Targeted grazing by sheep to control invasive species and reduce wildfire risk on western rangelands

View the project report

Commodities

• Animals: sheep

Practices

• Production Systems: agroecosystems

Cheatgrass invasion increases the risk of wildfire and negatively impacts agricultural production in the western United States. Grazing has been suggested as a tool to combat cheatgrass and increase resilience to wildfire. However, most research on targeted grazing of cheatgrass has been done with cattle. Studies on targeted grazing of sheep on cheatgrass remain sparse, despite interest from stakeholders. This project will answer the question of how sheep can be used to reduce cheatgrass and wildfire risk, while also examining the economic costs and benefits of this practice.

We will establish a sheep targeted grazing experiment at a management-relevant scale in central Idaho to examine vegetation responses and belowground processes affected by grazing. Grazing treatments will compare dormant-season grazing in spring and fall, when cheatgrass is growing but most perennial species are not, to “traditional” summer grazing. In addition to assessing treatment effects on the composition of aboveground vegetation and fuel loads, we will examine impacts on soil processes to enhance understanding of the ecological mechanisms underpinning our results. Fire behavior models and economic models will estimate the financial and societal costs and benefits of adopting sheep targeted grazing practices. 

Outreach to producers, land managers, researchers, and the general public—locally and regionally—will occur through diverse venues ranging from field days to podcasts. Rangeland monitoring workshops will build knowledge and shared understanding among land managers, sheep producers, and herders, with trainings offered in Spanish to serve the primarily Spanish-speaking sheepherder community. To contribute to youth education about rangeland issues, we will develop lesson plans about the invasive annual grass-fire cycle and targeted grazing with sheep, which will be shared with teachers in Idaho and beyond. These efforts will increase knowledge of the potential for using sheep as a management tool, while broadening public acceptance for active rangeland management.

This work will be of significance throughout the Intermountain West, much of which is invaded by cheatgrass. With over 2 million sheep still being raised in the western states, harnessing their ability to reduce cheatgrass and associated wildfire risk poses an opportunity to improve environmental conditions and enhance sheep producers’ role as stewards of the lands they manage.

Project information will be disseminated among agricultural stakeholders via podcasts, field days, industry newsletters, video, and fact sheets (available in Spanish), with assistance from the Idaho Rangeland Resources Commission and the Idaho Wool Growers Association. An online economic decision tool about sheep grazing as a cheatgrass management practice will be shared through these venues and professional networks. 

Expected outcomes: 

1. Ecological and economic understanding of sheep as a management tool for cheatgrass and wildfire risk reduction.

2. Improved skills to implement sheep grazing to reduce cheatgrass and fuel loads.

3. Increased collaboration among scientists, land managers, and livestock producers.

4. Wider public acceptance of active rangeland management.

Research objectives:

1. Evaluate the effects of sheep grazing treatments on vegetation communities by quantifying changes in cheatgrass and perennial species cover and density. 
2. Examine mechanisms driving vegetation responses by quantifying the impact of sheep grazing treatments on litter accumulation, soil organic matter content, and nitrogen cycling.  
3. Predict outcomes for wildfire risk by quantifying grazing treatment effects on fuel loads and modeling associated wildfire behavior.
4. Compare economic costs for achieving a change in ecological condition based on targeted grazing with sheep to other cheatgrass management strategies. 

Education objectives:

1. Increase knowledge of the ecological and economic impacts of invasive annual grass.
2. Increase knowledge of the potential for adopting sheep grazing as a management tool to minimize invasive annual grass and reduce wildfire risk.
3. Achieve wider public acceptance of active land management in rangelands.