Rooted or Canopy Dimensions

The ground rule for determining the frequency of herbaceous species is conventionally based on the presence of the base of the plant in the sample unit (i.e., rooted frequency). In some cases, particularly for shrubs, inclusion of a plant is based on canopy overhanging the quadrat (i.e., canopy frequency). This approach allows the same sized sample unit to be used to measure small and abundant herbaceous species as well as larger shrubby plants.

However, density measurements of herbaceous or woody species should be restricted to those plants found to be rooted in the sample unit, because also counting overhanging plants would bias the result by causing an effective increase in sample unit size.

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 13.

Laycock, W.A. 1985. Density as a method for measuring rangeland vegetation. In W.C. Krueger. (Chairman). Symposium on use of frequency and density for rangeland monitoring. Proceeding 38th Annual Meeting, Society for Range Management, Salt Lake City, UT, February 1985. p 93.

Greig-Smith, P. 1983. Quantitative plant ecology. Blackwell Scientific Publications, Oxford. 3rd ed. p 10, 17.