U.S. Joint Fire Science Program


Date of this Version


Document Type



Project Active ID: 01C-3-3-21


U.S. Government Work


In the southeastern United States prescription burning, fire danger rating and wildfire suppression strategies are constrained by limited knowledge of the influence of moisture content in live vegetation, organic soils, water table and weather. The interactive influence of these factors on fire behavior is not well studied. The 3+ year long study reported here was conducted to gain direct empirical understanding of seasonal fuel and soil moisture dynamics in shrub-dominated pocosin communities, in coastal Virginia and North Carolina, mixed hardwoods communities containing significant laurel and rhododendron understory fuels in western North Carolina and eastern Tennessee, and longleaf pine communities in the Piedmont and coastal plains of North and South Carolina. From late 2004 through August 2007 live leaf moisture, dead fuel moisture and soil moisture were repeatedly sampled in each of the three regional vegetation communities. The sites were instrumented with data loggers that recorded soil moisture and temperature. Water table depth data loggers were also installed on the pocosin sites. The results of this complex series of measurements meets the projects goal of filling local and regional knowledge gaps pertaining to soil and vegetation moisture relationships that are directly relevant to fire management plan development and implementation. Four broad areas where our current knowledge limits our ability to predict fire behavior, fire danger and fire effects include: the understanding of the contribution of live fuels to fire behavior in shrub-dominated fuel complexes, the influence of a large proportion of unsound dead fuel on equilibrium moisture content estimation, the moisture limits on consumption of litter, duff and fine fuels in mixed pine/hardwood and longleaf pine wiregrass fuel types, and the influence of hydrology and soil properties on organic soil moisture dynamics and the potential for smoldering combustion in highly organic soils.