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dc.contributor.authorIannucci, Frances Marie
dc.descriptionThesis (M.S.) University of Alaska Fairbanks, 2023en_US
dc.description.abstractCarbon emissions from headwater streams are derived from both terrestrial inputs and in-stream microbial processing of organic carbon, but the relative importance of metabolic processes in boreal streams remains uncertain. Determining the factors that regulate organic carbon processing will aid in predicting how the carbon balance of boreal streams will respond to future environmental change. In this study, I addressed the question: what controls organic carbon uptake in boreal headwater streams draining catchments with discontinuous permafrost? I hypothesized that organic carbon uptake is collectively regulated by organic carbon lability, phosphorus availability, and temperature, with discharge modulating each of these conditions. I tested these hypotheses using a combination of laboratory resource manipulation experiments and ecosystem metabolism measurements throughout the Caribou-Poker Creeks Research Watershed (CPCRW) in Interior Alaska, USA. In the laboratory experiments, respiration and dissolved organic carbon (DOC) loss were both co-limited by the supply of labile carbon and phosphorus, but temperature and residence time acted as stronger controls of DOC loss. Ecosystem respiration (ER) was largely predicted by discharge and between-site variance, although some within-site variance was explained by gross primary production (GPP) and temperature. Between sites, both ER and GPP were inversely related to watershed permafrost extent, with an inverse relationship between temperature and permafrost extent providing the most plausible explanation for this pattern. These results provide some of the first evidence of a functional response to permafrost thaw in stream ecosystems and suggest that the contribution of metabolism to stream carbon emissions may increase as climate change progresses.en_US
dc.description.sponsorshipBonanza Creek Long Term Ecological Research program (NSF award #DEB-1026415), NSF award #DEB-1926632, the Society for Freshwater Science, Alaska EPSCoR (NSF award #OIA-1757348) and the state of Alaskaen_US
dc.description.tableofcontentsPreface -- Chapter 1: Controls of organic carbon processing in boreal headwater streams -- Appendix.en_US
dc.subjectCarbon contenten_US
dc.subjectInterior Alaskaen_US
dc.subjectStream chemistryen_US
dc.subjectOrganic compound contenten_US
dc.subjectTaiga ecologyen_US
dc.subject.otherMaster of Science in Biological Sciencesen_US
dc.titleControls of organic carbon processing in boreal headwater streamsen_US
dc.identifier.departmentDepartment of Biology and Wildlifeen_US
dc.contributor.chairJones, Jeremy B. Jr.
dc.contributor.committeeArp, Christopher D.
dc.contributor.committeeMuscarella, Mario E.

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  • Biological Sciences
    Includes WIldlife Biology and other Biological Sciences. For Marine Biology see the Marine Sciences collection.

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