Physical Sciences and Mathematics Commons^™

Elucidating Peatland Disturbance Ecology And Carbon Dynamics Through The Lens Of Soil Using Infrared Spectrometry, Dominic Uhelski

Dissertations, Master's Theses and Master's Reports

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We sought to quantify the fire regimes of peatlands in the hemi-boreal zone of North America, and to understand the qualities of their peat. We used infrared spectrometry to accomplish both goals by gathering spectral information about the organic matter in each sample. We used a series of mixtures of natural peat and natural peat charcoal to isolate the spectral components associated with charcoal concentration. We built a multiple linear regression model which predicts the charcoal concentration in peat samples. We validated our data using nuclear magnetic resonance spectrometry. As a result, we can accurately predict the charcoal concentration of …

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Biogeochemical Response To Vegetation And Hydrologic Change In An Alaskan Boreal Fen Ecosystem, Danielle L. Rupp

Dissertations, Master's Theses and Master's Reports

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Boreal peatlands store approximately one third of the earth’s terrestrial carbon, locked away in currently waterlogged and frozen conditions. Peatlands of boreal and arctic ecosystems are affected increasingly by shifting hydrology caused by climate change. The consequences of these relatively rapid ecosystem changes on carbon cycling between the landscape and the atmosphere could provide an amplifying feedback to climate warming. Alternatively, the advancement of terrestrial vegetation into once waterlogged soils could uptake carbon as a sink. Previous work suggests that fens will become an increasingly dominant landscape feature in the boreal. However, studies investigating fens, their response to hydrologic and …

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Biogeochemical Cycling In Lake Superior Tributaries: Seasonality, Quantity And Quality Of Export, Ashley Anne Coble

Dissertations, Master's Theses and Master's Reports - Open

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Seasonal and spatial variability in environmental factors may affect dissolved organic matter composition and nutrient transformation and retention in streams. The objective of this research was to quantify and describe seasonality, quantity, and quality of nutrient processing and export of ammonium (NH₄), soluble reactive phosphate (SRP), and dissolved organic carbon (DOC) into Lake Superior through intensive study in a small 1st order watershed coupled with snapshot measurements across 12 tributaries that varied in size, location, and wetland coverage. Our results suggest biodegradable C is exported from a small headwater stream year-round and that DOC mineralization rates can be …

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Impacts Of Climate Change On Soil Microorganisms In Northern Hardwood Forests, Carley Jane Kratz

Dissertations, Master's Theses and Master's Reports - Open

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As global climate continues to change, it becomes more important to understand possible feedbacks from soils to the climate system. This dissertation focuses on soil microbial community responses to climate change factors in northern hardwood forests. Two soil warming experiments at Harvard Forest in Massachusetts, and a climate change manipulation experiment with both elevated temperature and increased moisture inputs in Michigan were sampled. The hyphal in-growth bag method was to understand how soil fungal biomass and respiration respond to climate change factors. Our results from phospholipid fatty acid (PLFA) analyses suggest that the hyphal in-growth bag method allows relatively pure …

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Parametric Study Of Reaxff Simulation Parameters For Molecular Dynamics Modeling Of Reactive Carbon Gases, Benjamin David Jensen

Dissertations, Master's Theses and Master's Reports - Open

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Abstract

The development of innovative carbon-based materials can be greatly facilitated by molecular modeling techniques. Although the Reax Force Field (ReaxFF) can be used to simulate the chemical behavior of carbon-based systems, the simulation settings required for accurate predictions have not been fully explored. Using the ReaxFF, molecular dynamics (MD) simulations are used to simulate the chemical behavior of pure carbon and hydrocarbon reactive gases that are involved in the formation of carbon structures such as graphite, buckyballs, amorphous carbon, and carbon nanotubes. It is determined that the maximum simulation time step that can be used in MD simulations with …

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Interactive Controls Of Water Table Position And Plant Functional Types On Peat Porewater Character In Northern Bog Ecosystems: Implications For Carbon Cycling Dynamics, Aleta L. Daniels

Dissertations, Master's Theses and Master's Reports - Open

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Northern wetlands, and particularly peatlands, have been shown to store around 30% of the world's soil carbon and thus play a significant role in the carbon cycle of our planet. Changes in climate are altering peatland hydrology and vegetation communities. These changes are possibly resulting in declines in the ability of peatlands to sequester carbon because losses through carbon oxidation and mineralization are likely to increase relative to C inputs from net primary production in a warmer, drier climate. However, the consequences of interactive effects of altered hydrology and vegetation on carbon storage are not well understood. This research evaluated …

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