HR: 1340h
AN: H43F-1697    [Abstracts]
TI: Post-fire Erosion: Long-term Recovery and Effectiveness of Rehabilitation Techniques
AU: * MacDonald, L H
EM: leemac@cnr.colostate.edu
AF: Watershed Science Program, FRWS Dept., Colorado State University, Fort Collins, CO 80524, United States
AU: Rough, D T
EM: caniella.rough@aata.com
AF: AATA International, 300 East Boardwalk Dr, Fort Collins, CO 80525, United States
AU: Schaffrath, K
EM: writetokeelin@gmail.com
AF: Watershed Science Program, FRWS Dept., Colorado State University, Fort Collins, CO 80524, United States
AB: Millions of dollars are spent each year to reduce runoff and erosion rates after high-severity wildfires, but there are relatively few data evaluating their effectiveness over longer time periods relative to natural recovery. In this study we summarize six years of hillslope erosion data from 18 untreated plots and five replicated post-fire rehabilitation treatments applied after the 2002 Hayman and Schoonover wildfires in the ponderosa pine zone in the central Colorado Front Range. The rate of recovery and effectiveness of these treatments are compared to the results from the 2000 Bobcat fire 130 km to the north (Wagenbrenner et al., 2006). On the Hayman fire straw mulching reduced hillslope-scale sediment yields by more than 90% in the first two summers after burning and by 77% in the third summer after burning. By the fourth summer the straw mulch had no significant effect on the amount of ground cover or sediment yields relative to the untreated controls. Aerial hydromulching had a similar effectiveness and longevity, but a ground-based hydromulch treatment was poorly formulated and did not significantly reduce sediment yields. Scarification and seeding did not increase the amount of surface cover or reduce sediment yields. The initial wet application of a polyacylamide appeared to reduce sediment yields, but subsequent applications did not have any significant effect. None of the treatments was effective for more than three summers after burning. The results confirm the fundamental importance of ground cover and are consistent with the mulching and seeding results from the Bobcat fire. The primary difference is the slower vegetative recovery rates for the coarser-textured soils in the Hayman and Schoonover fires, and this has caused post-fire sediment yields to remain elevated for six summers after burning as compared to a maximum of four summers for the Bobcat fire. Land managers must evaluate the duration of treatment effectiveness and post-fire erosion as well as the shorter-term efficacy of their proposed treatments, and these evaluations must be done on a site-specific basis.
UR: http://www.warnercnr.colostate.edu/frws/people/faculty/macdonald/macdonald.html DE: 1625 Geomorphology and weathering (0790, 1824, 1825, 1826, 1886)
DE: 1803 Anthropogenic effects (4802, 4902)
DE: 1815 Erosion
DE: 1850 Overland flow
DE: 1861 Sedimentation (4863)
SC: Hydrology [H]
MN: 2007 Fall Meeting