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Independent Variable

Also referred to as manipulated or experimental variable.

There may well be other ways of considering variables but as a guide an Independent variable can be thought of in one of two broad categories:

Abiotic
Biotic

Abiotic

These are the non-living factors in an environment 
Factors include:

• Temperature
• Precipitation
• Humidity
• Oxygen levels
• Sunlight intensity
• Salinity
• Light levels
• Turbidity
• Turbulence
• Chemical levels etc.

The abiotic factors will vary according to:

• the type of environment in which they are found, 
• the latitude of the ecosystem, and 
• seasonal variations which may occur.

These factors consequently characterise an ecosystem and hence limit the range of organisms which will be represented in it. The range of any one or more abiotic factors influence the distribution and abundance of organisms. 
Abiotic factors also determine the rate at which populations interact.

Biotic

These are the factors which result from the living or biological components of the environment that can affect an organism and may include for example;

• Amount of food source
• Density of populations - inter and intra species
• Interrelationships between organisms – inter and intra species

Click to Dependent Variable

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