Hydrologic effects of fire in sagebrush plant communities: Implications for rangeland hydrology and erosion modeling

Authors: Pierson Jr, Frederick; ROBICHAUD, PETER - Us Forest Service (FS); Moffet, Corey; SPAETH, KENNETH - Natural Resources Conservation Service (NRCS, USDA); Williams, Christopher - Jason

Submitted to: Society for Range Management Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 9/4/2008
Publication Date: 2/8/2009
Citation: Pierson Jr, F.B., Robichaud, P.R., Moffet, C.A., Spaeth, K.E., Williams, C.J. 2009. Hydrologic Effects of Fire in Sagebrush Plant Communities: Implications for Rangeland Hydrology and Erosion Modeling. In: Proceedings of the 62nd Annual Meeting, Merging Trails: Culture, Science, and Innovation, Society for Range Management, February 8-12, 2009, Albuquerque, NM.

Interpretive Summary: Millions of dollars are spent annually in the United States mitigating fire effects on rangeland hydrology and erosion. Rangeland managers and scientists need predictive tools to simulate hydrologic processes dictating post-fire responses, assist mitigation and risk assessments, and predict post-fire hydrologic recovery. Progress has been made in rangeland hillslope modeling; however current models do not include advancements in understanding of fire effects on rangeland hydrology. Recent research has demonstrated rill processes are the dominant post-fire sediment delivery mechanism, fire-induced runoff and erosion rates are greatest where ground cover is reduced below 40%, and the pre-burn strength of soil water repellency and its spatial and temporal variability may exert greater influence on the post-fire response than fire effects. The overall post-fire hillslope response and recovery is largely dictated by interaction of ground cover effects and highly variable soil water repellency. Soil water repellency primarily influences runoff generation whereas cover dictates sediment detachment and flow energy. Fire reductions in ground cover increase raindrop detachment rates and the connectivity of overland flow sources and facilitate rill formation where overland flow velocity and sediment detachment and transport increase. These fire effects are enhanced by strongly hydrophobic soil conditions and are reduced as ground cover increases to 60%. Future advancements to rangeland hillslope hydrologic models should include methods to simulate rangeland rill processes and account for plant growth and ground cover recruitment, soil water repellency, and the interaction of ground cover and soil water repellency effects.

Technical Abstract: Millions of dollars are spent annually in the United States mitigating fire effects on rangeland hydrology and erosion. Rangeland managers and scientists need predictive tools to simulate hydrologic processes dictating post-fire responses, assist mitigation and risk assessments, and predict post-fire hydrologic recovery. Progress has been made in rangeland hillslope modeling; however current models do not include advancements in understanding of fire effects on rangeland hydrology. Recent research has demonstrated rill processes are the dominant post-fire sediment delivery mechanism, fire-induced runoff and erosion rates are greatest where ground cover is reduced below 40%, and the pre-burn strength of soil water repellency and its spatial and temporal variability may exert greater influence on the post-fire response than fire effects. The overall post-fire hillslope response and recovery is largely dictated by interaction of ground cover effects and highly variable soil water repellency. Soil water repellency primarily influences runoff generation whereas cover dictates sediment detachment and flow energy. Fire reductions in ground cover increase raindrop detachment rates and the connectivity of overland flow sources and facilitate rill formation where overland flow velocity and sediment detachment and transport increase. These fire effects are enhanced by strongly hydrophobic soil conditions and are reduced as ground cover increases to 60%. Future advancements to rangeland hillslope hydrologic models should include methods to simulate rangeland rill processes and account for plant growth and ground cover recruitment, soil water repellency, and the interaction of ground cover and soil water repellency effects.