Background <p>Fire exclusion is recognized to play a crucial role in altering fuel bed flammability and fuel loads worldwide, which can influence the incidence and severity of wildfires and/or the effectiveness of prescribed burning in achieving management goals. Fire exclusion in the eastern USA is believed to have converted oak-dominated woodlands to hardwood forests that are less fire prone, with consequences for reduced biodiversity and ecosystem benefits. An issue that remains unresolved is how fire behavior differentially responds to variation in tree leaf litter surface fuels and grass-based fuels, both of which have been altered by fire exclusion. I examined the relative effects of mesophication (increased ratio of mesophytic to oak litter) and densification (increased tree density and reduced grass cover) on fire behavior by testing two specific hypotheses: 1) Mesophication: fuel consumption and/or fire temperatures in a restored oak woodland are strongly reduced by increasing the ratio of mesophytic to oak litter, and 2) Densification reversal via Graminification: Fuel consumption and/or fire temperatures in a restored oak woodland are reduced more by removing C4 grasses than by reducing the ratio of oak to mesophytic tree leaf litter.</p> Results <p>Both mesophication and graminification hypotheses were partially supported. Fuel consumption (but not fire temperature) was greater in meso-thinned fuel beds indicative of the restored woodland than in mesophied fuel beds indicative of fire-excluded forests. Fire temperatures (but not fuel consumption) were significantly lower in fuel beds in which C4 grasses have been removed than in intact controls.</p> Conclusions <p>Results indicate mesophication and densification, through the addition of mesophytic tree leaf litter and the loss of C4 grasses with canopy closure, respectively, alter fire behavior in different ways. By increasing the moisture of tree leaf litter fuels, mesophication reduced fuel consumption. Despite increasing tree leaf litter fuel loads, densification resulted in the loss of flammable C4 grasses, which in turn reduced fire temperatures. Increasing fuel bed flammability by reducing overstory mesophytes and promoting flammable grasses could facilitate land managers’ meeting fire frequency targets that will become more difficult to achieve with climate change and increasing restrictions on prescribed burning.</p>