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dc.contributor.authorHeslop, Calvin
dc.date.accessioned2021-10-20T21:50:01Z
dc.date.available2021-10-20T21:50:01Z
dc.date.issued2020-08
dc.identifier.urihttp://hdl.handle.net/11122/12299
dc.descriptionThesis (M.S.) University of Alaska Fairbanks, 2020en_US
dc.description.abstractAs tall shrubs increase in extent and abundance in response to a changing climate, they have the potential to substantially alter ecosystem nutrient availability and carbon (C) balance. Siberian alder (Alnus viridis ssp. fruticosa), a nitrogen (N) fixing shrub, is among the species responding to climate warming in both the Arctic and boreal forests. Alder-fixed N has the potential to increase decomposition of labile C, by relieving N limitation on microbial activity. Simultaneously, it has the potential to decrease decomposition of recalcitrant C by downregulating microbial N mining. The net effect of N additions is influenced by the relative quality of the soil C and could determine whether alder N additions result in a net sink or source of C to the atmosphere. We measured the activities of three extracellular enzymes in bulk organic soils under and away from alder canopies, in stands differing in soil organic matter quality, in both arctic and boreal forest regions of Alaska, USA. In the Alaskan arctic, the proximity of alder increased the activities of both recalcitrant and labile C-degrading enzymes regardless of soil C quality, potentially resulting in increased C losses. In the boreal forest, enzyme activities did not differ with alder proximity nor stand soil C quality, possibly due to long legacies of alder N inputs relieving microbial N limitation in these stands. As arctic and boreal forest ecosystems experience shifts in the distribution and abundance of this N fixing shrub, alders' influence on soil decomposition could have significant consequences for high latitude soil C budgets.en_US
dc.description.sponsorshipNSF DEB Ecosystems grant (1556481), NSF DEB (1636476), U.S. Forest Service, UAF Institute of Arctic Biologyen_US
dc.language.isoen_USen_US
dc.subjectEuropean green alderen_US
dc.subjectAlaskaen_US
dc.subjectSoilsen_US
dc.subjectSoil microbial ecologyen_US
dc.subjectForest soilsen_US
dc.subjectCarbon contenten_US
dc.subjectTaiga ecologyen_US
dc.subjectTaigasen_US
dc.subject.otherMaster of Science in Biological Sciencesen_US
dc.titleThe effect of Siberian alder on the activities of three extracellular enzymes and their implications for soil decomposition in Arctic and boreal Alaskaen_US
dc.typeThesisen_US
dc.type.degreemsen_US
dc.identifier.departmentDepartment of Biology and Wildlifeen_US
dc.contributor.chairRuess, Roger
dc.contributor.committeeBret-Harte, Syndonia
dc.contributor.committeeKielland, Knut
refterms.dateFOA2021-10-20T21:50:02Z


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