Early Succession Following Prescribed Fire in Low Sagebrush (Artemisia arbuscula var. Arbuscula) Steppe

Abstract

Abstract. We evaluated plant community succession following prescribed fire on Artemisia arbuscula var. arbuscula (Nutt.) McMinn (low sagebrush) steppe in southeastern Oregon. Treatments were “prescribed burned” (burn; fall 2012) and “unburned” (control) A. arbuscula steppe, and the study design was a randomized complete block with 4 replicates per treatment. Herbaceous yield and vegetation canopy cover and density were compared between treatments (2012–2020). Fire practically eliminated A. arbuscula and there was no recruitment of new plants in the first 8 years after burning. Herbaceous yield in the burn treatment was about double the control for most of the postfire period. Native perennial grasses and forbs constituted 94% to 96% and Bromus tectorum L. (cheatgrass) 0.2% to 2% of total herbaceous yield in the control. In the burn treatment, perennial grasses and forbs constituted 83% to 87%, native annual forbs 2% to 5%, and B. tectorum 3% to 9% of total herbaceous yield. Despite an increase in B. tectorum, the burned A. arbuscula sites were dominated by herbaceous perennial grasses and forbs and exhibited high levels of resilience and resistance. After prescribed fire, for the study sites and comparable A. arbuscula associations, weed control or seeding are not necessary to recover the native herbaceous community. However, the results in our study are for low-severity prescribed fire in intact A. arbuscula plant communities. Higher-severity fire, as might occur with wildfire, and in A. arbuscula communities having greater prefire invasive weed composition should not be assumed to develop similarly high levels of community resilience and resistance.