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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Publications at this Location » Publication #426659
Research Project: Precision Technologies and Management for Northern Plains Rangeland

Location: Livestock and Range Research Laboratory

Title: High mortality of huisache (Vachellia farnesiana) with extreme fire during drought

Author
item DONOVAN, VICTORIA - West Florida Research And Education Center
item SCHILTMEYER, ALLIE - University Of Nebraska
item WONKKA, CARISSA - West Florida Research And Education Center
item WAGNER, JACOB - Nebraska Game & Parks Commission
item McGranahan, Devan
item ROGERS, WILLIAM - Texas A&M University
item KREUTER, URS - Texas A&M University
item TWIDWELL, DIRAC - University Of Nebraska

Submitted to: Fire
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/17/2025
Publication Date: 6/21/2025
Citation: Donovan, V.M., Schiltmeyer, A.V., Wonkka, C.L., Wagner, J., McGranahan, D.A., Rogers, W.E., Kreuter, U., Twidwell, D. 2025. High mortality of huisache (Vachellia farnesiana) with extreme fire during drought. Fire. 8. Article 242. https://doi.org/10.3390/fire8070242.
DOI: https://doi.org/10.3390/fire8070242

Interpretive Summary: Woody plant species can encroach rangeland ecosystems and reduce the herbaceous forage ranchers rely upon for livestock grazing. Species like huisache are particularly difficult to control, and typical prescribed fire conditions produce insufficient intensity for huisache control. This experiment began by testing the effect of prescribed fire conducted under drought conditions, which reduced low fuel moisture and increased fire intensity, on huisache recovery, which was compared to follow-up management with prescribed fire under conventional conditions. Overall, high-intensity prescribed fire appeared to provide sufficient recovery of herbaceous fuels under huisache canopy that allowed subsequent fire, albeit of lower intensity, to further reduce seedling recruitment and huisache canopy area. These results highlight the potential for novel applications of prescribed fire to obtain better results in woody plant control, but also reinforce the importance of using repeated treatments to maximize control efforts.

Technical Abstract: The almost complete eradication of fire from grasslands in North America has led to non-linear hysteretic transitions to shrub- and woodlands that the reintroduction of low intensity fire is unable to reverse. We explore the ability of the extreme ends of variation in fire behavior to help overcome hysteretic threshold behaviors in huisache (Vachellia farnesiana) encroached grasslands. We contrasted experimental fire treatments with unburned control areas to assess the ability of extreme fires burned during drought to alter the density and structure of huisache. We found that extreme fires reduced the density of huisache by over 30% compared to control plots, both through driving huisache mortality and reducing the number of new recruits following treatments. For instance, extreme fire drove 48% huisache mortality compared to 4% in control treatments. For surviving plants, the number of stems increased but crown area did not significantly change. Fire, conducted under the right conditions, can drive high mortality in one of the most notorious encroaching species in the southern U.S. Great Plains. With the fire conditions observed in this study likely to increase under future climate projections, utilizing extreme fire as a management tool for huisache will help scale-up management to meet the growing extent of woody encroachment into grasslands. Enhancing the range of conditions under which we apply fire to landscapes displaying hysteretic dynamics from woody encroachment will help improve our ability to reverse unwanted ecological transitions.