Comparing burned and mowed treatments in mountain big sagebrush steppe

Fires in mountain big sagebrush [Artemisia tridentata spp. vaseyana (Rydb.) Beetle] plant communities historically shifted dominance from woody to herbaceous vegetation. However, fire return intervals have lengthened with European settlement, and sagebrush dominance has increased at the expense of herbaceous vegetation in some plant communities. Management actions may be needed to decrease sagebrush in dense sagebrush stands to increase herbaceous vegetation. Prescribed fire is often used to remove sagebrush; however, mechanical treatments, such as mowing, are increasingly used because they are more controllable and do not pose an inherent risk of escape compared with fire. However, information on the effects of burned and mowed treatments on herbaceous vegetation and whether fire and mowed applications elicit similar vegetation responses are limited. We evaluated the effects of prescribed burning and mowing for 3 years after treatment in mountain big sagebrush plant communities. The burned and mowed treatments generally increased herbaceous cover, density, and production compared with untreated controls (P < 0.05). However, neither treatment induced a response in native perennial forb cover, density, or biomass (P > 0.05). In contrast, annual forb (predominately natives) cover, density, and biomass increased with mowing and burning (P < 0.05). Vegetation generally responded similarly in burned and mowed treatments; however, the burned treatment had less sagebrush, greater herbaceous vegetation production, and more bare ground than the mowed treatment (P < 0.05). These differences should be considered when selecting treatments to decrease sagebrush.