Ozark mountain forests

• Category: Forest Biomes.
• Geographic Location: North America.
• Summary: This distinct forest in northeastern Arkansas, dominated by oak and hickory, has recently been threatened by an oak-decline event.

The Ozark Mountain Forests occur in one of the oldest mountain ranges in the United States, and exist mainly in the Ouachita and Boston Mountains ranges. This is a temperate and broadleaf mixed forests ecoregion. The forest is dominated by oak-hickory stands, and has a rich history of European timber harvesting and regrowth. Historic forest structure and species composition have been altered, and some recent oak-decline events have been linked to forest management practices. This hardwood forest stretches from the very southern part of Missouri through northern Arkansas and just past the border into Oklahoma, in the central United States.

The current Ozark Mountain Forests biome composition is dominated by mixed oak-hickory-shortleaf pine. Dominant species are red oak (Quercus rubra), white oak (Q. alba), and hickory (Carya spp., especially Carya texana). Disturbed sites, shallow soils, and south-and west-facing slopes are dominated by shortleaf pine (Pinus echinata) and eastern red cedar (Juniperus virginiana).

During the Pleistoncene era, spanning 2.6 million to 11,700 years B.C.E., the Ozark Mountain forests acted as refugia for lowland species. These forests represent some of the oldest in the country: There are thousands of acres of stunted, old growth oaks on sites in western Arkansas’s Ouachita National Forest that have never been cut. The topography here is rugged valley and ridge; peak elevations rise to 2,600 feet (780 meters), with valley descents ranging from 40 to 1,480 feet (150 to 450 meters).

Mean monthly temperatures range from 37 to 81 degrees F (3 to 27 degrees C), with an annual mean of 61 degrees F (16 degrees C). Most precipitation occurs during spring and fall, totaling approximately 49 inches (124 centimeters). The growing season consists of 180 to 200 days. The karst landscape consists primarily of limestone, shale, and sandstone, with many caves and valleys, and the mountainous topography of the Ozark Plateau results in highly variable soils. Soils are typically acidic and rocky, with low organic-matter content.

Wildlife

Only about 3 percent of the original forests remain as intact habitat. However, there is still a fair amount of biodiversity in the mountain forests; there are more than 200 endemic (not found elsewhere) species of plants and animals found here. The forest is also home to nineteen species that are listed as threatened or endangered by the federal government. Along with these vulnerable animals, the land hosts thirty-one Forest Service-listed sensitive species and sensitive plants.

Mammals that inhabit the ecoregion include: white-tailed deer, raccoons, red and gray foxes, coyotes, opossums, otters, minks, eastern chipmunks, beavers, bobcats, short-tailed shrews, squirrels, rabbits, and other small mammals. Black bears and mountain lions can still be found here, but their numbers are limited. Elk and plains bison are gone from the region.

Wild turkeys, quails, pheasants, great horned owls, and the bald eagles inhabit these forests. Other common bird species here are: black capped chickadees, blue jays, northern cardinals, Carolina wrens, cedar waxwings, downy woodpeckers, American goldfinchs, house wrens, northern flickers, red-tailed hawks, northern mockingbirds, white-breasted nuthatchs, red-eyed vireos, red-bellied woodpeckers, indigo buntings, juncos, tufted titmouses, and blue grosbeaks.

Reptiles and amphibians are abundant in the Ozark forests. Some of these include: ringed salamander, long-tailed salamander, dark-sided salamander, four-toed salamander, Ozark zigzag salamander, Ozark hellbender, wood frog, and various snakes and turtles.

In the streams, creeks, and rivers that flow through the region, there are many freshwater invertebrates and fish species, including: chert pebblesnail, black sandshell, Curtis’s pearly mussel, Neosho mucket, salamander mussel, scales hell, freshwater shrimp, belted crayfish, big creek crayfish, coldwater crayfish, blue-stripe darter, blunt-face shiner, channel darter, eastern slim minnow, flathead chub, least darter, Neosho mad tom, Niangua darter, Ozark chub, paddlefish, pallid sturgeon, and brook lamprey.

Human Impact

Historic evidence shows that open oak savanna dominated the Ozark Mountain Forests biome before European settlement. This was partly as a result of an indigenous fire regime that annually burned hundreds of acres (hectares) and decreased undergrowth and tree densities by decreasing tree recruitment and establishment. Thus, forest species composition historically favored shade-intolerant, fire-tolerant canopy species. Fire was an important feature of these landscapes before increased fire-prevention efforts around 1920. Increased European settlement, beginning around 1830, resulted in increased clearing for agriculture and grazing.

The Ozark National Forest was established in 1907 by President Theodore Roosevelt and the head of the U.S. Forest Service, Gifford Pinchot. This first national forest encompassed 55,000 square miles (142,500 square kilometers), but the new status of the forest did not much change the management until mandates were enacted in 1920 to combat large forest fires. Decreased forest fires meant establishment of closed-canopy forest stands, in contrast to historic open savanna ecosystems.

Further altering the ecosystem was the practice of industrial clear-cut timber harvesting, which boomed in northern Arkansas in the 1920s and 1930s, and resulted in even-aged stands of white, red, and black oak (Quercus); hickory (Carya); and shortleaf pine (Pinus echinata) in the Ozark Mountains range. Oak and shortleaf pines were the most important species in this landscape before European settlement, but changes in species and forest structure as a result of fire suppression beginning in the 1920s can be noted in changes in recent forest assessments in understory composition.

The Ozark chinquapin, recognized as a species in 1923, is an indigenous tree species in the Ozark Mountains that was believed extinct until a naturalist located living examples in Arkansas in 2006. Ozark chinquapin (Castanea ozarkensis) and black oak (Quercus velutina) decreased in the forest composition from 1934 to 2002. Chestnut blight (Cryphonectria parasitica) is likely responsible for the decrease in chinquapin, but the decrease in black oak is less well understood. An effort to restore the chinquapin population through a breeding program has commenced through the Ozark Chinquapin Foundation, which as of 2021 had established eighteen test plots. Also noted in the Ozark Mountain Forests was an oak-decline event in the early 21st century in the Boston Mountains range.

Ecosystem benefits are in part viewed as the economic, recreational, and social values of nature; thus, the ecosystem services provided by the Ozark Mountain Forests biome include water quality maintenance, timber-important species (predominantly red oaks), and potential carbon sequestration. Many of the communities of southern and middle Arkansas rely on the water resources located in the this region, which the forests in part help to purify for public use. Recreation opportunities in the Ozark Mountains include the Ozark Highlands Trail, which was constructed and maintained by more than 3,000 volunteers and is the longest hiking trail in the forest. The trail extends 168 miles (270 kilometers) from Buffalo National River to Lake Fort Smith State Park to the south.

The fragmentation of forest lands due to changing forest ownership and physical degradation are current threats to ecosystem health and functionality. The individual importance of tree species importance in the Ozark Mountains has related heavily to timber and, to a lesser degree, recreation. Oak-pine-hickory dynamics formerly represented the dominant forest species, with some decrease in the value of timber lands due to poor silvicultural management. The even-aged characteristics of the forest relate to the re-establishment of forests following agriculture, clear-cutting, and fire suppression. The U.S. Forest Service found that 72 percent of the hardwood forests existing in the Ozark Mountains regions are between 40 and 90 years old, with only 21 percent more than 90 years old.

Bibliography

Chapman, R. A., et al. “Long-Term Changes in Forest Structure and Species Composition of an Upland Oak Forest in Arkansas.” Forest Ecology and Management, vol. 236, no. 1, 2006.

Hunter, C. G. Trees, Shrubs, and Vines of Arkansas. Ozark Society Foundation, 1995.

“Ozark Mountains Stewardship and Restoration on the Ozark National Forest, Arkansas.” National Forests Foundation, 2014, www.nationalforests.org/assets/pdfs/Final-Site-Report-Template‗Ozark‗Design.pdf. Accessed 8 Oct. 2024.

Ricketts, T. H., et al. Terrestrial Ecoregions of North America: A Conservation Assessment. Island Press, 1999.

Starkey, Dale A., et al. Forest Health Evaluation of Oak Mortality and Decline on the Ozark National Forest, 1999. United States Forest Service, 2000.

Stebbins, Brennan. "Saving the Ozark Chinquapin." Missouri Life, 20 Jun. 2021, missourilife.com/saving-the-ozark-chinquapin/. Accessed 8 Oct. 2024.