Impacts of fire on hydrology and erosion in steep mountain big sagebrush communities

Wildfire is an important ecological process and management issue on western rangelands. Major unknowns associated with wildfire are its affects on vegetation and soil conditions that influence hydrologic processes including infiltration, surface runoff, erosion, sediment transport, and flooding. Post wildfire hydrologic response was studied in big sagebrush plant communities on steep slopes with coarse-textured soils. Significant rill erosion was observed following both thunderstorm and rapid snowmelt events. Rainfall simulation and controlled overland flow techniques were used to study post-fire effects on infiltration, and interrill and rill erosion processes on burned and adjacent unburned areas. Results indicate that burn severity and the development of water repellent soil conditions play significant roles in determining infiltration and interrill erosion rates, particularly on shrub coppice dunes characterized by high surface litter accumulations. The most dramatic and long-lasting affect of fire was on rill erosion processes by reducing ground cover needed to slow and spread water as it moves across the soil surface. Ongoing research efforts are aimed at characterizing the hydrologic impacts of prescribed fire used as a tool to manage vegetation and mitigate the impacts of catastrophic wildfire events