High-intensity site preparation burning is a common forest regeneration practice on harvested pine and mixed pine-hardwood sites in the southeastern USA. This practice could result in excessive losses of forest floor organic matter and nitrogen, and could subsequently decrease long-term productivity. In general, intensive burning may result in large losses of forest floor nitrogen, primarily by combustion and convection of N gases. However, past studies may have overestimated combustion losses due to inadequate knowledge of potential gaseous N retention mechanisms. Long-term inputs of N from biological fixation and atmospheric deposition may replace large amounts of N lost from fire, but more information on N2 fixation processes is needed over time and space. Also, additional studies are needed to determine practical N-fixation management applications, such as retention of coarse woody debris and enhancement of N2-fixing plant populations.