Cycling of Materials in Ecosystems

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Cycling of Materials in Ecosystems

• Cycles within an Ecosystem
• Water Cycle
• Carbon Cycle
• Phosphorous and Nitrogen Cycle

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Cycles within Ecosystems

• Almost everything within an ecosystem is
  recycled.
• Water, carbon, nitrogen phosphorus pass from
  the nonliving environment to living organisms
  then back to the environment.

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Water Cycle

• Water is the most important, non-living component
  of the ecosystem.
• Nonliving cycle involves condensation,
  precipitation, evaporation.
• Living cycle involves plants in a process
  called transpiration.

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Water Cycle

• Nonliving portion
• Water vapor, as it cools, condenses in the form
  of clouds and falls to the Earths surface as
  precipitation (as rain, snow, etc)
• Then water evaporates (turning from a liquid to a
  gas) and re-enters the atmosphere
• Living portion
• Water is absorbed by roots of plants
• After passing through the plant, the water
  evaporates from the leaves in a process called
  transpiration

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Carbon Cycle

• Carbon dioxide in the air (or dissolved water) is
  used by photosynthesizing plants, algae and
  bacteria as raw material to build organic
  molecules.
• What does that mean? Autotrophs take in carbon
  dioxide to help make food in order to grow and
  survive
• Involves
• Respiration (breathing where CO2 is a by product)
• Combustion (burning)
• Erosion (limestone)

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Phosphorous and Nitrogen Cycle

• You need phosphorous and nitrogen to build
  proteins and nucleic acids (part of DNA)
• Since more organisms are unable to use nitrogen
  gas (N2), nitrogen fixing bacteria bind nitrogen
  with hydrogen to form ammonia (NH3)
• What does that mean? We need nitrogen, but we
  cant use pure nitrogen gas (N2) so certain
  bacteria convert N2 into a usable forms (ammonia)

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Phosphorous and Nitrogen Cycle

• Stages
• Assimilation (absorption of nitrogen gas,N2, by
  plants)
• Ammonification (production of ammonia, NH3, by
  bacteria during organism decay)
• Nitrification (production of nitrate from
  ammonia)
• Denitrification (conversion of nitrate to N2)

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