Systematic sampling is a non-random sampling method where different areas within a habitat are sampled at regular intervals to avoid bias.

An advantage of systematic sampling is that it allows for the study of how species distributions change across different areas within a habitat.

It is often carried out using a belt transect.

Belt transect sampling is a method of studying the distribution of organisms in a specific area.

It involves marking a line (transect) and taking samples along this line either continuously or at regular intervals with a quadrat.

It can be useful to measure gradual changes in the distributions of plants and animals, for example, from the seashore to further inland.

Abiotic factors, like light intensity, pH and water availability, directly impact the living organisms in a habitat.

1. Record whether the species is present in each quadrat
2. Divide this by the total number of squares in the quadrat
3. Multiply this value by 100

For example, if you found dandelion plants in 6 quadrat squares in a quadrat with 100 squares, then the species frequency for dandelions in this quadrat is:

1006​×100=6% 

A point quadrat consists of a frame with a horizontal bar, and pins are pushed through at set intervals to touch the ground. Each species the pin touches is recorded.

A frame quadrat is a square frame divided into a grid. The type and number of species within each section of the quadrat is recorded.

Percentage cover is an estimate by eye of the area within a quadrat that a particular species covers.

The mark-release-recapture technique is a method used to estimate the abundance of motile animals by catching, marking, and releasing a known number of animals, then later collecting a another sample and recording the number of marked individuals.

1. Capture as many individuals as possible in a sample area
2. Mark or tag each individual
3. Release the marked animals back into the sample area
4. Allow time for them to redistribute themselves throughout the habitat
5. Recapture as many individuals as possible in the original sample area
6. Record the number of marked and unmarked individuals present in the sample
7. Input the values recorded into a formula to estimate the population size