An Ozark Fire History

Missouri's natural communities have been shaped by humans and wildland fires for thousands of years. In many ways, the history of fire in Missouri also is a history of human population, culture and migration. Fires caused by natural ignition, like lightning, are rare. Despite as many as 50 to 70 thunderstorm days per year, Conservation Department studies indicate that less than 1 percent of modern day fires are started naturally. Humans have been, and continue to be, the primary cause of most wildland fires in Missouri.In Native American cultures, fire was a tool used to create conditions to benefit farming and hunting. In the distant past, people of the Mississippian culture settled the rich fertile bottom lands in Missouri. These permanent populations may have used wildland fires to clear land to enhance defense of their villages and to improve production of cultivated crops. Fruits, berries and many other natural foods flourish on sites where fires have burned.

Wildfires of direct human causes also may have resulted from wars, hunting techniques or even accidents. But for hundreds, if not thousands, of years the most important reason for deliberately setting fires has been to maintain grasslands by preventing the forest from taking over. Grasslands and savannahs provided food for bison, elk and deer. Even today, fire is used in many parts of the world to promote grassland for domestic cattle.

French Jesuits, such as Father Vivier, were the first to describe the Missouri landscape. In 1750, he writes, " . . . wherein trees are almost as thinly scattered as in our public promenades. This is partly due to the fact that the savages set fire to the prairies toward the end of autumn, when the grass is dry; the fire spreads everywhere and destroys most of the young trees." Later travelers, including Henry Rowe Schoolcraft, who traveled through the Ozarks in 1819, described a landscape of prairies, oak savannahs and oak-pine forests shaped by fire.

How can we know, other than through accounts of early explorers in the area, what the long-term relationship of man and fire has been? The story of humans and their use of the land can be deciphered by studying burn scars on living trees or old stumps and snags.

When a low to moderately intense surface fire burns a tree, a portion of the living tissue under the bark, known as the cambium, may be killed by the heat. This injury 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. Acquisition of horses gradually gave this tribe greater mobility to hunt, exploit and influence (by fire) a large area. Then, diseases introduced by Europeans decimated many Native American tribes and probably greatly influenced the frequency of fire in the Ozarks and in all of North America. Outbreaks of diseases in 1698, 1747 and 1751, for example, killed 80 percent of the Quapaw people southeast of the Ozarks.

Migrations of tribes pushed westward by Euro-American settlement of the eastern United States coincided with an increase once again in fire frequency between 1780 and 1820. Delaware, Shawnee, Cherokee and other tribes passed through Missouri during this period.

By the 1820s and 1830s, Euro-American settlers spreading westward had displaced most of the Native American population. Exponential increases in human population explain the increase in fire frequency from 1810 to 1850. The relatively high density of settlement was responsible for widespread burning in the rugged terrain of the Ozarks during this period.

Settlement also brought railways and a more modern overland road system in the late 19th century. Transition to a regional economy from the historically local form of commerce in the Ozarks brought about yet another chapter in fire history. Timber became increasingly valuable and, in 40 years or so, loggers had harvested most of the shortleaf pine and much of the better quality hardwood in the region.

The slash left from logging operations fueled major wildfires ignited by farmers trying to convert forest into pasture. Not only were human lives threatened and homes destroyed by the rampant wildfires, but frequent burns significantly decreased the value of the remaining timber. When Missourians finally realized this method of resource exploitation degraded the value of remaining forest, the cycle of how they used fire changed.

Timber, once worth little to the settlers, became quite valuable. Population density made wildland fires a serious hazard to life and property. In the late 1930s, the Conservation Department, U.S. Forest Service and rural fire protection organizations developed successful fire suppression programs to protect lives, timber, homes, buildings and other rural improvements.

Although there are still some localities in Missouri where frequent burns take place, the role that wildland fire plays in our ecosystems and natural communities has been substantially reduced. Today, prescribed fire (fire with a defined purpose) is being introduced into some of our wildlands to foster wildlife habitat, plant diversity, prairie restoration and timber production.

The judicious use of prescribed fire and the suppression of wildfires should result in a natural heritage as diverse in ecology and beauty as what the first explorers described.