Coastwide
Phragmites, an invasive species, line this marsh at Sachuest Point in Middletown, Rhode island. Credit: Tom Sturm/USFWS

As climate change erodes US coastlines, an invasive plant could become an ally

Many invasive species are found along U.S. coasts, including fishes, crabs, mollusks and marsh grasses. Since the general opinion is that invasives are harmful, land managers and communities spend a lot of time and resources attempting to remove them. Often this happens before much is known about their actual effects, either good or bad.

The common reed Phragmites australis is a tall perennial grasswith long leaves that invades fresh and brackish wetlands. There it crowds out native species, reducing plant diversity. Managers frequently kill it with herbicides and replace it in brackish marshes with native Spartina alterniflora, or cordgrass, during restoration projects.

But despite its bad reputation, Phragmites provides many benefits that are generally unknown and unappreciated. After studying salt marsh ecology and the impacts of stressors, including invasive plants, for many years, I have concluded that removing this invasive species wherever it is found – especially along vulnerable coastlines – is a very expensive and often foolish procedure.

Providing food and shelter

Phragmites actually is native in the United States, but the native form comprises only a minor component of the high marsh – the zone that typically is above water. A new genetic variety arrived many decades ago and invaded brackish marshes.

In Europe and Asia, where Phragmites is also native, it is valued as an important wetland species. In China, where Spartina alterniflora has arrived, marsh scientists and managers are concerned with the effects of that invader replacing their beloved Phragmites. Human attitudes toward invasive species can be a bit subjective.

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