Wildfire effects on soil nutrients and leaching in a tahoe basin watershed.
A wildfire burned through a previously sampled research site, allowing pre- and post-burn measurements of the forest floor, soils, and soil leaching near Lake Tahoe, Nevada. Fire and post-fire erosion caused large and statistically significant (P < or = 0.05) losses of C, N, P, S, Ca, and Mg from the forest floor. There were no statistically significant effects on mineral soils aside from a decrease in total N in the surface (A11) horizon, an increase in pH in the A11 horizon, and increases in water-extractable SO4(2-) in the A11 and A12 horizons. Burning caused consistent but nonsignificant increases in exchangeable Ca2+ in most horizons, but no consistent or statistically significant effects on exchangeable K+ or Mg2+, or on Bray-, bicarbonate-, or water-extractable P concentrations. Before the burn, there were no significant differences in leaching, but during the first winter after the fire, soil solution concentrations of NH4+, NO3-, ortho-P, and (especially) SO4(2-) were elevated in the burned area, and resin lysimeters showed significant increases in the leaching of NH4+ and mineral N. The leaching losses of mineral N were much smaller than the losses from the forest floor and A11 horizons, however. We conclude that the major short-term effects of wildfire were on leaching whereas the major long-term effect was the loss of N from the forest floor and soil during the fire.
Murphy
J D
JD
Natural Resources and Environmental Science, University of Nevada, Reno, NV 89557, USA.
Johnson
D W
DW
Miller
W W
WW
Walker
R F
RF
Carroll
E F
EF
Blank
R R
RR
D002118:Calcium / Q000032:analysis; D002244:Carbon / Q000032:analysis; D004784:Environmental Monitoring; D005390:Fires; D006863:Hydrogen-Ion Concentration; D009505:Nevada; D009584:Nitrogen / Q000032:analysis*; D010758:Phosphorus / Q000032:analysis*; D012987:Soil / Q000032:analysis*; D013455:Sulfur / Q000032:analysis; D014197:Trees; D014881:Water Supply
D012987:Soil; D010758:Phosphorus; D013455:Sulfur; D002244:Carbon; D009584:Nitrogen; D002118:Calcium