Ecological Succession

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What is Succession?

  • The changes over time in species that occupy a particular area
  • Happens on barren land
  • Primary succession- happens when there is no previous colonisation
  • At each stage, species change the environment and allow the next species to develop
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The process of Succession

  • Barren land- no shelter or water
  • Primary colonisers (lichen) colonise areas and fix nitrogen from air. Die and decay, which provides humus for nutrients for secondary colonisers
  • Secondry colonisers (mosses) grow low to ground and absorb water. Secrete acid onto surface of rock, and release minerals when it is broken down
  • Tertiary colonisers occur when wind dispersal of seeds allows growth of roots. They cannot be blown away, and results in more competition for light, water and nutrients
  • Scrubland can grow now as death of plants releases nutrients and nitrates into the soil, allowing uptake of these by roots of shrubs, resulting in growth
  • Climax community occurs when woodland is able to grow due to nutrients being recycled from death and decay of other plants
  • Releases ammonium ions into the soil- converted to nitrates by nitrification
  • Taken up by tree roots
  • Stabilises community as leaf covering prevents as mcuh light reaching the ground, lessening photosynthesis of smaller plants
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