Effects of post-fire salvage logging and a skid trail treatment on ground cover, soils, and sediment production in the interior western United States
Joseph W. Wagenbrenner, Lee H. MacDonald, Robert N. Coats, Peter R. Robichaud, Robert E. Brown
Published in Forest Ecology and Management, vol. 335, 2015.
Post-fire salvage logging adds another set of environmental effects to recently burned areas, and previous
studies have reported varying impacts on vegetation, soil disturbance, and sediment production with limited
data on the underlying processes. Our objectives were to determine how: (1) ground-based post-fire
logging affects surface cover, soil water repellency, soil compaction, and vegetative regrowth; (2) different
types of logging disturbance affect sediment production at the plot and small catchment (‘‘swale’’)
scales; and (3) applying logging slash to skid trails affects soil properties, vegetative regrowth, and sediment
production. Four study areas were established in severely burned forests in the interior western
USA. We installed plots at two study areas to compare burned but unlogged controls against skid trails,
feller-buncher trails, and skid trails with added slash. Salvage logged and control swales were established
at each study area, but only one study area had simultaneous measurements on replicated swales. Data
were collected for 0-2 years prior to logging and from 2-8 years after logging.
The skidder and feller-buncher plots generally had greater compaction, less soil water repellency, and
slower vegetative regrowth than the controls. Sediment production from the skidder plots was 10–100
times the value from the controls. The slightly less compacted feller-buncher plots produced only 10–
30% as much sediment as the skidder plots, but regrowth was similarly inhibited. The relative differences
in sediment production between the disturbed plots and the controls tended to increase over time as the
controls exhibited more rapid regrowth. Adding slash to skid trails increased total ground cover by 20–
30% and reduced the sediment yields by 5–50 times compared to the untreated skidder plots.
The replicated logged swales at one study area generally had higher sediment production rates than
their controls but the absolute values per unit area were much lower than from the skidder and fellerbuncher
plots. Results from the swales at the other study areas indicated that logging did not increase
runoff, peak flows, or sediment yields. Vegetative regrowth and sediment production rates varied widely among the four study areas. This variation was largely due to differences in rainfall and soil properties, with the more productive sites having more rapid regrowth and thereby a more rapid reduction in sediment production. The susceptibility to surface runoff and erosion after high severity fires suggests that areas disturbed by ground-based
salvage logging need additional mitigation practices.