Bringing Elms Back: Restoring a Wetland at North Bar Lake, Sleeping Bear Dunes

Park rangers with Forest Service researchers Charlie Flower and Nancy Hayes-Plazolles at the study site. NPS photo / T. Withers.

Rows of green tubes

Step off the main trail at North Bar Lake in Sleeping Bear Dunes National Lakeshore and you may find a wetland full of green tubes on wooden stakes, each tagged. Every tube holds a young tree — part of a restoration and monitoring project by the national lakeshore, the U.S. Forest Service (USFS), the Grand Traverse Band of Ottawa and Chippewa Indians and the Little Traverse Bay Bands of Odawa Indians, and a symbol of resilience against invasive species and a changing climate.

The study site. NPS photo / T. Withers.

What invasive species took

American elm (Ulmus americana): umbrella-shaped and adaptable, elms were planted in cities — they're icons of Central Park and the National Mall — and once dominated wetland forests, feeding birds, mammals and insects.

• Dutch elm disease (DED), a fungus from Asia spread by bark beetles and other insects, arrived by accident in the 1930s. It blocks the cells that carry water to the leaves, so they wilt and die and the tree starves.
• It has killed millions of elms — more than 75% of U.S. elms by 1989. Small elms still grow in wetland forests, but most die once they reach about 15–20 feet.

Ash (Fraxinus spp.): now the emerald ash borer (EAB), a beetle from northeast Asia, is wiping them out. It was first recorded at Sleeping Bear Dunes in 2011; today a dead ash is more likely than a living one in northern Michigan's forests, and many of the park's trails are lined with fallen ash logs, their wood etched by larval tunnels.

Emerald ash borer tunnels in a dead ash. NPS photo.

A double loss. Elm and ash play similar roles: both grow in wetlands and form a buffer between floodplains and drier ground. As DED killed the elms, ashes often took their place — and now they're going too, leaving room for invaders that can keep other trees out.

Resistant elms

For about a decade, scientists at the USFS Northern Research Station in Delaware, Ohio, have worked on returning elms to northeastern forests, where dead ash once stood.

• They found "lingering trees" — American elms that survived DED — across 20 states in the Midwest and western New England.
• Cuttings were grafted into clones, together a genetically diverse, DED-resistant population ready for planting.

Testing it in the park

Would it work? That needs testing — which is where the Park Service comes in.

• The lakeshore's vegetation team looks after forest health, including wetlands like North Bar Lake's, once home to black ash (Fraxinus nigra) and American elm.
• Losing the ash changed the wetland: "Having the ash go missing really impacted the water table," ranger LeighAnna Peck says. A black ash wetland shouldn't be very wet, but in spring the crew found standing water sometimes past their knees.
• The site was chosen for its high-quality habitat on all sides, with no roads cutting through it. Planting will help restore it — and let the USFS test elm planting in wetlands, which hasn't been well studied.

Five trees, chosen together

On a warm day in mid-October, rangers and USFS researchers carried trowels, measuring gear, clipboards and hundreds of trees through dense growth to the site. The five species were chosen with the two tribes:

• red maple (Acer rubrum);
• wiinizik — yellow birch (Betula alleghaniensis);
• wiigwaas — paper birch (Betula papyrifera);
• giizhik — northern white cedar (Thuja occidentalis);
• aniib — DED-resistant American elm.

Each once grew in this kind of wetland, each is culturally important to the Anishinaabe, and each is expected to cope well with climate change. The plants came from as near the park as possible — most elms descend from lingering trees in Michigan and Ohio — so they should already suit northern Michigan.

Ranger Taylor Smith prepares to plant a young red maple. NPS photo / T. Withers.

Planting and measuring

This was a return trip — planting began in spring — and the crew split into groups of two or three.

• Planting: the wetland is divided into five blocks of 280 trees each, species assigned at random; the numbered flags placed in spring say which goes where, with cedars between blocks. A ranger digs a hole with a trowel, plants the sapling, and slips a green tube over it, zip-tied to a stake — protection from deer and rabbits — then tags it with the species and planting date.
• Checking the cedars: USFS researcher Charlie Flower and ranger Maggie Mcmillan measured the spring-planted cedars, fenced in chicken wire, noted those lost to the dry summer, and flagged each stake.

Charlie Flower flags a cedar while ranger Maggie Mcmillan records data. NPS photo / T. Withers.

• Measuring saplings: with researcher Nancy Hayes-Plazolles, rangers Lucas Hanson and Megan Machusko lifted each tube, measured the stem's diameter twice with calipers (trees don't grow evenly all round) and its height against a yardstick, then replaced the tube and added a mesh cap — which keeps birds from getting trapped and marks the tree as measured.

Ranger Lucas Hanson measures a young tree's diameter with digital calipers. NPS photo / T. Withers.

The researchers brought deep experience. Ranger Justin Donahue says Hayes-Plazolles talked about the young elms as if she had known them as children, and could say which varieties had done well at other plantings and which hadn't. Peck says Flower has big visions for future restoration work together.

What comes next

Donahue calls the project "a testament of collaboration." The USFS and the tribes, Peck says, have resources the park doesn't: the resistant elms came from the USFS, and the tribes' stories and knowledge have been indispensable.

• Early results are good. Winter is hard on seedlings, and some past plantings have yielded only dead trees — but at North Bar Lake, Flower says, up to 95% of the trees planted in May have survived, far better than most places they've worked.
• The hope: "big happy trees — and baby trees," says Peck; trees "not just living, but thriving," says Donahue, with wildlife returning too. He likes knowing he could come back in twenty or fifty years and see what they started.

But planting alone won't win. There's still no cost-effective way to control DED in a forest; resistant elms may take decades or centuries to re-establish, as new diseases appear; and limited funding has ended many elm-breeding programs. "There's not enough money or manpower to plant our way out of this," Flower says. Public education will matter as much as research.

Sources

Based on "Testament of Collaboration: Restoring a Wetland at North Bar Lake," Sleeping Bear Dunes National Lakeshore, National Park Service, drawing on U.S. Forest Service research on the American elm; a work of the United States government in the public domain. The source names one tribe both "Grand Traverse Band" and "Grand Traverse Bay Band"; this page uses the first. It also calls the Odawa tribe the "Little Traverse Bay Band"; the tribe's name is the Little Traverse Bay Bands of Odawa Indians.