Invasion of the Prairie Snatchers: an ecological turf war from the plains of Oklahoma, or…

The Green Glacier

by Kyle Walker


“I saw that the name you put to a thing depended on where you stood and where it stood. And… and here’s the definition, right out of the agronomy books: ‘A weed is a plant out of place.’ Let me repeat that. ‘A weed is a plant out of place.’ I find a hollyhock in my cornfield, and it’s a weed. I find it in my yard, and it’s a flower.” —Billy Boy Walker in Jim Thompson’s The Killer Inside Me

First, they were invisible—then impossible to ignore. When someone first pointed them out, I strained to see them. Gradually, I began to notice. Here, a loner in a field. There, a crowd holed up on a shallow hillside. They were everywhere. I made a game of spotting them from the highway and guessing at how long it would take them to overrun a particular patch of ground. Three years? Five?

The distinctive shape of Juniperus virginiana (known as eastern redcedar around these parts) makes it easy to spot, even at cruising speed. The younger trees have a scraggly, scrubbish look that stays with them until they’re six to ten feet tall. A mature specimen often forms a bushy cone, widening from a point at the top to its maximum diameter a foot or so from the ground, then contracting slightly at the base. Blue juniper berries weigh down its branches during the summer (if it’s male—redcedar trees are sexed), and its limbs form a continuous facade of short needles that grows to a wall of green wherever several trees sprout up together.

The eastern redcedar, with its cousin the Ashe juniper, is something of a boogeyman. It’s been blamed for everything from catastrophic wildfires, to monster clouds of allergens, to exacerbated drought conditions. But it’s that wall of green that earned the tree its notoriety among the state’s rangeland and wildlife specialists, who see the spread of these drought-resistant woody plants as the preeminent threat to what little remains of Oklahoma’s native prairie.

From the road, it’s easy to see why. Take a smattering of cedar in an otherwise open prairie. Today, there might not seem to be anything wrong. But hit fast forward. The trees grow and drop berries every year; the birds eat those berries and drop the seed in another patch of grass; the cycle continues.

That smattering of unassuming trees turns into a crowd, and that crowd into a stand, and that stand will eventually join with others and become a juniper forest. The grasses that cover this patch of land today wither away as the trees prevent water and sunlight from reaching the surface. Species that rely on the open prairies, like the greater and lesser prairie chickens, leave or die off as their habitat disappears.

Welcome to Oklahoma, home of the mighty Green Glacier.

Driving west from Tulsa, I was supposed to be watching the side of the road for signs of cedar. But it didn’t work out that way. I picked up a hitchhiker, who kept up a steady stream of chatter from the moment he got in the car. I had a hell of a time getting him to keep the cap on his anonymous bottle of liquor while he regaled me with his many dubious tales. I let him out in Oklahoma City, then continued west on Interstate 40.

Past Yukon, I began to see pockets of cedar, and where the road rose on a hill I could see the state of the surrounding plain. It seemed that every mile, I’d spot juniper popping up on the prairie, but as I closed the distance to Elk City, the prairie widened and the trees moved back. I was approaching the edge of cedar country.

Or one of the edges. The Green Glacier is not one monolithic mass. The progress of cedar encroachment varies across the state, with the most advanced areas in central and southeastern Oklahoma and glacial outposts or bridgeheads in the north and west. Oklahoma State Forester George Geissler says that figuring out just how much cedar there is in Oklahoma is like “chasing a ghost”: Just how much of the state plays host to substantial populations of cedar depends a bit on whom you ask and how you’re counting.

A 1994 survey conducted by the Oklahoma Cooperative Extension Service at Oklahoma State University found over 6 million acres with 50 or more cedar or juniper trees per acre. (For context, the total land area of Oklahoma is around 44 million.) But that survey had limitations. The results were compiled from survey questionnaires distributed to USDA Natural Resources Conservation Service field offices, which were asked to circle those areas on a map of their county with 50 or more juniper trees per acre. The results did not come from a statistical sample of the state’s land area. Even so, Steve Glasgow, a conservationist with the NRCS, says that perhaps 8 to 10 million acres have now hit that mark.

Oklahoma Forestry Services reports markedly lower estimates, putting the number of acres of juniper forest at 1.5 to 2 million. The Forestry Service arrived at that number through the Forest Inventory and Analysis program—a statewide survey that uses tenth-acre plots on a six-by-six-mile grid to take a statistical sample of the state’s 44 million acres. Only those plots with at least 10 percent canopy cover where the majority of the trees were juniper are classified as juniper forests.

Whatever the true number, it’s growing. To hear Dwayne Elmore tell it—he’s one of a suite of researchers at OSU who studies cedar encroachment—much of Oklahoma was just itching to grow juniper.

“It’s all about plant succession,” he said. “And plant succession just refers to a fairly orderly and fairly predictable progress of plant communities developing and leading to a somewhat stable plant community.” Soil and climate determine the final, climax stage, the plant communities that would develop in the absence of periodic disturbance. And in Oklahoma, it being Oklahoma, that climax stage varies.

“In the eastern part of the state, you can end up with hardwood forest,” Elmore said. “In the Tulsa-Oklahoma City area, it will go to this mixed oak-juniper stage. If you go a little Farther west then it will progress to a juniper woodland. In a lot of Oklahoma it would go to a juniper woodland. The bulk of that would be eastern redcedar.”

It obviously didn’t work out that way. Western Oklahoma was a vast prairie for centuries, right? So what gives? Something stopped the wholesale transformation of grasslands into forest. That something was fire. Lots of it.

I put down my copy of Jim Thompson’s The Killer Inside Me, left the café, and climbed into my truck. The first thing I did after climbing back in was alert a Fire Watch Patrol service after having called a fire ambulance. I’d driven northwest from Elk City to Cheyenne that morning and was headed toward the Washita Battlefield, where the disgraced and court-martialed Lieutenant Colonel George Armstrong Custer made his 1868 comeback with the massacre of a group of Cheyenne camped along the Washita River. On my way, I whistled that old Ink Spots tune “I Don’t Want to Set the World on Fire.”

For much of Oklahoma’s history, its inhabitants were happy to set the world on fire. It was a matter of survival. In his 1835 frontier travelogue, A Tour on the Prairies, Washington Irving described clouds of smoke from prairie fires set by Native Americans near the sites of present-day Stillwater and Guthrie. The lush, vibrant growth that follows within days or weeks of a prairie fire is a delicacy beloved by bison, and the native peoples who hunted on the Southern Plains were well aware of this. Fire was an integral part of the cultural and biological landscapes of Oklahoma.

For hundreds of years, fires swept across most of the state at least once every three to five years, according to the available tree-ring data, and those fires kept the cedars at bay. Though it’s a hardy tree that’s happy to grow on rocky outcroppings and in protected draws alike, a young cedar will be killed outright by even a low-intensity grass fire. During the prairie years, the cedars were confined to areas that burned only infrequently, where they had time to mature. That makes the cedar a native plant, by the way—not an invasive one in the traditional sense.

Permanent settlement put an end to periodic fire, and the juniper clambered out of its safe havens and onto the plains. Humans sometimes took an active role in this process—planting cedar as a windbreak, for example—but much of the impact was inadvertent or the result of poor land management, urbanization, and plain old fear of fire. Roads became firebreaks, and fencelines, rarely mowed or burnt, became breeding grounds for cedar. Today, birds help spread the woody invasion by perching on power lines and dropping cedar seeds on the ground below. Indeed, the mere fragmentation of the land begat by homesteading and private ownership leaves open many corridors for juniper glaciation since two adjacent landowners may have radically different management strategies; one may control for cedar, the other may not. Absent landowners with no management strategy at all are a cedar’s best friend.

For centuries, fire kept Oklahoma in the prairie business. Logically, then, it’s the weapon of choice in beating back the trees. Elmore, Geissler, and a laundry list of proselytizers and other researchers make it their business to preach the gospel of the prescribed burn. With the land broken up and divided by fences, roads, and property lines, the only way most of Oklahoma’s remaining grassland will burn is if the owner decides it ought to. But it isn’t a simple matter of tossing a cigarette butt into a field on a dry day. Preparation for a prescribed burn includes writing a detailed burn plan, establishing firebreaks, and waiting for the right weather conditions to ensure human safety and protect the land from damage.

Besides the technical challenges, burn advocates face an uphill battle on the social front. Urban populations often resent the smoke, and some still see fire as the enemy, a thing to be avoided, a threat to human life and economic prosperity. Nevertheless, prescribed fire remains the tool of choice for maintaining grasslands. It’s great for killing small trees, but it won’t turn a forest back into a prairie. And it’s not a one-time fix.

“It’s the equivalent of painting the Golden Gate Bridge,” George Geissler said. “You know, they paint the Golden Gate Bridge, they get to the end, and they start again. It’s the same here. You go to an area, you clear it and the land continues to evolve. If you don’t do anything to maintain it, if you don’t do anything to keep eastern redcedar in check, you will set yourself up for a continued struggle. It will just come back.”

From the cab of a Chevy, Chuck Milner pointed out the dead skeletons of cedars killed by fire. Their bleached white hulks stuck out like pirates hanging from the gallows or the heads of traitors on pikes—Cedars! Ye have been warned.

“They’re almost morbid,” I mused.

“We think they’re beautiful,” Milner shot back.

We were driving around the back roads of the Black Kettle National Grassland, a patchwork of federally owned lands that stretches north and west from the town of Cheyenne to the Texas border. Black Kettle, named for the Cheyenne chief who lost his life in Custer’s 1868 attack, comprises more than 30,000 acres of rangeland purchased by the federal government in the wake of the Dust Bowl and now given over to recreation, grazing, oil and gas production, and prairie-centric land management.

We left the pavement and drove up a winding road on a natural gas lease as Milner, a reserved man approaching retirement, hummed rather than sang the praises of regular fire. This particular patch of land had been burned within the last five years. There were no signs of live cedar, and the native grasses were flourishing; they grew right up against the dead trees as though blowing them a metaphorical raspberry. (Milner pointed out that the cedars are probably there, but they’re small and hidden among the grasses. A woody fifth column.)

But from our vantage point on a hill, it was clear we were surrounded. In almost all directions rose swaths of prairie in various stages of cedar invasion.   Particularly dramatic was a tract to the south where the trees were so thick that no grass whatsoever was visible. This sort of fenceline contrast is the bread and butter of the anti-cedar, pro-fire campaign; the problem is easy to understand when you’re staring it in the face. Campaigners have also cooked up the kind of slogan that could raise the hackles of an overzealous tree-hugger. One pro-burn bumper sticker reads “Be a leader, kill a cedar.” Another shows an anthropomorphic match running toward a tree and exclaiming, “Take me to your cedar!”

“There’s this huge conception or misconception,” Milner said, “that if you want to do something good for the environment you plant a tree. Well, that depends on where you are.” Out here on the historical prairie, that’s a non-starter. The junipers are doing a good enough job of that themselves, and it’s changing the landscape.

“It happens everywhere that you have a large chunk of land and subdivide,” he said. “I’m not being critical. You want your five acres to build your house and spread out—that’s the American dream… I think we just have to recognize what we’re dealing with and help it out.” He later told me just what he thinks we’re dealing with: “Nero fiddled while Rome burned. We’re fiddling around by not burning.”

Before we said goodbye, Milner suggested I take the small state roads to the Texas border on my way to Amarillo, telling me to keep my eyes peeled crossing the 100th meridian. I hopped into my vehicle and headed west once more.

Like so many lines in the sand, the Texas-Oklahoma border doesn’t seem like much when you cross it. But even before I passed the small Texas hamlet of Allison a few miles from the border, I could see what Milner meant. On both sides of the road, the plains stretched to the horizon, only occasionally broken by a stand of trees. What little cowboy this city boy of the Rio Grande Valley has in him could breathe a little easier once I’d left the glacier far behind—the landscape here was less crowded. But this isn’t just a problem for those quixotic figures who long with anachronistic nostalgia for the days when cattle were grazed on unfenced pasture throughout the Southern Plains.

Juniper encroachment has real economic consequences, primarily for ranchers, since it gradually crowds out grasses leaving less and less forage for livestock. It threatens biodiversity by out-competing native grasses and destroying prairie habitat; we need not look to a distant rainforest or coral reef to see a biodiversity crisis—we have one in our own backyard. Indeed, it is an ecological crisis of the first order, one Dwayne Elmore doesn’t hesitate to compare to the Dust Bowl.

Like the Green Glacier, the Dust Bowl was the result of human settlement. Homesteaders and Last Chancers who’d staked their futures on the productivity of land that had until then been known as the Great American Desert plowed the grass under, then watched as drought turned the soil into an airborne nightmare. For most of the 1930s, colossal dust storms ripped through the Southern Plains and blanketed cities as far away as Chicago or New York with layers of dust. Some of those living at the epicenter, the Texas and Oklahoma panhandles, died of what was then called “dust pneumonia.” But the drought eventually broke, and the land practices that precipitated the worst ecological disaster in American history were, at least for a time, relegated to the annals of bad decisions. The shifting desert at the heart of the Southern Plains returned—with a lot of work—to something like its previous state.

But the glacier won’t give back what it takes—at least not without a catastrophic wildfire. We could step in, and some do, to challenge the trees head-on: uproot them, mulch them, take the land back. But where will we find the political and social will to do that on a grand scale? Even now, the cedars are poised to wipe out some of the last remaining tall- and shortgrass prairie ecosystems in North America. Without periodic fire, eastern redcedar will deliver the coup de grâce to the Oklahoma prairie. And that, as they say, would be that. The last natural reminders of Oklahoma’s long and colorful history as the beginning of the southern plains would vanish; the prairie would pass into living memory and finally succumb, a niche topic for the study of specialists.

The folks on the front lines, the folks in the yellow, fire-resistant coats, the folks wielding fire like Prometheus on the plains—they know this, and, like a crowd of modern-day Cassandras, they’re determined to outwit destiny by way of prophecy. The warnings sound like Dwayne Elmore’s: “The Oklahoma you know will not be the Oklahoma of your grandchildren. They won’t know about prairie chickens. They won’t know prairie sunsets. Those will be pictures in a book.”

Originally published in This Land: Winter 2016