Show simple item record

dc.contributor.authorBurnett, Melanie S.
dc.date.accessioned2021-11-28T03:54:42Z
dc.date.available2021-11-28T03:54:42Z
dc.date.issued2021-05
dc.identifier.urihttp://hdl.handle.net/11122/12543
dc.descriptionThesis (M.S.) University of Alaska Fairbanks, 2021en_US
dc.description.abstractRapid warming in Alaska is causing permafrost to thaw, especially in the region of discontinuous permafrost, where soil temperatures may only be a few degrees below 0 °C. An intensifying fire regime may also be exacerbating permafrost thaw with more frequent and severe fires removing insulating organic layers above permafrost. Permafrost thaw releases carbon and nitrogen (N) into the actively cycling pools, and whereas carbon emissions following permafrost thaw are well documented, the fates of N remain unclear. Denitrification and release of nitrous oxide (N₂O) or nitrogen gas (N₂) could result in N loss from ecosystems, but the contributions of these processes to the high-latitude N cycle remain uncertain. I quantified microbial capacity for denitrification and nitrous oxide production in boreal soils, lakes, and streams, and assessed correlates of denitrifying enzyme activity in interior Alaska to determine if denitrification could contribute significantly to N loss from the boreal forest. Across all landscape positions, median potential denitrification rate under anoxic conditions with nitrate and organic carbon amendment was 4.15 [mu]g N₂O-N /kg dry soil*h (range -6.39 to 479.94). Denitrification potential was highest within and along streams in both sediments and adjacent riparian soils, upland soils were intermediate, and lakes supported lower rates, whereas deep permafrost soils supported little denitrification. Time since last burn had no effect on denitrification potential in upland soils. Across all landscape positions, denitrification potential was negatively correlated with ammonium pools. In lakes, potential rate of denitrification declined with sediment depth, and was positively driven by organic matter content. In this era of anthropogenic climate change, pervasive N loss to denitrification in the boreal forest could constrain the capacity for N-limited primary producers to preserve carbon stocks in soils following permafrost thaw.en_US
dc.description.sponsorshipNational Science Foundation via the Bonanza Creek Long-Term Ecological Research program (funded jointly by NSF-DEB-1026415, NSF-DEB-1636476, and United States Department of Agriculture Forest Service, Pacific Northwest Research Station grant PNW01-JV-11261952-231), and grants to T.K Harms (NSF OIA-1929217) and A. Liljedahl (NSF-ARCSS-1500931)en_US
dc.description.tableofcontentsGeneral introduction -- Chapter 1: Widespread capacity for denitrification in soils, streams, and thermokarst lakes of boreal Alaska -- General conclusions.en_US
dc.language.isoen_USen_US
dc.subjectDentrificationen_US
dc.subjectInterior Alaskaen_US
dc.subjectSoilsen_US
dc.subjectSoil nitrogen contenten_US
dc.subjectLakesen_US
dc.subjectLake nitrogen contenten_US
dc.subjectForest soilsen_US
dc.subjectTaiga ecologyen_US
dc.subjectPermafrost forest ecologyen_US
dc.subjectPermafrost ecosystemsen_US
dc.subjectPermafrost forestsen_US
dc.subjectNitrogenen_US
dc.subject.otherMaster of Science in Biological Sciencesen_US
dc.titleWidespread capacity for denitrification in soils, streams, and thermokarst lakes of boreal Alaskaen_US
dc.typeThesisen_US
dc.type.degreemsen_US
dc.identifier.departmentDepartment of Biology and Wildlifeen_US
dc.contributor.chairHarms, Tamara K.
dc.contributor.committeeRuess, Roger W.
dc.contributor.committeeWalter Anthony, Katey M.
refterms.dateFOA2021-11-28T03:54:43Z


Files in this item

Thumbnail
Name:
Burnett_M_2021.pdf
Size:
2.508Mb
Format:
PDF

This item appears in the following Collection(s)

Show simple item record