Importance of Soil

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Importance of Soil Succession

• Science 10

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Urban Sprawl

• Over the past few decades, the general trend of
  has seen the population move from rural areas to
  urban areas
• This has lead to urban sprawl as housing, malls,
  schools, hospitals, etc had to be built to
  support the new population
• Much of this urban sprawl has taken over land
  previously used for agriculture

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Productivity

• With the trend of urban sprawl and the loss of
  farmland, the productivity is decreasing
• Also, cities tend to be build close to or on the
  richest land (water, nutrients, etc) as that is
  where people naturally settled
• Also, the high quality soil that is available in
  these areas is no longer used to grow food

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Soil

• Soil is a layer that covers land and supports the
  growth of plants
• Seeds are able to germinate in soil, plants
  anchor their roots in soil and obtain water and
  nutrients for it
• The depth and characteristics of soil affect the
  growth and productivity of plants

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Soil Composition

• Soil is composed of
• Weathered rock
• Decomposing plant/animal matter
• In addition, it is able to hold air and water
• Soil is layered
• Top Soil (A Horizon)
• Sub Soil (B Horizon)
• Parent Material (C Horizon)

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Soil Ecosystem

• Healthy soil will support many different
  organisms at all trophic levels
• Many different organisms will make their home in
  and on the soil creating an unseen ecosystem

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Disturbing Soil

• Soil can be affected by many different
  mechanisms
• Erosion
• Urbanization
• Climate
• Vegetation
• Agriculture
• Deforestation

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Primary Succession

• The process by which bare rock is converted into
  a forest is called succession

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Lichens

• Lichens are called pioneer organism because they
  are the first to live on bare rock
• They release acids that breakdown the rock so
  that they can pull nutrients from the rock

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Mosses

• As lichens die, they begin to form soil
• With small amounts of soil, a more complex
  organism (moss) is able to grow
• The moss will also provide a habitat for insects
  and other small animals

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Ferns

• The organisms help to breakdown the rock faster
  (increases soil formation)
• With more soil, larger plants (like ferns) take
  root in cracks in the rock and further break down
  the rock

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Grasses

• With the ever expanding soil, grasses (along with
  wildflowers and other small plants) are
  established
• This attracts even more herbivores (bees,
  butterflies) and carnivores that feed on them

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Forest (Climax Community)

• Following the grasses, trees will begin to grow
• This will lead to larger animals moving into the
  area due to sufficient resources and shelter

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Primary Succession
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Secondary Succession

• Secondary succession occurs when a climax
  community is disturbed (development, forest fire,
  etc) and succession is allowed to resume from the
  point of interruption

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Secondary Succession

• Below is an example of what would happen if an
  agricultural field was left fallow for several
  years