Study targets Robel pole monitoring

Range monitoring on public lands grazing allotments is an important piece of grazing management for western ranchers, and University of Wyoming (UW) Extension Specialist Barton Stam, along with UW Extension Rangeland Specialist Derek Scasta and a group of graduate students, have teamed up to prove the efficacy and legitimacy of the Robel pole range monitoring method. 

“We just started a project in the Big Horn Mountains that will help us assess the accuracy and effectiveness of the Robel pole method,” Stam says, noting their study will also look specifically at how the monitoring method is applied on grazing allotments in the Big Horn Mountains. “There has been controversy for some years between permittees and the Forest Service as to if the Robel pole monitoring method works or not.” 

Robel pole method

The Robel pole monitoring method was developed by Kansas wildlife biologist Robert Robel to measure the hiding cover provided by vegetation for prairie grouse nesting cover. 

“A significant correlation of the weight of the vegetation with how much the pole height is obscured was determined by clipping plots around the base of the pole,” explains Michael Smith, former UW professor and Extension Specialist, in a UW Extension bulletin. 

“This method has since been used on U.S. Forest Service national grasslands in South Dakota to ensure enough residual forage is left to provide nesting cover for the sharptail grouse and greater prairie chicken,” continues Smith.

Stam adds, “This method is used across the U.S., and there are various methods of how it is used in each area.”

Using the method

The Robel pole technique is a method of “measuring residual forage after grazing,” according to Smith’s June 2008 publication. 

Stam describes the technique as a visual obstruction method of assessing vegetation left on the ground.

“The person who is monitoring uses an apparatus – the Robel pole – that is put into the ground,” he says. “An observer four meters away looks at how much of the pole is obscured by grass. Their eye needs to be on the ground.”

As a result, taller, thicker grass will obscure more of the pole.

The Robel pole is divided into half-inch bands that alternate in color, which are numbered, so the number of bands obscured can be easily determined. 

Application

“The Forest Service has a five-band standard in the Big Horns,” Stam explains. “During the grazing season, if grass doesn’t obscure five bands on the Robel pole, the permittee has to move pastures or go home, depending on where they are.”

Additionally, Stam says if the standard is failed, permittees may be subject to fines or restrictions on their permits – which may include shortening the timeframe a permittee is allowed on the allotment.

“Robel pole monitoring is supposed to be conducted within seven days after cattle leave an allotment, and if an allotment fails the five-band standard, the permittee could be held in non-compliance,” he says. 

Caveats

“The Robel pole only measure the biomass of vegetation present at the time of measurement,” Smith adds. “It is consistent, reliable, cost effective and covers a large area in a short amount of time if the procedure is followed.”

However, Smith continues, “The Robel pole is generally not applicable to areas with low productivity, such as many Bureau of Land Management lands or where shrubs are abundant. Calibrating this measurement to local vegetation, proper selection of key areas and developing site-specific guidelines when used as a grazing use assessment tool are essential for effective management applications.” 

Smith notes, as with any sampling strategy and method, opportunities for bias and argument exist as to whether the results are representative, which is the crux of Stam and Scasta’s study. 

Studying the method

To facilitate the study, last year, UW Extension, along with a slate of cooperators, applied for a Rangeland Health Assessment Program grant from the Wyoming Department of Agriculture to conduct their study. 

“We have quite a few permittees who are on board with our study,” Stam says, noting cooperative efforts have been exceptional. “We are also partnering with the Sheridan County Conservation District and the Forest Service.”

Stam also notes the Wyoming Stock Growers Association supports the project, and they received money from Guardians of the Range, as well as University of Wyoming Agricultural Experiment Stations. 

“This is an issue, and a number of folks are on board as we look at the Robel pole method,” he says. “Dr. Scasta and I hope to determine the accuracy and effectiveness of this method and how it is applied in Wyoming.” 

Saige Albert is managing editor of the Wyoming Livestock Roundup and can be reached at saige@wylr.net.