Wildfire effects on soil nutrients and leaching in a tahoe basin watershed

J Environ Qual. 2006 Feb 2;35(2):479-89. doi: 10.2134/jeq2005.0144. Print 2006 Mar-Apr.

Abstract

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.

MeSH terms

  • Calcium / analysis
  • Carbon / analysis
  • Environmental Monitoring
  • Fires*
  • Hydrogen-Ion Concentration
  • Nevada
  • Nitrogen / analysis*
  • Phosphorus / analysis*
  • Soil / analysis*
  • Sulfur / analysis
  • Trees*
  • Water Supply

Substances

  • Soil
  • Phosphorus
  • Sulfur
  • Carbon
  • Nitrogen
  • Calcium