Specific Guidelines on Sample Unit Shape for Frequency

The effect of the shape of sample units on precision and boundary decisions is highly pertinent to frequency sampling, but quadrats of almost any shape have been used. Much of the monitoring work throughout western USA rangelands have used square quadrats, usually with dimensions of 40 cm x 40 cm. Extended rectangular quadrats would probably not be practical, because the time taken to carefully search for various species would negate the speed advantages generally offered by frequency sampling.

Also refer to Sample Unit Shape in the Sampling Concepts section.

References and Further Reading

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. p. 12.

, M.1985. Frequency approaches to monitor rangeland vegetation. In: W.C. Krueger. (chairman). Proceeding 38th Annual Meeting, Society for Range Management, Salt Lake City, UT, February 1985. p. 85.

Hyder, D.N., Conrad, C.E., Tueller, P.T., Calvin, L.D., Poulton, C.E., and F.A. Sneva. 1963. Frequency sampling of sagebrush-bunchgrass vegetation. Ecology 44:740-746.

Hyder, D.N., Bement, R.E., Remmenga, E.E. and C. Terwilliger. 1966. Frequency sampling of blue grama range. Journal of Range Management 18:94-98.