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Title: Delaying sheep grazing after wildfire in sagebrush steppe may not affect vegetation recovery

Author
item ROSELLE, LOVINA - UNIVERSITY OF IDAHO
item Seefeldt, Steven
item LAUNCHBAUGH, KAREN - UNIVERSITY OF IDAHO

Submitted to: International Journal of Wildland Fire
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/7/2009
Publication Date: 2/20/2010
Citation: Roselle, L., Seefeldt, S.S., Launchbaugh, K. 2010. Delaying sheep grazing after wildfire in sagebrush steppe may not affect vegetation recovery. International Journal of Wildland Fire. 19(1):115-122.

Interpretive Summary: In Western grazing lands, many land managers prohibit grazing for two years after a fire. Very little research has been conducted to determine what impact grazing of any kind has on vegetation recovery after fire. To begin to address this lack of information, a study was conducted in sagebrush steppe rangelands after a 2000 wildfire at the United States Sheep Experiment Station in Idaho. The influence of delay and season of sheep grazing on vegetation recovery was measured. A moderate level of sheep grazing, designed to remove 40% of the vegetation was started 1, 2, or 3 years after fire in the autumn or 2 or 3 years after fire in the spring. Based on a variety of measurements, bluebunch wheatgrass, the dominant perennial grass, and arrowleaf hawksbeard, an important perennial forb, increased in the autumn and non-grazed treatment areas, whereas arrowleaf hawksbeard cover declined in the spring grazing treatment beginning the second year after fire. There was no impact of sheep grazing on cover of downy brome, an important exotic winter annual grass, probably due to the lack of autumn germination. In this study, moderate sheep grazing had subtle impacts on vegetation recovery after fire, with spring grazing having more negative consequences. Based on the results of this research, management decisions on when to start grazing livestock after fire should consider pre-fire ecological conditions, post-fire climatic conditions, and current knowledge of impacts of grazing on plant recovery.

Technical Abstract: Although many land managers prohibit grazing for two years after a fire, little research has been conducted to determine the interaction of grazing with vegetation recovery after fire. In a study conducted in sagebrush steppe rangelands after a 2000 wildfire at the United States Sheep Experiment Station in Idaho, the influence of delay and season of sheep grazing on vegetation recovery was measured. A moderate level of sheep grazing, designed to remove 40% of the vegetation was started 1, 2, or 3 years after fire (YAF) in the autumn or 2 or 3 YAF in the spring. Vegetation cover, density, and frequency of individual plant species and functional groups were determined. Pseudoroegneria spicata the dominant perennial grass and Crepis acuminata increased in the autumn and non-grazed treatment, whereas perennial forb and Crepis acuminata cover declined in the spring grazing treatment beginning the second YAF. There was no impact of sheep grazing on cover of Bromus tectorum an important exotic winter annual grass, probably due to the lack of autumn germination. In this study, moderate sheep grazing had subtle impacts on vegetation recovery after fire, with spring grazing having more negative consequences. Management decisions on when to start grazing livestock after grazing should consider pre-fire ecological conditions, post-fire climatic conditions, and current knowledge of impacts of grazing on plant recovery.