Changes in Ecosystems: Ecological Succession

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Changes in EcosystemsEcological Succession
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Learning Target

• I can record the role of ecological succession in
  a microhabitat.

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Ecological Succession

• Natural, gradual changes in the types of species
  that live in an area
• The gradual replacement of one plant community by
  another through natural processes over time

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Types of Ecological Succession

• There are 2 types of ecological succession
  primary and secondary.
• Primary Succession occurs on inorganic material
  such as rock. Primary succession occurs in an
  area that has never had plants growing there.
• Secondary Succession occurs in organic material
  such as soil or decaying biomass after events
  such as a clearing an area for a garden or
  construction, a drought, a freeze-anything that
  kills the plants in an area.

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Primary Succession

• Any soil has been eroded by wind or rain.
• There is no soil, just rock.
• Primary succession starts with the arrival of
  living things such as lichens that do not need
  soil to survive.
• These are called PIONEER SPECIES.

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Lichen
http//botit.botany.wisc.edu
PIONEER SPECIES
http//www.saguaro-juniper.com/
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Primary Succession

• Soil starts to form as lichens and the forces of
  weather and erosion help break down rocks into
  smaller pieces.
• When lichens die, they decompose, adding small
  amounts of organic matter to the rock to make
  soil.
• The simple plants move in and die, adding more
  organic material and soil.

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Primary Succession

• The soil layer thickens, and weeds, grasses,
  wildflowers, and other plants begin to take over.
  
• These plants die, and they add more nutrients to
  the soil.
• Shrubs and trees can survive now.

http//www.cwrl.utexas.edu
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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.
• This takes centuries to occur.

http//p2-raw.greenpeace.org
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Climax Community

• Succession ends with a climax community.
• This is a stable group of plants and animals that
  is the end result of the succession process.
• A climax community does not always mean big
  trees. It can be
• Grasses in prairies
• Cacti in deserts

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Primary Succession

• The establishment and development of an ecosystem
  in an area that was previously uninhabited.

Lichens and mosses
Grasses And small shrubs
Large shrubs and small trees
Large trees
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Secondary Succession

• This begins in a place that already has soil.
• The area was once the home of living organisms.
• Secondary succession occurs faster and has
  different pioneer species than primary
  succession.

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Secondary Succession

• Secondary succession occurs, for example
• When people stop taking care of a garden or a
  yard.
• On land is cleared for construction.
• On playgrounds.

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http//www.geo.arizona.edu
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http//www.ux1.eiu.edu
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Climax Community

• Succession ends with a climax community.
• This is a stable group of plants and animals that
  is the end result of the succession process.
• A climax community does not always mean big
  trees. It can be
• Grasses in prairies
• Cacti in deserts

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1993

• In 1993 the land here was cleared purposefully
  and then treated with Roundup to clear the site
  of all plants. The purpose was to observe the
  natural succession.

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1998
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2002