Restoring a Protected Preserve: Our Work at Nassawango

It's hard to say how many thousands of years the forest that encompasses Nassawango Creek Preserve on Maryland's Eastern Shore has been standing, but one thing is for certain: the unnaturally perfect rows of trees that can be seen from certain vantage points on the preserve haven't always been there.

The trees planted in these unusual rows are loblolly pines, a fast-growing evergreen that wasn't traditionally found in such abundance in the swamp and wet forest habitat of Nassawango. The swamps and wetlands surrounding this forest were historically filled with Atlantic white cedars, another native evergreen that thrives in the marshy wetland soil in this area. By the early 19th century, however, the Atlantic white cedar had been nearly decimated from the coastal Atlantic region, including in Nassawango; its dense, heat- and water-resistant lumber was highly desirable for ship building and making shingles and barrels.

Loblolly pines—another commercially valuable species—were planted to replace the decimated Atlantic white cedars, but the ecosystem and its natural hydrology had to be altered to make it hospitable for the pines. The nontidal wetland was ditched and drained; swells of land were built, and the pines were planted in perfect rows on top of the swells.

Fast forward to March of this year: National Aquarium staff and volunteers traveled to Nassawango for our 13th year partnering with The Nature Conservancy to plant Atlantic white cedar saplings with the Maryland Conservation Corps. The goal of this annual planting event is to restore the wetland forest habitat of Nassawango back to its original ecology—one tree at a time.

At every planting event, in the section of forest where the new cedar saplings will be planted, loblolly pine trees are first cut and cleared from the area. Controlled burns are then utilized to not only clear the land of shade-producing shrubs, but also keep the forest healthy and promote biodiversity. Since controlled burns have been reintroduced to Nassawango, plants that haven't been seen in the reserve in decades, including several rare species of orchid, have been spotted.

Removing loblolly pines from the forest gives the new Atlantic white cedar saplings a chance to grow and thrive. Since loblollies grow quickly—around twice the rate of the Atlantic white cedars—it wouldn't take long for them to grow tall enough to block sunlight to the under canopy where the smaller cedars reside. Clearing these pines allows more sun to reach the slower-growing cedars so they can survive.

The loblolly pines that we cut, clear and burn during our annual event—a similar process to performing maintenance in a garden by removing weeds—are relatively small and typically only a couple of years old. Because loblolly pines have such a heavy seed bank—meaning a supply of viable seeds in the soil, ready to germinate—they disperse seeds quickly, and those seeds quickly grow into the young trees that we remove during our annual event.

The older, larger loblolly pines in the forest are removed thanks to the hard work of The Nature Conservancy, which has worked to protect the preserve for over 40 years. After they identify a section of the preserve for restoration, their staff and volunteers clears and sustainably harvests the already-existing loblolly pines. Controlled burns are utilized before the area is flooded to restore the natural hydrology of this wetland ecosystem. Once these steps are complete, the area is ready for new Atlantic white cedars to be planted.

Planting Day: In With the New

At this year's event in March, which spanned two days, a total of 74 volunteers planted 2,768 Atlantic white cedar tree saplings. For the first time since the COVID-19 pandemic, local students from Worcester County participated in the event. The tiny trees they planted in March grew from saplings that they received in the fall and cared for on their campuses over the winter as part of the Atlantic white cedar head start program.

The saplings are planted in either newly burned sites or past planting sites to help create a forest with a denser population of Atlantic white cedar, helping to outcompete less desirable species like the loblolly pine.

These trees—though only an average of 1 foot tall when they're planted—grow 1 foot a year until they reach their maximum height of about 75 feet. On average, mature Atlantic white cedars live to about 200 years, although they can live to be 1,000 years old.

The overall results of 13 years of partnership and plantings are astounding. Over the lifetime of our work there with our partners, the numbers speak for themselves.

Although most Atlantic white cedars at the preserve were planted at our annual events over the past 13 years, there are some still-standing Atlantic white cedars left from the days before the local population was nearly eradicated. According to National Aquarium Director of Field Conservation Charmaine Dahlenburg, it's especially rewarding to return to the preserve and see the cedars planted in past years thriving.

"We hear of students who planted Atlantic white cedar trees during the early stages of our partnership with The Nature Conservancy returning as adults to see the mature trees that have grown from the small saplings they planted over 10 years ago," she explains. "Providing the opportunity for students and volunteers to see, firsthand, the restoration success they were a part of is invaluable."

An Ecosystem in Balance

The Atlantic white cedar is an important species to restore at Nassawango for the simple reason that it belongs there. Every plant and animal in the delicate web of an ecosystem has an important role to play; when a species is removed and unable to perform its essential natural functions, the negative effects ripple to the rest of the ecosystem. When the ecosystem in Nassawango is in balance, Atlantic white cedars are able to perform their critical functions of providing habitat for wildlife and acting as a sponge to prevent flooding and keep harmful stormwater runoff from entering the Chesapeake Bay.

Nassawango is a haven for wildlife. Several types of rare native orchids can be found among the trunks of the towering trees; other rare and threatened species found within the reserve include Briton's coast violet and purple pitcher plant. Dozens of species of native birds flitter among the treetops, and the preserve is an important stopover location for more than 60 recorded species of migratory birds as they make their spring and fall migrations. Mammals such as fox, otters and Delmarva fox squirrels can be found here; frogs, salamanders and other amphibians utilize the swampy wetland.

Considering the vastness of the preserve and the slow growth of the Atlantic white cedar, the name of the game is slow and steady—but we're committed to continuing our work to restore this swath of primal forest to its original state so that it can provide the functions that nature intended.

"The National Aquarium and The Nature Conservancy are well-established, conservation-led organizations committed to saving wildlife and habitats. Under the protection of The Nature Conservancy, these lands will be forever protected without threat of being sold or developed," Charmaine explains. "We look forward to continuing our partnership to restore, enhance and monitor Nassawango Creek Preserve with the help of local residents and students for years to come."