Date of Award

Spring 2010

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

Program/Concentration

Biology

Committee Director

Frank P. Day

Committee Member

G. Richard Whittecar

Committee Member

Rebecca Bray

Call Number for Print

Special Collections LD4331.B46 B54 2010

Abstract

The Virginia Coast Reserve's Long Term Ecological Research (LTER) site is of great interest because the barrier islands have been migrating, rapidly at times, and are exceptionally dynamic. The barrier islands have tidal saltwater marshes on the lagoon side and freshwater marshes on the island interiors. In these interior marshes on North Hog Island, South Smith Island, and North Parramore Island, salinity and depth to water table were measured to determine if these factors were influencing biomass and biomass allocation patterns in the marsh. Hog Island had the freshest interior marshes (0 and 0.7 ppm), and the most diverse (H'=0.84 and 1.026), but had the least aboveground biomass (36.69 and 161.92 g/m2). Smith and Parramore Islands were more saline (18.6 and 19.8 ppm, respectively), less diverse (H'=0.504 and 0.745), and had higher aboveground biomass (406.86 and 563.32 g/m2). The saltiest marsh, on Parramore Island, had the most aboveground biomass. Belowground biomass was primarily located in fine roots (less than 5 mm diameter). Depth did not have a significant effect on belowground biomass, though this could be due to a small sample size. Roots were found to be related to the vegetation type, and were located primarily in the top 20 cm of the soil, with the exception of Smith Island's marsh. Salinity, depth to water table, and soil nitrogen were all found to be different among marshes. Root: shoot ratios were highest in Hog Island's eastern marsh (0.5), and lowest in Parramore Island's marsh (0.12), and were significantly different. Correlation analysis suggests that salinity, nitrogen, and water table depth may have an influence on biomass and biomass allocation, though r values were not significant due to a low sample size. The results indicate that each island has a unique set of factors influencing the amount of belowground biomass and how biomass is allocated. The depth of the water table may be influencing root allocation in Smith Island's marsh, since its water table is deep, and causing other marshes to have anoxic soils that hinder root development and growth. Diversity and biomass were found to have an inverse relationship, with the most diverse marshes being the least productive. This relationship between diversity and biomass suggests heavy resource competition in these marshes. These barrier islands are different from each other and should be managed individually.

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DOI

10.25777/kzwf-ea78

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