WISCONSIN—Once common across eastern North America, the American elm is deeply ingrained in our nation’s history. However, a large portion of the tree population was affected by Dutch Elm Disease beginning in the 1930s.

Today, short-lived elms can still be found in forests, but because they tend to be much smaller, they no longer play such an important ecological role. A multifaceted collaborative effort is underway to restore the stately and once dominant American elm to persist on the landscape of the nation’s forests.

Today, there is still a small number of large, healthy surviving American elm that somehow emerged unscathed in the aftermath of the disease. Researchers are acquiring and testing clones of these survivors for resistance. Once enough DED-resistant parents have been collected, orchards will be established to produce seed that can be grown in nurseries, and then planted in appropriate forests to meet specific management goals. Of particular interest is the use of American elms in ash-dominated floodplains impacted by emerald ash borer. DED spreads through root grafts, so spreading out elms will reduce the risk of DED moving between elms.

Northern Research Station is leading the effort to identify disease resistant elms with projects currently focused on American elms from the Midwest and western New England. They are assisted by Eastern Region State, Private, and Tribal Forestry in addition to the Chippewa and Superior national forests in Minnesota, Chequamegon-Nicolet National Forest in Wisconsin, and Huron-Manistee and Ottawa national forests in Michigan. These national forests have been identifying and collecting shoots from survivor elms and providing testing sites for survivor elms.

The Northern Research Station is creating clones of the upper Midwest survivor elms through softwood cuttings. In the coming years these clones will be planted and tested at sites in Oconto River Seed Orchard in Wisconsin, connected to Chequamegon-Nicolet National Forest, and at a historic nursery site on the Huron-Manistee National Forests. The entire process takes about 15-20 years to complete.

“It is exciting to see us finally capturing clones of these magnificent trees. The progress we’ve made in the last two years would not have been possible without the cooperation of the many, many partners,” said Linda Haugen, plant pathologist with the State, Private, and Tribal Forestry field office in St. Paul, Minnesota. Haugen is coordinating capturing clones of survivor elms from northern cold hardiness zones and the Upper Mississippi watershed.

Work on American elm has been ongoing for several years. In 2014, foresters across several states conducted operational trials of thousands of seed origin American elms. They identified vulnerabilities such as deer browsing, weed competition and flooding that can contribute to planting failures. This earlier work helped to steer current elm restoration efforts.
That same year, researchers worked with the Army Corps of Engineers and the Oconto Seed Orchard to plant trees for study to determine whether DED-resistant elm parents produce resistant seedlings. The study results should be available by 2024.

“We need to develop populations of American elm that are locally adapted and genetically diverse. We hope to work with partners to establish similar programs throughout the range of the species,” said Cornelia “Leila” Pinchot, a Northern Research Station research ecologist, who co-leads the project with Kathleen Knight, also with the station.

Northern Research Station is working with collaborators on four distinct populations of elms across the Forest Service’s Eastern Region. The elm work is made possible through funding support from the Manton Foundation and the Forest Service Washington Office, as well as contributions from many partners.

Individuals and natural resource organizations are welcome to report survivor elms via the American Elm Survivor Database. Over 1,000 reports have been collected thus far.

Several state agencies are helping identify disease resistant elms. They include Michigan Department of Natural Resources, Minnesota Department of Natural Resources, University of Minnesota, Wisconsin Department of Natural Resources and the Wisconsin Board of Commissioners of Public Lands. The Nature Conservancy and Army Corps of Engineers are also key partners in the project, and a number of private landowners are participating.

This story is part of a series and highlights one of the 14 common themes identified in the 2020 Eastern Region State Forest Action Plan summary report. The theme for April 2023 is Forest Health.