Quadrat

A frame, typically square, which is divided into equal squares to help in the accurate assessment of an area. A quadrat can be used to assess the ground coverage, along with identified species of plants, disease, or pest within the quadrat. Typical sizes for grass surfaces are: 0.5mx0.5m; 0.75mx0.75m; and 1.0mx1.0m. each will typically be divided into 100 squares.


Photograph of a simple wire-framed quadrat


Besides short vegetation a quadrat can also be used for larger types of vegetation and in these cases would be marked out using string or tape, for example:
• Tall vegetation: 1m x 1m to 4m x 4m.
• Shrubs/scrub: 10m x 10m.
• Woodland: 20m x 20m; to 50m x 50m.

Quadrats can be used to measure:
• The frequency (presence or absence) of a species.
• Percentage cover.
• Density (number per unit area, e.g. 4 per m²).

Advantages
• Accurate.
• Range of vegetation types.
• Simple to use.
• Relatively cheap.

Disadvantages
• Time consuming.
• Planning sample design.
• May miss the frequency of populations.