SUCCESSION

• WHAT IS PRIMARY SUCCESSION?

  succession that occurs on land not previously colonised, e.g. bare rock
• EXAMPLES OF PIONEER SPECIES?

  lichen, algae, marram grass
• EXAMPLES OF CLIMAX COMMUNITIES?

  forests (lots of trees)
• WHAT IS SECONDARY SUCCESSION?

  succession that occurs on land which has previously been colonised, e.g. after a forest fire
• HOW IS SUCCESSION DEFLECTED/ PREVENTED?

  human activities
• WHAT CAN CAUSE DEFLECTED/ PREVENTED SUCCESSION?

  • mowing grass
  • herbicides
  • deforestation
  • grazing animals (eat grass seeds)
• PROCESS OF SUCCESSION?

  1. Bare ground/ rock (no soil)
  2. Pioneer species is first to colonise
  3. Competition for resources like light or CO2
  4. Pioneer species die and are decomposed by saprobionts
  5. Basic soil is formed
  6. Abiotic conditions are more favourable
  7. Environment is less hostile (more water retention/ mineral ions)
  8. New species are able to grow
  9. Increased species diversity
  10. Increased biomass of plants (bigger)
  11. Climax community forms
• WHAT CHARACTERISTICS MIGHT PIONEER SPECIES HAVE?

  nitrogen-fixers, high tolerance to salinity/ low pH
• WHAT ARE SAPROBIONTS?

  bacteria and fungi
• CHARACTERISTICS OF A CLIMAX COMMUNITY?

  • large plants with large biomass
  • stable populations
  • high biodiversity