Species Groups
Considering each individual species at the site, even to determine species composition, is often a time consuming and inefficient approach to collect data, especially for attributes determined by counting, such as frequency or density. Accuracy can be compromised from species misidentification (particularly for seedlings, grazed, or rare plants), and such detailed information may be unnecessary to satisfy many inventory or monitoring objectives. Many statistical inference procedures are also ineffective when a species is rarely recorded.
Instead, many studies focus on close inspection of a few key species that are nominated to meet the goals of the sampling program. Remaining species of interest can be allocated to broad groups that are based on either morphological characteristics, eg., Aristida sp., or functional features, eg., perennial forage grasses or succulents. Clear ground rules are needed to ensure that species are consistently designated to their correct group.
References and Further Reading
(Note: pdf files require Adobe Acrobat (free) to view)
Bartos, D.L., Brown, J.L., and G.D. Booth. 1994. Twelve years of biomass response in aspen communities following fire. Journal of Range Management 47:79-83. (pdf)
Mueller-Dombois, D., and H. Ellenburg. 1974. Aims and methods of vegetation ecology. John Wiley Sons, New York. pp. 140-145.
Haferkamp, M.R., Volesky, J.D., Borman, M.M., and Heitschmidt, R.K., and P.O. Currie. 1993. Effects of mechanical treatments and climatic factors on the productivity of Northern Great Plains rangelands. Journal of Range Management 46:346-350. (pdf)
Hartnett, D.C., Hickman, K.R., and L.E. Walter. 1996. Effects of bison grazing, fire, and topography on floristic diversity in tallgrass prairie. Journal of Range Management 49:413-420.
Jameson, D.A. 1991. Effects of a single season and rotation harvesting on cool- and warm-season grasses of a mountain grassland. Journal of Range Management 44:327-329. (pdf)