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Compass July 2006
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Compass is a quarterly publication of the USDA Forest Service's Southern Research Station (SRS). As part of the Nation's largest forestry research organization -- USDA Forest Service Research and Development -- SRS serves 13 Southern States and beyond. The Station's 130 scienists work in more than 20 units located across the region at Federal laboratories, universites, and experimental forests.

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Issue 6

Can We Bring Back Faulkner's Big Woods?

by John Stanturf

Say "deforestation" and the image that springs to mind for most people is the Amazon or some other tropical forest landscape. Few would equate the word with the clearing of the vast temperate forests of the Eastern United States that began with the first European colonists, but this country was founded on exploiting the biological wealth of eastern forests. One of the last wild areas in the East to be cleared for agriculture was the rich alluvial bottomland hardwood forest of the Lower Mississippi River flood plain.

Stretching from present day Cairo, IL, where the Upper Mississippi and Ohio Rivers join, to the beginning of the birdfoot- shaped Delta in southern Louisiana where the mighty Mississippi River ends, the Lower Mississippi Alluvial Valley (LMAV) supported extensive hardwood and deepwater swamp forests. This region of 25 million acres provided habitat for waterfowl and songbirds, the cougar, black bear, red wolf, and bison, snakes and gators--and of course, mosquitoes.

This bottomland hardwood forest was far from static, however. Long before the first humans reached the area, the flood plain of the world's third longest river was shaped by climatic and hydrologic cycles and changes. The fluctuating glacial ice sheets farther north sent pulses of sediment-laden water through the valley, building on the foundation laid down during previous ice ages. When the glaciers began to retreat after reaching their maximum extent about 18,000 years ago, the heavy bed load of rock and soil carried by their meltwater was spread across the flood plain of the lower river in a series of overlapping deposits.

The warmer, drier climate that arrived about 9,000 years ago meant less water and lower energy; the river began to meander, episodically changing course and leaving behind distinct landforms within the flood plain. As the climate changed again during the colder and wetter Little Ice Age that occurred between the 1300s and the mid-1800s, the present distribution of tree species emerged, with groups of species adapted to various levels of flooding depth, duration, and season.

Humans Arrive on the Scene

The first humans in the area, hunting and gathering Paleoindians, are now thought to have arrived about 16,000 years ago, using the natural levees of the rivers to traverse the watery lowland regions. Natural levees are the higher and drier sites closest to rivers where floodwaters drop their heaviest sediments. In the Lower Mississippi Valley, the natural levees were often covered with giant cane; the first settlements were located on these drier sites where, around 3,000 B.C., settlers began to develop agriculture, domesticating local species such as sumpweed, a relative of the sunflower grown as a grain.

Maize was introduced from Central America about A.D. 400 and farming took on greater importance. Larger areas were cleared, and eventually cities arose. Cahokia, near present day St. Louis, was the largest city of what archaeologists call the Mississippian culture, with a population of 30,000 in A.D. 1250. It was not until 1800 that another city in the United States--Philadelphia--approached this size.

After the DeSoto expedition (1538-41) and before French settlement began in the late 17th century, Native American populations drastically declined due to introduced diseases. The early French settlers in the Lower Mississippi Valley used the bottomlands much as the Native Americans had; they farmed the natural levees and other higher ground first, depending on the watercourses for transportation. Agricultural expansion was impeded by periodic flooding and the need for drainage, formidable obstacles that could only be overcome by arduous manual labor. The earliest attempt at flood control in the Lower Mississippi Valley was at New Orleans in 1717.

During the 18th century, French settlers along both sides of the Mississippi focused on commercial farming, following the plantation model imported from the West Indies. Some scattered settlements were established farther north along the Red and Missouri Rivers by the time the French settlements were secretly ceded to Spain in 1762, but most of the area's population lived between New Orleans and present-day St. Francisville, LA. The Yazoo River Basin in Mississippi remained Indian land.

Forest Clearing Commences

Photo of oxen hauling logs

Between the early 1800s and 1935, about one-half of the original bottomland forests of the Lower MIssissippi Alluvial Valley were cleared for cotton and other crops. (photo courtesy of Memphis Room, Memphis/Shelby County Public Library and Information Center)

The current agricultural economy of the valley was foreshadowed by the introduction of cotton in 1740 and sugar cane in 1751. An early observer riding up the river from New Orleans in 1810 described continuous plantations for 100 miles. The influx of Acadian settlers from Nova Scotia in 1766 to 1768 greatly changed the nature of European settlement in the area. These Cajuns established subsistence farming and hunting and a distinctive culture in the lower valley.

On December 16, 1811, the most severe earthquake recorded in North America occurred along the New Madrid Fault in Missouri. Towns and villages along the Mississippi River in Missouri, Kentucky, and Arkansas were destroyed. Though little property damage was recorded in the sparsely populated Lower Mississippi Alluvial Valley, the landscape was irreparably changed. The river was affected as far south as Vicksburg, where river islands disappeared. Thousands of acres of bottomlands sank from faulting, forming swamps and permanent lakes, including Reelfoot Lake in Tennessee.

Between the early 1800s and 1935, about one-half of the original forests in the LMAV were cleared. Nineteenth century settlers, searching for fertile farmland, cleared forests--starting from the highest and best drained sites, moving lower and away from the rivers into the backswamp areas over time. Following the transfer of sovereignty over the Mississippi Basin to the fledgling United States through the Louisiana Purchase of 1803, migration into the bottomlands increased considerably. A series of treaties with the Choctaw and Chickasaw tribes opened the east bank of the Mississippi River to European settlers. The first white settlers in the Yazoo Basin of Mississippi probably arrived between 1825 and 1827; within 20 years, it became the premier new planting area for cotton in the South.

By 1850, a continuous chain of plantations ran along the Mississippi and its tributary rivers. The interruption of cropping during the Civil War caused much cleared land to revert to forest, and the neglect of levees led to increased flooding. Severe floods in 1862 and 1865 washed away large sections of levees, while military operations damaged others. After the war, local districts were hard pressed financially to maintain the levees. Appeals were often made to the Federal Government, but a Federal flood control act was not passed until 1917; Federal responsibility for flood control was not firmly established until after the devastating flood of 1927.

Rice and Soybeans Take Over

From 1880 through the 1920s, the oldgrowth pine and cypress forests of the Mississippi Valley were cutover as the South became the center of the timber industry in the United States. Forest clearing in the bottomlands was aided by sales of public land to the expanding railroads, which sought to entice farmers to the unsettled parts of the area, and cut even more wood to fuel their engines. From the beginning to the middle of the 20th century, the LMAV saw new waves of immigration with some new clearing of forest land for agriculture. Farmers from the Lake States and the Corn Belt immigrated especially into the Yazoo Basin from 1907 until after World War I.

New crops such as rice brought new opportunities, beginning in the 1940s. Developing markets in postwar Asia caused an expansion of rice culture into Mississippi and Arkansas. Clearing for soybeans began in the 1950s and extended through the 1970s, extending agriculture into lower lying land that had been considered too wet to be economical. Soybeans have a short growing season as little as 90 days and are adapted to a wide range of soils. Thus, soybeans became yet another alternative to forests, even on those low-lying lands most prone to late-season backwater flooding. Soybean acreage in the LMAV increased fourteenfold from 1937 to 1977, with an estimated 7 million additional acres of forest cleared.

Time to Bring Back the Forest

Most (over 95 percent) of the remaining 5 million acres of LMAV bottomland hardwood forests occur in Louisiana, Mississippi, and Arkansas. The largest contiguous block of bottomland forests, which accounts for 31 percent of the total in the region, is in the Atchafalaya Basin of southern Louisiana. A considerable portion of the remainder lies between the mainline levees that parallel the banks of the Mississippi River between Cairo, IL, and the Gulf of Mexico. Since the 1990s, public and private sector groups have shown an increasing willingness to reverse the deforestation trend and attempt to restore bottomland hardwood forests of the Lower Mississippi Valley.

Early restoration efforts focused on establishing plantings of large-seeded species such as the oaks, assuming that natural processes (wind, water, and animals) would disperse enough lightseeded species to reconstruct the native forests. This low-intensity restoration relied on research conducted mostly at the USDA Forest Service, Southern Hardwoods Laboratory in Stoneville, MS.

Forest Service researchers at the lab in the 1960s and 1970s and their cooperators at universities, the Army Corps of Engineers, and the U.S. Department of the Interior, Fish and Wildlife Service studied ways to collect, store, and handle seed of native species; produce nursery-grown seedlings that were vigorous and would survive when planted on harvested forestland and former agricultural land; and improve the genetic composition of fast-growing hardwoods such as eastern cottonwood and sycamore.

Photo of wheel wagons

In the early 1920s, bottomland forests were logged for timber and fuel for railroad engines--and to clear the best drained sites for agriculture. (photo courtesy of Memphis Room, Memphis/Shelby County Public Library and Information Center)

The scientists who laid this foundation--including Bob Johnson, Harvey Kennedy, Bryce Schlaegel, Roger Krinard, Frank Bonner, and Tom Cooper--have retired, but their research (along with that of Walt Broadfoot and Jim Baker on recognizing the adaptations of different tree species to specific soil conditions and tolerance to seasonal flooding) was critical to successful plantings. Even though this work was motivated by the need to establish commercial hardwood plantations for fiber and solid wood products, the experience gained and technology developed were critical to the emerging efforts to restore hardwoods for wildlife habitat and water-quality protection.

Despite proven techniques that had worked well in the small hardwood stands planted on public land by experienced personnel, the early days of the federally funded restoration programs produced disappointing results. In 1992, for example, fully 90 percent of the plantings on private land under the Wetlands Reserve Program in Mississippi failed due to the low survival of planted seedlings.

A New Day for Restoration Science

Since 1990, a new generation of SRS researchers in a reorganized SRS Center for Bottomland Hardwoods Research in Stoneville, MS, has responded to the need for continued research on restoration methods for bottomland hardwoods, refining operational planting methods. Their continued research to identify the best way to grow good quality seedlings, prepare sites, and control competing vegetation has overcome many obstacles to successful restoration.

In the late 1990s, researchers at the center partnered with forest industry land managers to pioneer more intensive restoration methods. Modeling their approach on ecological processes and focusing on restoring functioning wetland forests as quickly as possible, they developed a cottonwood-red oak interplanting technique where a fastgrowing but short-lived native species (cottonwood) is planted with a slower growing, long-lived species (Nuttall oak).

Because cottonwood cannot tolerate shading, herbicides and mechanical methods are used to control competing weeds for 1 or 2 years, or until the cottonwoods are 12 to 15 feet tall--taller than even the most vigorous weed species. Since the methods used to control weeds would also kill any other tree seedlings planted at the same time as the cottonwoods, planting the Nuttall oak seedlings between every other row of cottonwoods is delayed until after the cottonwoods are 2 years old.

This method produces forested conditions within 3 years (that's how fast the cottonwood grows!), and has been shown to produce valuable wildlife habitat and other restored ecological functions in that time. Although not all functions and native understory species are fully restored in such a short interval, observations in commercial cottonwood plantations document that these young stands are used almost as much by forestdwelling songbirds as natural bottomland hardwood stands.

Restoring the bottomland hardwood forests of the Lower Mississippi Valley has come a long way in the last two decades, but the region is far from fully restored. Many public and private interests are now focused on restoring the area, all with their own motivations and agendas. Scientists at the Stoneville unit strive to produce restoration science that people can use, which means understanding the motivations and needs of users and focusing on the relevant questions.

Most of the land available for restoration in the LMAV is privately owned, making landowners decisionmakers, not just stakeholders. Most landowners want some financial return from their land, thus, the Lower Mississippi Valley will never be returned to its prehistoric condition (even if we knew exactly what that was). It will continue to be a working landscape, a patchwork of field and forest. Nevertheless, public lands will play a limited but very important role in the restoration of the region; public land managers ask somewhat different questions of researchers, many of these related to "ecosystem services" and "sustainability."

For restoration to be sustainable, the future restored landscape must provide a range of goods and services including timber, hunting, bioenergy, and ecosystem services such as storing carbon, moderating water flows, maintaining or improving water quality, and increasing biodiversity.

The Shape of Things to Come

The Lower Mississippi Alluvial Valley certainly has had a dynamic past, and gazing into the crystal ball of the future suggests more of the same--change and adaptation. One big challenge for today's natural resources community of interest (landowners and land managers, policymakers, regulators, and researchers) is anticipating and adapting to the future climate of the area.

Photo of tractor pulling wagons

The 1940s and 50s brought another wave of forest clearing to the region, this time in the lower lying lands that could support soybeans. (photo courtesy USDA Forest Service)

Climate, as we've seen in the history of the bottomland hardwood forests, drives the composition and productivity of forests by regulating available water and nutrients as well as the flooding regime. For the forests of the LMAV, there will be several direct and indirect effects of projected climate change that will have a bearing on restoration strategies and policies. Climate variability means more extremes in the weather; forests close to the coast will likely experience more severe and more frequent disturbance from hurricanes. A warming climate could cause rising sea levels that could flood coastal forests and raise the base level of the Mississippi River and its tributaries, leading to increased flooding longer into the growing season, causing a shift toward more flood-tolerant species such as baldcypress and water tupelo in expanding flood-plain forests.

These direct effects could be overshadowed by the indirect effect of a less certain climate on agriculture. If a generally drier or even a more droughtprone climate occurs, bottomland forests may see a renewed wave of clearing for cropland, especially for irrigated crops, because these flat, moist bottoms would be less risky to farm than the drier uplands.

One role of researchers is to look--over the horizon--and visualize possible futures and anticipate the needs of decisionmakers. Even if our predictions of the future are wrong, we will best serve decisionmakers 50 years from now if today's research continues to look at fundamental relationships among water, land, and people. The need for integrated, multidisciplinary, forward-looking research on the bottomland hardwood forests of the Lower Mississippi Valley is now greater than ever.

John Stanturf is project leader of the SRS Disturbance Ecology unit.

Photo of Regum Natural Area on the Delta National Forest
Regum Natural Area on the Delta National Forest.
(Photo by USDA Forest Service)

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