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Flow of Matter in Ecosystems

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Cycling of Matter in Ecosystems

License: CC BY-NC 3.0


  [Figure1]

What killed millions of sailors in the 15th through 18th centuries?

Millions of sailors in the 15th through 18th centuries died mysteriously. They developed a disease called scurvy. The scurvy, it turns out, was due to the lack of vitamin C in their diets. It wasn't until 1932 that the link between scurvy and vitamin C was made. Without the right nutrients in the right amounts, you can't live. Other animals and plants also need the right nutrients to live.

Flow of Matter in Ecosystems

The flow of matter in an ecosystem is not like energy flow . Matter enters an ecosystem at any level and leaves at any level. Matter cycles freely between trophic levels and between the ecosystem and the physical environment ( Figure below ).

Living things need nonliving matter as well as energy. What do you think matter is used for? One thing is to build bodies. They also need it to carry out the processes of life. Any nonliving matter that living things need is called a nutrient . Carbon and nitrogen are examples of nutrients. Unlike energy, matter is recycled in ecosystems .

License: CC BY-NC 3.0


  [Figure2]

This diagram shows the cycle of energy in an ecosystem. Compare this to the flow of energy in an ecosystem as shown in a food web. Why does the sun keeps adding energy to an ecosystem? That’s because energy is lost at each step of the food web. Matter doesn’t have to be added. Can you explain why?

Decomposers release nutrients when they break down dead organisms.

  • The nutrients are taken up by plants through their roots.
  • The nutrients pass to primary consumers when they eat the plants.
  • The nutrients pass to higher level consumers when they eat lower level consumers.
  • When living things die, the cycle repeats.

Nutrients

Nutrients are ions that are crucial to the growth of living organisms. Nutrients such as nitrogen and phosphorous are important for plant cell growth. Animals use silica and calcium to build shells and skeletons. Cells need nitrates and phosphates to create proteins and other biochemicals. From nutrients, organisms make tissues and complex molecules such as carbohydrates, lipids, proteins, and nucleic acids.

What are the sources of nutrients in an ecosystem? Rocks and minerals break down to release nutrients. Some enter the soil and are taken up by plants. Nutrients can be brought in from other regions, carried by wind or water. When one organism eats another organism, it receives all of its nutrients. Nutrients can also cycle out of an ecosystem. Decaying leaves may be transported out of an ecosystem by a stream. Wind or water carries nutrients out of an ecosystem.

Nutrients cycle through ocean food webs.

Decomposers play a key role in making nutrients available to organisms. Decomposers break down dead organisms into nutrients and carbon dioxide, which they respire into the air. If dead tissue would remain as it is, eventually nutrients would run out. Without decomposers, life on Earth would have died out long ago.

Vocabulary

  • nutrients : Nonliving matter that organisms need to live and grow.

Summary

  • Ions that are crucial to the growth of organisms are known as nutrients.
  • Decomposers break down dead organisms into nutrients and gases so that they can be used by other organisms.
  • Nutrients can enter or exit an ecosystem at any point and can cycle around the planet.

Practice

Use this resource to answer the questions that follow.

http://www.powerhouseanimation.com/gallery/projectArchive/publishers-resource-group/prg_flowOfEnergy.swf

1. What is carbon dioxide in the air a reservoir for?

2. What do producers do with carbon?

3. What do herbivores do with carbon?

4. Why is the biomass of carnivores less than herbivores?

5. What do decomposers do?

6. How is carbon returned to the atmosphere?

7. How are the flow of energy and the flow of matter diagrams different?  Why are they different?

Review

1. How does the flow of matter differ from the flow of energy through an ecosystem?

2. How do nutrients enter and exit and ecosystem?

3. What would happen to life on Earth if there were no decomposers?

Image Attributions

  1. [1]^ License: CC BY-NC 3.0
  2. [2]^ License: CC BY-NC 3.0

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