succession

• primary succession

  • occurs when an area previouslt devoid of life is first colonised by communities of organisms
  • eg after volcanic eruption
• stages of succession

  1. seeds/spores carried by wind and land on exposed rock- pioneer species eg moss- germinate easily and withstand harsh conditions
  2. pioneer species die and decompose- organic matter forms soil
  3. seeds of small plants/grass land on this soil and begin to grow- adapted to survive in shallow/poor nutrient soil(roots hold soil in place, these plants die and decay forming deeper, nutrient rich soil)
• 4. larger plants, shrubs and small trees can begin to grow- overtime soil is sufficiently deep and nutrient rich for larger trees

  5. final community formed- climax community- most productive, self sustaining and stable community
• secondary sucession

  • takes place of previously occupied land but soil already present so begins at later stage
  • humans prevemt succession by- grazing of livestock prevents new plants establishing or mowing prevents woodt plants establishing