The thinner bark of northern red oak may acount for its susceptibility to top-kill by fire. Bur oak and white oak are often maintained in oak savannas, whereas frequent fire reduces northern red oak to shrubby clumps of sprout origin. It sprouts after injury or top-kill. Mortality equations were derived for black oak, white oak, post oak, and scarlet oak. The black oak formula also applies to hickories and to northern red oak.
Frequent fire reduces tree and shrub cover in favor of prairie species.
The stand which had experienced frequent, low-severity surface fires was dominated by black oak and a few northern red oak, and there were few other woody species. In Illinois grassy openings with few trees were burned annually with prescribed fire from 1969 to 1973. With annual fire, prairie forbs increased and woody species declined. Fire was important in maintaining oak savannas at the forest-prairie ecotone. In Tennessee annual and periodic prescribed surface fires were conducted in upland oak-dominated vegetation.