n. The phenomenon of fire spreading across an already burned fuelbed.
The term reburn actually describes two separate phenomena. One is the burning of an upper fuel stratum after a fire has burned through a lower stratum. For example, a fire backing down a steep slope may burn only the litter beneath a shrub canopy (the lower fuel stratum) when the fire front first passes. Later, under the influence of stronger winds, drier fuel or a flaming front oriented in the heading direction, a second flaming front may spread through the upper shrub canopy layer even though the litter has already burned.
The second reburn phenomenon occurs when a fire burns in a fuelbed composed of fuel created by a previous burn. For example, fuel load increases following a stand-replacing fire as twigs, branches, scorched needles, and tree boles fall to the surface. A subsequent fire burning through that fuelbed is said to be a reburn.