Recent interactions between an invasive (Phragmites australis) and a native plant species (Spartina alterniflora) in the upper reaches of Great Sippewissett marsh, Cape Cod
Date
2024-05-20
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Abstract
Salt marshes are critical coastal ecosystems characterized by tidal flow, halophytic vegetation, and muddy sediment, serving as nurseries for marine species, erosion buffers, and carbon sinks. However, the invasion of the salt-tolerant haplotype of common reed, Phragmites australis, in Eastern North America poses a threat to salt marsh ecosystems historically dominated by Spartina alterniflora. While a range of management strategies, including chemical, biological, and physical control methods, are utilized to address invasive species, the emphasis tends to be primarily on their removal rather than on the long-term impact of restoration efforts.
This study investigates the competitive interactions between P. australis and S. alterniflora in Great Sippewissett Marsh on Cape Cod. I conducted a one-season experiment manipulating P. australis by cutting its stems at ground level in three treatment plots. I then measured the resulting changes in S. alterniflora percent cover and compared them to values in three control plots. The results revealed that the invasion of P. australis impedes the upland migration of S. alterniflora, potentially through shading effects. Clipping stems of P. australis led to a rapid increase in S. alterniflora % cover, nearly doubling that of unclipped areas by the end of the growing season. This result suggests cover of P. australis might be managed to encourage cover of native marsh vegetation and prevent habitat loss. On a broader scale, this project gives insight into not only into invasive species removal but also into ecosystem restoration, crucial for reinstating native plant communities and ensuring long-term ecological resilience.
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Keywords
Phragmites australis, Spartina alterniflora, invasive species, salt marsh