth, can be classified into different species based on certain characteristics. Figure 3-3

7. Case Study: Which Species Run the World?  Multitudes of tiny microbes such as bacteria, protozoa, fungi, and yeast help keep us alive. Harmful microbes are the minority. Harmful microbes are the minority. Soil bacteria convert nitrogen gas to a usable form for plants. Soil bacteria convert nitrogen gas to a usable form for plants. They help produce foods (bread, cheese, yogurt, beer, wine). They help produce foods (bread, cheese, yogurt, beer, wine). 90% of all living mass. 90% of all living mass. Helps purify water, provide oxygen, breakdown waste. Helps purify water, provide oxygen, breakdown waste. Lives beneficially in your body (intestines, nose). Lives beneficially in your body (intestines, nose).

8. Biosphere  Atmosphere Membrane of air around the planet. Membrane of air around the planet.  Stratosphere Lower portion contains ozone to filter out most of the sun’s harmful UV radiation. Lower portion contains ozone to filter out most of the sun’s harmful UV radiation.  Hydrosphere All the earth’s water: liquid, ice, water vapor All the earth’s water: liquid, ice, water vapor  Lithosphere The earth’s crust and upper mantle. The earth’s crust and upper mantle.

9. What Sustains Life on Earth?  Solar energy, the cycling of matter, and gravity sustain the earth’s life. Figure 3-7

10. Fig. 3-8, p. 55 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)

11. Fig. 3-10, p. 57 Sun Oxygen (O 2 ) Carbon dioxide (CO 2 ) Secondary consumer (fox) Soil decomposers Primary consumer (rabbit) Precipitation Falling leaves and twigs Producer Producers Water

12. Factors That Limit Population Growth  Availability of matter and energy resources can limit the number of organisms in a population. Figure 3-11

13. Fig. 3-11, p. 58 Zone of intolerance Optimum range Zone of physiological stress Zone of physiological stress Zone of intolerance TemperatureLowHigh No organisms Few organisms Upper limit of tolerance Population size Abundance of organisms Few organisms No organisms Lower limit of tolerance

14. Factors That Limit Population Growth  The physical conditions of the environment can limit the distribution of a species. Figure 3-12

15. Producers: Basic Source of All Food  Most producers capture sunlight to produce carbohydrates by photosynthesis:

16. Photosynthesis: A Closer Look  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 and oxygen. Figure 3-A

17. Consumers: Eating and Recycling to Survive  Consumers (heterotrophs) get their food by eating or breaking down all or parts of other organisms or their remains. Herbivores Herbivores Primary consumers that eat producersPrimary consumers that eat producers Carnivores Carnivores Primary consumers eat primary consumersPrimary consumers eat primary consumers Third and higher level consumers: carnivores that eat carnivores.Third and higher level consumers: carnivores that eat carnivores. Omnivores Omnivores Feed on both plant and animals.Feed on both plant and animals.

18. Decomposers and Detrivores Decomposers: Recycle nutrients in ecosystems. Decomposers: Recycle nutrients in ecosystems. Detrivores: Insects or other scavengers that feed on wastes or dead bodies. Detrivores: Insects or other scavengers that feed on wastes or dead bodies. Figure 3-13

19. Aerobic and Anaerobic Respiration: Getting Energy for Survival  Organisms break down carbohydrates and other organic compounds in their cells to obtain the energy they need.  This is usually done through aerobic respiration. The opposite of photosynthesis The opposite of photosynthesis

20. Aerobic and Anaerobic Respiration: Getting Energy for Survival  Anaerobic respiration or fermentation: Some decomposers get energy by breaking down glucose (or other organic compounds) in the absence of oxygen. Some decomposers get energy by breaking down glucose (or other organic compounds) in the absence of oxygen. The end products vary based on the chemical reaction: The end products vary based on the chemical reaction: Methane gasMethane gas Ethyl alcoholEthyl alcohol Acetic acidAcetic acid Hydrogen sulfideHydrogen sulfide

21. Two Secrets of Survival: Energy Flow and Matter Recycle  An ecosystem survives by a combination of energy flow and matter recycling. Figure 3-14

22. BIODIVERSITY Figure 3-15

23. Biodiversity Loss and Species Extinction: Remember HIPPO  H for habitat destruction and degradation  I for invasive species  P for pollution  P for human population growth  O for overexploitation

24. Why Should We Care About Biodiversity?  Biodiversity provides us with: Natural Resources (food water, wood, energy, and medicines) Natural Resources (food water, wood, energy, and medicines) Natural Services (air and water purification, soil fertility, waste disposal, pest control) Natural Services (air and water purification, soil fertility, waste disposal, pest control) Aesthetic pleasure Aesthetic pleasure

25. Fig. 3-16, p. 63 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 Protect habitat areas through private purchase or government action Eliminate or reduce populations of nonnative species from protected areas Manage protected areas to sustain native species Restore degraded ecosystems Tactics Legally protect endangered species Manage habitat Propagate endangered species in captivity Reintroduce species into suitable habitats Strategies Identify endangered species Protect their critical habitats

26. ENERGY FLOW IN ECOSYSTEMS  Food chains and webs show how eaters, the eaten, and the decomposed are connected to one another in an ecosystem. Figure 3-17

27. Food Webs  Trophic levels are interconnected within a more complicated food web. Figure 3-18

28. Energy Flow in an Ecosystem: Losing Energy in Food Chains and Webs  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.

29. Energy Flow in an Ecosystem: Losing Energy in Food Chains and Webs  Ecological efficiency: percentage of useable energy transferred as biomass from one trophic level to the next. Figure 3-19

30. Productivity of Producers: The Rate Is Crucial  Gross primary production (GPP) Rate at which an ecosystem’s producers convert solar energy into chemical energy as biomass. Rate at which an ecosystem’s producers convert solar energy into chemical energy as biomass. Figure 3-20

31. Net Primary Production (NPP)  NPP = GPP – R Rate at which producers use photosynthesis to store energy minus the rate at which they use some of this energy through respiration (R). Rate at which producers use photosynthesis to store energy minus the rate at which they use some of this energy through respiration (R). Figure 3-21

32.  What are nature’s three most productive and three least productive systems? Figure 3-22

33. SOIL: A RENEWABLE RESOURCE  Soil is a slowly renewed resource that provides most of the nutrients needed for plant growth and also helps purify water. Soil formation begins when bedrock is broken down by physical, chemical and biological processes called weathering. Soil formation begins when bedrock is broken down by physical, chemical and biological processes called weathering.  Mature soils, or soils that have developed over a long time are arranged in a series of horizontal layers called soil horizons.

34. Fig. 3-23, p. 68 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

35. Layers in Mature Soils  Infiltration: the downward movement of water through soil.  Leaching: dissolving of minerals and organic matter in upper layers carrying them to lower layers.  The soil type determines the degree of infiltration and leaching.

36. Soil Profiles of the Principal Terrestrial Soil Types Figure 3-24

37. Some Soil Properties  Soils vary in the size of the particles they contain, the amount of space between these particles, and how rapidly water flows through them. Figure 3-25

38. MATTER CYCLING IN ECOSYSTEMS  Nutrient Cycles: Global Recycling Global Cycles recycle nutrients through the earth’s air, land, water, and living organisms. Global Cycles recycle nutrients through the earth’s air, land, water, and living organisms. Nutrients are the elements and compounds that organisms need to live, grow, and reproduce. Nutrients are the elements and compounds that organisms need to live, grow, and reproduce. Biogeochemical cycles move these substances through air, water, soil, rock and living organisms. Biogeochemical cycles move these substances through air, water, soil, rock and living organisms.

39. Fig. 3-26, p. 72 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)

40. Effects of Human Activities on Water Cycle  We alter the water cycle by: Withdrawing large amounts of freshwater. Withdrawing large amounts of freshwater. Clearing vegetation and eroding soils. Clearing vegetation and eroding soils. Polluting surface and underground water. Polluting surface and underground water. Contributing to climate change. Contributing to climate change.

41. Fig. 3-27, pp. 72-73

42. Effects of Human Activities on Carbon Cycle  We alter the carbon cycle by adding excess CO 2 to the atmosphere through: Burning fossil fuels. Burning fossil fuels. Clearing vegetation faster than it is replaced. Clearing vegetation faster than it is replaced. Figure 3-28

43. Fig. 3-29, p. 75 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 Ammonification Uptake by autotrophs Excretion, death, decomposition Loss by denitrification Food webs on land Fertilizers Nitrogen fixation

44. Effects of Human Activities on the Nitrogen Cycle  We alter the nitrogen cycle by: Adding gases that contribute to acid rain. Adding gases that contribute to acid rain. Adding nitrous oxide to the atmosphere through farming practices which can warm the atmosphere and deplete ozone. Adding nitrous oxide to the atmosphere through farming practices which can warm the atmosphere and deplete ozone. Contaminating ground water from nitrate ions in inorganic fertilizers. Contaminating ground water from nitrate ions in inorganic fertilizers. Releasing nitrogen into the troposphere through deforestation. Releasing nitrogen into the troposphere through deforestation.

45. Effects of Human Activities on the Nitrogen Cycle  Human activities such as production of fertilizers now fix more nitrogen than all natural sources combined. Figure 3-30

46. Fig. 3-31, p. 77 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 miningFertilizer weathering Guano Marine Food Webs

47. Effects of Human Activities on the Phosphorous Cycle  We remove large amounts of phosphate from the earth to make fertilizer.  We reduce phosphorous in tropical soils by clearing forests.  We add excess phosphates to aquatic systems from runoff of animal wastes and fertilizers.

48. Fig. 3-32, p. 78 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

49. Effects of Human Activities on the Sulfur Cycle  We add sulfur dioxide to the atmosphere by: Burning coal and oil Burning coal and oil Refining sulfur containing petroleum. Refining sulfur containing petroleum. Convert sulfur-containing metallic ores into free metals such as copper, lead, and zinc releasing sulfur dioxide into the environment. Convert sulfur-containing metallic ores into free metals such as copper, lead, and zinc releasing sulfur dioxide into the environment.

50. Geographic Information Systems (GIS)  A GIS organizes, stores, and analyzes complex data collected over broad geographic areas.  Allows the simultaneous overlay of many layers of data. Figure 3-33

51. Fig. 3-33, p. 79 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

52. Systems Analysis  Ecologists develop mathematical and other models to simulate the behavior of ecosystems. Figure 3-34

53. Fig. 3-34, p. 80 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

54. Importance of Baseline Ecological Data  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. 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). 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).