Horn Point Laboratory

Scientists fill key role in island restoration

Researchers monitor marsh, elevation on Poplar Island

Lorie Staver scans the green and golden marsh on a small stretch of land in Chesapeake Bay called Poplar Island.

It’s something she has done hundreds of times from her graduate student days to now, as an assistant research scientist for the University of Maryland Center for Environmental Science’s Horn Point Laboratory.

Staver is monitoring the island from the dirt below her feet to the vegetation that grows around her as it transforms from a construction site to a wildlife habitat.

In the mid-1800s, Poplar Island was made up of 1,100 acres. Over time, erosion ate away at its sandy coast, and by 1995, it was a disjointed landscape totaling 5 acres.

Today, Poplar Island is looking more like its old self due to an ongoing, multi-faceted restoration project. The state of Maryland partnered with the Army Corps of Engineers to restore the island using dredged material from the shipping channels in the main stem of the Chesapeake Bay approaching the Port of Baltimore.  

With new marsh fields, higher elevation points, and a stone-based perimeter, the island has been built to better withstand future erosion. By 2040, they will build the island to 1,715 acres using 68 million cubic yards of material.

“By restoring island habitat that has been lost, we can help preserve populations of birds in the state of Maryland and at the same time provide a placement site for dredged material,” Staver said.

Years before its scheduled completion, Poplar Island has already become a home to more than 200 species of birds, including snowy egrets, osprey, and the American black duck, and more than 100 insect species. The island also serves as a nesting site for diamondback terrapins and safe harbor for the Bay’s fish and shellfish resources. 

“You know the saying, ‘If you build it, they will come,’” Staver said. “It’s amazing how fast the wildlife showed up once the habitat was restored.”

Soaking in the atmosphere

UMCES scientists, including Staver, research professor Jeffrey Cornwell and professor emeritus Court Stevenson, have been monitoring Poplar Island since 2003, shortly after the first marsh cell was planted and developed. UMCES works alongside Maryland Environmental Service on the ecosystem restoration project.

The UMCES scientists focus on vegetation and sediment characteristics on the island.

“The goal is to establish the marshes as efficiently and cost effectively as possible, and to create the most sustainable marshes possible,” Staver said.

Their work involves monitoring marsh health and noting details, such as plant height, stem density, species distribution and diversity, and seedling density, to evaluate the development of the marshes. Staver started this work with Stevenson as a faculty research assistant.

By restoring island habitat that has been lost, we can help preserve populations of birds in the state of Maryland and at the same time provide a placement site for dredged material.

Lorie Staver
Assistant Research Scientist, Horn Point Laboratory

She noted that in one section of the island, the vegetation soared about 10 to 12 feet tall. It’s an effect of the material at the base of that vegetation, which came from a nitrogen-rich, fine grain in the upper Chesapeake Bay. Over time, that effect will wear off and the marsh won’t grow as tall, she said.

Cornwell has been tracking changes in sediment chemistry across the island and over time as it becomes less like fresh dredged material and more like marsh soil. This work requires that he examine pH, iron, sulfide, nutrients, and grain size—all characteristics that potentially affect plant growth and water quality in the tidal creeks.

He also measures nitrogen fluxes from the sediment in the marsh and creeks to estimate losses of the gas to the atmosphere (denitrification), and to water, which could impact water quality in the estuary.

Another aspect Staver monitors is elevation change, which is affected by plant production, to see if the marshes are keeping up with sea-level rise.

Marshes are almost at sea level, but their roots and rhizomes (stems) can grow below ground to actually raise the elevation. The above-ground vegetation also works with dead organic matter to trap inorganic sediment that comes in with the tidal waters.

Basically, a marsh’s success is tied to its ability to keep up with the rising waters.

“As sea level rises—which it has been, but we’re expecting it to increase—the marshes have to keep up their elevation to keep up with sea-level rise, or they’ll drown,” Staver said.

UMCES scientists are measuring millimeter-scale change in the elevation of the marshes using surface elevation tables (SETs). They have 27 SETs on the island and compare the rates of elevation gain between island marsh and a marsh on the mainland.

Staver also uses a tide gauge at Poplar Island to monitor sea-level rise, and compares it with National Oceanographic and Atmospheric Administration tide gauges at Baltimore and Solomons.

Staver expects the island’s marshes can keep up with sea-level rise.

“Right now, it looks like these marshes are keeping up, at least with the historical rate. As we all know the rate of sea-level rise has been accelerating and around the middle part of this century, it’s expected to accelerate a lot more rapidly,” she said.

Lessons in the land

Because Poplar is being rebuilt in phases, the scientists have a time series all in one place of restored marshes, Staver said.

“We can really look at the trajectories of marsh development, sediment development, and elevation change. This really provides some lessons for other restorations, and also provides insight into the ecology of marshes and the effects of nutrient enrichment on marshes.”

Staver believes Poplar Island’s distinctiveness can expound on a study she read about planting methods. This study weighed two planting methods—in a grid versus grouping plantings—and found that grouping the plantings was more effective.

On Poplar, where grid plantings had been successful, Staver wondered about the role different environments play and whether Poplar’s high-nutrient environment would yield different results. She decided to take the idea further with her own study.

“This idea of planting in clumps, it may be best suited to low-nutrient environments, but the traditional method is better in high-nutrient environments,” Staver said. “We’re finishing that study right now.”

When the scientists aren’t on the island, they are in the lab at Horn Point, sorting samples of species they collected and weighing them. As part of the restoration project, they put together an annual report with their findings to provide input to the restoration project’s adaptive management strategy.