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Movement of Sediment Through a Burned Landscape:Sediment Volume Observations and Model Comparisons in the San Gabriel Mountains, California, USA.
Robichaud PR, Bone ED, Lewis SA, Brooks ES, Brown RE. 2021.
Effectiveness of post-fire salvage
logging stream buffer management for hillslope erosion in the U.S. Inland Northwest Mountains..
Hydrological Processes 35:e13943 DOI: 10.1002/hyp.13943.
Keywords: buffer, erosion, ground cover, riparian, salvage logging, soil burn severity
Links:
PDF 3,415 KB]
Abstract:
Active wildfire seasons in the western U.S. warrant the evaluation of post-fire
forest management strategies. Ground-based salvage logging is often used to
recover economic loss of burned timber. In unburned forests, ground-based logging
often follows best management practices by leaving undisturbed areas near
streams called stream buffers. However, the effectiveness of these buffers has
not been tested in a post-wildfire setting. This experiment tested buffer width
effectiveness with a novel field-simulated rill experiment using sediment-laden
runoff (25 g/L) released over 40 min at evenly timed flow rates (50, 100 and
150 L/min) to measure surface runoff travel length and sediment concentration
under unburned and high and low soil burn severity conditions at 2-, 10- and
22-month post-fire. High severity areas 2-month post-fire had rill lengths of up
to 100 m. Rill length significantly decreased over time as vegetation regrowth
provided ground cover. Sediment concentration and sediment dropout rate also
varied significantly by soil burn severity. Sediment concentrations were 19 g/L
for the highest flow 2-month post-fire and reduced to 6.9–14 g/L 10-month
post-fire due to abundant vegetation recovery. The amount of sediment
dropping out of the flow consistently increased over the study period with the
low burn severity rate of 1.15 g L-1 m-1 approaching the unburned rate of
1.29 g L-1 m-1 by 2-year post-fire. These results suggest that an often-used
standard, 15 m buffer, was sufficient to contain surface runoff and reduce sediment
concentration on unburned sites, however buffers on high burn severity
sites need to be eight times greater (120 m) immediately after wildfire and four
times greater (60 m) 1-year post-fire. Low burn severity areas 1-year post-fire
may need to be only twice the width of an unburned buffer (30 m), and 2-year
post-fire these could return to unburned widths.
Moscow FSL publication no. 2021h
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