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A shifting mosaic of prairie, savanna, and forest, Oklahoma’s Cross Timbers region is an environmentally significant ancient ecosystem a road trip away.
By Kelly Kurt
Published November/December 2013
High on a craggy bluff overlooking Keystone Lake, East meets West in a tangle of post oaks and blackjacks.
The Keystone Ancient Forest Preserve near Sand Springs is part of a transition from the forests of the eastern United States to the prairies of the West. It is, for the most part, a wild, primeval frontier. On these 1,360 acres, post oaks as old as the American Revolution grow in nearly impenetrable thickets. Blackjack oaks shed their lower branches and wear them like armored skirts. Eastern redcedars grip the rocky bluffs that have protected them from wildfires for centuries. Everywhere in between, the prairie stakes its claim with big and little bluestem grasses, Indian grass, and wildflowers.
This forest is part of an ecosystem called the Cross Timbers, which sprawls in ragged remnants across an estimated twelve million acres of central, southern, and eastern Oklahoma and extends into parts of Kansas, Arkansas, and Texas.
“It’s the only place in the world where this unique forest cover exists,” says Mark Bays, urban forestry coordinator for the Oklahoma Forestry Services.
These ancient woodlands helped shape the settlement of Oklahoma and are critical to the state’s wildlife, water quality, and soil conservation, yet they remain generally misunderstood. “It’s not what most people think when they hear the term forest,” says Kurt Atkinson, assistant director of the Oklahoma Forestry Services. “They don’t look at it as a real forest. They think it’s just scrubby old trees that could surely be replaced with better trees, taller trees.” But these craggy forests provide the backdrop for many lakes, parks, and wildlife preserves in the state. In more urban settings, their remnants grow along the Oklahoma River near downtown Oklahoma City and on hiking trails minutes from downtown Tulsa. Rooted in shallow soils and often well-adapted to the stress of drought and the scorch of wildfires, the trees of the Cross Timbers tend to grow slowly. They are, in other words, scrawny for their age. A two hundred- to three hundred-year-old post oak standing in an Oklahoma City suburb, for example, might be only twenty feet tall.
“You think of hundreds-of-years-old trees being hundreds of feet tall and having all these widespread branches,” Bays says, “but that’s not the case in the Cross Timbers.”
The Tulsa Botanic Garden’s two miles of trails are a convenient path through the forest.
Photo by KELLY KURT
The Cross Timbers ecoregion is not defined by timber alone but by a mix of forest, prairie, and savanna. It begins in southeast Kansas, brushes far western Arkansas, and extends into the sprawl of Dallas and Fort Worth, but Oklahoma has more old-growth tracts of Cross Timbers forest than any other state. In the 1990s, Bays says, scientists found a redcedar that was more than five hundred years old in the Keystone Ancient Forest Preserve.
“That means we had a cedar tree in Oklahoma that was alive when Christopher Columbus set foot on this continent,” he says.
When reenactors came to the forest in October 2012 to tell the story of Washington Irving’s trek through these woods more than 180 years ago, many trees played themselves. It was Irving, the famed author of “Rip Van Winkle” and “The Legend of Sleepy Hollow,” who dubbed the Cross Timbers “forests of cast iron” after his difficult 1832 passage.
“I shall not easily forget the mortal toil, and the vexations of flesh and spirit, that we underwent occasionally, in our wanderings through the Cross Timber,” he wrote in his 1835 book, A Tour on the Prairies.
A dozen years later, the explorer Josiah Gregg mapped a great band of such forests that paralleled an expanse he called “Range of the Comanches and Kiawas [sic].” His map makes clear that the landscape, like the tribes, proved a formidable force. The forests were drawn as tentacle-like clusters of huge trees and wore a label identical in size to one denoting the Southern Rocky Mountains.
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The Keystone Ancient Forest Preserve is open from 8 a.m. to 2 p.m. every second Saturday of the month—including November 9 and December 14—and available for guided group tours upon request, pending volunteer availability. There are two trails at the preserve: the 2.8-mile round-trip Frank Trail that leads to vistas of Keystone Lake and the paved .6-mile Childers Trail, which is ADA-accessible. The more challenging Wilson Trail is expected to open in spring 2014. (918) 246-2500 or sandspringsok.com. The entrance to the Tulsa Botanic Garden is at the intersection of North Fifty-Second West Avenue and West Forty-Third Street North in Tulsa. (918) 289-0330 or ocbg.org.