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dc.contributor.authorBokhorst, Stef
dc.contributor.authorBerg, atty P.
dc.contributor.authorEdvinsen, Guri K.
dc.contributor.authorEllers, Jacintha
dc.contributor.authorHeitman, Amber
dc.contributor.authorJaakola, Laura
dc.contributor.authorMæhre, Hanne K.
dc.contributor.authorPhoenix, Gareth K.
dc.contributor.authorTømmervik, Hans
dc.contributor.authorBjerke, Jarle W.
dc.date.accessioned2018-12-04T14:36:46Z
dc.date.available2018-12-04T14:36:46Z
dc.date.issued2018
dc.identifier.issn1664-462X
dc.identifier.urihttp://hdl.handle.net/11250/2576027
dc.description.abstractClimate change is one of many ongoing human-induced environmental changes, but few studies consider interactive effects between multiple anthropogenic disturbances. In coastal sub-arctic heathland, we quantified the impact of a factorial design simulating extreme winter warming (WW) events (7 days at 6–7 C) combined with episodic summer nitrogen (CN) depositions (5 kg N ha�����1) on plant winter physiology, plant community composition and ecosystem CO2 fluxes of an Empetrum nigrum dominated heathland during 3 consecutive years in northern Norway. We expected that the CN would exacerbate any stress effects caused by the WW treatment. During WW events, ecosystem respiration doubled, leaf respiration declined (�����58%), efficiency of Photosystem II (Fv/Fm) increased (between 26 and 88%), while cell membrane fatty acids showed strong compositional changes as a result of the warming and freezing. In particular, longer fatty acid chains increased as a result ofWWevents, and eicosadienoic acid (C20:2) was lower when plants were exposed to the combination of WW and CN. A larval outbreak of geometrid moths (Epirrita autumnata and Operophtera brumata) following the first WW led to a near-complete leaf defoliation of the dominant dwarf shrubs E. nigrum (�����87%) and Vaccinium myrtillus (�����81%) across all experimental plots. Leaf emergence timing, plant biomass or composition, NDVI and growing season ecosystem CO2 fluxes were unresponsive to the WW and CN treatments. The limited plant community response reflected the relative mild winter freezing temperatures (�����6.6 C to �����11.8 C) recorded after the WW events, and that the grazing pressure probably overshadowed any potential treatment effects. The grazing pressure and WW both induce damage to the evergreen shrubs and their combination should thereforebe even stronger. In addition, CN could have exacerbated the impact of both extreme events, but the ecosystem responses did not support this. Therefore, our results indicate that these sub-arctic Empetrum-dominated ecosystems are highly resilient and that their responses may be limited to the event with the strongest impact.nb_NO
dc.language.isoengnb_NO
dc.rightsNavngivelse 4.0 Internasjonal*
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/deed.no*
dc.subjectcryptogamnb_NO
dc.subjectCO2 fluxesnb_NO
dc.subjectfatty acidsnb_NO
dc.subjectfrostnb_NO
dc.subjectgeometrid mothnb_NO
dc.subjectherbivorynb_NO
dc.subjectmultiple stressnb_NO
dc.subjectsnownb_NO
dc.titleImpact of Multiple Ecological Stressors on a Sub-Arctic Ecosystem: No Interaction Between Extreme Winter Warming Events, Nitrogen Addition and Grazingnb_NO
dc.typePeer reviewednb_NO
dc.rights.holderCopyright © 2018 Bokhorst, Berg, Edvinsen, Ellers, Heitman, Jaakola, Mæhre, Phoenix, Tømmervik and Bjerke.nb_NO
dc.subject.nsiVDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480nb_NO
dc.source.journalFrontiers in Plant Sciencenb_NO
dc.identifier.doi10.3389/fpls.2018.01787


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Navngivelse 4.0 Internasjonal
Except where otherwise noted, this item's license is described as Navngivelse 4.0 Internasjonal