Methods and Future Plans

Background

Wildfiresareanaturalandimportantecologicalprocessintheborealforest(Paye9e1992).Plantcommuni?esinblacksprucedominatedforestsare?ghtlylinkedwiththeirfirecycleintermsoftheirspeciesdiversityandplanttraits(Roberts2004;NilssonandWardle2005).§  Highlyflammableneedlesofblackspruceandotherevergreenshrubs

promotethespreadoffireoveranarea,whereasthicksphagnummossmatsresistburningduetotheirhighwaterreten?onabili?es,resul?nginalowseverityfireandcompletecrownmortality(Johnson2001;Boby2010;Turetsky2010).

§  Thestructureandcomposi?onofthesepre-firecommuni?es,amongotherthings,caninfluencefireseveritythroughtheirplantfunc?onaltraitsandpromoteafireregimethatpermitsforself-replacementsuccessionalpathways(Kurkowskietal.2008;Kasischkeetal.2010;Bernhardtetal.2011).

ResultsfromrecentstudieshaveshownthatshiRsinInteriorAlaska’sfireregimeisresul?nginlarger,morefrequentfires(KasischkeandTuretsky2006).§  OngoingandfutureclimatechangeacrossAlaskaisinfluencingthefire

regimeandhasthepoten?altoshiRthecurrentstateofInteriorAlaska’sblackspruceforeststodeciduousdominatedforests(Gilletetal.2004;Duffyetal.2005Johnstoneetal.2010).

§  AstateshiRtodeciduous-dominatedforestsisexpectedtohaveimplica?onsontheglobalcarboncycle,nutrientcycling,plantproduc?vityandlocalwildlife(Johnstoneetal.2010).

M.Sc. Candidate: Emilia Grzesik

Hypotheses and Predictions

Advisor: Teresa Hollingsworth

1.   Ihypothesizethatvariabilityinplantspecies’fire-ecologicaltraitplas9city(specifically,fire-resis9veandfire-adap9veplanttraits)isinfluencedbyasite’spreviousburnseverity.•  Ipredictpost-fireblacksprucedominatedplantcommuni9esthatundergohigh-severityfireswillcontaingreater

plas9cityinspecies-specificfire-ecologicalplanttraitsthancommuni9esthatundergolow-severityfires.•  Ipredictblacksprucedominatedplantcommuni9esthatoccurinareasofmoderatemoisturewillcontainagrater

plas9cityinspecies-specificfire-ecologicalplanttraitsthanacommunityinanareaofloworhighmoisture(figure2).

2.   Ihypothesizethatthereareemergentproper9esofblacksprucedominatedplantcommuni9es,suchasplantspeciesrichnessandbiomass/fuelloads,thatcanindicatethepoten9alofasitetoreburnorburnseverelybasedoncommunity-levelflammability.•  Ipredictblacksprucedominatedplantcommuni9esthatcontainhighfuelloadsandhighpercentcoverof

flammable,finefuelswillhaveagreaterpoten9altoreburn/burnseverelythancommuni9eswithlowerfuelloadsandlowerpercentcoverofflammable,finefuels.

3.Iplantoapplytheresultsofthisstudytoaframeworkthatcanbeusedbyfiremanagerstoassessablacksprucedominatedcommunity’sabilitytoreburnbasedonsitecharacteris9cs,plantcomposi9onandfuelload.

Figure2.Ahypothe?calmodeldepic?nghowpoten?alforseverefire(throughsmoulderingcombus?on)andthemagnitudeofitseffectschangeovergradientsofmoistureandorganiclayerdepth(reproducedfromJohnstoneandChapin2006).

The28BNZLTER’sRSNsitesthatweresampledforthisstudyvaryacross3ecoregionsinInteriorAlaska,spanamoisturegradientandvaryinage(?me-since-fire).Eachsitewaspreviouslysampledforplantandlichenspeciesrichness(percentcover)usingtheBraun-Blanquetmethodofcoverclassifica?on.Wecollectedtraitplas?citydataforVacciniumuliginosumandHylacomiumsplendens,thetwomostubiquitousspecieswithinthesesites.Wemeasuredfunc?onaltraitsrelatedtorhizomatousrootsprou?ngandandwaterreten?oninV.uliginosumandH.splendens,respec?vely.Addi?onally,wemeasuredunderstoryvegeta?onandsoilorganicbiomasstoquan?fyfuelloads.Wewillusethisdatatoinves?gatepa9ernsbetweenfuelloadandspeciesrichnesswithinasitetounderstandhowcommunity-levelflammabilitycanindicatethepoten?alofasitetoreburn.Theresultsofthisstudywillhighlightthevulnerabilityofcertainloca?onsalongtheborealblacksprucedominatedlandscapetosevereburningandtheabilityoftheblackspruceforesttypetoremainresilienttofireasawhole.

Figure1.Distribu?onofalltheLTER’sRSNsitesinenvironmentalspace.Individualsitesarerepresentedbypointsandsitesagebycolor(pink=1orYoung,green=2orIntermediateandblue=3orMature).Thisfigureisinsupportoftherecentchangeinfireregime.Youngsitesencompassagreaterrangeovertheenvironmentallandscape,signifyingagreaterpropor?onoflandhasburnedinrecentfires.

ReferencesBernhardt,E.,Hollingsworth,T.N.,Chapin,F.S.,&Viereck,L.A.(2011).FireseveritymediatesclimatedrivenshiRsinunderstorycomposi?onofblacksprucestandsininteriorAlaska.JournalofVegeta7onScience,22,32–44.Gille9,N.P.,&Weaver,A.J.(2004).Detec?ngtheeffectofclimatechangeonCanadianforestfires,31.Group,D.M.,&Arc?c,I.(2005).IMPACTSOFLARGE-SCALEATMOSPHERIC–OCEANVARIABILITYONALASKANFIRESEASONSEVERITY,15(4),1317–1330.Johnstone,J.F.,Iii,F.S.C.,Hollingsworth,T.N.,Mack,M.C.,Romanovsky,V.,&Turetsky,M.(2010).Fire,climatechange,andforestresilienceininteriorAlaska1,1312,1302–1312.Kasischke,E.S.,&Turetsky,M.R.(2006).RecentchangesinthefireregimeacrosstheNorthAmericanborealregion—Spa?alandtemporalpa9ernsofburningacrossCanadaandAlaska,33(July).Kasischke,E.S.,Verbyla,D.L.,Rupp,T.S.,Mcguire,A.D.,Murphy,K.A.,Jandt,R.,…Turetsky,M.R.(2010).Alaska’schangingfireregime—implica?onsforthevulnerabilityofitsborealforests1,1324,1313–1324.Kurkowski,T.A.,Mann,D.H.,Rupp,T.S.,&Verbyla,D.L.(2008).Rela?veimportanceofdifferentsecondarysuccessionalpathwaysinanAlaskanborealforest.CanadianJournalofForestResearch,38(7),1911–1923.Lynch,J.A.,Clark,J.S.,Bigelow,N.H.,Edwards,M.E.,&Finney,B.P.(2003).Geographicandtemporalvaria?onsinfirehistoryinborealecosystemsofAlaska,108.Nilsson,M.,&Wardle,D.A.(2005).Understoryvegeta?onasaforestecosystemdriver :evidencefromthenorthernSwedishborealforest.Oby,L.E.A.B.,Chuur,E.D.A.G.S.,Ack,M.I.C.M.,&Erbyla,D.A.V.(2010).Quan?fyingfireseverity,carbon,andnitrogenemissionsinAlaska’sborealforest,20(6),1633–1647.Paye9e,S.1992.FireasacontrollingprocessintheNorthAmericanborealforest.In:Shugart,H.H.,Leemans,R.&Bonan,G.B.(eds.)Asystemsanalysisoftheglobalborealforest,pp.144–169.CambridgeUniversityPress,Cambridge,UK.Roberts,M.R.(2004).ResponseoftheherbaceouslayertonaturaldisturbanceinNorthAmericanforests,1283,1273–1283.Turetsky,M.R.,Mack,M.C.,Hollingsworth,T.N.,&Harden,J.W.(2010).Theroleofmossesinecosystemsuccessionandfunc?oninAlaska’sborealforest1,1264,1237–1264.

Figure3.Averagesoilorganicfuelload(g/cm^2)plo9edagainsta)moistureclass(R^2=0.62andp=0.038)andb)age(R^2=0.70andp=0.25).Soillayerfuelloadswereaverageforeachsite,thenaveragedforeachmoistureorageclass.Fibricandmesicfuelloadaveragesweresummedtodeterminetotalaveragesoilfuelload.

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