Ecosystems and energy_flow

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  • 2. Ecosystem
    • A community and its physical environment
    • Made up of two essential components:
      • Abiotic factors
      • Biotic factors
  • 3. Abiotic factors
    • The non-living components of an ecosystem
    • Consists of the elements which may be found in the environment
    • Abiotic factors may be:
      • Physical
      • Chemical
  • 4. Physical factors
    • Sunlight and shade
    • Temperature and wind
    • Amount of precipitation
    • Altitude and latitude
    • Nature of soil
  • 5. Chemical factors
    • Salinity of water
    • Level of dissolved O 2 and other gases
    • Level of plant nutrients
    • pH of soil and water
    • Level of natural or artificial toxic substances
  • 6. Biotic factors
    • The organisms in an ecosystem are either:
      • Autotrophs
      • Heterotrophs
    • Autotrophic organisms may be photoautotrophic or chemoautotrophic.
    • The heterotrophs include humans, animals and microorganisms.
  • 7. Autotrophs
    • Photoautotrophs possess chlorophyll and carry on photosynthesis.
    • Chemoautotrophs are bacteria that obtain energy from the oxidation of inorganic compounds such as ammonia, nitrites and sulfides.
  • 8. Heterotrophs
    • Heterotrophic organisms need a source of pre-formed nutrients and consume tissues of other organisms.
    • Consumers are classified according to the type of food they eat.
  • 9. Types of Consumers
    • Herbivores are animals that feed directly on green plants.
    • Carnivores are animals that eat other animals.
    • Omnivores feed on both plants and animals.
  • 10. Types of Consumers
    • Decomposers are fungi and bacteria that extract energy from dead matter, including waste and return nutrients back to the soil.
    • Scavengers are animals that feed on dead matter.
  • 11. Food Chain
    • Artificial devices that illustrate how energy and nutrients move from one organism to another though the ecosystem
    • Shows transfer of energy from one trophic level to another
  • 12. Trophic levels
    • A trophic level includes a group of organisms that obtain food in a similar manner.
      • Producers
      • Primary consumers
      • Secondary consumers
      • Tertiary consumers
      • Quaternary consumers
  • 13. Food Chain
  • 14. Food Webs: Who Eats Whom?
  • 15. Food Web
    • A complex network of interconnected food chains
    • The feeding relationship that actually exists in nature
    • May be:
      • Grazing food web
      • Detrital food web
  • 16. Energy Flow
    • Ecosystems are dependent upon solar energy flow and finite pools of nutrients.
    • The primary source of energy for ecosystems is sunlight.
    • All energy content of organic matter is eventually lost to the environment as heat.
  • 17. Laws of Thermodynamics
    • Energy can neither be created nor destroyed, but can be transformed into different forms.
    • When energy is transformed from one form to another, there is always some loss of energy from the system, usually as low grade heat.
  • 18. 10% Law of Energy Transfer
    • In general, about 10% of energy at a particular trophic level is incorporated into the next trophic level.
    • This rapid loss loss of energy explains why a food chain rarely has five links.
  • 19. Energy Flow
    • Energy enters ecosystems from an external source. What is it?
    • Energy flows linearly and exits an ecosystem through ___________.
    • What happens to the amount of energy as it travels through an ecosystem?
  • 20. Ecological Pyramids
    • Graphic representations of the relative energy amounts at each trophic level.
    • 3 Types of Pyramids
    • 1. Pyramid of Energy
    • 2. Pyramid of Biomass
    • 3. Pyramid of Numbers
  • 21. Pyramid of Energy
    • Energy content of each trophic level
    • Unit of energy = Kilocalories/meter 2 /year
    • Pyramid has large base and gets significantly smaller at each level.
    • Organisms use energy for work and respiration, so less energy is available to each successive trophic level .
  • 22. Pyramid of Energy
    • The figures represent the amount of energy at each trophic level expressed in kcal/m2/yr .
  • 23. Pyramid of Biomass
    • Biomass is a quantitative estimate of the total mass (amount) of living material…or
    • … the amount of fixed energy at a given time .
    • Measuring biomass: total volume, dry weight, or live weight
    • A 90% reduction occurs between each trophic level
  • 24. Pyramid of Biomass
    • Biomass also diminishes with the distance along the food chain from the autotrophs which make the organic molecules in the first place.
  • 25. Pyramid of Numbers
    • Illustrates number of organisms at each trophic level
    • Most pyramids show that there are many more individuals at the lower trophic levels. For example: the number of herbivores on the African plains (zebra, wildebeests) is far greater than the number of carnivores (lions).
    • BUT some number pyramids can be inverted.
  • 26. Pyramid of Numbers
    • Small animals are more numerous than larger ones.
    • If the size of the individuals at a given trophic level is small, their numbers can be large and vice versa.
  • 27. Write the trophic level that each organism belongs to in this food web.