The distribution of organisms in a habitat may be affected by physical factors, such as temperature and light.
When investigating the number of organisms it is difficult to cover a large area because of time constraints.
To overcome this, a number of small sections within a larger area are investigated or sampled.
It is important that sampling methods are:
The method of data collection depends on the organism being sampled. A quadrat (a square frame) can be used if the organism moves slowly or not at all.
Organisms found inside the quadrat can be counted or their percentage cover can be estimated.
Percentage cover is the percentage of the quadrat covered by each species, which is usually rounded up to the nearest 10%. However, if percentage cover is between 1-5%, it is rounded down to 1%.
When data for all the quadrats has been collected an average for each species can be calculated.
This gives an idea of the percentage cover of that organism across the entire area being investigated.