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      • HARVEST
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      Assessing the impact of climate-induced vegetation changes on soil organic matter composition

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      PURTON-THESIS.pdf (9.283Mb)
      Date
      2015-02-26
      Author
      Purton, Kendra
      Type
      Thesis
      Degree Level
      Masters
      Metadata
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      Abstract
      Despite the importance of soil organic matter (SOM) in C storage and provision of ecosystem services, the magnitude and direction of the response of SOM to climate change remains debated. Particularly contested is the role of biochemical recalcitrance in determining the biological stability of SOM, which in turn, may also vary with climate. Employing a climosequence study design controlling for confounding pedogenic factors, the research described in this thesis aimed to uncover the response of both SOM chemistry and SOM biological stability to changes in climate and associated land use shifts at the grassland-forest ecotone in west-central Saskatchewan. Characterization of SOM chemistry was achieved using two advanced analytical techniques: X-ray absorption near edge structure (XANES) spectroscopy and pyrolysis-field ionization mass spectrometry (Py-FIMS). Agreements between XANES and Py-FIMS revealed only minor differences in SOM chemistry resulting from a 0.7 °C mean annual temperature (MAT) gradient and associated broad differences in land use, but revealed a clear influence of depth within soil profiles. In contrast, long-term aerobic incubations revealed that biological stability of SOM varied with both climate and climate-induced differences in land use, but was not largely influenced by depth. Together, these findings suggest a decoupling of SOM chemistry and its biological stability, indicating that factors other than biochemical recalcitrance are the primary drivers of SOM persistence in these soils.
      Degree
      Master of Science (M.Sc.)
      Department
      Soil Science
      Program
      Soil Science
      Supervisor
      Pennock, Daniel J.; Walley, Fran L.
      Committee
      Peak, Derek; Bedard-Haughn, Angela K.
      Copyright Date
      January 2015
      URI
      http://hdl.handle.net/10388/ETD-2015-01-1937
      Subject
      soil organic matter
      carbon
      nitrogen
      climosequence
      land use
      biological stability
      biochemical recalcitrance
      mineralization
      Py-FIMS
      XANES
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      • Graduate Theses and Dissertations
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