Understanding Ecosystems: Connections in Nature

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. Updates Online The latest references for topics covered in this section can be found at the book companion website. Log in to the book’s e-resources page at www.thomsonedu.com to access InfoTrac articles. • InfoTrac: Rescuers race to save Central American frogs. Blade (Toledo, OH), August 6, 2006. • InfoTrac: Climate change puts national parks at risk. Philadelphia Inquirer, July 13, 2006. • InfoTrac: Deep-Spied Fish: Atlantic Expeditions Uncover Secret Sex Life of Deep-Sea Nomads. Ascribe Higher Education News Service, Feb 21, 2006. • Environmental Tipping Points • NatureServe: Ecosystem Mapping • U.S. Bureau of Land Management: Soil Biological Communities

4. 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

5. 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.

6. THE NATURE OF ECOLOGY • Ecology is a study of connections in nature. • How organisms interact with one another and with their nonliving environment. Figure 3-2

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

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

9. Other animals 281,000 Known species 1,412,000 Insects 751,000 Fungi 69,000 Prokaryotes 4,800 Plants 248,400 Protists 57,700 Fig. 3-3, p. 52

10. 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. • Soil bacteria convert nitrogen gas to a usable form for plants. • They help produce foods (bread, cheese, yogurt, beer, wine). • 90% of all living mass. • Helps purify water, provide oxygen, breakdown waste. • Lives beneficially in your body (intestines, nose).

11. Populations, Communities, and Ecosystems • Members of a species interact in groups called populations. • Populations of different species living and interacting in an area form a community. • A community interacting with its physical environment of matter and energy is an ecosystem.

12. Populations • A population is a group of interacting individuals of the same species occupying a specific area. • The space an individual or population normally occupies is its habitat. Figure 3-4

13. Populations • Genetic diversity • In most natural populations individuals vary slightly in their genetic makeup. Figure 3-5

14. THE EARTH’S LIFE SUPPORT SYSTEMS • The biosphere consists of several physical layers that contain: • Air • Water • Soil • Minerals • Life Figure 3-6

15. Oceanic Crust Continental Crust Atmosphere Vegetation and animals Biosphere Lithosphere Soil Upper mantle Crust Asthenosphere Rock Lower mantle Core Mantle Crust (soil and rock) Biosphere (living and dead organisms) Hydrosphere (water) Lithosphere (crust, top of upper mantle) Atmosphere (air) Fig. 3-6, p. 54

16. Biosphere • Atmosphere • Membrane of air around the planet. • Stratosphere • 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 • Lithosphere • The earth’s crust and upper mantle.

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

18. Biosphere Carbon cycle Phosphorus cycle Nitrogen cycle Water cycle Oxygen cycle Heat in the environment Heat Heat Heat Fig. 3-7, p. 55

19. What Happens to Solar Energy Reaching the Earth? • Solar energy flowing through the biosphere warms the atmosphere, evaporates and recycles water, generates winds and supports plant growth. Figure 3-8

20. Solar radiation Energy in = Energy out Reflected by atmosphere (34% ) Radiated by atmosphere as heat (66%) UV radiation Lower Stratosphere (ozone layer) Absorbed by ozone Greenhouse effect Troposphere Visible Light Heat Absorbed by the earth Heat radiated by the earth Fig. 3-8, p. 55

21. ECOSYSTEM COMPONENTS • Life exists on land systems called biomes and in freshwater and ocean aquatic life zones. Figure 3-9

22. Average annual precipitation 100–125 cm (40–50 in.) 75–100 cm (30–40 in.) 50–75 cm (20–30 in.) 4,600 m (15,000 ft.) 25–50 cm (10–20 in.) 3,000 m (10,000 ft.) below 25 cm (0–10 in.) 1,500 m (5,000 ft.) Coastal mountain ranges Sierra Nevada Mountains Great American Desert Rocky Mountains Great Plains Mississippi River Valley Appalachian Mountains Coastal chaparral and scrub Coniferous forest Prairie grassland Coniferous forest Desert Deciduous forest Fig. 3-9, p. 56

23. Nonliving and Living Components of Ecosystems • Ecosystems consist of nonliving (abiotic) and living (biotic) components. Figure 3-10

24. Sun Oxygen (O2) Producer Carbon dioxide (CO2) Secondary consumer (fox) Primary consumer (rabbit) Precipitation Producers Falling leaves and twigs Soil decomposers Soluble mineral nutrients Water Fig. 3-10, p. 57

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

26. 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 intolerance Zone of physiological stress Zone of physiological stress Optimum range Low Temperature High Fig. 3-11, p. 58

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

28. Sugar Maple Fig. 3-12, p. 58

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

30. Producers: Basic Source of All Food • Chemosynthesis: • Some organisms such as deep ocean bacteria draw energy from hydrothermal vents and produce carbohydrates from hydrogen sulfide (H2S) gas .

31. 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

32. Sun Chloroplast in leaf cell Chlorophyll H2O O2 Light-dependent Reaction Energy storage and release (ATP/ADP) Glucose Light-independent reaction CO2 Sunlight 6CO2 + 6 H2O C6H12O6 +6 O2 Fig. 3-A, p. 59

33. 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 • Primary consumers that eat producers • Carnivores • Primary consumers eat primary consumers • Third and higher level consumers: carnivores that eat carnivores. • Omnivores • Feed on both plant and animals.

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

35. Scavengers Decomposers Termite and carpenter ant work Carpenter ant galleries Bark beetle engraving Long-horned beetle holes Dry rot fungus Wood reduced to powder Mushroom Time progression Powder broken down by decomposers into plant nutrients in soil Fig. 3-13, p. 61

36. 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

37. 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. • The end products vary based on the chemical reaction: • Methane gas • Ethyl alcohol • Acetic acid • Hydrogen sulfide

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

39. Abiotic chemicals (carbon dioxide, oxygen, nitrogen, minerals) Heat Solar energy Heat Heat Producers (plants) Decomposers (bacteria, fungi) Consumers (herbivores, carnivores) Heat Heat Fig. 3-14, p. 61

40. BIODIVERSITY Figure 3-15

41. 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

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

43. Solutions • Goals, strategies and tactics for protecting biodiversity. Figure 3-16

44. The Ecosystem Approach The Species Approach Goal Goal Protect populations of species in their natural habitats Protect species from premature extinction Strategy Strategies Preserve sufficient areas of habitats in different biomes and aquatic systems • Identify endangered species • Protect their critical habitats Tactics Tactics • Protect habitat areas through private purchase or government action • Legally protect endangered species • Manage habitat • Eliminate or reduce populations of nonnative species from protected areas • Propagate endangered species in captivity • Manage protected areas to sustain native species • Reintroduce species into suitable habitats • Restore degraded ecosystems Fig. 3-16, p. 63

45. 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

46. First Trophic Level Second Trophic Level Third Trophic Level Fourth Trophic Level Tertiary consumers (top carnivores) Secondary consumers (carnivores) Producers (plants) Primary consumers (herbivores) Heat Heat Heat Solar energy Heat Heat Heat Heat Detritivores (decomposers and detritus feeders) Heat Fig. 3-17, p. 64

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

48. Humans Blue whale Sperm whale Crabeater seal Elephant seal Killer whale Leopard seal Adelie penguins Emperor penguin Squid Petrel Fish Carnivorous plankton Krill Herbivorous plankton Phytoplankton Fig. 3-18, p. 65

49. Energy Flow in an Ecosystem: Losing Energy in Food Chains and Webs • In accordance with the 2nd law of thermodynamics, there is a decrease in the amount of energy available to each succeeding organism in a food chain or web.