The Surprising Upside of Phragmites

Invasive species often get a bad rap, seen as harmful newcomers that disrupt ecosystems and need to be removed. But what if the story isn’t so black and white? 

With support from the NERRS Science Collaborative, a team led by Dr. Andrew Wozniak from the University of Delaware and the Delaware Reserve dug into the pros and cons of Phragmites australis, a wetland reed that hopped over the pond from Europe in the 1800s. Along the Mid-Atlantic, it proceeded to outcompete native vegetation, decrease biodiversity, and make habitats less friendly for local fauna. All of this has made P. australisthe target of decades-long removal efforts. However, it turns out that alongside the problems it creates, P. australishas a surprising upside.

“Phragmites provide ecological benefits in wetlands that are often overlooked,” says Dr. Mollie Yacano, research coordinator at the Delaware Reserve. “They can stabilize soil, reduce erosion, and even help mitigate the impacts of sea level rise by building up marsh elevation faster than many native species. Their dense root system also can filter pollutants and improve water quality.”

As a result, efforts to remove Phragmites and restore native plants could impact a wetland’s capacity for carbon storage. The team explored whether prescribed burns—a common method for vegetation removal that produces biochar—could increase the underlying soil’s capacity to remove nitrogen pollution from stormwater and keep carbon trapped in the ground. 

“We wanted to see if the loss of carbon storage that could occur when you burn Phragmites may be mitigated by the biochar that’s left behind,” says Yacano. “We found that areas with recent burns were associated with higher soil carbon, but the addition of Phragmites biochar to sediments in areas that did not have a burn do not currently appear to enhance nutrient removal potential in the longer term.”

To discuss this research, the Delaware Reserve (part of the Delaware Department of Natural Resources and Environmental Control) and the University of Delaware recently hosted a Phragmites management workshop, bringing together participants from state agencies, city governments, academic institutions, non-profits, and businesses.

“It was very popular; 91 people participated in-person and online,” says Lynne Pusey, the Reserve’s coastal training program coordinator. “It’s clear that Phragmites management is a topic that brings people from a wide range of sectors together.”

The workshop presented a range of perspectives on Phragmites management, including traditional removal methods using prescribed burns, mechanical removal, and herbicide use, as well as emerging research on potential ecological benefits.

Participants mentioned that removal is often expensive, doesn’t always work, and is often temporary, requiring repeated efforts and adding to the cost. They also flagged that restoration should be monitored for five to ten years afterward, which isn’t currently happening but would allow for adaptive management. 

“The Phragmites management workshop provided a wealth of information to me as a town manager for a coastal community,” says Maureen Hartman, Town Manager of South Bethany. “It afforded an opportunity to network with professionals and provided a better understanding of marsh science management.”

The team is committed to continuing the dialogue and developing practical solutions to the challenges posed by this complex species. For more details, visit DNREC’s website.

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