Frame Quadrat

Frame Quadrat

A square (sensu stricto) or rectangle (sensu lato), marked by stakes and/or frames to measure abundance within a given area. Estimation of abundance, such as cover, density and height within quadrats. By monitoring quadrats, we can detect temporal changes in vegetaiton (see, LTER).

When we set up quadrats, we have to mention three characteristics.

* alignment of quadrats (random, regular, or arbitrary)
* quadrat size (and shape)
* number of quadrats

A quadrat is typically a square frame constructed of plastic (i.e. pvc), metal rod, or wood that is placed directly on top of the vegetation. Quadrats are also commonly called "plots."

Quadrats do not have to be square but their area must be known. Other quadrats shapes commonly include circles and rectangles.

Square quadrats can be any size. Common sizes include: 25 by 25 cm, 50 by 50 cm, 1 by 1 m and similar sizes in feet. Quadrats are used in many different scientific disciplines from vegetation assessment to archeological finds. Quadrats are required for estimating several vegetation attributes including:

• Density - for counting the number of objects within the unit area of the quadrat.
  
• Biomass - achieved by "clipping" all the material of a given type (grass, shrub, forb, etc.) or species within a quadrat.Cover - often accomplished by estimating the area of a quadrat that is covered by a plant's canopy.
• Frequency - the proportion of quadrats in which a species occurs is called frequency, thus quadrats are required to estimate plant frequency.
  

Frame Quadrat