The Forest in the City

Researchers are looking for answers to the mysterious die-off of sword ferns in Seattle’s Seward Park.

Story and Photos by Emma Bjornsrud

December 12, 2020

At Seward Park, a diverse ecosystem of old growth forest, wetland and prairie on the west shore of Lake Washington in Seattle, researchers and nature lovers have teamed up to solve the mystery of the dying sword ferns.

Sword ferns, a dominant understory species of Pacific Northwest forest ecosystems, have 75 to 100 fronds that grow, pointed and blade-like, up to one meter long. Each frond arches outwards in a crown, creating a lush, round and delicately feathered fern. In the Magnificent Forest, the old growth forest of Seward Park, what was once a waist-high sea of sword ferns is now barren earth.

Paul Shannon has lived in the area for 25 years and frequently volunteers at the park. He spends much of his time there greeting others out on the trails, maintaining stewardship projects and collecting data about the forest.

“To me, it’s a bit like finding out that there’s an intact, vibrant, medieval, walled city down the hill, that is complex and stable,” Shannon said. “It’s a beautiful thing to study, and we do a lot to try to protect it. I’m not sure how we’re doing on that score.”

Shannon’s doubt stems from a threat plaguing the forest: an unknown pathogen killing off sword ferns in waves. The die-off has been spreading north from ‘ground zero,’ an area off the Sqebeqsed (skuh-BUHK-suhd) Trail near the old fish hatchery at the eastern end of the park, since 2013.

A similar decline in sword fern populations has been seen in Jefferson, Snohomish and Kitsap Counties. However, the cause remains unidentified.

In 2018, researchers, environmentalists, volunteers and government officials came together to create a plan which lays out goals for further research and collects scientific literature about the die-off.

Lisa Ciecko, a plant ecologist with the Green Seattle Partnership, contributed to the plan. According to Ciecko, many possibilities — from drought to past applications of herbicides — have been explored. The Green Seattle Partnership and Seattle Parks and Recreation have funded mapping projects and experiments at Seward Park.

“We’re thinking about a next step of looking more at what patterns exist across the landscape, what ecological conditions might be influencing sword fern decline,” Ciecko said. “So we’re just at the really beginning steps of working with the forest ecologist to develop a research plan.”

Volunteers at Seward Park are also continuing to test their own hypotheses. Last year, Seward Park received almost $8,000 to fund research on the sword ferns from a group called 100 Women Who Care — a philanthropic giving circle.

Paula Rothkopf, the leader of the Seattle branch of 100 Women Who Care said the group meets three times a year to elect a deserving non-profit to receive a donation. Shannon convinced the group that the sword fern decline deserved their support.

“What [Shannon] was saying to us was all parts of our communities are important, and nature is one of them. We have to value our environment, take care of our environment,” said Rothkopf. “That was the way he presented it to us, and it was not even a close vote … it was a big win.”

Many changes could come as a result of such a large-scale sword fern decline, including soil erosion, wildlife habitat loss and even the aesthetic impact, according to Ciecko.

“Sword ferns are a really critical component of Seattle’s forests, and at Seward Park in particular they are a really dominant understory species and provide that lush, green understory that we’re all familiar with,” Ciecko said.

However, the sword ferns are just one piece of the puzzle that is the 300-acre forest.

Other species in the park, including Western red cedar, big leaf maple, Western hemlock and an understory species called salal, are also in decline.

“At Seward Park, that’s one of the story lines that we need to come back to in the coming years and with the next round of research: what more broadly is happening,” Ciecko said. “There’s definitely other decline at play.”

One of the most characteristic assets of Seward Park is the Magnificent Forest: old growth trees, mostly Douglas firs, ranging from 200 to almost 500 years old.

As defined by the state Department of Natural Resources, old growth is forest originating prior to 1850 that has reached certain late stages of development. Disturbances, such as wildfires, windstorms, insect infestations and logging, have the ability to destroy old growth populations, said Daniel Donato, a natural research scientist who runs the agency’s old growth conservation program. These disturbances, along with the time it takes for old growth to regenerate, account for the widespread loss of old growth forests statewide. The environmental impacts are significant.

When old growth trees die, the carbon stored inside their trunks from centuries of providing oxygen and absorbing carbon dioxide is released back into the atmosphere, contributing to climate change.

“The other big piece of what’s happening in Seattle parks is that we are very actively experiencing climate change,” said Ciecko.

Old growth forests deserve respect for their complexity and resiliency, said James Freund, a forest ecology researcher with University of Washington.

“The old trees, the large trees, provide the ecological anchor for those systems. If you were thinking about animal biology, they’re a keystone species,” Freund said. “They have controls on what those ecosystems are and how they can function. They do it in a way that many other elements simply cannot do.”

Each piece works together at Seward Park. From the ferns on the forest floor to the trees reaching into the sky, the park’s biology can enchant visitors — a forest that has lived a human’s lifespan many times over is indicative of its resiliency.

“One thing that feels really clear, especially in an urban context, is that humans are part of the ecosystem at the park,” Ciecko said. “There’s a story, especially in traditional environmentalism, around separating people from wilderness, and I think that parks like Seward remind us that, even if it’s a space that’s preserved and not to be developed, the structure of the forest and the stewardship of the forest is all related to how people engage with it.”

That engagement may come in many different forms. For some, the park might represent relaxation, or time spent away from work in nature. But for others, the ecosystem at Seward holds a deeper significance.

Ken Workman, a retired Boeing systems and data analyst and the great-great-great-great-grandson of Chief Si’ahl (commonly known by the Anglicized name Chief Seattle) of the Duwamish and Suquamish Tribes, spoke of the human DNA preserved in each living tree.

Referencing a speech given by Chief Si’ahl in 1855, Workman said the lives of his ancestors are still present in the modern world.

“When our material — all that biologic material that was grandma and grandpa and aunties and uncles — goes down into the ground and the spring rains come, they get sucked back up into the trees,” Workman said. “Therefore, Chief Seattle has recognized that the people aren’t really dead, they just changed. Now, at a molecular level, they’re in the trees. And the trees continue to grow, and the trees give us our oxygen, they give us the wood for our houses, for our canoes, for our clothes, for all of that.”

Standing on the trails of Seward Park, looking around at all of the species that live together in the Magnificent Forest, it is clear how interdependent the ecosystem truly is. From the sword ferns that once covered the ground to the highest branches that stretch toward the sun, each part of the whole is important. Humans are a part of the environment, and by interacting with it — whether it be a walk through the forest or the biological absorption of our lost loved ones through the roots of the trees beneath our feet — we become part of the extensive history of the old growth forest.

“When you’re walking around in Seward Park, you might want to hug a tree,” Workman said. “That’s who we are; that’s where we are.”

Emma Bjornsrud is majoring in environmental journalism at Huxley College, aspiring to communicate the most pressing environmental and social justice issues with the broader public through activist-journalism.