Spartina Alterniflora Responses to Flooding in Two Salt Marshes on the Eastern Shore of Virginia

Abstract
The primary aim of this project was to analyze the vulnerabilities of the salt marshes on the eastern shore of Virginia, USA by identifying the optimum elevation for Spartina alterniflora growth in two marshes, . Models such as this have the potential to result in more rapid assessment of marsh vulnerabilities and focused conservation efforts, two increasingly important elements for marsh research as rising sea-levels continue to threaten the survival of these ecosystems and the numerous services they provide.
To carry out these objectives, I analyzed growth across flooding gradients in both man-made planters (“marsh organs”) and transects. I considered the growth responses of different S. alterniflora genotypes to changes in flooding over two growing seasons, and at two different sites. At the end of the two growing seasons I observed no definitive optimum elevation for S. alterniflora growth for either location, but instead saw differences in growth responses between years, plant sources, and growing scenario (i.e. organ-grown versus transect-grown, and plant source used). I therefore conclude that the growth response of S. alterniflora is highly dependent on a large number of variables, and that the results obtained through simplified models and approaches such as the Morris model and marsh organs are likely not accurate on a large scale due to the complexities of each individual salt marsh. Thus, my results support the idea that, as of now, traditional sampling methods, such as the use of transects to sample the natural marsh, remain the most accurate method for observing marsh responses to varying environmental conditions. It is, therefore, important for researchers to consider carefully the implementation of methods such as models and marsh organs, and the appropriate applications of any results obtained therein, in order to ensure that the results accurately reflect the responses of the natural marsh.