BY LISA OWENS VIANI

A retired cranberry bog inspires an innovative approach to wetland restoration.

FROM THE JANUARY 2018 ISSUE OF LANDSCAPE ARCHITECTURE MAGAZINE.

In 2005, Glorianna Davenport began to think about retiring the cranberry farm she owned in Plymouth, Massachusetts. In the late 1980s, the 600-acre farm was producing 1 percent of Ocean Spray’s cranberry harvest, but Davenport had become concerned about the amount of pesticides being used—and the way those pesticides were applied. “Because cranberries are grown on former wetlands, we had to farm with helicopters,” Davenport says. “And spraying chemicals from helicopters is not really great in a densely populated area.” Davenport, a visiting scientist at the MIT Media Laboratory, whose husband bought the cranberry farm in the early 1980s, could also see the handwriting on the wall for older cranberry farms, with new cultivars producing five times as many berries, farmed in places easier to access than wetlands and river bottoms. “The industry was changing pretty radically,” Davenport says. “The way we had been farming was really the legacy of another era.”

Davenport learned that a nearby cranberry farm had been restored back to wetlands—said to be the first project of its kind in the United States—and that she was eligible for assistance through the U.S. Department of Agriculture Natural Resources Conservation Service’s Wetlands Reserve Program, which pays farmers to take land out of production to preserve, restore, and enhance wetlands on their properties. The program was established by the 1990 Farm Bill. In 2008, Davenport decided to retire from MIT to undertake the restoration of Tidmarsh Farms. With federal and state funding in hand, she began working with the state’s Department of Fish and Game to pull together an interdisciplinary team of state and federal scientists and river, wetland, and other experts to help restore the bog at Tidmarsh Farms, an effort that took several years.

Ten thousand years ago, glaciers moved down across the northeastern United States, then retreated. As they did, big chunks of ice were left, forming kettle holes, some of which filled with water. Over thousands of years, as much as 30 feet of organic matter built up in some of those holes, pushing the water up and out, and becoming peat bogs with stream channels flowing across their surface. The wet, acidic soil was the perfect environment for the American cranberry, Vaccinium macrocarpon, which also grew wild along some of the Great Lakes and was a staple food for Native Americans. The cranberry, which is related to the blueberry, grows as a small, creeping shrub that sends out runners, forming a mat. Colonists named it “craneberry” for the beautiful, pink flowers that bloom in June and resemble the head of a sandhill crane. Today farmers grow several varietals along with the native cranberry.

European settlers began cultivating the cranberry as early as 1816 after a Revolutionary War veteran noticed a cranberry vine growing on his property on Cape Cod—and saw that the vine grew faster when sand blew in from nearby dunes. Throughout the 19th century, farmers boosted cranberry production through intensive farming methods. They drained and flattened the swamps and cut down the Atlantic white cedar that thrived there. They cut off the natural stream channels and dug extensive irrigation ditches. To control pests and encourage the berries to spread, they applied a thin layer of sand to the bog surface every few years. And they installed berms to impound the water and flood the berries for harvesting (the berries floated to the surface, where they were rounded up and scooped into machines).

Inter-Fluve placed woody debris in the channel to provide habitat and hiding places for fish. Photo by Nick Nelson, Inter-Fluve.

Although Massachusetts is the oldest cranberry growing region in the United States, Wisconsin and Quebec, Canada, now produce more berries. The berries are farmed more cost-effectively on large commercial farms in upland areas in laser-leveled beds, using state-of-the art irrigation and water management systems. An increased market demand for sweetened, dried cranberries has resulted in newer, hybrid varieties of cranberries being grown on commercial farms; many of the Massachusetts bogs still grow the smaller, native fruit that has lower yields.

In 2011, Davenport founded the Living Observatory, a nonprofit partnership with MIT researchers, artists, and students, with the goal of increasing public understanding of wetlands and developing methods for evaluating ecological restoration projects. The team measures baseline temperatures, light, humidity, barometric pressure, soil moisture, greenhouse gases, and even the sounds of the wetland itself, with 32 embedded microphones. “We wanted to do deep science, but also animate a virtual Tidmarsh,” Davenport says.

Image courtesy of Inter-Fluve.

After four years of planning, design, engineering, and permitting, restoration work began in 2015. The team had to undo everything that had been done in the past. “It boils down to the natural movement and storage of water on the land and the ways in which ag had impaired that over the past century,” says Alex Hackman, a restoration specialist with the Massachusetts Department of Fish and Game. “Our restoration approach systematically addressed those impairments to renaturalize the movement of water over the landscape.”

To restore the site’s natural hydrology, the old irrigation ditches were plugged and dams and berms removed so that water from the stream that flows through the site could break up the old cranberry mat. The stream had been straightened and redirected into an agricultural canal, but Inter-Fluve, an engineering company that specializes in ecological restoration, was able to reconstruct its shape by using remnants of the original stream, which could still be seen in a forested patch on the farm, as a model. And the new (or, rather, old) stream channel was reconnected to the bog surface elevation to ensure frequent flooding of the wetland. “The goal is to make this area wet again,” says Nick Nelson, a regional director and fluvial geomorphologist with Inter-Fluve. Nelson’s team also used ground-penetrating radar to create a map of “where and how deep the peat is,” he says.

The team planted Atlantic white cedar saplings and other native shrubs and sedges to bring back a functioning wetland. Photo by Nick Nelson, Inter-Fluve.

Sediment testing revealed persistent pesticides such as DDT and dieldrin. But rather than haul the soil away, the team decided to manage the sediment on site. “Those contaminants have been on the site for a very long time. If we disturb the soils, we’re not making it any worse,” Nelson says. In the meantime, Davenport worked with two botanists who specialize in plants native to Plymouth County to compile an online, illustrated catalog of plants historically found at Tidmarsh. She set up her own native plant nursery on site to grow the necessary plants—30,000 trees, shrubs, and sedges in total, including 6,000 Atlantic white cedars grown from seed, which “jump-started the swamp,” Hackman says. The town of Plymouth and the Massachusetts Audubon Society have purchased other parcels of the farm and will restore the bogs on those areas as well.

Image courtesy of Inter-Fluve.

Hackman says the 225-acre restoration project, completed in June 2017, could provide a model for other cranberry farmers. Massachusetts has approximately 14,000 acres of cranberry farms, many of them struggling economically. In 2016, the state created a Cranberry Revitalization Task Force. Among its recommended “exit strategies” is wetland restoration. “We have not yet identified specific new funding sources, but will be trying over the next few years to increase our ability to help,” Hackman says. “We are actively considering how to scale up capacity.”

Lisa Owens Viani is a California-based freelance writer who specializes in ecology, science, and water-related topics.