Saving a beanfield oasis.

Towering hardwoods, canebrakes, and hooded warblers are only a few of the resources at risk in this green remnant drowning in an agricultural sea.

Big Oak Tree is one of 78 state parks and historic sites in Missouri, which celebrated the 75th anniversary of its state park system in 1992. With a modest park fund established in 1917, one year after the creation of the National Park Service, Missouri began acquiring its first parks in 1924. Within four years, it joined the front ranks of the states in the size and quality of its holdings.

Though park advocates had thought initially of a chain of parks centered on the stunningly beautiful big springs of the Ozarks, citizens in other regions of the state organized to ensure that their heritage was preserved as well. No campaign attracted more notice and support statewide than a 1937 effort to prevent the logging of the last remnant of old-growth hardwoods from the great forest that once blanketed "swampeast" Missouri, the northernmost reach of the ancient delta of the Mississippi River. At the time, much of the focus was on a single gigantic oak that has since fallen. But today the very ecosystem is in danger--a classic case of a fragmentary island in an agricultural sea.

This essay, printed with the permission of the University of Missouri Press, appears in Exploring Missouri's Legacy: State Parks and Historic Sites, book edited by Susan Flader and co-authored with R. Roger Pryor, John A. Karel, and Charles Callison. It is available for $29.95 through your bookstore or directly from the University of Missouri Press; phone toll-free 800/828-1894.

If you drive south on State Route 102 from East Prairie, across the table-flat farmlands of Mississippi County, it's easy to pick out the boundaries of Big Oak Tree State Park. The 1,000-acre preserve stands out as an oasis of tall trees surrounded by miles of soybeans, a living time capsule for an environment that once stretched across the entire bootheel of southeast Missouri. Big Oak Tree is a monument to both the original forested wilderness of "swampeast" Missouri and to the dedication of citizens who wished to ensure that at least some part of that once-great landscape would be forever protected from logging and drainage.

Your first impression is of the height of the forest and the size of the trees. The canopy rises to 120 feet, with some of the park's giants grabbing another 20 feet of sky. For a time in the 1960s, this small park was home to nine national champions on AMERICAN FORESTS National Register of Big Trees, the directory of the largest trees of some 750 species in the United States. Tiny Big Oak Tree State Park outranked Washington's Olympic National Park, which had seven champions on nearly a million acres and, in turn, was outranked by only Great Smoky Mountains National Park, which had 15. Today Big Oak Tree is home to at least eight state-champion trees and a national-champion persimmon. One swamp chestnut oak--near the picnic grounds at the park's entrance--has a height of 142 feet and a crown spread of nearly 100 feet, making it Missouri's tallest tree. The circumference of this old oak is fully 21 feet. That makes it only a foot shorter and four inches less in circumference than the giant for which the park was named.

The great bur oak that gave its name to the park lived there for 396 years. Once scheduled to be cut down as a curiosity for visitors to the 1904 Louisiana Purchase Exposition in St. Louis, the stately tree survived another half-century before finally succumbing in 1952 to tree rot and lightning strikes. So in 1954 the giant came down, but the park it inspired and the bottomland forest in which it grew both lived on.

The big oak and all the incipient state and national champions were found on an 80-acre tract of virgin hardwoods that, in 1937, became the object of an urgent campaign by local residents to save some remnant of their natural heritage. Reaching the front page of the St. Louis Post-Dispatch and other newspapers, the effort to save the big oak became a statewide crusade. Even Governor Lloyd Stark, a prominent nurseryman in private life, fired off a telegram to the Mississippi Valley Hardwood Company of Memphis asking it not to destroy the tree. Though some people no doubt thought only in terms of a single tree, many realized that what was at stake was the very survival of a part of Missouri's heritage--the magnificent swamp forest of the bootheel.

Logging had begun with a vengeance in the area as soon as railroads crisscrossed the lowlands in the 1880s. New legal mechanisms for land drainage in the early 20th century and an extraordinary cotton boom in the 1920s resulted in the nearly complete transformation of bootheel lands from about 70 percent "unusable" in 1907 to only 3 percent by 1930. But the logging continued on the last vestiges of forest, no doubt spurred on by economic pressures during the depression years of the 1930s. The Mississippi Valley Hardwood Company and associated firms had already cut nearly 750,000 acres in the area when they were asked to spare the 80-acre tract surrounding the big oak.

Still, with the Great Depression constricting the state's finances, Missouri officials could not afford to pay $100 to $125 per acre for the key tract and the sufficient cutover land surrounding it to serve as a buffer or game refuge--especially at a time when parkland in the Ozarks was being purchased for $2 to $5 per acre. The state, with help from a private donor, Jacob Babler, agreed to split the cost of the original 80-acre tract provided local citizens could raise enough money for a 920-acre buffer. Thus began a campaign for donations to save the big trees. Area schoolchildren contributed small change, business leaders gave big change; everyone wanted to help, it seemed, despite the Depression. In 1938 the 1,000-acre park was dedicated.

The 80-acre tract of virgin forest was designated a National Natural Landmark in 1986, and more than 90 percent of the park has been designated a state natural area in recognition of both the virgin timber and the high quality of the second-growth forest surrounding it. Very little remains of the Mississippi lowlands forest that once stretched from southeastern Missouri to the Gulf of Mexico.

The general characteristics of the park--the poorly drained clay soil, the dense understory, and, of course, the big trees--are so different from anything else in the park system that even casual observers find themselves wanting to know more about the local ecology. A boardwalk allows the less adventurous to explore the dense, damp woods and gaze, awestruck, at the towering canopy. Some find it almost spooky to be there, while others think of the forest as a natural cathedral. (Bring along some bug spray in the summertime, though, if you want to be able to enjoy your reverie.)

In the wetter areas, the forest is made up mostly of baldcypress with its odd-looking "knees," along with cottonwood and willow. But on the higher ground--six inches is enough to make a difference here--forest inundation is more seasonal. This periodic flooding with slow drying provides a richly diverse overstory of mixed hardwoods: shellbark hickory, pecan, slippery elm, sweetgum, hackberry, persimmon, pawpaw, possumhaw, blue beech, pumpkin ash, and the great oaks: bur, Shumard, overcup, and swamp chestnut. Various kinds of vines draped throughout the understory create a jungle-like setting, and colonies of resurrection fern cling to the giant trees up near the canopy. The fern is only one of the epiphytes--plants that grow on other plants without parasitizing their hosts--found in Big Oak Tree; bittersweet is also apparent, and pretty, in the fall.

Liant cane, a common species of tall grass on the forest floor, has such an affinity for its own kind that it forms thickets, or canebrakes. It was here amid the canebrakes that one of Missouri's rarest birds, the Swainson's warbler, was last known to nest in the late 1970s.

Birdwatchers from all over the country visit Big Oak Tree to record some of its more than 150 known species, including several that are rare in Missouri. The chirp of the hooded warbler is hard to describe but easy to remember, and the bird's bright yellow plumage makes it easier to spot than some other warblers. The woods are sometimes pierced by a loud "cuh-cuh" from the blackfish crow, a species usually found along the Atlantic and Gulf coasts. And high overhead you might see the Mississippi kite gathering a meal of insects. This rare bird was seen nesting in the park in 1990. More common species include the prothonotary warbler, pileated woodpecker, rose-breasted grosbeak, wintering bald eagle, and a host of waterfowl.

For all its marvels, Big Oak Tree State Park is today an endangered landscape, just as it was in the 1930s. Many of the park's oaks are growing older and dying, with virtually no young ones to replace them. The Swainson's warbler has disappeared from the canebrake, though no one seems to know why. The park's original open marshy lake, known as Grassy Pond, is now an unhealthy thicket of dying cottonwoods and black willows. On the fringes of this now-obscured lake are massive baldcypress trees, hidden by a young growth of willows, red maples, and sugarberries. As the baldcypress trees die, only these thickets will be there to replace them. A new park interpretive center, imaginatively designed like a tree house, explains not only the natural forest and swamp ecosystem that once existed throughout the southeastern lowlands, but also what threatens the health of that ecosystem in the park today.

In 1959 park officials, unaware of the potential consequences, agreed that an artificial lake for fishing would be built in the heart of the swamp. That decision destroyed a biologically rich natural bayou that provided food, shelter, and nesting for many wetland plants and animals. Another, more ironic consequence is that the best fishing today is not in the lake but in borrow pits all around it.

Compounding the problem, officials further agreed to build a drainage ditch through the swamp because some adjacent farmland became flooded when water levels were high. Beavers dammed the ditch, but park officials obligingly dynamited the dams. In the 1980s, park scientists observed that the swamp was dry for most of nearly every year, owing to the disruption of natural flood cycles by the drainage canals circling and bisecting the park. They stopped the dynamiting, offering instead to buy the affected farmland--though farmers were not eager to sell. They also initiated studies to determine whether different water cycles might encourage regeneration of oaks.

The magnificent forest at Big Oak Tree is dying, and extraordinary measures must be taken soon to resuscitate it: more land, a more natural flood cycle, less pollution. Those children who worked so hard to save the big oak trees from annihilation in the 1930s may today as adults decide whether to save the very swamp-forest ecosystem in which those oaks were born.

Susan Flader, a former board member of AMERICAN FORESTS, is a professor of history at the University of Missouri in Columbia.