The burn that took two years to plan was done about a week ago by lighting a combustible mixture of three parts diesel fuel blended with one part gasoline. Teams of spotters followed those who lit the fire to ensure that the blaze remained inside the fire breaks and didn't spread outside the target area of the 238,000-acre forest in southeast Ohio.
Fire is considered vital to help the oak maintain its longtime dominance in the woodland and stop the slow crowding out of oak by other species, most notably the red maple, according to foresters.
Ohio-based research supervisor Dan Yaussy of the National Forest Service compared the potential demise of the nation's widespread oak forests to "losing the Amazon." He said the environmental ripple effect on forest plants and wildlife is a major one.
"We don't even have a grasp of it all yet," said Yaussy.
Even though the reason for the change is not clear, forest experts say they know lack of fire contributed to it.
Oak-dominated tracts traditionally make up more than half of Ohio's timberland. A 2005 woodland census by federal officials shows that more than 45 percent of the state's largest trees, the century-old oaks of the forest, drop acorns that should develop into other oaks, but the next generation is missing.
"Walk around in the woods and look at the young trees," said Roger Williams, an associate professor of forestry at Ohio State University. "Oak's just not there."
Red maple has been flourishing and the oak has been declining for about 80 years, since major efforts began to prevent and control forest fires. Before then, occasional fires helped the oak by killing its competitors that shut out the sun that oak trees need. A thick bark and deep root system make oak trees more tolerant to fire than other species.
Seeds from red maple - which grows well even in the shade - sprouted on the forest floor, with no fires to stop them. Between 1991 and 2005, the red maple's share of the forest grew nearly 25 percent, while the oak's hold dropped by about 7 percent, according to the woodland census data.
Williams said a forest made up mostly of red maples is a climax forest, or the end of the line. The dense canopy of maple foliage blocks sunlight from reaching the ground, which reduces the green flora needed by numerous animals to survive.
The growing dominance of the red maple can be seen in the hardwood region that stretches across the eastern United States, from southern New England down to the Carolinas and west into Texas, Yaussy said.
Researchers started looking into the problem more than a decade ago, and foresters found that fire encouraged oak regeneration. Additional methods include selective harvest to thin the woods and herbicide treatments.
In Ohio, the number of forest acres burned annually rose from just a few hundred in 2001 to more than 5,000 last year. Most of the fires take place on government-owned property in the southern part of the state.
Intense heat created with the burn destroys the life-giving layer of cambium between the bark and the wood of smaller trees - said Gary Willison, the national forest's timber and watershed manager.

Not everyone agrees with the forest burn concept. Protesters used air-quality appeals to delay planned fires at Shawnee State Forest in Scioto and Adams counties along the Ohio River. More than 6,000 people signed petitions against the project.
"It does 100 years of damage in a few hours," said Barbara Lund, 70, of Lynx, a self-described naturalist who doesn't accept the oak regeneration theory.