Transects

Transects are used to study the distribution of organisms across an area, in a straight line. A tape measure is laid out across the area that is to be studied. You can then either count all the organisms that touch the line or place quadrats at regular intervals along the line and count/calculate the abundance of organisms at each point.

Example:

You can investigate how the abundance of marram grass changes as you move up a beach by placing quadrats at regular intervals along a transect. Notice how the abundance of marram grass increases with distance from the sea. 

To make the results more reliable you could carry out many transects along the beach and calculate a mean abundance at each interval.