|Williams, Christopher - Jason|
|AL-HAMDAN, OSAMA - University Of Idaho|
Submitted to: Catena
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/7/2016
Publication Date: 5/25/2016
Citation: Williams, C.J., Pierson Jr, F.B., Kormos, P.R., Al-Hamdan, O.Z., Hardegree, S.P., Clark, P. 2016. Ecohydrologic response and recovery of a semi-arid shrubland over a five year period following burning. Catena. 144:163-176.
Interpretive Summary: Increasing wildfire activity across western rangelands necessitates improved understanding of fire impacts on vegetation, soils, hydrology and erosion. This study investigated the impacts of fire on vegetation, soils, hydrology, and erosion for a sagebrush rangeland in the western US. Rainfall simulation and concentrated flow experiments were used to measure infiltration, runoff, and erosion before and after fire for a five year period. Soil water repellency and vegetative and basal cover factors that influence runoff and erosion were quantified. Runoff responses were affected more by soil water repellency than burning and exhibited high temporal variability. Erosion increased dramatically post-fire, but decreased over time as vegetation and ground cover returned. Amplified soil erosion rates persisted over four growing seasons post-fire. The results contribute to improved scientific understanding of post-fire hydrologic and erosion responses on rangelands, and aid determination of relative ecohydrologic recovery of sagebrush ecosystems in the years following fire.
Technical Abstract: Increasing trends in wildfire activity on semi-arid rangelands necessitate advancement in understanding of fire impacts on vegetation, soils, and runoff and erosion processes. This study used artificially applied rainfall and concentrated overland flow experiments to evaluate the ecohydrologic response and recovery of a semi-arid shrubland in the Great Basin Region, USA, following fire. Rainfall experiments were conducted at the 0.5 m2 plot scale to assess fire impacts on rainsplash and sheetflow processes. Concentrated flow experiments were applied on 9 m2 plots to evaluate fire impacts on concentrated overland flow processes. Vegetation, soil, hydrologic, and erosion variables were assessed at each scale pre-fire and 1, 2, and 5 yr post-fire. Infiltration and runoff on rainfall simulation plots was effected more by measured background soil water repellency than fire effects on vegetation and soils. Runoff from rainfall on shrub-dominated plots was unchanged 1 yr post-fire, but runoff from interspace plots between shrubs declined 1 yr post-fire. Runoff increased on shrub and interspace rainfall plots 2 yr post-fire and then declined in the 5 yr post-fire. Vegetation and ground cover increased across all study years, implicating the temporal variability in soil water repellency as the causal factor for infiltration and runoff trends. Erosion on rainfall plots increased by factors of 8 to 10 following fire removal of vegetation and ground cover and declined with vegetation recovery through four growing seasons. Concentrated overland flow plots generated slightly more runoff and 25-fold more erosion 1 yr following burning relative to pre-fire measures. Erosion from concentrated overland flow remained greater on burned than unburned plots after four growing seasons even though ground cover returned to approximately 80%. The relative recovery of vegetation and total ground cover were typical for the shrubland community assessed, but elevated erosion with 80% ground cover 5 yr post-fire was unexpected. The persistent high erosion on concentrated plots is attributed to the fine textured soils. The importance of considering erodibility in context with sediment supply and vegetative recovery is discussed. The results demonstrate the complexity of post-fire ecohydrologic interactions, advance process understanding of post-fire ecohydrologic responses for semi-arid rangelands, and underscore the need for additional studies on post-fire recovery over time.