Written by Jason Karl

Quantitative

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The Cole Browse Method is one of a set of methods for quantifying utilization that is specific for shrubby vegetation. This method collects data on browse species, age, availability and hedging, estimated utilization, and growth and use indices for the browse component of a plant community. From these data, estimates of annual utilization and utilization trends can be made.

Data for the Cole Browse Method are collected along transects. Separate transects must be run for the different browse species. Each browse plant along the transect is rated according to the following classes where available refers to accessibility to the animals and hedging is the appearance of being browsed or clipped:

In addition, Age class of each plant is estimated as is the percent of the leader (that year's annual growth) that has been browsed. Measurements of unbrowsed leaders are taken to estimate average annual growth.

The following information is calculated from the plants sampled:

• Percent composition by form class,
• Percent composition by age class,
• Average leader use,
• Use index (i.e., an indication of the volume of browse removed)

Confidence intervals can be constructed around median or average leader use, and statistical tests (e.g., Chi Square analysis) can be used to determine if age or form class proportions are different than expected.

The Cole Browse Method is usually faster than other browse utilization methods that require measurements. But, the gain in speed of implementation is typically accompanied by a decrease in precision. Variability between observers can be considerable, and factors like plant growth characteristics, and weather and site conditions can influence results.

The accuracy of utilization estimates using this method is heavily dependent on how thoroughly the observers have been trained. Observers need to be able to reliably: 1) identify browse species and age class of browse plants; and 2) recognize annual leader growth, percent utilization, and degree of hedging.

• Utilization Studies and Residual Measurement: Interagency Technical Reference (BLM 1999). This manual includes field forms for the Cole Browse Method (see below).

_{Image from Utilization Studies and Residual\\Measurements Interagency Technical Reference}
Example of a filled-out Cole Browse form from the Utilization Studies and Residual Measurements Manual.

• Bureau of Land Management. 1984. Rangeland Monitoring - Utilization Studies. TR4400-3.
• Cole, C. F. 1963. Range survey guide, revised edition. Grand Teton National Park, Moose, Wy.
• Eddington, D.B. 2006. Effects of cheatgrass control on Wyoming big sagebrush in southeastern Utah. Master's Thesis, Brigham Young University. (http://contentdm.lib.byu.edu/ETD/image/etd1606.pdf).
• Howery, L. D. Ruyle, G. B., and J Hiller. 2007. Using herding and strategic mineral supplement placement to improve cattle distribution in west-central Arizona. USDA Research, Education, and Economics Information System. (http://www.reeis.usda.gov/web/crisprojectpages/204692.html).
• Launchbaugh, K. [accessed 12/2009]. Techniques to determine utilization: Range 357 class notes. College of Natural Resources, University of Idaho. (http://www.cnr.uidaho.edu/range357/notes/Utilization.pdf).
• Summers, D.D. Vegetation response of a Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) community to 6 mechanical treatments in Rich County, Utah. Master's Thesis, Brigham Young University. (http://wildlife.utah.gov/gbrc/dllprospectus.pdf).

Other browse removal methods include:

• Browse Removal - Twig Length Measurement Method
• Browse Removal - Extensive Browse Removal

Related utilization and residue measurement methods include:

• Residue Measurement - Stubble Height
• Herbaceous Removal - Paired Plot Method
• Comparative Yield Method
• Utilization - Grazed Class Method (photo guides)
• Herbaceous Removal-Height-Weight Method
• Herbaceous Removal-Actual Weight Method
• Herbaceous Removal - Ocular Method

• The class notes from Range 357 at University of Idaho have a good, succinct comparison of different techniques for measuring utilization. http://www.cnr.uidaho.edu/range357/notes/Utilization.pdf.

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