Dormant-season prescribed fires can enhance forage quality for two growing seasons in the northwestern Great Plains

Authors: Porensky, Lauren; SCASTA, J - University Of Wyoming; OCHELTREE, TROY - Colorado State University; SYMSTAD, AMY - Us Geological Survey (USGS); Estep, Catherine; OTT, JACQUELINE - Us Forest Service (FS)

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/16/2026
Publication Date: 6/25/2026
Citation: Porensky, L.M., Scasta, J.D., Ocheltree, T.W., Symstad, A.J., Estep, C.E., Ott, J.P. 2026. Dormant-season prescribed fires can enhance forage quality for two growing seasons in the northwestern Great Plains. Rangeland Ecology and Management. 108:23-34. https://doi.org/10.1016/j.rama.2026.05.003.
DOI: https://doi.org/10.1016/j.rama.2026.05.003

Interpretive Summary: Historically and today, humans have used prescribed fire to enhance forage quality for livestock and wildlife, and to achieve other management objectives. Prescribed fire can have different effects on forage quality depending on where, when, and how it is applied, and research is needed to understand when and where fires have the most benefit. We conducted 152 small-plot, prescribed burns at 36 sites across two U.S. states to understand how forage quality outcomes can be shaped by ecosystem type (northern mixed-grass prairie vs. sagebrush grassland ecotone), burn seasonality (fall vs. spring), and fuel characteristics (ambient or added fuel). Across ecosystems, we found strong positive effects of fall fires on forage quality during the first growing season after fire. We also saw energy benefits that lasted into the second growing season after fire. In northern mixed-grass prairie sites, spring and fall prescribed fires had similar, positive effects on forage quality for one growing season. Artificially increased fuel loads did not change forage quality improvements. Our results suggest that dormant-season prescribed fire can reliably improve multiple aspects of forage quality for one growing season, and can create energy benefits that last into the second growing season after fire. The forage quality improvements we observed after both fall and spring prescribed fires would likely support enhanced livestock performance.

Technical Abstract: Fire is an ecological disturbance that can increase nutrient availability and alter herbivore distribution in grasslands and shrublands. Historically and today, humans have used prescribed fire to enhance forage quality for wild and domestic large herbivores, and to achieve other management objectives. Contextual factors such as ecosystem type, burn timing, and fuel characteristics can determine how prescribed fire affects forage quality. For example, forage quality enhancements are relatively short-lived in shortgrass steppe and subhumid grasslands but may persist for multiple years in northern mixed-grass prairie and sagebrush steppe, and outcomes near ecosystem boundaries are uncertain. Using 152 independent, small-plot, prescribed burns completed over multiple years at 36 sites in Wyoming and South Dakota, USA, we tested the effects of ecosystem type (northern mixed-grass prairie vs. sagebrush grassland ecotone), burn seasonality (fall vs. spring), and fuel characteristics (ambient or added fuel) on forage quality responses. Across ecosystems, we found strong positive effects of fall fires on forage quality parameters during the first growing season after fire, and energy benefits that persisted into the second growing season after fire. In northern mixed-grass prairie sites, spring and fall prescribed fires implemented before the same growing season yielded similar forage quality enhancements for one growing season. In sagebrush grassland ecotone sites, effects of spring fires were weaker and less durable than those of fall fires conducted before a different growing season. Finally, artificially increased fuel loads had few impacts on forage quality. Our findings suggest relatively consistent forage quality responses to prescribed fire across ecosystem types, seasonality of dormant-season burns, and fuel characteristics. Although forage quality rarely dropped below critical nutrition thresholds regardless of burning, dormant-season prescribed fire reliably improved multiple aspects of forage quality for at least one growing season, and some parameters remained elevated into a second growing season after fall burns.