Title page for ETD etd-03232009-092544


Type of Document Master's Thesis
Author Templeton, Benjamin Sean
Author's Email Address btmpltn@vt.edu
URN etd-03232009-092544
Title Environmental And Stand Variables Influencing Soil CO2 Efflux Across The Managed Range Of Loblolly Pine
Degree Master of Science
Department Forestry
Advisory Committee
Advisor Name Title
Seiler, John R. Committee Chair
Fox, Thomas R. Committee Member
Jones, Robert H. Committee Member
Wynne, Randolph H. Committee Member
Keywords
  • Carbon Cycle
  • Carbon Sequestration
  • Soil Respiration
  • Region Wide
  • Pinus taeda
Date of Defense 2009-02-03
Availability unrestricted
Abstract
Managed loblolly pine forests comprise an important pool in the global carbon cycle. Understanding the influences upon inputs and outputs of this pool, including the effects of management activities, will allow landowners to understand how carbon can be sequestered in their stands. Specific to this study, we sought to create multivariate models of the output of carbon from the soil in the form of soil CO2 efflux (Rs) and a component of that total efflux, heterotrophic respiration index (Rh), from data collected across the managed range of loblolly pine in the Southeastern U.S. We also performed tests of significance on controlled subsets of these data for the effects of fertilization and of thinning. Finally, we sought a connection between stand leaf area index (LAI) and total soil CO2 efflux or heterotrophic respiration. Our models indicated variability in both Rs and Rh across latitude and physiographic province, respectively, within this range. The Rs (R2 = 0.56) model included temperature, latitude, a soil moisture by temperature effect, soil nitrogen, and bulk density variables. The Rh (R2 = 0.50) model included soil moisture, a temperature by moisture interaction, and physiographic province. Rs was not significantly affected by either fertilization or thinning, yet Rh was influenced by both (negatively and positively, respectively). This indicates a shift in relative contributions of heterotrophic respiration and root respiration components to Rs in response to these treatments. Heterotrophic respiration was shown to have a weak negative response (R2 = 0.04) to increasing stand LAI.
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