Abiotic Factors

Abiotic factors are any non-living factors that affect an organism or shape its environment. These include:

  • Temperature
  • Moisture levels
  • Light intensity
  • Soil pH and mineral content
  • Wind intensity and direction
  • Carbon dioxide levels
  • Oxygen levels of the water

Changes in abiotic factors can affect the number of organisms in a population and the rate of growth.

Effects of Abiotic Factors

Temperature

The rate of photosynthesis is affected by the temperature. This is because the enzymes involved are able to work faster. As a result, there is an increase in the rate of plant growth.

An increase in temperature also means that animals are able to spend less energy trying to keep warm.

Moisture levels

Animals and plants both need a sufficient amount of water to survive.

Light intensity

Plants need light for photosynthesis and the rate of photosynthesis affects the rate of plant growth.

  • Increased light intensity leads to an increased rate of photosynthesis occurs. As a result, there is an increased rate of plant growth.
  • Reduced light intensity leads to a reduced rate of photosynthesis occurs. As a result, there is a reduced rate of photosynthesis occurs.

In areas of slow plant growth, there will be fewer plants for organisms to eat.

Soil pH and mineral content

The pH of soil affects the rate of decay. Therefore, it affects how fast mineral ions return to soil (which are then taken up by other plants).

Different species of plants thrive in different nutrient concentration levels.  

  • If the species of plant thrives in low pH (acidic) soil – There is a slow rate of decay, so the return of mineral ions to the soil is slow. Therefore, the rate of plant development is relatively slow.
  • If the species of plant thrives in high pH (alkaline) soil – There is a fast rate of decay, so the return of mineral ions to the soil is quick. Therefore, the rate of plant development is relatively fast.

Wind intensity and direction

The wind affects the rate of transpiration that occurs in plants.

Transpiration affects the rate of photosynthesis as it is involved in the transportation of water and mineral ions from the roots to the leaves. 

  • Lower wind speed– Results in a lower rate of transpiration. So, less water and mineral ions are transported from the roots to the leaves.
  • Higher wind speed– Results in a higher rate of transpiration. So, more water and mineral ions are transported from the roots to the leaves.

Carbon dioxide levels

The carbon dioxide levels affect the rate of photosynthesis in plants.  

  • Lower level of CO2 – Slower rate of photosynthesis.
  • Higher level of CO2 – Faster rate of photosynthesis.

Oxygen levels for aquatic animals

Oxygen levels in water are usually relatively lower compared to the oxygen levels in the air. Aquatic animals have adapted to survive in water. However, some can only survive in water with high concentrations of oxygen.