Succession

• In succession, why do organisms change its abiotic conditions?


  So they can be replaced by its better adapted colonisers
• 1. Pioneer species: e.g. marram grass

  • 1st species to colonise an area
  • Seeds/spores are blown in by the wind & grow
  • Can withstand harsh conditions e.g. extreme temp, extreme dryness, low levels of nutrients
  • Specially adapted to cope
• 2. Decomposition: e.g. mosses & ferns

  • Pioneer species invade & break up rock to change abiotic conditions
  • Pioneer species die and decompose, hummus builds up and forms basic soil
  • Less hostile conditions means simple plants can grow
• 3. Grasses:

  • Mosses & ferns cast shade, this stops lichens from growing more
  • They have longer roots, so they break up the rock more

  • Organic matters increase, as bigger plants die
  • More water is saved so grasses, small flowering plants & shrubs can grow
• 4. Shrubs:

  • Larger plants grow with animals inside them, this changes the soil and light conditions even more
  • Shade from larger plants kills some of the smaller plants
• 5. Climax community: e.g. oak trees in UK

  • Area is colonised by a dominant plant species
  • Climax community is reached
  • Ecosystem is supporting the more larger, complex community of plants
  • Stable & will not change