The most affected soil appears to have lost its entire organic horizon, all of the top mineral horizon (A), as well as over 10%
of the upper B horizon.  More than 5 kg/m2 of soil (organic and fine-mineral components) are now missing, with associated changes in particle-size distribution (for example, many rocks at the surface), bulk density, charcoal content, and many other factors. Nitrogen associated with these losses and changes in remaining
soil add up to about 400 kg/ha.  Combined with vegetative losses (not yet quantified) we expect that up to 18 years of typical N uptake in vegetation was lost.  Losses of other elements know to volatilize at lower temperature (S, P, K) have yet to be quantified.  Taken together, changes in soil organic matter, bulk density, particle size, and nutrient content are likely to impact forest productivity for some time to come.  Tracking new growth against that observed before the fire, and that in unburned treatments will reveal direct measures of wildfire on productivity.  Of particular interest will be to follow the nitrogen-fixing plants that may or
may not come to dominate burned stands.  The LTEP program is considering growth plots of uniform seedlings to evaluate fires of different intensities.  Unlike background changes in vegetation, soils appear relatively unchanged in unburned stands.  Thus, observed changes are easily attributable to the Biscuit Fire.