Brush Mower/Mixed Mountain Shrub Enhancement

Final Report for FW05-035

Project Type: Farmer/Rancher
Funds awarded in 2005: $19,370.00
Projected End Date: 12/31/2006
Region: Western
State: Wyoming
Principal Investigator:
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Project Information


Sampling and monitoring of mixed mountain shrub communities in southeast Wyoming reveals old stands of shrubs depleted of nutrients for wild and domestic ungulates. Part of the problem is a lack of disturbance, mainly because of wildfire suppression. This project is designed to test whether using a skid-steer tractor with a brush mower attachment can refurbish shrub stands. The plan is to mow at several demonstration sites composed of mixed mountain shrubs known to sprout after treatment. The goal of this Western SARE Farmer/Rancher grant is to improve mountain shrub and grassland communities for domestic livestock, mule deer, elk, whitetail deer, antelope and bighorn sheep. Up to now, cost-effective treatment of mixed mountain shrub communities has been limited to prescribed fire. This project attempted to determine whether mowing could become another tool to keep these communities healthy.

• Increase quantity and nutritive quality of mixed mountain shrubs
• Set back succession in shrub communities to allow for recruitment of young shrubs and improve herbaceous understory production
• Improve livestock grazing distribution by increasing herbaceous forage quality and quantity in uplands
• Utilize brush mower and compare results of treatments with areas treated by prescribed fire or herbicide application
• Demonstrate to private landowners, via news releases, field trips and publications, the benefits associated with using the brush mower

Mowing treatments were conducted on Wyoming big sagebrush, silver sagebrush, rubber rabbitbrush, true mountain mahogany, skunkbush sumac, black sagebrush, antelope bitterbrush and winterfat. The brush mower is effective at cutting brush with stem diameters up to 3 inches.

The skid-steer tractor and brush mower was able to mow 1.5 to 2 acres of brush per hour compared with the ability to treat 50 acres per acre of similar habitat with prescribed fire. The skid-steer rented for this project was undersized, resulting in overheating and poor performance, especially in heavier shrub stands on steep hillsides. Equipment breakdowns in remote areas resulted in lost time and fewer acres treated than had been planned.

Livestock grazing did not have to be deferred before, during or after the mowing treatments, while areas planned for burning required rest from grazing before treatment to build up fine fuels and rest after treatment to allow perennial vegetation time to regenerate. At the time of this report, most of the mowed shrubs were beginning to resprout, although extreme drought in spring 2006 probably resulted in less than optimal plant response after treatment.

Shrub nutrient samples taken before treatment in all mixed mountain shrub types are being analyzed at Colorado State University. Deer and elk fecal samples collected at the same sites are also being analyzed to determine plant composition in animal diets before treatment.

It is anticipated that extensive follow-up will be required in the coming years at treatment sites to evaluate changes in nutrient content within the shrubs and to see if any changes in big game diets and amount of use can be detected within treatment areas.

It was difficult to speculate, at the time of this report, what long-term benefits or impact for producer may be. But project team speculates that as the data are analyzed and comparisons are drawn between areas treated and control areas general recommendations can be made to producers on the validity of using brush mowing and prescribed burning, or a combination of both, can achieve desired vegetative conditions.

Costs of all types of habitat treatments are increasing, and it is important to provide a cost-benefit analysis to producers so that can determine whether treatment is cost effective and warranted.

In areas where the brush mower was used, numerous neighbors commented on the project sites and the short-term results. This may lead to several more treatments in the coming year. It was anticipated that results of trial would be shared with producers and that a field tour of the mowed and burned sites would be conducted in spring 2007.

The project coordinator collected several comments from participating producers. Some described the mower as “heavy duty” but “slow-going at only 1 acre per hour.” Other comments included:

• “Would like to utilize the mower to actually kill brush, not make it resprout. How about trying a herbicide application after mowing to get effective kill with less herbicide applied?”
• “Interested to see if big game use increases.”
• “Grass growth increased significantly in areas where the mower removed shrubs this spring.”
• “I like the control offered with the mower as we were able to delineate specific areas for treatment. We were able to create a nice mosaic/islands in big blocks of sagebrush.”
• “Use of prescribed fire is much more economically feasible.”
• “Would like to use the mower to create breaks in big shrub stands to better control wildfires in the area.”
• “Can’t afford to own the mower and skid steer, but would rent one for a few days of work on our ranch.”

Brochures on the project were planned for production in 2007 after the comparisons of treated and untreated areas had been completed. A field tour was scheduled for spring 2007, possibly in conjunction with the annual Platte County Resource District’s Field Day/Plant Identification and Grazing Management Practices Tour. An article on the project appeared in the spring 2006 issue of the Platte County Resource District’s Conservation Quarterly Newsletter.

The nature of this project makes it difficult to share information within the timeframe of the grant.


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  • Ryan Amundson


Participation Summary

Research Outcomes

No research outcomes
Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.