Do rings of Herbie the elm have age, climate data?
YARMOUTH, Maine—Herbie, the giant American elm tree, is giving his trunk over to science.
Since the tree was felled two weeks ago, scientists from Columbia University, the University of Maine and the National Oceanic and Atmospheric Administration have contacted the Maine Forest Service about examining Herbie's trunk to see what can be learned about the tree's age and about the climate over the years.
Peter Lammert of the Maine Forest Service said his computer has been clogged with e-mails from scientists interested in the stories that Herbie's growth rings might tell.
In particular, Herbie's demise is bringing out of the woodwork highly specialized scientists who study tree rings: Dendroclimatologists, who look to tree rings for answers about the climate, and dendrochronologists, who specialize in determining the age of trees based on rings.
The tallest American elm in New England, the 110-foot-tree survived 14 bouts of Dutch elm disease, thanks to the town's long-time tree warden, Frank Knight, who's now 101.
But Herbie was cut down on Jan. 19 after the fungal disease became fatal. Most of the tree's remains will go to artisans who'll create salad bowls, cutting boards and furniture, but several cuttings will be displayed prominently in the town hall, state arboretum and elsewhere. Scientists are interested in taking a look, as well. The tree, with a circumference of 244 inches, had a diameter of about 6.5 feet.
George Jacobson, Maine state climatologist, said it'll be interesting to see whether Herbie's trunk reflects climatic anomalies such as the "year without a summer" in 1816, when volcanic activity halfway around the world led to an exceptionally cold summer in New England.
That year, frost was recorded in every month of the summer, and the colder temperatures and lack of sunlight caused by volcanic ash might be seen in Herbie's rings, Jacobson said.
"I'm glad that people are interested in this type of analysis. We'd have to know more about the tree and its environment and its history before we know what its scientific value is," he said.
For now, Lammert is focused simply on determining the tree's age. Based on the growth rings, Lammert announced after Herbie was cut down that the tree was about 212 years old. But that's subject to change.
On Friday, Lammert and others returned to Herbie's stump to slice away a cross-section of the stump. An examination indicated Herbie likely grew in the wild for 10 to 20 years under the shade of other trees before being transplanted, said Jan Ames Santerre, senior planner with the Maine Forest Service.
That discovery will add 10 to 20 years to Lammert's preliminary age estimate, bringing it closer to Frank Knight's estimate of about 235 to 240 years, Santerre said. The tree would have been a seedling in about 1770-75, by Knight's estimate.
Ultimately, Lammert said he'll invite others to join him for a final examination. The cross-section is big enough for a half-dozen scientists to count rings at the same time. Lammert said it's important to get it right because Herbie was New England's champion elm, watched over for five decades by Knight.
"I want to be real careful," Lammert said. "I want to give Frank a true account of how old that tree is, for the record books."