Succession

• succession 


  how an ecosystem changes overtime
• Primary succession


  on land that is newly formed or exposed
• Secondary Succession


  on land that is cleared of the plants, where soil still remains
• Stages of primary succession

  1. pioneer species
  2. early colonists
  3. opportunists
  4. climax community
• Pioneer species (lichen, moss)


  • often extremophiles
  • autotrophic
  • can survive harsh, hostile conditions
  • specialised with shallow roots to break up rocks, small and flat to survive harsh abiotic factors
  • come from seeds and spores carried by the wind
  • when they die, they provide nutrients to the soil
• Early colonists (smaller plants, grass)


  • extensive roots for stability, water and structure
  • grow rapidly
  • live in somewhat low mineral levels
  • soil gradually gets deeper, roots can go deeper and hold soil together
  • can support insects
• Opportunists (shrubs, saplings)


  • taller and denser plant life is supported by improved and deeper soil allowing for deeper roots
  • pollination can occur
  • can support mice and birds
• Climax community (oak, ash trees)


  • stable equilibrium, self-perpetuating
  • can support birds of prey and foxes
• Seral stages


  different communities in succession before the climax community
• Preventing succession


  Human activities can artificially prevent succession, resulting in a plagioclimax
• Deflected succession


  plagioclimax is different to the natural stages of the ecosystem, path of succession has been deflected from it's natural course
• Deflected succession


  • mowing grass, grazing and burning prevents further development, even if the ecosystem could support it
  • growing parts of woody plants are cut off so larger plants can't establish themselves
  • only the grass survives - grassy field is the climax community and is a plagioclimax
  • grassy field is not a natural stage, succession has been deflected