BENSON — Elm trees in New England were nearly wiped out by disease more than 50 years ago, but a small number of the majestic trees survived.
Now researchers are asking why and hoping the answer could help restore the trees to the landscape and even limit flood damage in the process.
It all started nearly a decade ago when workers with the U.S. Forest Service and The Nature Conservancy planted around 5,300 elm trees in a 28-acre orchard in hopes of restoring the once-abundant tree to New England’s landscape.
Elm trees suffered a mass die-off in the 1970s, said Gus Goodwin, a conservation planner with The Nature Conservancy in Vermont. The tree is tied to the region’s history and is integral for future flood resilience, he said.
Researchers identified 53 “survivor” elm trees in New England, Goodwin said. These are trees that survived around outbreaks of Dutch elm disease, said Chris Hansen, a research technician with the University of Vermont. This experiment will test if the trees are truly resistant.
“In order for this to be successful for restoration efforts, we need diversity of elms,” Hansen said. “We need to keep finding more survivor elms. We need to keep propagating them. We need to keep creating seed orchards and having that available for restoration efforts.”
Elm trees can grow in low light conditions and are a prime species for flood plain forests that help slow and store floodwaters, ultimately making it safer for people to live in flood plains, Goodwin said. Many Vermonters live in flood plains because of typography and the way the state has settled, he added.
“One of the most important pieces of the natural infrastructure that protects us are these flood plains, so investing in their health and function is important,” Goodwin said. “Elm is one of those ways we can invest in them.”
Last week, The Nature Conservancy and the Forest Service came back to the Benson orchard to infect the trees with the same fungal disease that caused the species’ decline, putting their decadelong experiment to the test.
“We really don’t know how well they’re going to respond,” said John Butnor, research plant physiologist with the U.S. Forest Service. “There’s probably only a few of these that may be totally unaffected, but there are some that might tolerate it and actually bounce back, so that’s what we’re really looking for.”
Butnor said the team will be coming back to the site to rate trees’ response to disease like dieback and then analyze the data to identify which trees to focus on in the future.
Butnor — who is based out of the Forest Service research lab in Burlington that is under threat of closure due to national reorganization efforts — said he studies the elm trees’ cold adaptation and budding timing to understand how the trees will react to weather changes.
Leila Wilson, a research ecologist with the Forest Service, said she and the team at a U.S. Forest Service lab in Ohio took branches of the 53 New England-adapted “survivor” trees and made them flower and collected the pollen, which they then crossed with other elm trees planted in Ohio. The 5,000-plus trees in Vermont are the resulting progeny.
Once the surviving progeny trees are identified, the clones of the parent species will be planted in seed orchards on Nature Conservancy-owned land in Shelburne and elsewhere in New England for further study, said Wilson.
There are similar efforts in three other regions of the U.S., Wilson said, but this is the biggest regional effort, given the number of trees planted, the number of survivor elms represented and the number of partners involved in the effort.
The goal of the project is to make elm tree seeds widely available to plant the key species both in flood plains and urban areas, so eventually fully developed American elms can once again contribute to biodiversity and resilience of the New England forest canopy, Goodwin said.
“Elm would be a tremendous species to have in the mix there. It’s fast growing. It’s really hardy and vigorous. It’s cold tolerant, so it thrives in a wide range of climates,” Goodwin said. “It’d be great to see it planted out in the landscape.”
