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ARS Home » Pacific West Area » Burns, Oregon » Range and Meadow Forage Management Research » Research » Publications at this Location » Publication #338830
Title: Fall and spring grazing influence fire ignitability and initial spread in shrub steppe communities

Author
item Davies, Kirk
item GEARHART, AMANDA - Bureau Of Land Management
item Boyd, Chad
item Bates, Jonathan - Jon

Submitted to: International Journal of Wildland Fire
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/12/2017
Publication Date: 6/6/2017
Citation: Davies, K.W., Gearhart, A., Boyd, C.S., Bates, J.D. 2017. Fall and spring grazing influence fire ignitability and initial spread in shrub steppe communities. International Journal of Wildland Fire. 26:485-490.

Interpretive Summary: Across the world wildfires are becoming more common. Grazing has been suggested as a potential management tool to counter this increase in fires. However, relatively little is known about the influence of grazing on fire in rangelands and how it varies by grazing management differences. We evaluated the effect of fall and spring grazing on fuels, fire ignition and initial spread in sage-steppe communities. Both grazing treatments decreased fine fuels and increased fuel moisture and, subsequently decrease the probability of fire ignition and initial spread. Effects, however, varied by grazing management. Grazing either the fall or spring before the wildfire season appears to reduce the probability of fire propagation and thus, grazing is a potential fuel management tool.

Technical Abstract: The interaction between grazing and fire influences ecosystems around the world. However, relatively little is known about the influence of grazing on fire, in particular ignition and initial spread and how it varies by grazing management differences. We investigated effects of fall grazing, spring grazing, and not grazing on fuel characteristics, fire ignition and initial spread during the wildfire season (July and August) at five shrub steppe sites in Oregon. Both grazing treatments decreased fine fuel biomass, cover, and height and increased fuel moisture and, thereby, decreased ignition and initial spread compared to the ungrazed treatment. However, effects differed between fall and spring grazing. The probability of initial spread was 6-fold greater in the fall grazed compared to the spring grazed treatment in August. This suggests that spring grazing may have a greater effect on fires than fall grazing, likely, because fall grazing does not influence current year’s plant growth. Results of this study also highlight that the grazing-fire interaction will vary by grazing management. Grazing either the fall or spring before the wildfire season appears to reduce the probability of fire propagation and thus, grazing is a potential fuel management tool.