Methods to Determine Cover

Much effort and imagination have been devoted to developing methods to estimate cover, reflecting its long tradition as an important attribute for rangeland inventory or monitoring purposes. Unlike other attributes such as biomass, density, and frequency, techniques involving sampling in quadrats to determine cover play a minor role. Instead, approaches incorporating points, lines and plotless approaches are more regularly adopted. Many of these techniques are able to assess a larger proportion of the vegetation and integrate the small scale spatial patterns present within each sample unit, which leads to more efficient sampling procedures.

One of the problems in assessing the accuracy of various methods is that actual cover can never really be determined for a site, unlike density where all plants can be carefully counted or biomass where all plant material can be harvested and weighed. In these situations, the adequacy of a method can only be evaluated by its precision, which is determined by assessing the repeatability of results for a site among observers and over time.

The following techniques are the standard methods of determining cover:

References and Further Reading

Bonham, C.D. 1989. Measurements for terrestrial vegetation. John Wiley Sons, New York, NY. pp 11-12, 56-61.

Cook, C.W., and J. Stubbendieck. (eds). 1986. Range research: Basic problems and techniques. Society for Range Management, Denver, CO. pp 56-61.

Greig-Smith, P. 1983. Quantitative plant ecology. Academic Press, New York, NY. pp 5-9.

Mueller-Dombois, D., and H. Ellenburg. 1974. Aims and methods of vegetation ecology. John Wiley Sons, New York, NY. pp 80-92.