An Ozark Fire History
results in a scar on the growth ring of that year. Scientists can date fire scars to an exact calendar year by using a dendrochronological method called tree-ring dating.
Tree-ring dating identifies unique patterns of wide and narrow rings of growth in the wood created by variations in climate and growing conditions. The tree rings in wood and stumps of unknown age can be compared to known tree-ring patterns and, thus, any fire scar can be attributed to a specific year.
Some shortleaf pine stumps in the Missouri Ozarks have been preserved for centuries by resins-compounds produced by injured trees that protect wounds and prevent wood decay. The scars on these old stumps provide a record of wildland fire that dates as far back as the early 1600s.
Combining fire scar dates from several stumps and trees in a forest yields a fire scar chronology, or fire history, for that area. Fire histories can be compared with changes in vegetation, land use, wildlife, human population and culture to help us better understand how humans interact with the ecosystem.
Site-specific fire histories developed in parts of the Missouri Ozarks reveal that human population and culture are closely linked to the frequency and intensity of fire over the last 400 years. Where population density was greater than one person per square mile, fires occurred every one to five years. In more sparsely populated areas, fires burned every 10 to 30 years on average.
Before European settlement, widespread fires burned over large portions of the Ozarks. Fire scar data compiled from a number of different sites show that extensive fires occurred in 1728, 1753, 1772, 1777, 1780, 1795, and 1800. Extreme drought combined with fires set during Native American migrations and territorial conflicts set the stage for these conflagrations.
In 1780, for example, the drought conditions and the mass movement of Native Americans westward were of continental proportions. Fires burned almost 70 percent of 30 fire history sites in the eastern Ozarks. In the Current River watershed alone, hundreds of thousand of acres burned. A thousand miles northeast of Missouri, dated fire scars from pine stumps in the Algonquin Highlands of southern Ontario show that in 1780 thousands of acres burned, as well.
Native American populations fluctuated in the 1700s and 1800s. The pattern of fires was, in turn, affected by these fluctuations. In the early period of recorded fire history, the Osage tribe dominated much of the Missouri Ozarks.