What is "quadrat"

Quadrat \Quad"rat\, n. [F. quadrat, cadrat. See Quadrate.]

1. (Print.) A block of type metal lower than the letters, -- used in spacing and in blank lines. [Abbrev. quad.]

2. An old instrument used for taking altitudes; -- called also geometrical square, and line of shadows.

"a blank, low-cast type used by typographers to fill in larger spaces in printed lines," 1680s, from French quadrat "a quadrat," literally "a square," from Latin quadratrus, past participle of quadrare "to square, make square" (see quadrant). Earlier in English it meant a type of surveying instrument (c.1400).

Etymology 1 n. (context sciences English) An area of land, marked for studying its plants, animals, soil, natural processes, etc. While originally rectangular, modern quadrats can be rectangular, circular, irregular, etc. (e.g.: Krebs, C.J., 1999. Ecological Methodology. Addison-Welsey Educational Publishing, Inc., Menlo Park, California; Wheater, C.P., Bell, J.R., Cook, P.A., 2011. Practical Field Ecology: A Project Guide. John Wiley and Sons, Chichester, West Sussex, England.) Etymology 2

n. (context metal type obsolete English) A quad; a blank metal block used to fill space in lines of type.

A quadrat is a plot used in ecology and geography to isolate a standard unit of area for study of the distribution of an item over a large area. While originally rectangular, modern quadrats can be rectangular, circular, irregular, etc.,. The quadrat is suitable for sampling plants, slow-moving animals (such as millipedes and insects), and some aquatic organisms.

When an ecologist wants to know how many organisms there are in a particular habitat, it would not be feasible to count them all. Instead, they would be forced to count a smaller representative part of the population, called a sample. Sampling of plants or animals that do not move much (such as snails), can be done using a sampling square called a quadrat. A suitable size of a quadrat depends on the size of the organisms being sampled. For example, to count plants growing on a school field, one could use a quadrat with sides 0.5 or 1 metre in length. Choice of quadrat size depends to a large extent on the type of survey being conducted. For instance, it would be difficult to gain any meaningful results using a 0.5m2 quadrat in a study of a woodland canopy.

It is important that sampling in an area is carried out at random, to avoid bias. For example, if you were sampling from a school field, but for convenience only placed quadrats next to a path, this might not give a sample that was representative of the whole field. It would be an unrepresentative, or biased, sample. One way one can sample randomly is to place the quadrats at coordinates on a numbered grid.

Long-term studies may require that the same quadrats be revisited months or even years after initial sampling. Methods of relocating the precise area of study vary widely in accuracy, and include measurement from nearby permanent markers, use of total station theodolites, consumer-grade GPS, and differential GPS.

A quadrat block (or quadrate block) is a virtual rectangle or square in Egyptian hieroglyphic text.

The glyphs (hieroglyphs) can be variable in number within the virtual block, though they are often proportioned according to variable standardized rules of scribal methods.

The definition for the block in Illustrated Hieroglyphics Handbook by Schumann-Antelme and Rossini, is: "A 'quadrate' is a virtual square, which although not drawn, guides the hand of the scribe. Hieroglyphs must be aesthetically positioned within the quadrate and their size must be proportioned accordingly. They form groups that are pleasing to the eye and based on the laws of balance."

Quadrat may refer to:

• Quadrat, in ecology
• Quadrat (hieroglyph block), in Egyptian hieroglyphic text or equivalent glyph texts
• In music, alternate name for natural sign
• In printing, an archaic term for a quad (typography)