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Alternative biomass strategies for bioenergy: implications for bird communities across the southeastern United States

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Alternative biomass strategies for bioenergy: implications for bird communities across the southeastern United States
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Gottlieb, I. G. W. , R. J. Fletcher, Jr., M. M. Nunez-Regueiro, H. Ober, L. Smith, and B. J. Brosi. 2017. Alternative biomass strategies for bioenergy: implications for bird communities across the southeastern United States. Global Change Biology Bioenergy 9:1606-1617.
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Fletcher, Robert
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Global Change Biology Bioenergy
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Concerns over energy demands and climate change has led the United States to set ambitious targets for bioenergy production in the coming decades. The southeastern U.S. has had a recent increase in biomass woody pellet production and is projected to produce a large portion of the nation’s cellulosic biofuels. We conducted a large-scale, systematic comparison of potential impacts of two types of bioenergy feedstocks--corn (Zea mays) and pine (Pinus spp.)--on bird communities across the southeastern U.S. In addition, we evaluated three biomass alternatives for woody biomass from pine plantations: thinning, residue harvest, and short-rotation energy plantations (SREPs). We conducted transect counts for birds in eight different land-uses across the region (85 sites), including corn fields, reference and plantation forests, 2013-2015. We then used hierarchical occupancy models to test the effect of these biomass alternatives on 31 species. Across all species, birds had lower rates of occupancy in corn fields compared to pine stands. Thinning had positive effects on the average occupancy across species, while residue harvest and the potential conversion of conventional plantations to SREPs had negative effects. Cavity nesters and species with bark-gleaning foraging strategies tended to show the strongest responses. These results highlight the potential negative effects of corn as an energy crop relative to the use of pine biomass. In addition, harvesting biomass via thinning was a bird-friendly harvest method in comparison to other alternatives. While SREPs may negatively impact some bird species, previously reported yields emphasize that they may provide an order of magnitude greater yield per unit area than other alternatives considered, such that this land-use practice may be an important alternative to minimize the bioenergy impacts across the landscape.
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Collected for University of Florida's Institutional Repository by the UFIR Self-Submittal tool. Submitted by Robert Fletcher.

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Alternativebiomassstrategiesforbioenergy:implications forbirdcommunitiesacrossthesoutheastern UnitedStates ISABELG.W.GOTTLIEB 1,2 ,ROBERTJ.FLETCHERJR 1,2 MAURICIOM.NU ~ NEZ-REGUEIRO 1,2 ,HOLLYOBER 1 ,LORASMITH 2 andBERRYJ.BROSI 3,4 1 DepartmentofWildlifeEcologyandConservation,UniversityofFlorida,Gainesville,FL32611,USA, 2 SchoolofNatural ResourcesandtheEnvironment,UniversityofFlorida,Gainesville,FL32611,USA, 3 JosephW.JonesEcologicalResearch Center,Newton,GA39870,USA, 4 DepartmentofEnvironmentalSciences,EmoryUniversity,Atlanta,GA30322,USA Abstract ConcernsoverenergydemandsandclimatechangehaveledtheUnitedStatestosetambitioustargetsforbioenergyproductioninthecomingdecades.ThesoutheasternUnitedStateshashadarecentincreaseinbiomass woodypelletproductionandisprojectedtoproducealargeportionofthenation’scellulosicbiofuels.Weconductedalarge-scale,systematiccomparisonofpotentialimpactsoftwotypesofbioenergyfeedstocks – corn ( Zeamays )andpine( Pinus spp.) – onbirdcommunitiesacrossthesoutheasternUnitedStates.Inaddition,we evaluatedthreebiomassalternativesforwoodybiomassfrompineplantations:thinning,residueharvest,and short-rotationenergyplantations(SREPs).Weconductedtransectcountsforbirdsineightdifferentlanduses acrosstheregion(85sites),includingcornelds,referenceforest,andplantationforests,2013 – 2015.Wethen usedhierarchicaloccupancymodelstotesttheeffectofthesebiomassalternativeson31species.Acrossallspecies,birdshadlowerratesofoccupancyincorneldscomparedtopinestands.Thinninghadpositiveeffectson theaverageoccupancyacrossspecies,whileresidueharvestandthepotentialconversionofconventionalplantationstoSREPshadnegativeeffects.Cavitynestersandspecieswithbark-gleaningforagingstrategiestendedto showthestrongestresponses.Theseresultshighlightthepotentialnegativeeffectsofcornasanenergycroprelativetotheuseofpinebiomass.Inaddition,harvestingbiomassviathinningwasabird-friendlyharvest methodincomparisonwithotheralternatives.WhileSREPsmaynegativelyimpactsomebirdspecies,previouslyreportedyieldsemphasizethattheymayprovideanorderofmagnitudegreateryieldperunitareathan otheralternativesconsidered,suchthatthisland-usepracticemaybeanimportantalternativetominimizethe bioenergyimpactsacrossthelandscape. Keywords: biofuels,corn,land-usechange,occupancy,pineplantations,residueharvest,short-rotationenergyplantations, songbird,thinning Received1February2017;revisedversionreceived7April2017andaccepted12April2017 Introduction Concernsoverrisingenergydemands,climatechange, andtheeconomicsandpoliticssurroundingcrudeoil productionhavecreatedglobalinterestindiversifying andgrowingdomesticenergyportfolios(Klass,2003). In2007,theU.S.CongressadoptedtheRenewableFuel StandardProvision(RFS2)asapartoftheEnergyIndependenceandSecurityAct(EISA),whichsetagoalfor theUnitedStatestoproduce36billiongallonsofliquid biofuelsperyearby2022(Sissine,2007).Thisambitious goalwasscaledbackwiththeRFS2mandateof2013, yetlong-term,renewablefuelgoalsremainhigh.These andotherpoliciescollectively(e.g.,BiomassCrop AssistanceProgramofthe2014FarmBill)emphasizea diversepotentialportfolioforbiomassandbioenergy productionacrosstheUnitedStates,wheredifferent cropsandharvestingmethodsmaybeusedtoextract biomassforbioenergy. TheUSDAandDOEprojectthatamajorportionof thenationalproductionofbiofuelsandbioenergywill comefromthesoutheasternUnitedStates(USDA,2010, DOE,2016).Inaddition,therehasbeenarecentincrease inwoodybiomassproductioninthesoutheastfor bioenergyintheformofwoodypelletproduction(Galik &Abt,2016;Dale etal. 2017 ).Asaconsequence,largescaleland-usechangemayoccur(Fargione etal. ,2010), suchastheconversionofplantationstandsfortimber productiontothatofshort-rotationstandsdedicatedto biomass(Munsell&Fox,2010).Understandingthe potentialimpactsthatland-usechangesforbioenergy Correspondence:RobertJ.FletcherJr,tel.+13528460632,fax+1352 3926984,e-mail:robert.etcher@u.edu 2017TheAuthors. GlobalChangeBiologyBioenergy PublishedbyJohnWiley&SonsLtd. ThisisanopenaccessarticleunderthetermsoftheCreativeCommonsAttributionLicense, whichpermitsuse,distributionandreproductioninanymedium,providedtheoriginalworkisproperlycited. 1 GCBBioenergy(2017),doi:10.1111/gcbb.12453

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mayhaveonwildlifecommunitiesisneededtoencourageuseofbestmanagementpracticesthatlimitimpacts onbiodiversityonalocalandregionalscale. Twoprimarybiomassfeedstocksbeingconsideredin thesoutheastincludecorn( Zeamays )rowcropsand pine( Pinus spp.)plantations(DOE,2011,2016).Cornis thedominantrowcropgrownforethanolproductionin theUnitedStatesandcouldbegrownaseitherarstgeneration(i.e.,ethanolderivedfromsugarsextracted fromthefruit)orsecond-generation(i.e.,ethanol derivedfromcellulose)biofuelcropinthesoutheast (Gonzalez etal. ,2012).Loblolly( Pinustaeda )andslash pine( Pinuselliottii )plantationsarelikelytobeaprimarysourceofbiomassinthesoutheastandarealready widelycultivatedacrosstheregionforotherpurposes (Nesbit etal. ,2011;DOE,2016,Costanza etal. ,2017). Threemajorharvestmethodsforextractingbiomass frompineplantationsinclude(i)biomassfromthinning conventionalpineplantations(‘thinning’);(ii)the harvestofcoarsewoodydebris(CWD)residuesfrom clear-cuts(‘residueharvest’);and(iii)theconversionof conventionaltimberstandstoshort-rotationenergy plantations(‘SREP’)(Munsell&Fox,2010).Meta-analysesandscenariomodelinghaveprovidedkeyinsights regardingeffectsofthesecropsandpotentialwildlife responses(Fletcher etal. ,2011;Riffell etal. ,2011a,b; Verschuyl etal. ,2011;Tarr etal. ,2017)andsomerecent investigationshaveprovidedusefulinformationfor specicalternatives(Homyack etal. ,2014;Fritts etal. 2016;Grodsky etal. ,2016a).Yettheextenttowhich theseharvestmethodsdifferentiallyimpactwildlifeis largelyunknown,asasystematicland-usecomparison acrosseachoftheselanduseshasnotyetbeendoneto allowformalcomparisonamongthesealternatives.Such acomparisonisessentialforpolicymakersandthe bioenergyindustrytobeabletomakeinformeddecisionsaboutenvironmentalissuesrelatedtolandmanagementpracticesforbioenergyproduction. Ourobjectivewastoconductasystematiccomparison oftheconservationimplicationsofpotentialbioenergy alternativesforbirdcommunitiesinthesoutheast.We contrastedtwoprimarybioenergyfeedstocks – cornand pinebiomass(Fig.1a).Withinpineplantations,wecontrastedthreemajorharvestmethods:(i)thinning,(ii) residueharvest,and(iii)SREPs.Wealsocontrastedbird communitiesincorneldandplantationstoreference longleafpine( Pinuspalustris )savannaforests.Wechose tostudytheresponseofbirdstolandmanagementfor bioenergydevelopmentbecausetheyareahighly diversetaxonthatcanbesampledrapidlytodetermine patternsofoccupancyacrossalandscape(Ralph etal. 1995).Wefocusedonchangesinoccupancyofbirds acrosslandusesreectingthesebioenergyconditions (Fig.1b – h).Wefocusedonoccupancybecausethis parametercanbeestimatedfordozensofspeciesacross severallandusesinastandardizedwaythatrigorously accountsforobservationerror(i.e.,imperfectdetection; Kery&Royle,2016;Mackenzie etal. ,2002),whichcan impactinferencesandpredictionsregardingoccurrence inbirds(e.g.,Rota etal. ,2011). Weexpectedthatwhilebirdswouldoccuratthe highestratesofoccupancyinreferenceforests,bird occupancywouldbehigherinpineplantationsthanin corn(Fargione etal. ,2010;Fletcher etal. ,2011).Fewbird speciesareknowntoconsistentlybreedincornelds (Best etal. ,1997),whereasagreaterdiversityofbirds hasbeenreportedinpineplantations(Brockerhoff etal. 2008),presumablybecauseofgreaterhabitatheterogeneitythanincornelds(Fletcher etal. ,2011).Within thepineplantations,wepredictedthatplantationthinningwouldhaveapositiveorneutraleffectonspecies occupancybycreatingmoreheterogeneityandprovidingmoreopenhabitatsneededforsomebirdspecies (Verschuyl etal. ,2011).Incontrast,wepredictedthat residueremovalandSREPsalternativeswouldhave,on average,negativeeffectsonoccupancybyreducing coverfromresidueandviareducedheterogeneityin treeageandspacingforSREPs(Riffell etal. ,2011a,b). YetweexpectedthattheeffectofSREPswouldbe greaterthanthatofresidueremovalbecauseofgreater structuralchangesinvegetation.Weendbycontrasting theseeffectswithreportedpotentialbiomassyieldsgeneratedbythesealternatives(Varvel etal. ,2008;Eisenbies etal. ,2009;Evans&Cohen,2009;Guo etal. ,2010;Munsell&Fox,2010;Gonzalez etal. ,2012).Materialsandmethods StudyareaWesampledbirdsat85sitesacrossthreebreedingseasons, April – July,2013 – 2015(Fig.2).Samplingoccurredinmature, naturallyregeneratedlongleafpinesavannas,slashandloblolly pineplantations,andcorneldsevenlydistributedamongthree geographicregions(Fig.1,TableS1)withintheSoutheastern PlainsandSouthernCoastalPlainsecoregionsinthekeybioenergystatesofFlorida,Georgia,andAlabama(USDA,2010). Wecomparedbirdspeciesoccurrenceamongreferenceforest,twocroptypes – cornandpine – andthreepineharvest methods:thinning,residueharvest,andSREPs.Weidentied eightrelevantland-useconditionsthatenabledustoestimate effectsofalternativesforbiomassproduction(Fig.1b – i;and seebelow).Foreachofthesecroptypesandharvestingmethods,existingrelevantlandusesoccuracrosstheregionwhere biomasswasbeingremovedoraltered.However,biomassat someofthesesiteswasnotbeingusedforbioenergyatthe time.Welocated7 – 12sitesofeachtype(TableS1)byconsultingwithlocalextensionspecialistsandindustrypartners, whichwerestratiedamongthreegeographicregions(Fig.2). 2017TheAuthors. GlobalChangeBiologyBioenergy PublishedbyJohnWiley&SonsLtd.,doi:10.1111/gcbb.124532 I.G.W.GOTTLIEB etal.

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Weselectedcorneldsineachregiontocontrastcornwith pinebiomassalternatives.Corneldsarecurrentlyusedforbiomassasarst-generationbiofuel,althoughcornstovercould beanalternatesourceofcellulosicbiomass.Althoughcornis notcurrentlyproducedinthestudyregionatlevelssimilarto themidwesternUnitedStates,cornyieldscanbehighinmany areasofthesoutheast(Evans etal. ,2010).Tointerpretthe effectsofresidueharvest,wesampledloblollyandslashpine plantationsthathadbeenclear-cutwithinthepasttwoyears whereCWDwasleftontheground(clear-cutdebrisleft, CCDL, n = 11)andcomparedthemtoclear-cutswhereCWD wasremovedfromtheplot(clear-cutresiduesremoved,CCRR, n = 10).Whentimberisharvestedwithinthecontextoftraditionalforestry,asubstantialamountofnonmerchantablecoarse woodydebris(CWD)isoftenleftonsiteandisapotential sourceofbiomassforbiofuelproduction(Riffell etal. ,2011a). Tointerpreteffectsofthinning,wecomparedunthinned loblollyandslashpineplantationsaged12 – 16years(unthinned, n = 11)torecentlythinnedstandsofsimilarage (thinned, n = 12).Thiscomparisonattemptstocontrolforstand agewhilecontrastingstandsthathavebeenthinnedtothoseof similaragethathavenotbeenthinned.Inaconventionalpine productionsystem,plantationsaretypicallyrstthinned betweenages12and15topromotethehealthandgrowthof CornResidues removedResidues leftYoung UnthinnedThinnedMatureReference Biomass production No biomass production Corn Pine Residue Thinning Short-rotaon Reference (longleaf pine) Crop type Harvest type (a) (b)(c)(d)(e) (f)(g)(h)(i) Fig.1 (a)WeconsideredtheeffectsofseveralbiomassalternativesonbirdcommunitiesinthesoutheastUnitedStates.Weconsideredtwocroptypes,pineandcorn,andthreebiomassharvestingalternativesforpine,contrastingthesealternativestoreferencelongleafforest.(b – i)Tointerpretthesebiomassalternatives,wesurveyedeightland-usetypesthatarerelevanttoalternativebiomass strategies,including(b)cornelds,(c)clear-cutpineforestswithresiduesremovedand(d)withresiduesleft( 3years),(e)young pineplantations(8 – 10years),(f)unthinnedand(g)thinnedplantations(12 – 16years),(h)matureplantations(20 – 32years),and(i)referencelongleafforests( > 40years). 2017TheAuthors. GlobalChangeBiologyBioenergy PublishedbyJohnWiley&SonsLtd.,doi:10.1111/gcbb.12453IMPACTSOFBIOENERGYALTERNATIVESONBIRDS 3

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remainingtrees.Toexamineashort-rotationeffect,wefocused oncomparingsitesaround8 – 10yearsofage(‘young’)(Gonzalez etal. ,2011)toconventionaltimberproduction,inwhich treesarefrequentlyharvestedon24-to25-yearrotationsand thinnedatleastonce.See Methods:Analysis formoredetailson thiscomparison.Latesuccessionalorold-growthlongleafpine savannas(‘reference’)wereconsideredtorepresenthistoricforestconditions.Thesesitesallowedforunderstandinghowgeneralpineproductionforbiofuelsandothertimberpurposes mayimpactbirdcommunitiesrelativetohistoricconditions.SurveydesignWeidentiedeldsitesprimarilyinpatches > 16ha( n = 83) andestablishedtwo,200 9 100mtransects.Tocontrolfor potentialedgeeffectsthatcanbecommoninbirddistributions (Ries etal. ,2004),inallsiteswesampledbothattheedgeand intheinteriorofsites.Anedgetransectwasplaced50mfrom, andparallelto,theedgeofthestandwiththegreatestcontrast toadjacenthabitat.Aninteriortransectwasplaced 150m fromanyedge,withatleast100mbetweenthetwotransects. Twositeswere < 16habut > 4.5ha,andasingle-edgetransect wasestablishedinthesestands.BirdsurveysWeconductedlinetransectsurveysforbirdsbetweenApril1 andJune30ofeachyear.Trainedobserverswalkedatastandardpacedownthecenterlineofeach200 9 100mtransect andrecordedallbirdsobservedbysightorsoundwithinthe boundariesofthetransect.Eachtransectwassurveyedonthree samplingoccasionsseparatedbyapproximately4weeks.Duringthesethreesamplingoccasions,eachtransectwassurveyed twiceinthesamemorningtoaccountforvariationinimperfect detection,betweensunriseand9:30AM.Eachsitewassurveyedonlyduringoneofthethreeyearsinordertomaximize thespatialcoverageofthestudy.Surveyswerepostponedif weatherconditions(windorrain)compromisedanobserver’s abilitytodetectbirds.VegetationsamplingWesampledvegetationtocontrastdifferencesinourmanagementland-usecategories.Atthemidpointofeachtransect,we establishedavegetationplotfollowingtheprotocoldescribed bytheForestInventoryandAnalysisprogramoftheUSDA ForestService(Woudenberg etal. ,2010)tocharacterizethevegetationstructureundertheeightmanagementconditions.Each vegetationplotconsistedoffour,7.3-m-radiussubplotsin whichthediameteratbreastheight(DBH)andspeciesofall trees > 12.7cmDBHwererecorded.Inthecenterofeachsubplotwithinaradiusof2.1m,wealsorecordedtheabundance ofshrubsineachofthefollowingheightclasses:a.0 – 1m;b. > 1 – 2m;c. > 2 – 3m,d. > 3m.Radiatingfromthecenterofeach subplotwerethree7.3-mtransectsalongwhichwemeasured thelengthanddiameterofeachpieceofcoarsewoodydebris (CWD)thatintersectedthetransect.Weestimatedthepercent groundcoverofwoody,forb,gramminoid,andbare/litter coverwithina1-m2groundcoverplotlocatedattheendof eachCWDtransect.StatisticalanalysesTestingeffectsofbiomassproductionalternativesonbird occurrence.Toestimateeffectsofbioenergyoptionsonbirds, weusedasingle-species,single-seasonoccupancymodeling approachdevelopedbyMackenzie etal. (2002)inwhichpresence – absence(ormoreappropriately,detection – nondetection) datafromindependent,repeatedsurveyswereusedtoaccount forerrorsinspeciesdetection.Webasedouranalysisonthe BayesianoccupancymodelofRoyle&Dorazio(2008)because ofitsabilitytoestimateuncertaintysurroundingpointestimatesofoccupancy,includerandomeffectsintothemodels, andquantifyappropriate apriori contrastsamonglanduses. Wemodeledoccupancyforbirdspeciesthatweredetectedin atleast20%oftheeldsites( n = 31species).Foreachspecies, weestimatedtheprobabilityofoccurrence( w )acrossthe85 eldsitesasafunctionofmanagementcondition(eightland uses)asacovariateon w ,andweincludedsiteasarandom effect.Althoughwewereprimarilyinterestedhow w varied acrosslanduses,wealsoinitiallyconsideredeffectsofpatch sizebecauseoccupancyiswidelyknowntovarywithpatch sizeinbirds(Prugh etal. ,2008)andoursitesvariedinpatch size.Yetwefoundnoevidenceofpatchsizeeffectsaltering ourestimatesofhow w variedacrosslanduses( unpublished analysis ),soweremovedthiscovariatefrommodelstoreduce modelcomplexity.Becausethebreedingpopulationcouldbe potentially‘open’duringthe3-monthsurveyperiod(Rota etal. ,2009),whereoccupancycouldchangeovertimefromdispersalintooroutofthesite,weformattedourmodelto accountforthispotentialissue,whilefocusingonaverage occupancy(ratherthanlocalcolonization – extinctionparameters;Mccarthy etal. ,2012).Todoso,weusedthetwosurveys fromasite(poolingedgeandinteriortransectswithinsites)in asinglemorningtoproduceadetectionhistoryfromwhichwe estimatedspecies-specicdetectionprobabilities(Mackenzie etal. ,2002).Thesepaireddetectionhistorieswererepeated threetimes(one/visit)foreachsite,andweusedsiteasarandomeffecton w toaccountforwithin-sitedependenceandsitelevelvariationnotcapturedbyourland-usecategories.This approachincreasesthelikelihoodofadequatelyaddressingthe assumptionofclosureinoccupancymodels,becauseclosure wasonlyassumedwithinvisits(Rota etal. ,2009).Toaccount forheterogeneityindetectionprobabilities,weincludedsurvey-speciccovariatesofJuliandate(linearandquadratic terms)andtimeofday.Formoredetailsontheoccupancy modelingframework,seeSupportingInformation. Foreachspecies,wecalculatedtheprobabilityofoccurrence w ineachland-usecondition.Toisolatepotentialeffectsof land-usechangesassociatedwithbiomassproductionscenarios,wealsofocusonthechangeintheprobabilityofspecies occurrence, D w ,associatedwitheachharvestmethodforbioenergyproductionusing apriori contrastsbasedonposterior distributionsfrommodelsforeachspecies.Contrastsincluded residueeffect,thinningeffect,twotypesofshort-rotationeffect, andcorneffect.Thecontrastforresidueharvesteffectwas 2017TheAuthors. GlobalChangeBiologyBioenergy PublishedbyJohnWiley&SonsLtd.,doi:10.1111/gcbb.124534 I.G.W.GOTTLIEB etal.

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quantiedas: D wresidue wCCRR wCCDL 1 Thethinningeffectcontrastcomparedoccupancyinthinned vs.unthinnedplotsofsimilarage: D wthin wthin wunthinned 2 Fortheshort-rotationeffect,wedecomposeditintotwoseparateparts,therstrelatedtotheharvestofCWDandthesecond relatedtothedifferenceinthelengthoftheplantationrotation. Therefore,toassesstheimpactofaSREPcomparedtoconventionaltimberproduction,weusedthe‘residueharvesteffect’ describedabove,aswellasthe‘short-rotation’effect,which describesthedownwardshiftintheageoftheplantation.We comparedoccupancydatafromyoungstands,representativeof SREPsatthemaximumstageoftheirrotation,andcompared themtotheaverageoccupancyofunthinned,thinned,and mature.Therationaleforthiscomparisonisthatashifttoshortrotationproductionwilleliminateolderageclassesfromthelife cycleofaplantationstandandthecomparisonismostrepresentativeofhowthismanagementchangewouldmanifestoverthe courseofatimberrotation.Thiscontrastcanbeformalizedas: D wSREP wyoung wunthin wthin wmature = 3 3 Wecombinedthesetwoissuesas: D wSREPTOTAL wCCRR wyoung = 2 wCCDL wunthin wthin wmature = 4 4 Finally,forthecorneffectcontrast,wetestedfordifferences inoccupancyofcorneldscomparedtotimberstandsbycombiningoccupancydatafromalltimberland-useconditionsand comparingthemasagrouptocornelds: D wcorn wcorn wCCDL wCCRR wyoung wunthinned wthin wmature = 6 5 Inadditiontospecies-specicresults,weprovideaverage effectsacrossallspeciesandconsideredrelationships betweenthechangesin w andspeciestraits,includingforagingguild(Degraaf etal. ,1985)andnesttype(Martin,1993), andwealsoidentiedregionalconservationstatusofspecies asdenedbyPartnersinFlightandlocalstateagencies(Carter etal. ,2000,FWC,2012;GDNR,2014,ADCNR,2015).To doso,weusedposteriordistributionsfromcontrasts (Eqns1 – 5)toestimatepooledeffectsacrossallspeciesconsideredandspeciesgroups,similartothederivationofcommunityparametersfroman‘N-foldsingle-speciesoccupancy model’(Kery&Royle,2016). WeestimatedparametersusingMarkovchainMonteCarlo (MCMC)algorithmusingJAGS4.0.1(Plummer,2012)inprogramR(Team,2016).Weranthreechainsfor100000iterations,usingtherst50000samplesasburn-inandusinga thinfactorof5toselectsamples.Convergencewasassessed usingtheRubin – Gelmanstatistic(all R -hatvalues < 1.1).We usedvaguepriorsforallxedcovariates(N ~ (0,100))and usedauniformdistributionforstandarddeviationparametersoftherandomsiteeffects(U ~ (0,10)).Wemadeinferences basedon95%credibleintervalstakenfromtheposteriordistributions.Differencesinvegetationbetweenlanduses.Tohelpinterpret habitatvariationacrosslanduses,wedeterminedwhether therewerequantiabledifferencesinvegetationamongthe landusesweconsidered.Fromourvegetationsampling,we summarizedDBHbasedonthemeanforeachplotandthe coefcientofvariation(CV),tall( > 1m),andshort( < 1m)shrub density(shrubs/m2),andwecalculatedthetotalvolume(cm3) usinglengthanddiametermeasurementsandfrequency(proportionofplotswithCWD)ofcoarsewoodydebris,andthe averagegroundcover(%)forwoody,graminoid,forb,and bare/litter. Wersttestedforageneraleffectofwhetherforestlanduse wasstructurallydifferentusingamultivariateanalysisofvariance(MANOVA).Wethenused apriori contrastsdescribedabove forbirdcommunities(Eqns1 – 4)todeterminevariationineach componentvegetationstructuredescribedabovebetweenkey land-usecomparisonsrelevantforbiomassproductionalternatives.Foranalyses,allvegetationvariableswerecenteredand scaled,butweprovideeffectsizesontherawscaletoaidin interpretation.Wedidnotincludecornsitesinthiscomparison becauseoftheirextremedifferencesinvegetationfromforested sites(e.g.,nocanopy,shrubcover).Results AvianresponsestobiomassalternativesWecollectedatotalof6641individualdetectionsof81 speciesofbirdsinthe85studysites.Twenty-oneof thesespecieswerecategorizedas‘ofregionalconcern’ intheSoutheasternCoastalPlainbythePartnersin Flight,orasa‘SpeciesofGreatestConservationNeed’ bythestatesofFlorida,Georgia,orAlabama(TableS2). Seventypercentofbirdobservationswerebysound only,12%bysightonly,and18%bysightandsound. Consequently,weexpectedtimeofmorninganddateto berelevantcovariatesfordetectabilityinoccupancy modelsbecausesingingbehaviorisgreatlyinuenced bytimeanddate(Brown&Handford,2003).See TableS3forparameterestimatesofdetectabilitybased ontimeanddate. Acrossall31speciesconsideredforoccupancymodeling,theaverageoccupancyvariedamongland-use types(Fig.3a),withlowratesofoccurrenceincorn eldsandinclear-cutswithresiduesremovedand higherratesofoccurrenceinallotherforestslanduses (Fig.3a;SeeFig.S1foroccupancyofeachspeciesby land-usetypes).Basedoncontrastsfrompoolingacross allspeciesconsidered,thinning(Eqn.2)tendedtohave positiveeffects,whileresidueharvest(Eqn.1),thetotal short-rotationalternative(SREPtotal;Eqn.4),andcorn (Eqn.5)tendedtohavenegativeeffects(Fig.3b). Yetthereweremanyindividualspeciesthatexperiencedsignicantincreasesordecreasesintheirprobabilityofoccurrenceassociatedwitheachharvest 2017TheAuthors. GlobalChangeBiologyBioenergy PublishedbyJohnWiley&SonsLtd.,doi:10.1111/gcbb.12453IMPACTSOFBIOENERGYALTERNATIVESONBIRDS 5

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method(Fig.4),whichcanbeexplained,inpart,based onspeciestraitsandresponsestospecicvegetation variables(seeGottlieb,2016foranalysesbasedonvegetationcovariatesratherthanland-usetypes).Allve specieswithsignicantresponsestothethinningeffect increasedintheprobabilityofoccurrencewiththinning.Groupsthathadthelargestincreasesinoccurrenceassociatedwiththethinningeffectincluded cavitynestersandbarkexcavators/gleaners,twoguilds withconsiderablespeciesoverlap(Fig.5;TableS2). Ninespecieshadsignicantresidueharvesteffects; eachofthesespeciesdecreasedinoccurrencewithresidueharvest.Allforagingandnestingguildstendedto havenegativeresponsestoresidueharvest,although themostsensitivegroupswerelowercanopyforagers andcavitynesters(Fig.5).FortheSREPscenario, sevenspeciesdecreasedinoccurrencerelatedtothe short-rotationeffect(lossofolderagestands).Onlythe white-eyedvireo( Vireogriseus )increasedinoccurrence inoccupancyinresponsetotheshort-rotationeffect. Again,barkexcavators/gleanersandcavitynesters werethemostsensitivegroupstotheshort-rotation effect(Fig.5).TheSREPtotalscenariothatincludedboth residueharvestandalossofolderplantationstages had14specieswithsignicanteffects,allofwhich decreasedinoccurrence(Fig.4).Forthecornscenario, 20specieshadsignicanteffectsizes(Fig.4),allof whichdecreasedinoccurrenceincornrelativetomanagedpine.VegetationdifferencesacrosslandusesOverall,vegetationstructureofthesevenlandusesconsidered(cornnotconsidered;seeMethods)wasdifferentbasedonMANOVA(Pillai’strace = 1.67;df = 6,71; P < 0.0001;Table1).Siteswithresiduesremovedhad lowerDBH,basalarea,lesswoodycover,lowerfrequencyofcoarsewoodydebris,andatendencyforlower volumecoarsewoodydebristhansiteswithresidues retained(4.1 2.7vs.8.6 4.4,SE,respectively).While thevolumeofcoarsewoodydebriswasnotsignicantly differentinthiscomparison,wenotethatvolumehada highlyskeweddistributionandthatthisdifferencewas signicantwhenassessedwitharank-basedtest (Kruskal – Wallistest: v2= 6.43,df = 1, P = 0.011).Thinnedsiteshadlowerbasalareathanunthinnedsitesof similarage.FortheSREPeffect,wefoundlowerDBH, basalarea,woodycover,andalowerfrequencyofCWD. FortheSREPtotaleffect,wefoundlowerDBH,lowercoefcientofvariationofDBH,basalarea,woodycover,and alowerfrequencyofCWD(Table1).DiscussionInterpretingthepotentialeffectsofanexpansioninbiofuelandbioenergyproductiononbiodiversityrequires systematiccomparisonsregardingpotentialalternative biomassstrategiesbeingconsidered.Todate,mostcomparisonsonthebiodiversitywithinbioenergycrops 0150300 75Kilometers Fig.2 (a)OurstudyareaspannedcoreofthecoastalplaininthesoutheasternUnitedStates.Wesampled85sitesspreadacross threegeographicstratalocatedinAlabama,Georgia,andnorthernFlorida.Foreachgeographicstrata,wesurveyedeightlanduses, whereweestimatedoccupancyof31birdspecies. 2017TheAuthors. GlobalChangeBiologyBioenergy PublishedbyJohnWiley&SonsLtd.,doi:10.1111/gcbb.124536 I.G.W.GOTTLIEB etal.

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comparethesestandstonative,naturalhabitatsoronly considersingleharvestmethods(Fritts etal. ,2016; Grodsky etal. ,2016a).Whilesuchcomparisonsareuseful,thesecomparisonsdonotallowaformalassessment ofrelativeimpactstobiodiversityofbiomassalternativesbeingconsideredacrossregions.Ourresultsallow formalcontrastbetweenbothkeycroptypesandbiomassharvestalternativesrelevanttobiofuelandbioenergyexpansioninthesoutheastUnitedStates.In addition,thesegeneralalternativesarebeingconsidered inotherportionsoftheUnitedStates(DOE,2016)and couldprovideinsightintogeneraltrade-offsinregardingtobioenergyproductionandbiodiversity.CroptypeWhencontrastingpotentialeffectsofpinevs.cornbiomass,timberstands,regardlessofwhethertheyare managedasconventionalorshort-rotationplantations, supportedfargreateroccurrenceofbirdsthancorn elds.Everynestingandforagingguildexaminedhad loweroccupancyratesincornsitesthanintimbersites, withlowercanopyforagers,cavitynesters,andbark excavators/gleanersshowingthestrongestnegative responses(Fig.4,5).Mostofthespeciesfoundincorn eldsweredetectedonlyonceortwice,andonlyinone ortwosites,suggestingthattheiruseofcorneldsfor breedingislikelylimited.Further,onlyonespeciesof conservationconcern(northernbobwhite; Colinusvirginianus )occurredinacorneld(cf.Robertson etal. 2012),whileallsevenspeciesofconservationconcern weconsideredinourstudy(TableS2)occurredwidely acrosstimberplantations,suggestingthattimberplantationscanprovidehabitatforthesespecies,whereas corneldsdonot.Theseresultsaddtoagrowingconsensusthatonlyfewbirdspeciespersistincornelds (Christian etal. ,1997;Fletcher&Koford,2003;Fargione etal. ,2010;Robertson etal. ,2011;Blank etal. ,2016),and ourresultsdemonstratedthatbirdsoccurredathigher ratesinpineplantationsthanincornelds.AlternativepinebiomassharvestoptionsWhiletherewerecleardifferencesinaviancommunities betweencornandpinestands,thebirdresponsetopine biomassharvestmethodsvariedwidelyamongspecies. Thepositiveimpactofthinninginplantationforestson wildlifebiodiversityhasbeenwelldocumented.The proposedmechanismisthatthinningthedense,closed canopyallowslighttopenetratetotheforestoor,facilitatinganincreaseincomplexityofverticalstructurein theunderstory,andsubsequently,theabundanceand diversityofbirdsandotherspecies.Indeed,thinning wastheonlybiomassharvestmethodwithanetpositiveimpactonavianoccupancyrates(Fig.3b).Most guildsbenettedfromthethinningeffect,althoughthe strongestresponseswereobservedinbarkgleaners, cavitynesters,treenesters,anduppercanopyforagers (Fig.5)suchasthedownywoodpecker( Picoidespubescens )andthetuftedtitmouse( Baeolophusbicolor ). Ashypothesized,theharvestofloggingresidues fromclear-cutplantationshadconsistentlynegative effectonavianoccupancyacrossallnestingandforagingguildsinthestudy,butthemagnitudeofthe effectwassurprising.Inaddition,arecentexperiment onresidueremovalfoundlittleeffectsonbreeding andwinteringbirds(Grodsky etal. ,2016a,b);rather, Grodsky etal. (2016a,b)andinsteadsuggestedthat thesuccessionaltrajectoryofvegetation(e.g.,sapling growth/treesuccessionalstage)wasmorecriticalthan residueretentionperse.Similarly,theunderstoryof clear-cutswheredebriswasretainedvariedsubstantiallyinourstudyarea,andsomehadawell-developedunderstoryandverticalstructure(e.g.,snags andnontargettrees),whichwasreectedbyvariation (a) (b) Reference Mature Thinned Unthinned Young Residue left Residue removed Corn SREP Total SREP Thinning Residue Corn 0.000.250.500.751.00 0.500.250.000.250.50Average probability of occurrence Average effect size Fig.3 Averageoccupancyrate(with95%credibleintervals) for31birdspeciessurveyedat85sitesinAlabama,Georgia, andnorthernFlorida.(a)Averageoccupancyforeachland-use typeconsidered,and(b)effectsizestakenfromland-usecontrastsforeachbiomassalternative(with95%credibleintervals, CRI).For(a),plantationland-uselabelsareshowningreen, longleafforestingray,andcorneldinyellow.Foreffectsizes shownin(b),‘corn’comparedtheaverageoccupancyratein alltimberstandstocornelds,‘residue’comparedclear-cuts wheretheresidueswereleftonsitetoclear-cutswheretheresidueswereharvested,‘thinning’comparedunthinnedstandsto recentlythinnedstandsofsimilarstandage,short-rotation, ‘SREP’comparedyoungstands(8 – 10years)atthemaximum ageofashort-rotationplantation(SREP)totheaverageoccupancyrateofaconventionalpineplantationstages > 12years thatmaybeabsentinaSREPscenario,and‘SREPTotal’combinedtheSREPandresidueeffectsizes. 2017TheAuthors. GlobalChangeBiologyBioenergy PublishedbyJohnWiley&SonsLtd.,doi:10.1111/gcbb.12453IMPACTSOFBIOENERGYALTERNATIVESONBIRDS 7

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inbasalareaandDBHofremainingtrees(Table1). Wehypothesizethatthisstructure,ratherthansolely theretentionofCWD,providedhabitatforsummer tanager( Pirangarubra ),pileatedwoodpeckers,and red-headedwoodpeckers( Melanerpeserythrocephalus ), whichwereneverobservedinclear-cutswherethe residueshadbeenremoved.Instandswheretheresidueswereremoved,muchofthesubstrateforperching,foraging,andcoverwasremoved,andveryfew birdsremained.Thisuniformpatternoflowoccupancyacrossthetaxaisconsistentwitharecent meta-analysisreportingthatbothcavityandopennestingbirdsconsistentlydeclineinresponsetoresidueharvest(Riffell etal. ,2011a).Cavitynestersand lowercanopyforagerswerethemostsensitivegroups tothisharvestmethod(Fig.5).Retentionofselected livetrees,snags,andCWDonclear-cutsitesmay increasetheabilityofmanybirdstopersistinclearcuts(Hansen etal. ,1995). TheSREPalternativehadthelargestoverallnegative effectonthebirdcommunityofthethreewoodybiomassharvestmethodsconsidered,intermsofthenumberofspeciesshowingnegativeeffects,becauseofthe combinedeffectsoftheresidueharvestandtheshortrotationeffect(lossofolderagestands).Betweenthe twoeffects,14ofthe31speciesconsideredwerenegativelyaffectedbymanagementforSREPs.Thespecies negativelyaffectedbytheshort-rotationeffectshowa strongpattern:Sevenoftheninespecieswerecavity nesters,andvewereeitherbarkgleanersorairsalliers thatrequirelargetreesandanopencanopyand/or understoryinwhichtoforage.Fourspeciesof conservationconcern(Bachman’ssparrow, Peucaeaaestivalis ;brown-headednuthatch ; Easterntowhee, Pipilo erythrophthalmus; red-headedwoodpecker)showeda negativeresponsetotheresidueharvesteffectorshortrotationeffect,supportingpreviousndingsthatwhile short-rotationenergyplantationsmayprovidehabitat Corn Residue Thinning SREP SREP Total 101 101 101 101 101 Yellow-throated Vireo White-eyed Vireo Tufted Titmouse Summer Tanager Red-headed Woodpecker Red-bellied Woodpecker Pine Warbler Pileated Woodpecker Palm Warbler Northern Parula Northern Mockingbird Northern Cardinal Northern Bobwhite Mourning Dove Indigo Bunting Hooded Warbler Great-crested Flycatcher Eastern Wood-pewee Eastern Towhee Eastern Bluebird Downy Woodpecker Common Yellowthroat Carolina Wren Carolina Chickadee Brown-headed Nuthatch Brown-headed Cowbird Blue Jay Blue Grosbeak Blue-gray Gnatcatcher Bachman's Sparrow American Crow Effect size (95% CRI) Fig.4 Species-speciceffectsizestakenfromland-usecontrastsforeachbiomassalternative(with95%credibleintervals,CRI)for 31speciessurveyedat85sitesinAlabama,Georgia,andnorthernFlorida.Foreffectsizes,corncomparedtheprobabilityofoccurrenceinalltimberstandstocornelds,residuecomparedclear-cutswheretheresidueswereleftonsitetoclear-cutswheretheresidueswereharvested,thinningcomparedunthinnedstandstorecentlythinnedstandsofsimilarstandage,short-rotation(SREP) comparedyoungstands(8 – 10years)atthemaximumageofashort-rotationplantation(SREP)totheaverageoccupancyrateofa conventionalpineplantationstages > 12yearsthatmaybeabsentinaSREPscenario,andSREPTotalcombinedSREPandresidue effectsizes.Bluepointshighlightsignicantpositiveeffectsizes,whileorangepointshighlightsignicantnegativeeffectsizes,based on95%CRIs.SeeSupportingInformationforscienticnames. 2017TheAuthors. GlobalChangeBiologyBioenergy PublishedbyJohnWiley&SonsLtd.,doi:10.1111/gcbb.124538 I.G.W.GOTTLIEB etal.

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formanycommonforearlysuccessionalbirdsandother wildlife,theywerenotvaluableforprotectingrarespeciesofconservationconcernthatdependonmature pinesavannas(Campbell etal. ,2012).Thewhite-eyed vireowasthesinglespeciesthatshowedasignicant positiveresponsetotheshort-rotationeffect.These ndingsareconcordantwithRiffell etal. ’s(2011b) meta-analysis,whichfoundmostlynegativeresponses toSREPsfromcavitynesters,butanincreaseinsome speciesofshrub-associatedbirds.LimitationsOurresultsprovidenewempiricalinformationonbird communitiesacrosslandusesrelevanttoseveralbiomassalternatives.However,thereweresomelimitations toourstudy.First,wedidnotconsiderthepopulation demographyofspeciesandinsteadfocusedoncommunitystructure.Aviandemography(e.g.,nestsuccess, (a) (b) SREP Total SREP Thinning Residue Corn SREP Total SREP Thinning Residue Corn 0.60.30.00.30.6Effect size (95% CRI)Nesting guild Cavity Ground Shrub Tree Foraging guild Bark Ground Low canopy High canopy Sally Fig.5 Effectsizes(with95%credibleintervals,CRI)taken fromland-usecontrastsforeachbiomassalternativeasafunctionofspeciestraits:(a)nestingguildand(b)foragingguild. Foreffectsizes,corncomparedtheprobabilityofoccurrencein alltimberstandstocornelds,residuecomparedclear-cuts wheretheresidueswereleftonsitetoclear-cutswheretheresidueswereharvested,thinningcomparedunthinnedstandsto recentlythinnedstandsofsimilarstandage,short-rotation (SREP)comparedyoungstands(8 – 10years)atthemaximum ageofashort-rotationplantation(SREP)totheaverageoccupancyrateofaconventionalpineplantationstages > 12years thatmaybeabsentinaSREPscenario,andSREPTotalcombinedSREPandresidueeffectsizes. Table1 Summaryofvegetationvariablesbylanduse(mean(SE))and apriori contraststhatindicatewhethertherearesignicantdifferencesineachvegetationvariableamong biomassproductionalternatives( apriori contrasts;seeEqns1 – 4ofmaintext) VegetationVariable Landuse Biomassalternative ResidueleftResidueremovedYoungUnthinnedThinnedMatureReferenceResidueThinSREPSREPtotal DBH(mean)14.4(4.53)5.4(3.71)16.1(0.52)19.1(0.40)21.7(0.72)29.9(1.56)29.3(1.91) 8.98***2.61 7.45*** 10.50***DBH(CV)0.2(0.09)0.0(0.04)0.1(0.01)0.2(0.03)0.2(0.02)0.2(0.02)0.4(0.03) 0.12 0.01 0.08 0.11*Basalarea(m2/ha)0.9(0.28)0.1(0.04)11.7(2.14)12.8(1.87)7.9(0.75)8.0(1.42)5.3(0.47) 0.85*** 4.91**2.15*** 1.51***Tallshrubdensity(m2)0.3(0.05)0.1(0.03)0.2(0.03)0.2(0.03)0.1(0.03)0.3(0.05)0.2(0.06) 0.17 0.04 0.01 0.07 Shortshrubdensity(m2)2.4(0.51)2.0(0.44)1.8(0.28)0.9(0.18)2.0(0.54)2.6(0.46)2.8(0.92) 0.371.08 0.03 0.05 CWDvolume(cm3)8.6(4.40)4.1(2.67)0.9(0.80)18.2(12.89)4.2(3.49)21.8(14.09)6.7(4.91) 4.50 13.92 13.85 10.72 CWDfrequency0.6(0.06)0.3(0.07)0.1(0.02)0.2(0.04)0.3(0.06)0.4(0.08)0.2(0.05) 0.35***0.13 0.23*** 0.20***Woody21.8(4.63)14.4(3.41)11.1(3.05)10.0(2.00)11.8(2.00)14.8(3.12)13.0(5.14) 7.37*1.87 1.10* 1.85*Forbs21.3(4.12)17.8(2.99)13.4(4.32)15.7(5.74)15.6(5.74)28.3(5.09)18.8(4.88) 3.46 0.07 6.49 4.61 Graminoid13.6(3.51)13.1(2.84)8.9(2.38)11.3(2.02)15.9(2.02)17.0(3.85)22.9(5.61) 0.494.66 5.90 3.49 Bare/litter43.4(5.89)54.7(5.52)66.7(5.93)63.1(6.74)56.7(6.74)39.9(5.00)45.3(8.08)11.32 6.4213.489.94 P < 0.05; ** P < 0.01; *** P < 0.001. 2017TheAuthors. GlobalChangeBiologyBioenergy PublishedbyJohnWiley&SonsLtd.,doi:10.1111/gcbb.12453IMPACTSOFBIOENERGYALTERNATIVESONBIRDS 9

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survival)canvaryconsiderablyacrosslandscapesand canbeimportantinformationforinterpretinghabitat qualityforbirds(e.g.,Bock&Jones,2004;Fletcher etal. 2006).Thisissueisparticularlyrelevantwhenassuming thatanincreaseinoccurrencereectshabitatquality, suchasassumingthatthinningandretentionofresiduesonclear-cutsincreasehabitatqualityforsomespecies.Althoughevidencesuggeststhatoccupancyand relatedcount-basedindicesmayoftencorrelatewith measuresofhabitatquality(Sergio&Newton,2003; Bock&Jones,2004),notableexceptionsexist(Chalfoun &Schmidt,2012).Insuchcases,ecologicaltrapsmay occur(Robertson&Hutto,2006),whichcanhavedetrimentalimpactsonpopulations(Fletcher etal. ,2012). Yetdemographicinformationisdifculttocollecton severalspeciesandacrossmanydifferentlanduses, anddemographicratescannotbecollectedwhenspeciesdonotoccurincertainlanduses,oftenlimiting demographicestimationtomoreabundantspecies. Second,oursamplingwaslimitedtoasinglebreeding seasonineachsite.Wechosetofocussamplingonas manysitesaspossibleacrosseldseasons,ratherthan repeatsamplingatthesamesitesacrossyearstoboth capturemorevariationacrosslandusesandbecausefor somesites,conditionschangedacrossyears(e.g.,an unthinnedsitesampledinoneyearmaybethinnedin thefollowingyear).Yetourdesignlimitedtheabilityto makeinferencesregardingchangesinbirdcommunities overtimewithland-usechange(e.g.,colonizationrates ofspeciestobioenergylanduses).Third,wetargeted land-useconditionswherebiomasswasremovedor alteredandhavebeenemphasizedasbeingpotential pathwaysforgeneratingbiomass(DOE,2011,2016), althoughbiomassatsomeofthesesiteswasnotbeing usedforbioenergyatthetime.Asbioenergyproduction expands,subtledifferencesinlanduseforbioenergy andcurrentlylandusesmayoccur,suchaschangesin plantingdensitiesforSREPs(Munsell&Fox,2010). Finally,ourresultsonlyapplytobirdcommunities. Effectsonothertaxacoulddifferfrombirds.For instance,lessmobiletaxon(e.g.,somesmallmammals) orspeciesthatrequiremultiplehabitats(e.g.,some amphibians)mayhaveverydifferentresponsesthan birds.Furtherresearchonothertaxa,particularlythose thatprovidecriticalecosystemservices(e.g.,bats,bees; Boyles etal. ,2011;Brosi etal. ,2008),wouldbeuseful.Contextforthelandscape – yieldandnetenergybenetShort-rotationenergyplantationshadanoverallnegativeeffectonthebirdcommunity,buttheenergyyield fromtheseintensivelymanagedplantationshasbeen estimatedtobemorethananorderofmagnitude greaterthantheyieldperhectareperyearacquired throughthinning,residueharvest,orcornproduction (Varvel etal. ,2008;Eisenbies etal. ,2009;Evans& Cohen,2009;Guo etal. ,2010;Munsell&Fox,2010; Gonzalez etal. ,2012).Consequently,minimizingthe industry’simpactonthelandscapecouldmeanchoosingthemostintensivemanagementregime,becausefar lesslandwouldberequiredtomeetthebioenergyproductiongoalsbyrelyingonshort-rotationenergyplantationsinsteadofacquiringbiomassthroughother methods(cf.Heaton etal. ,2008).Thespeciccontextof landchangeforshort-rotationenergyplantationswillbe importantforbioenergy,regardlessofregionorfeedstock(Efroymson etal. ,2013).Convertingaconventionalplantationtoashort-rotationenergyplantation mayresultinnegativeimpactsonthebirdcommunity, whereasconvertingacorneldordegradedagricultural landtoashort-rotationenergyplantationcouldresultin anetincreaseintheoccurrenceofseveralbirdspecies. Residueremovalhasbeenestimatedtohavethelowestyieldofbiomassperhectareofthewoodybiomass harvestmethodsconsideredhere(Eisenbies etal. ,2009; Guo etal. ,2010;Munsell&Fox,2010),andithadalarge negativeimpactonthebirdcommunity.However,the timeperiodduringwhichaclear-cutexistsonthelandscapebeforeitistreatedandreplantedistypicallyonly 1 – 3years,sothenegativeeffectofremovingresidues fromthesestandsissomewhatephemeraloverthetypical25-yearrotationofaconventionalpineplantation. Thinninghasahigherbiomassyieldthanresidue removal(Guo etal. ,2010;Munsell&Fox,2010),butitis stillmodestincomparisonwithSREPs.Thinningwas theonlybiomassharvestmethodinthestudythatbenetedavianbiodiversity,sodespiteitsmodestyield, thinningmaybeagoodchoiceforawildlife-friendly biomassharvestmethodforsoutheasternbirdcommunities.Harvestingplantationthinningsforbioenergy productionmayalsoprovideeconomicgainsfornonindustrialprivatelandowners,whomaybenetfrom competitivepricesfromthebiomassindustrycompared tocurrentpricesforpulpwoodandroundwood(Gruchy etal. ,2012). Althoughcornisnotaswidelycultivatedaspinein thesoutheast,itiscurrentlytheprimarybioenergyfeedstockintheUnitedStateswithmillionsofacrescurrentlyinproductionforcornethanol,primarilyinthe midwest.Corngrainandstovercanyieldsimilar amountsofethanolcomparedtoplantationthinning andresidueharvest(Hill etal. ,2006;Gibbs etal. ,2008; Varvel etal. ,2008;Don etal. ,2012;Gonzalez etal. 2012);however,theNetEnergyBalance(NEB)isless. TheNEBofcornhasbeenestimatedas0.56 – 1.26,andin somecases,theenergyinputforproductionmayexceed ethanolyield(Pimentel&Patzek,2006;Pimentel etal. 2007;Evans&Cohen,2009).Incontrast,theNEBfrom 2017TheAuthors. GlobalChangeBiologyBioenergy PublishedbyJohnWiley&SonsLtd.,doi:10.1111/gcbb.1245310 I.G.W.GOTTLIEB etal.

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pinebiomasshasbeenestimatedas2.2 – 2.97,approximately50 – 300%higherthanrst-generationcorn, increasingitsfeasibilityasamajorfeedstockinthe southeast(Dwivedi etal. ,2009;Evans&Cohen,2009). Bioenergyproductionhasthepotentialtoalterland useacrossbroadregions,andmaypotentiallyimpactlargerareasthansomeotherenergyalternatives(Mcdonald etal. ,2012;Trainor etal. ,2016).Consequently,itisessentialtoevaluatepotentialland-usealternativesthatcan arisefromanincreaseintheemergingbioenergyeconomy(Fargione etal. ,2010).Weprovideoneoftherst systematicassessmentsthatcontrastsseveralbiomass alternativesidentiedbytheDOEandUSDAacrossthe southeasternUnitedStates(USDA,2010,DOE,2016)and useadvancedstatisticalmodelsthataccountforkey issuesofimperfectdetectionthatcanbiasresultsfrom wildlifesurveys.Ourresultsemphasizetwokeyresults. First,cornbiomasshasgreaternegativeeffectsonaveragethanthatofpinebiomassinthisregion.Second,for pinebiomass,thinningtendedtobeabird-friendlyway toacquirebiomasswhiletheremovalofresiduefrom clear-cutsandpotentialconversiontoshort-rotation energyplantationstendedtohavenegativeeffectson birdcommunities.Becausethesepinealternativescan generatedifferentamountsofbiomass,landscape-scale planningisneededtobalancepotentialland-usechange alternativesforbioenergyproductionandtheintensity ofpotentialeffectsthatmayarisefromdifferentbiomass alternatives.AcknowledgementsWethankournumerouseldtechniciansandvolunteersfor theirassistancewithdatacollection,andthemanylandowners andlandmanagersthatallowedaccesstotheirproperties, especiallyLoncala,Inc.,andResourceManagementService LLC.WealsothanktheU.S.DepartmentofAgriculture, USDA-NIFAInitiativeGrantNo.2012-67009-20090,andthe UniversityofFlorida’sSchoolofNaturalResourceandEnvironmentforsupport.Wethanktwoanonymousreviewersfor valuablefeedback,includingthesuggestionforFig.1a.ReferencesADCNR(2015) AlabamaWildlifeActionPlan,2015 – 2025 .ADCNR,Montgomery,Alabama. BestLB,CampaH,KempKE etal. (1997)BirdabundanceandnestinginCRPelds andcroplandintheMidwest:aregionalapproach. WildlifeSocietyBulletin 25 864 – 877. BlankPJ,WilliamsCL,SampleDW,MeehanTD,TurnerMG(2016)Alternativescenariosofbioenergycropproductioninanagriculturallandscapeandimplications forbirdcommunities. EcologicalApplications 26 ,42 – 54. BockCE,JonesZF(2004)Avianhabitatevaluation:shouldcountingbirdscount? FrontiersinEcologyandtheEnvironment 2 ,403 – 410. BoylesJG,CryanPM,MccrackenGF,KunzTH(2011)EconomicImportanceofBats inAgriculture. Science 332 ,41 – 42. BrockerhoffEG,JactelH,ParrottaJA,QuineCP,SayerJ(2008)Plantationforests andbiodiversity:oxymoronoropportunity? BiodiversityandConservation 17 925 – 951. BrosiBJ,ArmsworthPR,DailyGC(2008)Optimaldesignofagriculturallandscapes forpollinationservices. ConservationLetters 1 ,27 – 36. BrownTJ,HandfordP(2003)Whybirdssingatdawn:theroleofconsistentsong transmission. Ibis 145 ,120 – 129. CampbellSP,FrairJL,GibbsJP,VolkTA(2012)Useofshort-rotationcoppicewillow cropsbybirdsandsmallmammalsincentralNewYork. Biomass&Bioenergy 47 342 – 353. CarterMF,HunterWC,PashleyDN,RosenbergKV(2000)SettingconservationprioritiesforlandbirdsintheUnitedStates:thepartnersinightapproach. Auk 117 ,541 – 548. ChalfounAD,SchmidtKA(2012)Adaptivebreedinghabitatselection:isitforthe birds? Auk 129 ,589 – 599. ChristianDP,CollinsPT,HanowskiJM,NiemiGJ(1997)Birdandsmallmammal useofshort-rotationhybridpoplarplantations. JournalofWildlifeManagement 61 171 – 182. CostanzaJK,AbtRC,MckerrowAJ,CollazoJA(2017)Bioenergyproductionand forestlandscapechangeinthesoutheasternUnitedStates.GlobalChangeBiology Bioenergy 9 ,924 – 939. DaleVH,KlineKL,ParishES etal. (2017)Statusandprospectsforrenewableenergy usingwoodpelletsfromthesoutheasternUnitedStates. GlobalChangeBiology Bioenergy .https://doi/org/10.1111/gcbb.12445. DegraafRM,TilghmanNG,AndersonSH(1985)ForagingguildsofNorthAmerican birds. EnvironmentalManagement 9 ,493 – 536. DOE(2011) U.S.Billion-TonUpdate:BiomassSupplyforaBioenergyandBioproducts Industry (edsPerlackRD,StokesBJ),OakRidgeNationalLaboratory,OakRidge. DOE(2016) 2016Billion-TonReport:AdvancingDomesticResourcesforaThrivingBioeconomy,Volume1:EconomicAvailabilityofFeedstocks (edsLangholtzMH,Stokes BJ,EatonLM).DOE,OakRidge. DonA,OsborneB,HastingsA etal. (2012)Land-usechangetobioenergyproductioninEurope:implicationsforthegreenhousegasbalanceandsoilcarbon. GlobalChangeBiologyBioenergy 4 ,372 – 391. DwivediP,AlavalapatiJRR,LalP(2009)CellulosicethanolproductionintheUnited States:conversiontechnologies,currentproductionstatus,economics,andemergingdevelopments. EnergyforSustainableDevelopment 13 ,174 – 182. EfroymsonRA,DaleVH,KlineKL etal. (2013)Environmentalindicatorsofbiofuel sustainability:whataboutcontext? EnvironmentalManagement 51 ,291 – 306. EisenbiesMH,VanceED,AustWM,SeilerJR(2009)Intensiveutilizationofharvest residuesinsouthernpineplantations:quantitiesavailableandimplicationsfor nutrientbudgetsandsustainablesiteproductivity. BioenergyResearch 2 ,90 – 98. EvansJM,CohenMJ(2009)RegionalwaterresourceimplicationsofbioethanolproductionintheSoutheasternUnitedStates. GlobalChangeBiology 15 ,2261 – 2273. EvansJM,FletcherRJJr,AlavalapatiJ(2010)Usingspeciesdistributionmodelsto identifysuitableareasforbiofuelfeedstockproduction. GlobalChangeBiology Bioenergy 2 ,63 – 78. FargioneJE,PlevinRJ,HillJD(2010)Theecologicalimpactofbiofuels. Annual ReviewofEcology,Evolution,andSystematics 41 ,351 – 377. FletcherRJJr,KofordRR(2003)Changesinbreedingbirdpopulationswithhabitat restorationinnorthernIowa. AmericanMidlandNaturalist 150 ,83 – 94.FletcherRJJr,KofordRR,SeamanDA(2006)Criticaldemographicparametersfor decliningsongbirdsbreedinginrestoredgrasslands. JournalofWildlifeManagement 70 ,145 – 157. FletcherRJJr,RobertsonBA,EvansJ,DoranPJ,AlavalapatiJRR,SchemskeDW (2011)Biodiversityconservationintheeraofbiofuels:risksandopportunities. FrontiersinEcologyandtheEnvironment 9 ,161 – 168. FletcherRJJr,OrrockJL,RobertsonBA(2012)Howthetypeofanthropogenic changealterstheconsequencesofecologicaltraps. ProceedingsoftheRoyalSociety B-BiologicalSciences 279 ,2546 – 2552. FrittsS,MoormanC,GrodskyS,HazelD,HomyackJ,FarrellC,CastleberryS(2016) Dobiomassharvestingguidelinesinuenceherpetofaunafollowingharvestsof loggingresiduesforrenewableenergy? EcologicalApplications 26 ,926 – 939. FWC(2012) Florida'sWildlifeLegacyInitiative:Florida'sStateWildlifeActionPlan FWC,Tallahassee,FL,USA. GalikCS,AbtRC(2016)Sustainabilityguidelinesandforestmarketresponse:an assessmentofEuropeanUnionpelletdemandinthesoutheasternUnitedStates. GlobalChangeBiologyBioenergy 8 ,658 – 669. GDNR(2014)Rarespeciesproles.Availableat:www.georgiawildlife.com/node/ 2223/(accessed1October2015). GibbsHK,JohnstonM,FoleyJA,HollowayT,MonfredaC,RamankuttyN,ZaksD (2008)Carbonpaybacktimesforcrop-basedbiofuelexpansioninthetropics:the effectsofchangingyieldandtechnology. EnvironmentalResearchLetters 3 ,034001. https://doi.org/10.1088/1748-9326/3/3/034001. 2017TheAuthors. GlobalChangeBiologyBioenergy PublishedbyJohnWiley&SonsLtd.,doi:10.1111/gcbb.12453IMPACTSOFBIOENERGYALTERNATIVESONBIRDS 11

PAGE 12

GonzalezR,PhillipsR,SaloniD,JameelH,AbtR,PirragliaA,WrightJ(2011)BiomasstoenergyinthesouthernUnitedStates:supplychainanddeliveredcost. BioResources 6 ,2954 – 2976. GonzalezR,DaystarJ,JettM,TreasureT,JameelH,VendittiR,PhillipsR(2012)Economicsofcellulosicethanolproductioninathermochemicalpathwayforsoftwood, hardwood,cornstoverandswitchgrass. FuelProcessingTechnology 94 ,113 – 122. GottliebIGW(2016)ImplicationsofFutureBiofuelsExpansiononAvianCommunitiesintheSoutheasternUnitedStates.UnpublishedM.S.ThesisUniversityof Florida,74pp. GrodskySM,MoormanCE,FrittsSR,CastleberrySB,WigleyTB(2016a)Breeding, early-successionalbirdresponsetoforestharvestsforbioenergy. PLoSONE 11 e0165070.https://doi/org/10.1371/journal.pone.0165070. GrodskySM,MoormanCE,FrittsSR,HazelDW,HomyackJA,CastleberrySB,WigleyTB(2016b)WinterbirduseofharvestresiduesinclearcutsandtheimplicationsofforestbioenergyharvestinthesoutheasternUnitedStates. ForestEcology andManagement 379 ,91 – 101. GruchySR,GrebnerDL,MunnIA,JoshiO,HussainA(2012)AnassessmentofnonindustrialprivateforestlandownerwillingnesstoharvestwoodybiomassinsupportofbioenergyproductioninMississippi:acontingentratingapproach. Forest PolicyandEconomics 15 ,140 – 145. GuoZM,GrebnerD,SunCY,GradoS(2010)EvaluationofloblollypinemanagementregimesinMississippiforbiomasssupplies:asimulationapproach. SouthernJournalofAppliedForestry 34 ,65 – 71. HansenAJ,MccombWC,VegaR,RaphaelMG,HunterM(1995)BirdhabitatrelationshipsinnaturalandmanagedforestsinthewestCascadesofOregon. EcologicalApplications 5 ,555 – 569. HeatonEA,DohlemanFG,LongSP(2008)MeetingUSbiofuelgoalswithlessland: thepotentialof Miscanthus GlobalChangeBiology 14 ,2000 – 2014. HillJ,NelsonE,TilmanD,PolaskyS,TiffanyD(2006)Environmental,economic, andenergeticcostsandbenetsofbiodieselandethanolbiofuels. Proceedingsof theNationalAcademyofSciencesoftheUnitedStatesofAmerica 103 ,11206 – 11210. HomyackJA,Lucia-SimmonsKE,MillerDA,Kalcounis-RueppellM(2014)Rodent populationandcommunityresponsestoforest-basedbiofuelproduction. Journal ofWildlifeManagement 78 ,1425 – 1435. KeryM,RoyleJA(2016) AppliedHierarchicalModelinginEcology:AnalysisofDistribution,AbundanceandSpeciesRichnessinRandBUGS .AcademicPress,London. KlassDL(2003)AcriticalassessmentofrenewableenergyusageintheUSA. Energy Policy 31 ,353 – 367.MackenzieDI,NicholsJD,LachmanGB,DroegeS,RoyleJA,LangtimmCA(2002) Estimatingsiteoccupancyrateswhendetectionprobabilitiesarelessthanone. Ecology 83 ,2248 – 2255. MartinTE(1993)Nestpredationamongvegetationlayersandhabitattypes:revising thedogmas. AmericanNaturalist 141 ,897 – 913. MccarthyKP,FletcherRJ,RotaCT,HuttoRL(2012)Predictingspeciesdistributions fromsamplescollectedalongroadsides. ConservationBiology 26 ,68 – 77. McdonaldRI,OldenJD,OppermanJJ etal. (2012)Energy,waterandsh:biodiversityimpactsofenergy-sectorwaterdemandintheUnitedStatesdependonefciencyandpolicymeasures. PLoSONE 7 ,e50219.https://doi/org/10.1371/ journal.pone.0050219 MunsellJF,FoxTR(2010)AnanalysisofthefeasibilityforincreasingwoodybiomassproductionfrompineplantationsinthesouthernUnitedStates. Biomass& Bioenergy 34 ,1631 – 1642. NesbitTS,AlavalapatiJRR,DwivediP,MarinescuMV(2011)Economicsofethanol productionusingfeedstockfromslashpine( Pinuselliottii )plantationsinthe SouthernUnitedStates. SouthernJournalofAppliedForestry 35 ,61 – 66. PimentelD,PatzekT(2006)Greenplants,fossilfuels,andnowbiofuels. BioScience 56 ,875. PimentelD,PatzekT,CecilG(2007)Ethanolproduction:energy,economic,and environmentallosses.In: ReviewsofEnvironmentalContaminationandToxicology Vol 189 (edWareGW),pp.25 – 41.Springer,NewYork. PlummerM(2012)JAGSversion3.3.0usermanual. PrughLR,HodgesKE,SinclairARE,BrasharesJS(2008)Effectofhabitatareaand isolationonfragmentedanimalpopulations. ProceedingsoftheNationalAcademyof SciencesoftheUnitedStatesofAmerica 105 ,20770 – 20775. RalphCJ,SauerJR,DroegeS(1995)Monitoringbirdpopulationsbypointcounts. USDAForestServiceGeneralTechnicalReportPSW-GTR 149 ,1 – 181. RiesL,FletcherRJ,BattinJ,SiskTD(2004)Ecologicalresponsestohabitatedges: mechanisms,models,andvariabilityexplained. AnnualReviewofEcologyEvolutionandSystematics 35 ,491 – 522. RiffellS,VerschuylJ,MillerD,WigleyTB(2011a)Biofuelharvests,coarsewoodydebris,andbiodiversity – Ameta-analysis. ForestEcologyandManagement 261 ,878 –887. RiffellS,VerschuylJ,MillerD,WigleyTB(2011b)Ameta-analysisofbirdandmammal responsetoshort-rotationwoodycrops. GlobalChangeBiologyBioenergy 3 ,313 – 321. RobertsonBA,HuttoRL(2006)Aframeworkforunderstandingecologicaltrapsand anevaluationofexistingevidence. Ecology 87 ,1075 – 1085. RobertsonBA,DoranPJ,LoomisLR,RobertsonJR,SchemskeDW(2011)Perennial biomassfeedstocksenhanceaviandiversity. GlobalChangeBiologyBioenergy 3 235 – 246. RobertsonBA,RiceRA,SillettTS etal. (2012)Areagrofuelsaconservationthreator opportunityforgrasslandbirdsintheUnitedStates? Condor 114 ,679 – 688. RotaCT,FletcherRJJr,DorazioRM,BettsMG(2009)Occupancyestimationandthe closureassumption. JournalofAppliedEcology 46 ,1173 – 1181. RotaCT,FletcherRJJr,EvansJM,HuttoRL(2011)Doesaccountingfordetectability improvespeciesdistributionmodels? Ecography 34 ,659 – 670. RoyleJA,DorazioRM(2008) HierarchicalModelingandInferenceinEcology:theAnalysis ofDatafromPopulations,Metapopulations,andCommunities .AcademicPress,Oxford. SergioF,NewtonI(2003)Occupancyasameasureofterritoryquality. JournalofAnimalEcology 72 ,857 – 865. SissineF(2007)Energyindependenceandsecurityactof2007:asummaryofmajor provisions.In: CongressionalResearchService (edsSissineF),Congressional ResearchService,Washington,DC.Availableat:https://www1.eere.energy.gov/ manufacturing/tech_assistance/pdfs/crs_report_energy_act_2007.pdf(accessed6 April2016) TarrNM,RubinoMJ,CostanzaJK,MckerrowAJ,CollazoJA,AbtRC(2017)Projectedgainsandlossesofwildlifehabitatfrombioenergy-inducedlandscape change. GlobalChangeBiologyBioenergy 9 ,909 – 923. TeamRC(2016) R:ALanguageandEnvironmentforStatisticalComputing .(edComputingRFFS),TeamRC,Vienna,Austria. TrainorAM,McdonaldRI,FargioneJ(2016)Energysprawlisthelargestdriverof landusechangeinUnitedStates. PLoSONE 11 ,e0162269,https://doi/org/10. 1371/journal.pone.0162269. USDA(2010)AUSDARegionalRoadmaptoMeetingtheBiofuelsGoalsofthe RenewableFuelsStandardby2022. VarvelGE,VogelKP,MitchellRB,FollettRF,KimbleJM(2008)Comparisonofcorn andswitchgrassonmarginalsoilsforbioenergy. Biomass&Bioenergy 32 ,18 – 21. VerschuylJ,RiffellS,MillerD,WigleyTB(2011)Biodiversityresponsetointensive biomassproductionfromforestthinninginNorthAmericanforests –ameta-analysis. ForestEcologyandManagement 261 ,221 – 232. WoudenbergSW,ConklingBL,O’connellBM,LapointEB,TurnerJA,WaddellKL (2010)TheForestInventoryandAnalysisDatabasedescriptionanduser’smanual.In:U.S.ForestServiceGeneralTechnicalReportRMRSGTR-245.ppPage, FortCollins,U.S.DepartmentofAgriculture,Forestervice,RockyMountain ResearchStation.SupportingInformationAdditionalSupportingInformationmaybefoundonlinein thesupportinginformationtabforthisarticle: TableS1. Description,distribution,andsamplesizesof managementconditionsineachregion:Alabama(AL),Panhandle(PH),andGainesville(GV). TableS2. Informationoneachbirdspeciesincludedinthe occupancymodels. TableS3. Parameterestimates ( 95%credibleintervals, LCL = lowercredibleinterval,UCL = uppercredibleinterval)ofdetectabilityparametersforeachspecies. FigureS1. Estimatedoccurrenceprobability( w 95% credibleintervals)for31birdspeciesineightlanduses considered,2013 – 2015.SeeTableS1forland-usecodes. Yng = Young;Mat = Mature,andRef = ReferencecategoriesinTableS1. 2017TheAuthors. GlobalChangeBiologyBioenergy PublishedbyJohnWiley&SonsLtd.,doi:10.1111/gcbb.1245312 I.G.W.GOTTLIEB etal.