Date of Award

1-1-2011

Document Type

Campus Access Thesis

Department

Marine Science

First Advisor

James T Morris

Abstract

As the dominant macrophyte in Southeastern and Gulf Coast salt marshes of the United States the smooth cord grass Spartina alteriflora Loisel is responsible for maintaining the elevation of its environment, in equilibrium with sea level rise (SLR), through mineral (sediment) and biogenic accumulation. Accelerating rates of relative sea level rise pose the greatest threat to these systems as it will eventually outpace S. alterniflora's ability to maintain an equilibrium elevation. This study looked at the impact of nutrient availability and location in the tidal frame on plant primary production and growth range. Nutrient addition (nitrogen and phosphorus) and manipulation of the growth elevation were used to determine their effects on S. alterniflora above and below ground production, the primary drivers of accretion for these systems. 3 year averages of fertilized sample production showed a significant increase in above and below ground biomass with respect to the control (P<0.0001). Elevation also had a significant influence on both the above and below ground production of the control samples (P<0.0001) as well as the fertilized above ground (P=0.003) but not on fertilized below ground production. Nutrient addition also resulted in the plants ability to thrive at elevations lower in the tidal frame, relative to the control, resulting in a lower optimal growth elevation for the fertilized samples. Increased above ground production and the ability to grow under greater levels of inundation can provide S. alterniflora with the means to maintain their elevation in equilibrium with future rates of SLR.

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