Influence of Wildfire Severity On Forest Floor and Upper Soil Carbon, Nitrogen and Mercury Pools.

Fire is a large-scale disturbance that has important implications on short and long-term soil nutrient, carbon and mercury dynamics.  Although we know fire leads to combustion of forest floor and soil organic matter and losses of carbon, nitrogen and mercury from soil, little research has been conducted to assess how fire severity influences post-fire carbon, nitrogen and mercury pools. If we can relate fire severity with changes in soil pools, fire severity can be used as a surrogate to assess soil impacts from fire.  In this study we assessed the influence of wildfire severity on forest floor and upper soil carbon, nitrogen and mercury pools following the Pagami Creek Fire that burned from August-October 2011 in northern Minnesota.  We sampled forest floor and 0-10, and 10-20 cm mineral soil depth directly after fire in November of 2011. We assessed severity with two methods using both tree crowns and ground-level disturbance.  We compare both methods to identify relationships with severity metrics and post-fire soil pools, including unburned controls.