Maryland Sea Grant

Maryland’s coastal wetlands provide diverse ecosystem services for the Chesapeake Bay region, reduce flooding risks, and help to improve local water quality. These natural communities, however, also face threats from rising sea levels and invasive species. Of particular concern is the non-native reed Phragmites australis, which has displaced native marsh grasses in many Mid-Atlantic wetlands in recent decades. To inform the management of this invasive reed, Maryland Sea Grant funded research to better understand how climate change might affect the growth of Phragmites populations around Chesapeake Bay.

Through this effort, researchers at the Smithsonian Environmental Research Center in Maryland exposed stands of Phragmites to elevated levels of atmospheric carbon dioxide and soil nitrogen —simulating conditions that these plants will likely encounter in the future as greenhouse gas emissions and nutrient runoff increase. In 2012 and 2013, the team found that elevated carbon dioxide and nitrogen levels increased the capacity of Phragmites to displace native marsh grasses. However, wetlands dominated by Phragmites also seem to accrete upward at faster rates than habitats made up of native grasses. These results suggest that while Phragmites decreases biodiversity in Maryland wetlands, it may also increase the resilience of these communities to rising sea levels.

The scientists have worked with the U.S. Fish and Wildlife Service to develop improved Phragmites management tools based on their findings. The researchers also shared their findings and their implications in a national webinar attended by about 100 natural resource managers who work on Phragmites. The results of the team’s research were incorporated into a review paper published in AoB Plants in 2014. The study was also highlighted in a news podcast produced by Maryland Sea Grant.