How Ecosystems Change

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How Ecosystems Change

• Ecosystems are changing constantly

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Ecological Succession

• The gradual process of change and replacement of
  some or all of the species in a community.
• May take 100s to 1000s of years

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Ecological Succession Key Terms

• Pioneer species the 1st organism to colonize
  any newly available area and begin succession.
  The pioneer species will make the new area
  habitable over time. (Ex moss, weeds, bacteria,
  fungi)
• Climax community final, stable community that
  will remain the same through time if not
  disturbed. (Ex mature hardwood trees)

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Think Pair - Share

• Imagine that on your graduation day the school is
  bulldozed and a tall fence is placed around the
  bare school grounds.
• What would the school grounds look like after
• 1 month?
• 1 year?
• 5 years?
• 100 years?

http//www.youtube.com/watch?vAWwe0udewD8
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Primary Succession

• Succession that occurs on a surface where no
  ecosystem existed before

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Primary Succession

• Where?
• Places without soil
• Rocks
• New islands created by volcanic eruptions
• Areas exposed when glaciers retreat
• Other surfaces that had not previously supported
  life (parking lot)

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Primary Succession

• Pioneer species?
• Lichen or bacteria on a rock (eventually they
  will break down the rock to make soil).
• Mosses, lichens, and weeds in pavement cracks or
  an uncared for roof.

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PRIMARY SUCCESSION
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Think Pair - Share

• How does the pioneer species lichen help to make
  primary succession possible?

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Secondary Succession

• Succession that occurs on a surface where an
  ecosystem has previously existed.

Ex occurs on ecosystems that have been
disturbed or destroyed
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Secondary Succession

• Where?
• Ecosystems disturbed by humans and animals
• Ecosystems destroyed by storms, floods, fires,
  earthquakes, and volcanic eruptions.
• Ex Mt. St. Helens erupted in 1980, burning and
  flattening more than 44,460 acres of forest.
  Over time, plants that began to grow over the
  volcanic debris.

Immediately after Mt. St. Helen eruption
12 years after the eruption
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Secondary Succession

• Pioneer Species?
• Annual plants and flowers
• Grasses and weeds

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SECONDARY SUCCESSION
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Secondary Succession

• Old-Field Succession occurs when farmland is
  abandoned.
• Abandoned land changes into grassland, then
  shrubs, then young trees, then mature trees.

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Think Pair - Share

• Over a period of 1000 years, a lake becomes a
  maple forest. Is this process primary or
  secondary succession? Explain.