An Experimental Study Evaluating the Burning Dynamics of Pitch Pine Needle Beds Using the FPA

Abstract

Pine needle litters, a key fuel in coniferous forest systems, are highly porous fuel beds. They provide a source of continuous fuel medium that can be easily ignited and will sustain flame spread on the ground during forest fires. This work represents an experimental study that is focused on the influence of the fuel moisture content on the burning dynamics and the flammability characteristics of forest fuel beds. The FM Global Fire Propagation Apparatus was utilized to obtain time to ignition, heat release rate, total heat released and CO/CO2 concentration data. The methodologies applied in previous studies were improved with new modifications. The results were analyzed with respect to the sample’s fuel moisture content as well as other test conditions, such as airflow condition (wind), sample holder openness and external heat flux. The importance of the fuel moisture content is critical to understand as the majority of fuels present in the natural environment have elevated moisture content compared to dead dry fuel. Samples studied are representative of wet ground fuels as well as live fuels which do burn when crowning conditions develop. The results presented here are a building block for developing an experimental database that can be used to understand the influence of environmental conditions on the flammability of porous forest fuels and assess the risks that comes with a wildfire. Furthermore, the data can also be used for fire behavior model validation.