Date of Award

Spring 2001

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

Program/Concentration

Biology

Committee Director

Frank P. Day, Jr.

Committee Member

Kneeland Nesius

Committee Member

Gerald Levy

Call Number for Print

Special Collections LD4331.B46 H88 2001

Abstract

Fine root dynamics are an important yet poorly understood component of terrestrial ecosystems. In recent years a number of researchers have focused on fine root dynamics; their work has looked at patterns across one or multiple growing seasons on a scale of monthly measures. The purpose of this study was to add to the overall understanding by looking at fine root dynamics on a shorter temporal scale. Minirhizotron observation tubes were used to assess the effect of nitrogen fertilization on short-term fine root dynamics in a nutrient limited, barrier island dune system. Root length elongation and mortality rates followed expected patterns with soil depth, with the highest values for both occurring in the upper 22 cm. Unexpectedly, soil nutrient analyses did not confirm decreasing nitrogen levels with increasing depth although high variability suggests an inadequate sample size. Total % nitrogen was significantly increased by the fertilization regime and corresponded to significantly higher root elongation and mortality rates. However, mortality rates (0.61 mm cm-2 day-1) greatly exceeded root length elongation rates (0.18 mm cm-2 day-1) in both control and treatment plots. These results support one of the two hypotheses summarized by Hendricks et al. (1993a), namely that fine root turnover rates increase with nitrogen availability. The effect of N fertilization was much more pronounced on mortality rates than on root length elongation rates. This is suggestive of a belowground die back in response to nitrogen fertilization, perhaps associated with a shift in allocation to aboveground production.

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DOI

10.25777/s0rm-7j03

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