Ch 5 What do we know about ecosystems?

1. Ch 5 What do we know about ecosystems?

2. An ecosystem consists of all the organisms (biotic) in a community and the environment (abiotic) with which they interact. Ecosystems can be as small as the microorganisms living on your skin or as large as the entire biosphere.

3. Nutrients cycle WITHIN ecosystems – closed system Energy flows THROUGH ecosystems – open system

4. HOW DO ECOSYSTEMS WORK? • FOLLOW THE FLOW OF ENERGY THROUGH AN ECOSYSTEM • FOLLOW THE CYCLING OF MATERIALS THROUGH AN ECOSYSTEM • FOLLOW THE CHANGES IN AN ECOSYSTEM

5. The Earth’s Life-Support Systems • Atmosphere • Troposphere -weather • Greenhouse gases • Stratosphere • Lower portion (ozone) • filters out harmful sun rays • Allows life to exist on earth • Geosphere- Lithosphere • Earth’s crust • Hydrosphere • Water 3% is fresh • Biosphere • Living and dead organisms

6. Solar Capital: Flow of Energy to and from the Earth Greenhouse gasses water vapor CO2 Methane Ozone Increases kinetic energy, Helps warm troposphere. Allows life to exist (as we know it) on earth. As greenhouse gasses increase, temperature of troposphere increases.

7. Ecosystem Components • Abiotic factors • energy • mineral nutrients • CO2 • O2 • H2O • Biotic factors • Range of tolerance for • each species

8. ABIOTIC components: • Solar energy provides practically all the energy for ecosystems. • Inorganic substances, e.g., carbon, oxygen, sulfur, boron, tend to cycle through ecosystems. • Organic compounds, such as proteins, carbohydrates, lipids, and other complex molecules, form a link between biotic and abiotic components of the system.

9. BIOTIC components: The biotic components of an ecosystem can be classified according to their mode of energy acquisition. In this type of classification, there are: Autotrophs and Heterotrophs

10. Life Depends on the sun

11. Natural Capital: Sustaining Life of Earth • One-way flow of energy from Sun • Cycling of crucial elements • Gravity

12. Three hundred trout are needed to support one man for a year. The trout, in turn, must consume 90,000 frogs, that must consume 27 million grasshoppers that live off of 1,000 tons of grass. -- G. Tyler Miller, Jr., American Chemist (1971)

13. Types of energy: heat energy chemical energy = energy stored in molecular bonds Light Mechanical Nuclear Electrical Magnetic gravitational

14. First Law of Thermodynamics • Energy is neither created nor destroyed • Energy only changes form • You can’t get something for nothing • Or “There is no such thing as a free lunch!” • ENERGY IN = ENERGY OUT • Energy flow is a one-directional process. • sun---> heat (longer wavelengths)

15. Second Law of Thermodynamics • In every transformation, some energy is converted to heat • You cannot break even in terms of energy quality • You cannot break even in terms of energy quality

16. SECOND LAW of THERMODYNAMICS Transformations of energy always result in some loss or dissipation of energy or In energy exchanges in a closed system, the potential energy of the final state will be less than that of the initial state or Entropy tends to increase (entropy = amount of unavailable energy in a system) or Systems will tend to go from ordered states to disordered states (to maintain order, energy must be added to the system, to compensate for the loss of energy)

17. Internal combustion engines in cars are 25% efficient in converting chemical energy to kinetic energy; the rest is not used or is lost as heat. My desk goes from a complex, ordered state to a simpler, disordered state

18. ENERGY FLOW IN ECOSYSTEMS • All organisms require energy, for growth, maintenance, • reproduction, locomotion, etc. • Hence, for all organisms there must be: A source of energy • A loss of usable energy

19. Life depends on the sun • Energy in an ecosystem originally comes from the sun • Energy enters an ecosystem when a plant/algae uses sunlight to make sugar in photosynthesis

20. Photosynthesis is the process of converting solar energy into chemical energy stored in food CO2 + H20 ---> C6H12O6 + O2

21. How Photosynthesis Works • Light strikes leaf • Energy absorbed by chemical pigments • Absorbed energy drives chemical processes to convert CO2 into larger molecules • Energy absorbed in building larger molecules, released as they are broken down

23. Absorption spectra of chlorophylls and carotenoids Wavelength reflected

24. In many plants production of chlorophyll ceases with cooler temperatures and decreasing light other pigments become visible

25. CO2 must enter though stomata • stomata (sing., stoma) are tiny holes on the undersides of leaves • CO2 enters and moisture is released • In hot, dry climates, this moisture loss is a problem

26. SUNLIGHT C6H12O6 + 6 O2 6 CO2 + 6 H20 ENERGY RICH CARBOHYDRATES GLUCOSE

27. Organisms are classified by the source of their energy PRODUCERS – organisms that make their own food Also known as AUTOTROPHS Examples: plants, algae, some bacteria CONSUMERS – get energy by eating other living things Also known as HETEROTROPHS

28. TWO TYPES OF PRODUCERS AUTOTROPHS Photosynthetic – algae, plants, some bacteria that use sun’s energy to synthesize organic compounds Chemosynthetic – bacteria that synthesize organic compounds from inorganic chemicals (hydrogen sulfide, ammonia) use energy in chemical bonds

29. Autotrophs (=self-nourishing) are called primary producers. Photoautotrophs fix energy from the sun and store it in complex organic compounds (= green plants, algae, some bacteria) light simple inorganic compounds complex organic compounds photoautotrophs chloroplasts CO2 + H2O Glucose C6H12O6

30. Chemoautotrophs (chemosynthesizers) are bacteria that oxidize reduced inorganic substances (typically sulfur and ammonia compounds) and produce complex organic compounds. oxygen reduced inorganic compounds complex organic compounds chemoautotrophs

32. Other chemoautotrophs: Nitrifying bacteria in the soil under our feet

33. When an animal eats a plant, energy is transferred from the plant to the animal. l

34. Respiration is the process of releasing chemical energy stored in food to be used by living things. C6H12O6 + O2 ---> CO2 + H20

35. Heterotrophs (=other-nourishing) cannot produce their own food directly from sunlight+ inorganic compounds. They require energy previously stored in complex molecules. heat simple inorganic compounds complex organic compounds heterotrophs glucose mitochondria CO2 + H2O + ATP

36. TYPES OF CONSUMERS HETEROTROPHS Herbivore - Carnivore - Omnivore - Scavenger - Detrivore - Decomposer -

37. Classes of Herbivores Browsers – woody material Grazers – plant material Granivores - seeds Frugivores – fruit Other: nectar & sap feeders • Hummingbirds, moths, aphids, sap suckers …

39. ENERGY TRANSFER • Follow energy transfer through an ecosystem: • Food chain: follows path of energy • Food web: multiple food chains • Energy pyramids: shows loss of energy as you move up trophic levels • The arrow follows the flow of energy

40. Food chain • Plant rabbit snake Arrows follow the flow of energy NOT who eats who __________________________________ NO: Plant rabbit snake

41. Food chain

42. Food chain

44. Problems Too simplistic No detritivores Chains too long

45. Rarely are things as simple as grass, rabbit, hawk, or indeed any simple linear sequence of organisms. More typically, there are multiple interactions, so that we end up with a FOOD WEB.

46. Food Web • Multiple food chains • Rarely does 1 organism only eat 1 thing • Shows many possible feeding relationships that are possible in an ecosystem. • Arrows still follow the flow of energy from producers through consumers to the top of the food web.