Term of Award

Fall 2015

Degree Name

Master of Science in Biology (M.S.)

Document Type and Release Option

Thesis (restricted to Georgia Southern)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Department

Department of Biology

Committee Chair

Tiehang Wu

Committee Member 1

John Van Stan

Committee Member 2

Doug Aubrey

Committee Member 3

Carl Rosier

Committee Member 3 Email

crosier@udel.edu

Abstract

Forest canopy structure controls the timing, amount, and chemical character of precipitation supply to soils through interception and drainage along crown surfaces. Yet, few studies have examined forest canopy structural connections to soil microbial communities (SMCs), and none have measured how this affects SMC Nitrogen functions. The maritime Quercus virginiana Mill. (southern live oak) forests of St Catherine’s Island, GA, USA provide an ideal opportunity to examine canopy structural alterations to SMCs, as their throughfall spatially varies substantially due to dense Tillandsia usneoides L. (spanish moss) mats bestrewn throughout. To examine the impact of throughfall variability on SMC N functions, we examined points along the canopy coverage continuum: large canopy gaps (0%), bare canopy (50-60%), and canopy of heavy T. usneoides coverage (>=85%). Five sites beneath each of the canopy cover types were monitored for throughfall water/ions over the growing period (7 months, Mar-2014 to Sep-2014) to compare with soil chemistry and SMC communities sampled every two months throughout that same period (Mar, May, Jul, Sep). Nitrogen functional genes evaluated in this study facilitate N-cycling transformations for nitrification (ammonia oxidizing bacteria and archaea) and mineralization (chitinolytic bacteria). Denaturing Gradient Gel Electrophoresis (DGGE) and quantitative Polymerase Chain Reaction (qPCR) analyses were used to determine changes in the diversity and abundance, respectively, of these SMCs. Diversity was significantly altered for chitinolytic bacterial and ammonia oxidizing archaeal communities across the canopy cover classes, and negatively correlated with throughfall Cl-, SO42-, and PO43- concentrations produced by these differing cover types.

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