At the burned site we chose to collect both burned SOM and the
underlying unburned soil because we reasoned that both of these
materials are fueling microbial decomposition at the burned site.
The presence of unburned soil in our burned SOM sample might in
part explain why we did not observe significant differences in SOM
chemistry between the two study sites. A second consideration is
that we collected SOM from the burned site approximately 13
months after the fire. Given this time lapse, we may not have
captured the more ephemeral soil changes that occur following
forest fires. For example, ash deposition on the soil surface can
increase inorganic N availability (Wan et al., 2001), but this increase
is typically transient because recovering vegetation and soil microbes
can quickly assimilate this nutrient pulse. In the Gilles Creek
fire scar, the availability of NO3
returned to pre-fire levels within 3
months of the fire (Holden et al., 2013). Therefore, our experiment
captured the more long-lasting effects of fire on SOM rather than
the short-term effects. Similar studies comparing the decomposition
rate of burned SOM collected at multiple depths and time
points following a forest fire would advance our understanding of
the effects of fire on SOM and the corresponding consequences for
decomposition.