4.3 Quadrat Sampling

4.3 Describe the use of the quadrats as a technique for sampling the distribution of organisms in their habitats.

Take the same Sand dune habitat as before, and say we wanted to sample the daisy population.

This sample must be unbiased and representative, meaning that it is of a random area of the region and as large as possible to be more reliable.

The easiest way to do this is to place a grid over the region and number it (like a graph) like below...

• Then use a random number generator to calculate two integers (one for each co-ordinate) and select the appropriate quadrat.
• Count the number of daisies in the randomly generated quadrat.
• And repeat several times in other quadrats until roughly 10% of the total area is covered.
• Finally find the average results by adding up the total number of daisies counted and dividing by the number of quadrats to give a result of 'so-many daisies per quadrat size'