U of I study questions two-year grazing rest after rangeland fires

MOSCOW, Idaho — When wildfire burns through rangeland, it’s standard practice to keep livestock off the land for two years to allow vegetation to recover. But a new analysis of previous studies led by the University of Idaho Rangeland Center suggests that a blanket two-year rest period may not be necessary in every situation. 

The study, “Precipitation and Grazing Utilization Influence Postfire Herbaceous Plant Cover: A Meta-Analysis on Grazing After Fire,” found that the amount of time burned areas were rested before grazing resumed did not affect perennial grass cover. However, grazing within a few years of a fire slightly reduced perennial grass cover compared with no grazing. Factors such as average annual precipitation and grazing use influenced the extent of that reduction. The findings suggest that the decision about when to return livestock to burned rangelands may need to account for conditions on the ground rather than rely on a standard two-year time frame.  

Fire is a natural and common occurrence in rangelands, but wildfires have increased in size and severity in recent decades. For livestock producers and rangeland managers, determining when and under what conditions to resume grazing after fire can have significant ecological and economic consequences.  

“Our research shows a blanket two-year rest wouldn’t necessarily improve perennial grass cover after fire,” said Eric Winford, interim director of the Rangeland Center, research assistant professor of rangeland ecology and management and lead author of the study. “Instead, average annual precipitation and grazing utilization are the important factors to consider.”

Researchers analyzed results from 18 studies on grazing after fire and found that several factors influence the best time to return livestock to the range. Average annual precipitation and grazing utilization — the proportion of available forage consumed by livestock — affected how much perennial grass cover declined. Greater precipitation and lighter grazing were associated with smaller reductions.  

Grazing also reduced annual grass cover in some circumstances, with the effect varying according to precipitation and how heavily the land was grazed. The findings highlight the importance of considering postfire precipitation, vegetation recovery and grazing use when making management decisions.  

“Well-managed grazing that results in low utilization may be compatible with postfire recovery where there is sufficient precipitation,” said Winford. “In areas with low average annual precipitation, more care will be needed.”

The analysis also points to areas where more research could clarify how grazing can support postfire recovery. The researchers recommend that future studies include more information about livestock management, including the timing, utilization and season of grazing, and the duration of rest.

This meta-analysis is one of several postfire recovery initiatives from the Rangeland Center. In partnership with the McClure Center for Public Policy Research, the center focused its annual Rangeland Fall Forum last month on postfire recovery, adaptation and restoration. The event included a field tour of an ongoing postfire grazing study at U of I’s Rinker Rock Creek Ranch, led by Jim Sprinkle, a Rangeland Center member and study co-author.

Media contact

Ella Hall 
Rangeland Center communications director 
Department of Forest, Rangeland and Fire Sciences 
406-550-2136 
erhall@uidaho.edu