Date of Award

Fall 2001

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

Program/Concentration

Biology

Committee Director

Frank P. Day, Jr.

Committee Member

Lytton J. Mussleman

Committee Member

Kneeland K. Nesius

Call Number for Print

Special Collections LD4331.B46 R635 2001

Abstract

This work addresses seasonal and successional factors of root dynamics in natural and restoration Atlantic white cedar (AWC) wetlands. Using minirhizotrons, fine root dynamics in a chronosequence of naturally-regenerating and restoration AWC wetlands were measured to compare ecosystem development trends with restoration conditions. A second study was conducted to compare fine root dynamics in AWC wetlands with contrasting hydroperiods. In addition, a technical study was conducted to determine the feasibility of estimating root biomass with indirect minirhizotron measurements.

Root biomass estimates using minirhizotrons were significantly higher in naturally regenerating AWC wetlands and significantly lower in the restoration site relative to soil core estimates. Differences in root viability determinations between the two methods and overestimation of fine roots were identified as factors contributing to observed differences between the two methods.

The chronosequence study revealed significant seasonal variation of root dynamics in the young naturally regenerating and restoration sites. The mature and intermediate-aged sites did not exhibit seasonal variability in root abundance or mortality. Root production was variable but not seasonally consistent. Results suggest that root dynamics become less seasonal as AWC communities shift from herbaceous to woody vegetation dominance. There was no apparent trend in fine root abundance along the chronosequence, suggesting that roots rapidly recover from tree harvest disturbances. Annual root length production measurements suggest increasing annual production with decreasing stand age. However, the combining of length: mass root relationships with minirhizotron measurements resulted in a reversal of this trend. These findings underscore the importance of supplementing minirhizotron data with root allometric relationships if comparing across vegetation gradients. Overall, results suggest that root contributions to soil organic matter may be substantially less in the restoration site relative to naturally regenerating sites.

Root dynamics and rooting depths were similar between the persistently and variably flooded AWC wetlands. While results indicated higher root production in the shallow depths of the persistently flooded wetland, root abundance and mortality rates were similar between sites. These results are contrary to other investigations of belowground processes along hydrologic gradients in forested wetlands. Results suggest that AWC may express substantial morphological and physiological root plasticity in order to adapt to varied degrees of soil inundation.

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DOI

10.25777/qcer-gd66

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