Witness Tree

Nearly two hundred years ago, a fellow by the name of Daniel Miller drove a survey post into the virgin prairie, marking the northwest corner of Section 14, Wilmington Township, Will County. As part of his job, he measured to the nearest sturdy tree he could find. His field notes reveal he selected a white oak, twenty inches in diameter. He blazed the tree with his axe, thus bearing witness to the boundary marker.

The marker is long gone. The tree remains. A witness to so much change at Midewin. From prairie to farmland to arsenal and now back to prairie.

Today, I watch Steve Ringhofer measure the tree. Trained in forestry, he uses a logger tape, specially calibrated to measure both circumference and diameter. He anchors the flexible metal tape to the tree at chest height. He takes a slow walk around the tree, keeping the tape taut, until he arrives back at the starting point. “A hundred ninety-eight inches around,” he calls out. “Sixteen and a half feet.”

Then he surprises me with a quiz. “Do you remember your math? Do you remember how to calculate diameter?” I don’t. “Diameter equals circumference divided by pi,” he says matter-of-factly, before revealing the answer on the logger tape: sixty-six inches across.

Next, he paces off sixty-six feet from the base of the tree. He uses an inclinometer to measure the height. “125 feet tall,” he says. “Same as the spread of the crown.”

The numbers are impressive. I try to impress him back with some numbers of my own. Rather, those of Marlin Bowles, of the Morton Arboretum, who surveyed a large number of different kinds of oak trees — counting tree rings from dead specimens and cores from live specimens — then compiled the date into a table of estimated oak tree ages based on their diameters. According to his table, our Midewin Witness Tree would have been about 130 years old at the time it was blazed in 1821. That means the tree is now over three hundred years old.

“That’s about right,” Steve replies with a nod. “Not a champion tree,” he points out. That distinction is held by a pair of downstate bur oak trees — one in Union County, measuring 23.4 feet in diameter, and one in Wabash County measuring 21.6 feet DBH (Diameter at Breast Height.) “Still pretty impressive, though.”

If you’re wondering why we’re talking bur oaks rather than white oaks, well. it’s possible the original surveyor made a mistake identifying the tree or he might have ID’d it correctly enough, since bur oaks are a sub species of the larger white oak family.

In any event, the tree is impressive. For its age. For its beauty. For the fact that it has survived and watched as cattle replaced bison on the prairie. As the prairie pasture got plowed up for corn. As the corn gave way to munitions bunkers storing record-setting amounts of TNT. As the bunkers are getting busted and the land is returning to tallgrass prairie.

I ask Steve how many witness tree remain at Midewin. Thus far, he’s confirmed three. There are several more he plans to check out, guided by the Witness Trees of Illinois Project — a joint effort of the Morton Arboretum, the Field Museum and several other partners to identify all of the remaining witness trees throughout the entire state of Illinois.

As we hike back to the trailhead, both of us sweating through out shirts in the August heat and humidity, I ask Steve how long our bur oak Witness Tree might live.

“A while yet,” he replied. “It’s healthy.”

I glance back at the oak, its crown rightly towering above all the other trees at the edge of the recovering prairie. It’s pretty certain that I’ll long be dust by the time Midewin is fully restored. But I find it comforting that this oak may still be standing witness when that day finally arrives.