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Hydrologic and erosion responses to wildfire along the rangeland-xeric forest continuum in the western US: a review and model of hydrologic vulnerability
Williams, C.J.; Pierson, F.B.; Robichaud, P.R.; Boll, J. 2014.
Hydrologic and erosion responses to wildfire along the rangeland-xeric forest continuum in the western US: a review and model of hydrologic vulnerability.
International Journal of Wildland Fire 2014, 23, 155–172.
http://dx.doi.org/10.1071/WF12161
Keywords: cheatgrass, climate change, fire effects, grass-fire cycle, Great Basin, hydrologic risk, invasive plants, juniper, pinyon, runoff, sagebrush, wildland-urban interface, woodland encroachment
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Abstract:
The recent increase in wildfire activity across the rangeland–xeric forest continuum in the western United
States has landscape-scale consequences in terms of runoff and erosion. Concomitant cheatgrass (Bromus tectorum L.)
invasions, plant community transitions and a warming climate in recent decades along grassland–shrubland–woodland–xeric
forest transitions have promoted frequent and large wildfires, and continuance of the trend appears likely if warming
climate conditions prevail. These changes potentially increase overall hydrologic vulnerability by spatially and temporally
increasing soil exposure to runoff and erosion processes. Plot and hillslope-scale studies demonstrate burning may
increase event runoff or erosion by factors of 2–40 over small-plot scales and more than 100-fold over large-plot to
hillslope scales. Reports of flooding and debris flow events from rangelands and xeric forests following burning show the
potential risk to natural resources, property, infrastructure and human life. We present a conceptual model for evaluating
post-fire hydrologic vulnerability and risk. We suggest that post-fire risk assessment of potential hydrologic hazards
should adopt a probability-based approach that considers varying site susceptibility in conjunction with a range of
potential storms and that determines the hydrologic response magnitudes likely to affect values-at-risk. Our review
suggests that improved risk assessment requires better understanding in several key areas including quantification of
interactions between varying storm intensities and measures of site susceptibility, the varying effects of soil water
repellency, and the spatial scaling of post-fire hydrologic response across rangeland–xeric forest plant communities.
Moscow FSL publication no. 2014b
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