Biotic and abiotic factors

• Biotic factors


  The living parts of an environment
• Abiotic factors


  The non-living parts of an environment
• Biotic factors


  • Availability of food
  • Arrival of a new predator
  • Competition between species
  • New pathogens
• Availability of food


  All animals eat other living organisms, whether animals or plants
• Availability of food falls


  Number of organisms in that community will also fall
• Arrival of a new predator


  Can cause the population of a prey species to fall, and affect existing predators
• Competition between species


  If a species is out-competed, its population can fall to the point where it becomes extinct
• New pathogens


  If an infectious disease emerges and spreads, it can wipe out a population of a species
• Abiotic factors


  • Light intensity
  • Temperature
  • Water
  • pH and mineral content of soil
  • Wind intensity and direction
  • Carbon dioxide
  • Oxygen
• Light intensity


  Can affect the rate of photosynthesis in plants, and thus their growth
• Light intensity is too low


  Rate of photosynthesis falls, plants will grow more slowly
• Temperature


  Can affect the distribution of species
• Water


  Needed for survival of both plants and animals
• pH and mineral content of soil

  Important for plant growth, many plants cannot grow in soil that is too acidic or too alkaline
• Wind intensity and direction

  Can affect water loss in plants
• Carbon dioxide


  Needed for plants to photosynthesize
• Carbon dioxide levels fall

  Rate of photosynthesis can decrease
• Oxygen


  Needed for aerobic respiration, levels in water can fall and be harmful to aquatic organisms