Abiotic factors that affect communities

The abundance of organisms in an ecosystem and their distribution is affected by abiotic factors. These are factors that are non-living.

They include:

  • light intensity:
  • temperature:
    • animals and plants have evolved to grow healthily at their optimum temperatures
  • moisture levels:
    • animals and plants are adapted to growing at the moisture levels available
    • most plants are killed by waterlogging, as they are unable to respire
    • bog plants will be adapted to growing in these wet conditions
  • soil pH and mineral content:
    • many plants are sensitive to pH
    • plants such as heathers, grow best in acidic soils
    • plants such as lavender, prefer alkaline soils
  • wind intensity and direction:
    • wind can increase the supply of carbon dioxide to plants
    • but wind increases the rate of transpiration and therefore water loss
    • wind can cause mechanical damage to plants
  • carbon dioxide levels for plants:
    • carbon dioxide is required for photosynthesis, so increased concentrations will increase growth and yields
    • some plant growers therefore raise the concentration of carbon dioxide in greenhouses for increased growth
    • carbon dioxide is an acidic gas, and because some plants are sensitive to pH, this is not suitable for raising yields of all plants
  • oxygen levels for aquatic animals:
    • oxygen dissolves in water and is required for the animals' respiration
    • moving lakes and rivers have high levels of oxygen
    • stagnant and polluted waters often have low levels of oxygen
    • animals such as sludgeworms can survive low oxygen levels
    • some animals are bioindicator species because their presence or absence informs us about the condition of the habitat