Quadrats Arranged as a Group of Subsamples to Determine Frequency
Quadrats arranged as a group of subsamples under the principles of systematic sampling is the most common sampling design used for frequency. The quadrat-groups (usually positioned along a transect to traverse an area) are taken to represent the sample unit. Frequency for each transect is determined from the quadrat subsample by calculating the proportion within that group where the species was found. Frequency values for each transect contribute to the sample data set that usually tends toward a normal distribution. Therefore, conventional inferential statistical procedures can be followed for the statistical analysis of frequency data collected in this manner.
References and Further Reading
Bonham, C.D. 1989. Measurements for terrestrial vegetation. John Wiley Son, New York, NY. pp. 95-96.
Despain, D.W., Ogden, P.R., and E.L. Smith. 1991. Plant frequency sampling for monitoring rangelands. In: G.B. Ruyle. (ed). Some methods for monitoring rangelands and other natural area vegetation. University of Arizona, College of Agriculture, Extension Report 9043. pp. 15-16.
Whysong, G.L., and W.H. Miller. An evaluation of random and systematic plot placement for estimating frequency. Journal of Range Management 40:475-479.