Measuring Abundance

Radom sampling and transects with

quadrats gives us a measure of

abundance.

Abundance is the number of

individuals of a species within a given

space.

It can be measured in several different

ways.

Measuring Abundance:

Frequency Is the likelihood of a particular species

occurring in a quadrat.

This method is useful when a species

is hard to count e.g. grass.

Advantage: gives a quick idea of

species present and their general

distribution.

Disadvantage: does not provide

information on density and a detailed

distribution.

Measuring Abundance:

Percentage Cover

Is an estimate of the area within a quadrat that a particular species covers.

Useful when a species is abundant or difficult to count.

Advantages: data can be collect rapidly. Individuals need not be counted.

Disadvantage: Less useful where organisms occur in overlapping layers e.g. plants.

When measuring abundance you

must remember to:

Use a large sample size.

Calculate a mean

Why?