Succession

• Succession


  The process where ecosystems change from being very simple to being relatively complex over time
• Ecosystems are dynamic, meaning they are constantly changing
• Primary succession


  Newly formed or newly exposed land (with no species present) is gradually colonised inhabited by an increasing number of species
• How new land can be created for primary succession

  • Magma from erupting volcanoes cools and forms new rock surfaces or rocky islands
  • Sea-level dropping or drying up of a lake, leaving bare rock
• Other areas that undergo primary succession

  • Sand dunes in coastal areas
• Stages of primary succession

  1. Pioneer species (moss and lichens) colonise bare rock

  2. Dead organic matter forms basic soil

  3. Small plants and grasses grow in the soil

  4. Larger plants and shrubs grow

  5. Large trees become the dominant species in the climax community
• Pioneer species


  • First species to colonise new land
• Climax community


  • Final community formed, containing all the different plant and animal species that have now colonised the new land
• Pioneer species change the abiotic conditions

  Making the environment less hostile for new colonising species
• New colonising species change the environment

  Making it less suitable for the previous species
• How lichens change the environment during primary succession

  • Lichens break apart the rock surface, forming basic soil
  • As mosses grow, the soil builds up and becomes suitable for small plants and grasses
  • As trees grow, they out-compete smaller plant species due to lack of light
• Deflected succession


  Human activities that prevent or interrupt the process of succession
• Activities that prevent succession

  • Regular mowing of a grassy field
  • Grazing by livestock such as sheep, horses or cattle
• Preventing an area from reaching its climax community can be good for conservation, as it maintains a diverse range of plant and animal species
• Ways to deliberately prevent succession for conservation

  1. Introducing grazing animals temporarily

  2. Managed burning to remove shrubs and trees