User Tools

Site Tools


This is an old revision of the document!

Key Species Method

Description and Uses

The Key Species Method is a combination of the Landscape Appearance Method and the Ocular Estimate Method. This method bases utilization levels on an ocular estimate of the amount of forage removed by weight on individual key species with observations recorded in one of seven utilization classes. It was developed to be used in areas where perennial grasses, forbs, and/or browse plants are the key species.

Advantages and Limitations

With the Key Species method there is no need to disturb the vegetation (i.e., harvesting). It is also very rapid since the estimated percentage of forage removed is recorded in one of seven broad classes rather than as an exact percentage. This is also a more accurate approach since different observers are more likely to estimate utilization in the same classes than to estimate the same utilization percentages.

However, observer bias can be a concern and it requires fairly rigorous training. It can also be reduced through proper training since the accuracy of estimating utilization percentages depends upon the ability of observers to identify plant species and the amount of use. In order to accomplish this precision, the observers must first compare their ocular estimates against actual weight values obtained by clipping and weighing. Exclosures, cages, or fenced areas are typically necessary for training purposes.

This can be reduced by limiting observations to individual plants or small areas (quadrats).


Technical and Application References

  • Schmutz, Ervin M. 1971. Estimation of range use with grazed-class photo guides. Coop. Extension Service and Agr. Exp. Sta., Univ. of Ariz., Tucson, AZ, Bull. A-73. 16 p.
  • Schmutz, E.M., G.A. Holt, and C.C. Michaels. 1963. Grazed class method of estimating forage utilization. Journal of Range Management. 16:54-60.

The following are sources of existing photo guides:

  • University of Arizona, Cooperative Extension Service and Agricultural

Experiment Station, Tucson Arizona 85721. Bulletin A-73.

  • University of Idaho, College of Forestry, Wildlife and Range Science,

Moscow, Idaho 83843. Station bulletin 54.

  • Montana State University. Forage Use - A Tool for Planning Range

Management. Extension Service. July 1988.

  • Kinney and Clary. 1994. A Photographic Utilization Guide for Key Riparian

Graminoids. USFS GTR-308.

Similar Approaches

Additional Information

field_methods/key_species_method.1230752833.txt.gz · Last modified: 2012/02/22 13:28 (external edit)