Longer-term post-fire succession on Wyoming big sagebrush steppe

Authors: Bates, Jonathan - Jon; Boyd, Chad; Davies, Kirk

Submitted to: International Journal of Wildland Fire
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/19/2019
Publication Date: 2/13/2020
Citation: Bates, J.D., Boyd, C.S., Davies, K.W. 2020. Longer-term post-fire succession on Wyoming big sagebrush steppe. International Journal of Wildland Fire. 29(3):229-239. https://doi.org/10.1071/WF19109.
DOI: https://doi.org/10.1071/WF19109

Interpretive Summary: Long-term recovery of burned big sagebrush steppe is needed to improve management and planning following fire. We evaluated the effects of prescribed fire on big sagebrush steppe in eastern Oregon, burned in 2002. In the Burn treatment; (1) herbaceous production was about double the Control for most of the study period, (2) exotic annuals responded in two phases with pale alyssum the main exotic from 2003 to 2009 and cheatgrass the main exotic from 2009 to 2018, and (3) sagebrush recovery was slow and we estimated sagebrush cover would return to preburn levels in 115 years. Burning Wyoming big sagebrush steppe could be detrimental to sagebrush obligate wildlife for an extended time period but would benefit livestock and big game by the increase in available forage. The additional forage provided on burned areas may provide managers greater flexibility to rest or defer unburned habitat for wildlife species of critical concern. Prescribed burning should only be applied when mortality of native perennial grasses and forb species can be minimized and is to be avoided in areas where cheatgrass and other exotics are a substantial threat.

Technical Abstract: We assessed plant community succession following prescribed fire on ungrazed Wyoming big sagebrush steppe, eastern Oregon. Treatments were burned (Burn; September and October, 2002) and unburned (Control) sagebrush steppe. Herbaceous yield, vegetation canopy cover and density were compared between treatments after fire (2003–18). Herbaceous yield in the Burn treatment was about double the Control for most of the study period. Prior to fire, native perennials comprised 90–95% of herbaceous yield. After fire, native perennials represented 78% (range 67–93%) and exotic annuals 22% (range 7–33%) of total yield. Exotic annuals increased after fire and responded in two stages. In the first 8 years after fire, desert alyssum dominated the annual plant composition. In the last half of the study, cheatgrass co-dominated the annual component with alyssum. Sagebrush recovery was slow and we estimated sagebrush cover would return to pre-burn levels, at the earliest, in 115 years. Burning Wyoming big sagebrush steppe would be detrimental to sagebrush-obligate wildlife for an extended time period, because of lost cover and structure provided by sagebrush. The additional forage provided on burned areas may give livestock manager’s greater flexibility to rest or defer unburned habitat for wildlife species of critical concern.