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Submitted to: Fire Ecology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 10/26/2017 Publication Date: 5/1/2018 Citation: Dufek, N.A., Augustine, D.J., Blumenthal, D.M., Kray, J.A., Derner, J.D. 2018. Dormant season fire inhibits sixweeks fescue and enhances forage production in shortgrass steppe. Fire Ecology. 14(1):33-49. doi:10.4996/fireecology.140132048. DOI: https://doi.org/10.4996/fireecology.140132048 Interpretive Summary: In the western, semiarid rangelands of the Great Plains, recent studies indicate that prescribed fire can be used to reduce undesirable plant species, increase the quality of forage for livestock, and manage wildlife habitat. However, changes in weather conditions from year to year can influence the role of fire in these rangelands, so long-term studies are needed to determine how prescribe fire effect vary with weather conditions. We report on an 11-year (2006 – 2016) study of annual and triennial dormant season (late spring and early autumn) prescribed fires in shortgrass steppe of northeastern Colorado. The plant community was dominated by warm-season shortgrasses, and production of these dominant grasses was not was not reduced by dormant-season burns in any year of the study. However, other subdominant plants varied widely in abundance in response to burning and varying precipitation patterns. The annual grass, sixweeks fescue (Vulpia octoflora), which interferes with livestock grazing, was rare during the first 7 years (2006 – 2012), but increased dramatically in unburned plots during the latter 4 years (2013 – 2016). Both late spring and early autumn annual burn treatments reduced fescue biomass during 2014 – 2016, by an average of 87%. Autumn triennial burns implemented prior to the 2013 and 2016 growing seasons reduced fescue biomass to a similar degree (86%). In contrast, spring triennial burns did not prevent fescue proliferation. Our results indicate that prescribed burning during fescue establishment can prevent proliferation. All 3 burn treatments that suppressed fescue subsequently enhanced warm-season forage production. We suggest that rangeland managers be aware of the potential for sixweeks fescue germination and establishment during warm, wet winters that follow drought years, and consider the use of dormant–season prescribed fire to adaptively reduce negative impacts on forage production and availability for grazers. Prescribed fire may provide a valuable alternative to herbicides because it also can benefit wildlife species of conservation concern in shortgrass steppe, and enhance livestock forage quality early in the subsequent growing season. Technical Abstract: In the Great Plains of central North America, fire effects on vegetation vary considerably along an east–to–west gradient of declining mean annual precipitation and aboveground plant productivity. In the western, semiarid region of the Great Plains, recent studies demonstrate that prescribed fire can be used to influence plant species composition, forage quality, and wildlife habitat. However, weather conditions are highly variable in the Great Plains, so understanding how fire effects vary with weather is needed by land managers. Here, we report on an 11-year (2006 – 2016) study of annual and triennial dormant season (late spring and early autumn) prescribed fires in shortgrass steppe of northeastern Colorado. The plant community was dominated by C4 shortgrasses, and C4 grass production was not reduced by dormant-season burns in any year. However, other subdominant plants varied widely in abundance in response to burning and varying precipitation patterns. The C3 annual grass, sixweeks fescue (Vulpia octoflora), which interferes with livestock forage intake, was rare during the first 7 years (2006 – 2012), but increased dramatically in unburned plots during the latter 4 years (2013 – 2016). Both late spring and early autumn annual burn treatments reduced fescue biomass during 2014 – 2016, by an average of 87%. Autumn triennial burns implemented prior to the 2013 and 2016 growing seasons reduced fescue biomass to a similar degree (86%). In contrast, spring triennial burns implemented prior to the 2012 and 2015 growing seasons did not prevent fescue proliferation. Our results indicate that prescribed burning during fescue establishment can prevent proliferation. Burning 2 years later, when fescue had already reached peak abundance, however was ineffective in reducing proliferation. Furthermore, all 3 burn treatments that suppressed fescue subsequently enhanced C4 grass production. We suggest that rangeland managers be aware of the potential for sixweeks fescue germination and establishment during warm, wet winters that follow drought years, and consider the use of dormant–season prescribed fire to adaptively reduce negative impacts on forage production and availability for grazers. Prescribed fire may provide a valuable alternative to herbicides because it also can benefit wildlife species of conservation concern in shortgrass steppe, and enhance livestock forage quality early in the subsequent growing season. |
