Predicting the Impact of Sea Level Rise on the Distribution of Phragmites Australis and Spartina Alterniflora and Changes in Community Compositions in Tidal Freshwater Marshes of James City County, Va
Master of Science (M.Sc.)
With ongoing sea level rise (SLR), tidal freshwater marshes (TFMs) eventually will be flooded with more brackish water. The impact of more water and salt on the plant community of TFMs, however, is unknown. With SLR, both the invasive reed Phragmites australis and the native salt marsh grass Spartina alterniflora could become dominant species in TFMs. I am looking at determining how increases in salinity and inundation caused by sea level rise will impact the relative distribution of Phragmites and Spartina in tidal freshwater marshes in Southeastern Virginia. Using GIS, I summarized past expansion patterns by mapping the current and historical distribution of Phragmites and Spartina. With soil samples collected from 6 TFMs in James City County with established Phragmites stand, I tested the effects of salinity and flooding on the germination of Phragmites and Spartina seeds and the subsequent effects of competition with these conditions. Inundation positively impacted the abundance of Phragmites and Spartina, while competition form Phragmites and Spartina decreased native species richness. Based on germination success and historical distributions, SLR-caused range shifts were predicted for Phragmites and Spartina and suggest Phragmites and Spartina will be more abundant in number within TFMs and in more TFMs in James City County. TFM area across James City County will diminish if accretion rates cannot keep pace with sea level rise and current TFMs will transition to oligohaline marshes, causing significant community changes.
© The Author
Humphreys, Abbey, "Predicting the Impact of Sea Level Rise on the Distribution of Phragmites Australis and Spartina Alterniflora and Changes in Community Compositions in Tidal Freshwater Marshes of James City County, Va" (2017). Dissertations, Theses, and Masters Projects. William & Mary. Paper 1516639677.