Initial divergent post-fire recovery converges over the long-term: a case study in juniper-encroached sagebrush steppe

Authors: Bates, Jonathan; Davies, Kirk

Submitted to: Elsevier
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/17/2025
Publication Date: 11/1/2025
Citation: Bates, J.D., Davies, K.W. 2025. Initial divergent post-fire recovery converges over the long-term: a case study in juniper-encroached sagebrush steppe. Elsevier. 103(2025)377-387. https://doi.org/10.1016/j.rama.2025.09.009.
DOI: https://doi.org/10.1016/j.rama.2025.09.009

Interpretive Summary: We evaluated plant community succession 20 years after prescribed fire in mountain big sagebrush steppe to control western juniper woodlands (mid and late succession) expansion in southeastern Oregon. Native species dominated vegetation composition of both woodland successional phases and sites proved to be highly resilient to fire. The difference was that sagebrush steppe recovery in the late succession woodlands required about twice as much time as the mid-succession sites. Patience and appropriate grazing management was all that was required to allow these sites to recover, however, to speed recovery managers could consider re-seeding burned areas with appropriate native bunchgrass and shrub species.

Technical Abstract: Reduced fire frequency is recognized as a main cause of Piñon-juniper (Pinus-Juniperus L.) expansion in western North American sagebrush steppe and grasslands. Piñon-juniper woodland control using prescribed fire and mechanical treatments have increased the past three decades with the goal of maintaining and restoring sagebrush steppe plant communities. Conditions shaping the response of sagebrush steppe communities following woodland treatment include shrub and herbaceous composition, level of tree dominance and site characteristics resulting in variable recovery rates of shrub-herbaceous communities. We compared vegetation recovery following prescribed fire on Phase 2 (mid succession) and Phase 3 (late succession) western juniper (Juniperus occidentalis Hook.) woodlands on Steens Mountain, Oregon. The first decade after fire vegetation on Phase 2 woodland sites were co-dominated by native herbaceous perennials and sprouting shrub species and on Phase 3 sites vegetation was co-dominated by nonnative cheatgrass (Bromus tectorum L.) and snowbrush (Ceanothus velutinus Dougl.). During the second decade after fire vegetation composition converged and both Phase 2 and Phase 3 sites were co-dominated by native herbaceous perennials, mountain big sagebrush (Artemisia tridentata spp. vaseyana (Rydb.) Beetle, round-leaf snowberry (Symphoricarpos rotundifolius A. Gray) and snowbrush. Vegetation composition of both woodland phases proved to be highly resilient to fire, the difference was that recovery in the Phase 3 sites required about twice as much time as the Phase 2 sites. The resilience of both Phase 2 and Phase 3 woodland sites was probably a product of ecological site characteristics. The study areas ecological sites have frigid soil temperature regimes and are in a high precipitation zone (300-400 mm annually), characteristics which typically confer a competitive advantage for native perennials over invasive annual grass species.