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Soil water repellency and infiltration in coarse-textured soils of burned and unburned sagebrush ecosystems
Pierson, F.B.; Robichaud, P.R.; Moffet, C.A.; Spaeth, K.E.; Williams, C.J.; Hardegree, S.P.; Clark, P.E.
2008.
Soil water repellency and infiltration in coarse-textured soils of burned and unburned sagebrush ecosystems.
Catena 74:98-108.
Keywords: Rangeland, Sagebrush, Fire, Infiltration, Runoff, Hydrophobicity; water repellency
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Abstract:
Millions of dollars are spent each year in the United States to mitigate the effects of wildfires and reduce the
risk of flash floods and debris flows. Research from forested, chaparral, and rangeland communities indicate
that severe wildfires can cause significant increases in soil water repellency resulting in increased runoff and
erosion. Few data are available to document the effects of fire on the spatial and temporal variability in soil
water repellency and potential impacts on infiltration and runoff on sagebrush-dominated landscapes. Soil
water repellency, infiltration and runoff were assessed after two wildfires and one prescribed fire in three
steep, sagebrush-dominated watersheds with coarse-textured soils. Water repellency was generally greater
on unburned hillslopes and annual variability in water repellency had a greater impact on infiltration
capacity than fire effects. The most significant impact of fire was canopy and ground cover removal on
coppice microsites. Infiltration rates decreased on coppice microsites after fire even though soil water
repellency was reduced. Fire-induced reduction in infiltration resulted from the combined effect of canopy
and ground cover removal and the presence of naturally strong water repellent soils. Removal of ground
cover likely increased the spatial connectivity of runoff areas from strongly water repellent soils. The results
indicate that for coarse-textured sagebrush landscapes with high pre-fire soil water repellency, post-fire
increases in runoff are more influenced by fire removal of ground and canopy cover than fire effects on soil
water repellency and that the degree of these impacts may be significantly influenced by short-term
fluctuations in water repellent soil conditions.
Moscow FSL publication no. 2008f
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