Changes in Ecosystems: Ecological Succession

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Changes in EcosystemsEcological Succession
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Definition

• Primary or Secondary
• Series of predictable, natural and gradual
  changes that occur in a community over time

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Primary Succession

• Begins in a place without any soil
• Sides of volcanoes
• Landslides
• Glacier melting exposing bare rock
• Starts with the arrival of living things such as
  lichens that do not need soil to survive
• Called PIONEER SPECIES

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LICHENS Symbiotic fungus/algae -break down
rock to make soil -Nitrogen fixation -add
organic material to rock/soil when they die and
decompose
http//botit.botany.wisc.edu
http//www.saguaro-juniper.com/
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http//www.life.uiuc.edu
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Primary Succession

• Simple plants like mosses and ferns can grow in
  the new soil

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Primary Succession

• Some die ? adds more organic material
• The soil layer thickens, and grasses,
  wildflowers, and other plants begin to grow

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Primary Succession

• These plants die ?adding more nutrients to the
  soil
• Shrubs and tress can grow now

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Primary Succession

• Insects, small birds, and mammals have begun to
  move in
• What was once bare rock now supports a variety of
  life

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Primary Succession
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Secondary Succession

• Begins in a place that already has soil and was
  once the home of living organisms
• Example after forest fires, hurricane or other
  disturbance
• Occurs faster and can sometimes have different
  pioneer species than primary succession

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Secondary Succession
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Climax Community

• A stable group of plants and animals that is the
  end result of the succession process