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Testament of Collaboration: Restoring a Wetland at North Bar Lake

A group of NPS rangers and USDA Forest Serviceresearchers, many wearing orange hats, pose with plants and equipment in an open wetland environment. — NPS rangers and USFS researchers, Charlie Flower and Nancy Hayes-Plazolles, pose with equipment at their research site.
NPS Photo / T. Withers

Stepping off the main trail at North Bar Lake, you might find yourself in a wetland filled with rows of green tubes and wooden stakes. The tubes, each marked with their own tag, are part of a restoration and monitoring project. This is a collaboration between multiple agencies, including Sleeping Bear Dunes National Lakeshore, the US Forest Service (USFS), the Grand Traverse Band of Ottawa and Chippewa Indians, and the Little Traverse Bay Band of Odawa Indians. Each tube in this wetland contains a young tree. Collectively, they serve as a symbol of resilience in the face of invasive species and a changing climate.

Green tubes attached to upright wooden stakes stand in rows in a wetland habitat among white tree trunks, yellowing ferns, and other plants. — The wetland study site near North Bar Lake.
NPS Photo / T. Withers

Invasive Species in US Forests

Forests in the eastern United States have been heavily impacted by invasive species. Some historically prominent trees, like the American elm (Ulmus americana), have been affected more than most. Elms, with their umbrella-like shape, are versatile trees that have often been used in urban landscaping. They are iconic in places like Central Park and the National Mall in Washington, DC. Elms were also historically dominant trees in wetland forests, providing an important food source for birds, mammals, and insects.¹

The accidental introduction of Dutch elm disease (DED) in the 1930s has since devastated elm populations. A fungal infection native to Asia, DED is easily spread by bark beetles and other insects that move from tree to tree. DED disrupts the cells that carry water to the leaves, causing the leaves to wilt and die, eventually starving the tree. The disease has killed millions of elms since its introduction, wiping out over 75% of the elm trees in the United States by 1989.² While you can still find small elm trees in wetland forests today, most die of DED once they reach about 15-20 ft tall.²

Overlapping tunnels are visible in the exposed wood underneath the bark of a dead tree. — Tunnels from the emerald ash borer are often seen in the wood of dead ash trees.
NPS Photo

More recently, ash trees (Fraxinus spp.) have been decimated by the invasive emerald ash borer (EAB), a beetle native to northeast Asia. EAB was first recorded at Sleeping Bear Dunes in 2011. Today, you are more likely to find a dead ash tree in the forests of northern Michigan than a living one. Many trails within the Lakeshore are lined with sections of fallen ash trees. Looking closely at these logs, you will see that they are scarred by the mazes of tunnels chewed by EAB larvae.

Trees like ash and elm have similar ecological functions. Both can grow in wetland environments. They create a crucial buffer between floodplains and other, drier, habitats. As the spread of DED killed elms, ashes often replaced them in wetland environments. Now that the ash trees are disappearing too, other wetland species are suffering the effects. The decline of ash creates opportunities for new species to inhabit the wetlands, including invasive species that may prevent other trees from growing.³ This plight has been the focus of scientists at the USFS’s Northern Research Station in Delaware, OH.

Over the last decade, USFS scientists at the Northern Research Station have been studying how to reintroduce elms into forests throughout the northeastern United States. The goal is for elms to reestablish themselves where the now dead ash trees had taken over.

The project began by identifying American elm trees that survived infection by DED, known as “lingering trees”. These trees were located across 20 states throughout the Midwest and western New England. Scientists collected cuttings from these trees and grafted them to create clones. Together, the variety of samples create a genetically diverse population of DED-resistant clones. After growing for a time, these trees are ready to be planted.

Testing a Habitat

How do scientists know that this plan will work? In short, they can’t—at least, not without testing it first. This is where the National Park Service comes in. The vegetation team at Sleeping Bear Dunes maintains forest health across the park, including in wetland areas like the one near North Bar Lake. These areas were historically populated by trees like black ash (Fraxinus nigra) and American elm, which have now been wiped out by invasive species. The team has seen major changes in the wetland at North Bar Lake as the ash have died. “Having the ash go missing really impacted the water table,” says ranger LeighAnna Peck. “Black ash wetlands shouldn’t be super wet, but in the spring when we went out there was standing water, sometimes past your knees.” Planting new trees in these wetlands will help to restore the habitat. LeighAnna adds that the wetland at North Bar Lake was chosen specifically because there is “high quality habitat on all sides,” which isn’t separated by roads. Planting new trees in these wetlands will help to restore the habitat. It will also allow the USFS to test the success of planting American elms in wetlands: something that hasn’t been well studied yet.

Two NPS rangers, both wearing orange hats, walk through a wetland. The ranger on the left is carrying a trowel and a bag filled with sapling trees. — Two rangers walk through the wetland, carrying sapling trees to plant.
NPS Photo / T. Withers

And so, during a warm day in mid-October, a team of park rangers and USFS researchers trek through the dense vegetation to their study site. With them, they carry trowels, measuring equipment, clipboards, and bags containing hundreds of trees. The five species of trees were carefully chosen through discussions with the Grand Traverse Bay Band of Ottawa and Chippewa Indians and the Little Traverse Bay Band of Odawa Indians:

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; Ulmus americana)

Much consideration went into choosing these trees. Each of these species would have historically been found in this wetland ecosystem. Additionally, each is culturally important for the Anishinaabe people. The trees are also predicted to do well in response to climate change. Even the plants themselves have been carefully selected. Rangers, researchers, and the tribes wanted to use plants from as close to Sleeping Bear Dunes as possible. For example, most of the DED-resistant elm trees are offspring of lingering trees in Michigan and Ohio. These plants should already be well-adapted to the climate of northern Michigan, so they will be more likely to survive in their new habitat at North Bar Lake.

An NPS ranger wearing an orange hat kneels in a wetland and prepares to plant a sapling tree in the soil.l — NPS ranger Taylor Smith prepares to plant a young red maple tree.
NPS Photo / T. Withers

The Reforestation Process

This is a return trip. Rangers and researchers were already planting here in the spring, and this week they are back to finish the job. When they reach the study site, they split into groups of two or three. Most of the rangers are focused on planting sapling trees. The wetland has been divided into five blocks. Each block will be planted with 280 trees, each of a random species. As they wander through the vegetation, they search for the planting sites they flagged in the spring. The number on the flag indicates which species will be planted there. The cedar trees are planted between each block.

Once they find the site, one ranger uses a trowel to dig into the soil. They create a hole big enough for the sapling’s roots to fit. The planted tree is then covered by a green tube, which is zip-tied to a wooden stake to hold it upright. The tube prevents animals, like deer and rabbits, from eating the young tree while it is still vulnerable. Finally, they label the tube with a tag identifying the tree species and when it was planted.

Some park rangers stick with the USFS researchers, Charlie Flower and Nancy Hayes-Plazolles, as they focus on recording measurements for their research. Charlie and park ranger Maggie Mcmillan examine the northern white cedar trees planted in the spring. Surrounded in chicken wire, the cedars stand out from the other young trees. Together, Charlie and Maggie measure how tall the surviving trees have grown. They also note any that did not survive the dry summer. Charlie then flags and labels the stakes at each tree.

A USFS researcher ties orange flagging around a stake inside of chicken wire fencing while an NPS ranger in an orange vest and hat records data on a clipboard. — USFS researcher Charlie Flower flags a cedar tree, while NPS ranger Maggie Mcmillan records data.
NPS Photo / T. Withers

Meanwhile, rangers Lucas Hanson and Megan Machusko work with Nancy to measure the saplings planted earlier in the week. They use the tag to identify the tree, then gently lift the tube to expose the plant. Lucas holds the stem upright while using a tool called calipers to measure its diameter. He takes two measurements since trees don’t grow perfectly in all directions. While he does this, Megan holds a yardstick next to the sapling so Lucas can measure its height. Once Nancy has recorded all the data she needs, the protective tube is replaced over the tree and Megan fits a mesh cover over the top. The cover serves a dual purpose. It keeps birds from becoming trapped in the tube while also indicating to Nancy that they have already recorded data for that plant.

Both Charlie and Nancy bring a different perspective to the project. Ranger Justin Donahue describes how Nancy talked about how the sapling elms got there: “It was like she knew them as a child.” Recounting experimental plantings at other locations, “she was able to say, ‘this variety did well here, but not over here.’” On working with Charlie, LeighAnna adds, “he has big visions for restoration and what we can work on together in the future.”

A ranger's hands hold a young tree upright next to a ruler while also measuring the tree with calipers. In the left hand are small mesh tubes. — NPS ranger Lucas Hanson uses digital calipers to measure the diameter of a young tree.
NPS Photo / T. Withers

A Look to the Future

This project has been “a testament of collaboration,” says Justin. LeighAnna adds that the USFS and the tribes “have resources we don’t have access to.” The DED-resistant elms brought by the USFS wouldn’t have been available if it was just the NPS or just the tribes working on this restoration effort. The stories and knowledge brought by the tribes have also been indispensable.

Going forward, the Sleeping Bear Dunes vegetation team and the USFS will return to the wetland to check on growth and plant diversity. “The winter is notoriously difficult for seedlings,” says Justin. Some return trips to past planting sites have led only to dead trees. At North Bar Lake, however, they are already seeing good results from the trees planted in the spring. So far, Charlie says, this ecosystem has seen up to a 95% survivorship rate in the trees planted back in May. This result is much better than most other systems they’ve worked with. It is a promising indication for the future of American elm restoration efforts.

In the future, LeighAnna says that the vegetation team hopes to find “big happy trees – and baby trees!” Justin agrees, adding that they want to know that the trees they planted are “not just living, but thriving” in their new habitat. As the trees grow, they hope that wildlife will also thrive in the restored ecosystem. “There is an element of thinking towards the future,” Justin says, reminiscing on the project. “Everyone collaborated to restore the area, and I can come back twenty, fifty years later and know that I was a part of that.”

The project at North Bar Lake is an important step in the fight against invasive species. Research here may provide the basis for improving forest and wetland health in areas across the northeast. However, research alone will not be enough. As of now, there is no cost-effective way to control DED in a forest.² It could take decades or even centuries of planting DED-resistant elms to reestablish themselves in an ecosystem,⁴ especially as new diseases rear their heads. Limited funding has also ended many research programs focused on breeding DED-resistant American elms.⁵ “There’s not enough money or manpower to plant our way out of this,” says Charlie. Going forward, the success of ecosystem recovery efforts will depend on public education as much as research.