Chapter 6 Quantifying Greenhouse Gas Sources and Sinks in ... · Greenhouse Gas Sources and Sinks...

Authors:

CoeliHoover,USDAForestService(LeadAuthor)RichardBirdsey,USDAForestService(Co‐LeadAuthor)BruceGoines,USDAForestServicePeterLahm,USDAForestServiceGreggMarland,AppalachianStateUniversityDavidNowak,USDAForestServiceStephenPrisley,VirginiaPolytechnicInstituteandStateUniversityElizabethReinhardt,USDAForestServiceKenSkog,USDAForestServiceDavidSkole,MichiganStateUniversityJamesSmith,USDAForestServiceCarlTrettin,USDAForestServiceChristopherWoodall,USDAForestService

Contents:

6 QuantifyingGreenhouseGasSourcesandSinksinManagedForestSystems....................6‐46.1 Overview.........................................................................................................................................................6‐5

6.1.1 OverviewofManagementPracticesandResultingGHGEmissions.........................6‐66.1.2 SystemBoundariesandTemporalScale..............................................................................6‐96.1.3 SummaryofSelectedMethods/Models..............................................................................6‐106.1.4 SourcesofData..............................................................................................................................6‐116.1.5 OrganizationofChapter/Roadmap......................................................................................6‐12

6.2 ForestCarbonAccounting......................................................................................................................6‐156.2.1 DescriptionofForestCarbonAccounting..........................................................................6‐156.2.2 DataCollectionforForestCarbonAccounting.................................................................6‐236.2.3 EstimationMethods....................................................................................................................6‐256.2.4 Limitations,Uncertainty,andResearchGaps...................................................................6‐28

6.3 Establishing,Re‐establishing,andClearingForests....................................................................6‐296.3.1 Description.....................................................................................................................................6‐296.3.2 ActivityDataCollection.............................................................................................................6‐336.3.3 EstimationMethods....................................................................................................................6‐346.3.4 SpecificProtocolforComputation........................................................................................6‐376.3.5 ActualGHGRemovalsandEmissionsbySourcesandSinksfromForestClearing...

.............................................................................................................................................................6‐436.3.6 LimitationsandUncertainty....................................................................................................6‐44

6.4 ForestManagement..................................................................................................................................6‐45

Chapter 6Quantifying Greenhouse Gas Sources and Sinks in Managed Forest Systems

Chapter 6: Quantifying Greenhouse Gas Sources and Sinks in Managed Forest Systems

6.4.1 Description.....................................................................................................................................6‐456.4.2 ActivityData...................................................................................................................................6‐536.4.3 ManagementIntensityCategories........................................................................................6‐576.4.4 EstimationMethods....................................................................................................................6‐646.4.5 LimitationsandUncertainty....................................................................................................6‐66

6.5 HarvestedWoodProducts.....................................................................................................................6‐666.5.1 GeneralAccountingIssues.......................................................................................................6‐666.5.2 EstimationMethods....................................................................................................................6‐686.5.3 ActivityDataCollection.............................................................................................................6‐696.5.4 Limitations,Uncertainty,andResearchGaps...................................................................6‐70

6.6 UrbanForests..............................................................................................................................................6‐716.6.1 Description.....................................................................................................................................6‐716.6.2 ActivityDataCollection.............................................................................................................6‐736.6.3 EstimationMethods....................................................................................................................6‐746.6.4 LimitationsandUncertainty....................................................................................................6‐80

6.7 NaturalDisturbance–WildfireandPrescribedFire...................................................................6‐826.7.1 Description.....................................................................................................................................6‐826.7.2 ActivityDataCollection.............................................................................................................6‐826.7.3 EstimationMethods....................................................................................................................6‐826.7.4 LimitationsandUncertainty....................................................................................................6‐87

Appendix6‐A:HarvestedWoodProductsLookupTables.....................................................................6‐88Chapter6References..........................................................................................................................................6‐107

SuggestedChapterCitation:Hoover,C.,R.Birdsey,B.Goines,P.Lahm,GMarland,D.Nowak,S.Prisley,E.Reinhardt,K.Skog,D.Skole,J.Smith,C.Trettin,C.Woodall,2014.Chapter6:QuantifyingGreenhouseGasSourcesandSinksinManagedForestSystems.InQuantifyingGreenhouseGasFluxesinAgricultureandForestry:MethodsforEntity‐ScaleInventory.TechnicalBulletinNumber1939.OfficeoftheChiefEconomist,U.S.DepartmentofAgriculture,Washington,DC.606pages.July2014.Eve,M.,D.Pape,M.Flugge,R.Steele,D.Man,M.Riley‐Gilbert,andS.Biggar,Eds.

USDAisanequalopportunityproviderandemployer.

Acronyms,ChemicalFormulae,andUnitsBA BasalareaC CarbonCH4 Methanecm CentimetersCO2 CarbondioxideCO2‐eq CarbondioxideequivalentsCOLE CarbonOnLineEstimatorCRM ComponentratiomethodDBH DiameteratbreastheightDDW DowndeadwoodDOE DepartmentofEnergyEPA EnvironmentalProtectionAgencyFFE FireandFuelsExtensionFIA ForestInventoryandAnalysisFIADB ForestInventoryandAnalysisDatabaseFIDO ForestInventoryDataOnlineFOFEM FirstOrderFireEffectsModelFVS ForestVegetationSimulator modelft Feetg GramGHG GreenhousegasH Heightha Hectarehp Horsepowerhr HourHW HardwoodHWP Harvestedwoodproductsin Incheslbs PoundsIPCC IntergovernmentalPanelonClimateChangem Metersmm MillimetersMcf ThousandcubicfeetN2O NitrousoxideNOx Mono‐nitrousoxidesO2 OxygenPW PulpwoodSL SawlogsSOC SoilorganiccarbonSSURGO SoilSurveyGeographicdatabaseSTATSGO StateSoilGeographicdatabaseSW SoftwoodTg TeragramsUFORE UrbanForestEffectsmodelUNFCCC UnitedNationsFrameworkConventiononClimateChangeUSDA U.S.DepartmentofAgriculture

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6 QuantifyingGreenhouseGasSourcesandSinksinManagedForestSystems

Thischapterprovidesguidanceforreportinggreenhousegas(GHG)emissionsassociatedwithentity‐levelfluxesfromtheforestrysector.Inparticular,itfocusesonmethodsforestimatingcarbonstocksandstockchangefrommanagedforestsystems.Section6.1providesanoverviewofthesector.Section6.2describesthemethodsforforestcarbonstockaccounting.Section6.3describesthemethodsforestimatingcarbonstocksandstockchangefromestablishingandclearingforest.Section6.4describesmethodsforestimatingcarbonstocksandstockchangefromforestmanagement.Section6.5describesmethodsforestimatingcarbonstocksandstockchangefromharvestedwoodproducts.Section6.6describesmethodsforestimatingcarbonstocksandstockchangefromurbanforests(i.e.,treesoutsideofforests).Finally,Section6.7describesmethodsforestimatingemissionsfromnaturaldisturbancesincludingforestfires.

6.1 Overview

AsummaryofproposedmethodsandmodelsforestimatingGHGemissionsfrommanagedforestsystemsisprovidedinTable6‐1.

Table6‐1:OverviewofManagedForestSystemsSources,MethodandSection

Section Source Method

6.2.3 ForestCarbonAccounting

Rangeofoptionsdependentonthesizeoftheentities’forestlandincluding:ForestVegetationSimulatormodelwithFireandFuelsExtension(FVS‐FFE)(entitiesthatfitthelargelandownerdefinition);anddefaultlookuptables(entitiesfittingthesmalllandownerdefinition).

6.3.3Establishing,Re‐establishing,andClearingForests

IntergovernmentalPanelonClimateChange (IPCC) algorithmsdevelopedbyAaldeetal.(2006).Theseoptionsuse:allometricequationsfromJenkinsetal.(2003a),orFVSwiththeJenkinsetal.equationswhereapplicable;anddefaultlookuptablesfromSmithetal.(2006;GTRNE‐343)—defaultregionalvaluesbasedonforesttypeandageclassdevelopedfromFIAdata.

6.4.4 ForestManagement

Rangeofoptionsdependentonthesize/managementintensity/dataavailabilityoftheentity’sforestlandincluding:FVS‐FFEwithJenkins(2003a)allometricequations;Defaultlookuptablesofmanagementpracticescenarios;andFVSmaybeusedtodevelopasupportingproductprovidingdefaultlookuptablesofcarbonstocksovertimebyregion;foresttypecategories,includingspeciesgroup(e.g.,hardwood,softwood,mixed);regeneration(e.g.,planted,naturallyregenerated);managementintensity(e.g.,low,moderate,high,veryhigh);andsiteproductivity(e.g.,low,high).

6.5.2 HarvestedWoodProducts

MethodusesU.S.‐specificharvestedwoodproducts(HWPs)tables.TheHWPstablesarebasedonWOODCARBIImodelusedtoestimateannualchangeincarbonstoredinproductsandlandfills(Skog,2008).TheentityusesthesetablestoestimatetheaverageamountofHWPcarbonfromthecurrentyear’sharvestthatremainsstoredinendusesandlandfillsoverthenext100years.

6.6.3 UrbanForests

Rangeofoptionsdependsondataavailabilityoftheentity’surbanforestland.Theseoptionsuse:i‐TreeEcomodel(http://www.itreetools.org)toassesscarbonfromfielddataontreepopulations;andi‐TreeCanopymodel(http://www.itreetools.org/canopy/index.php)toassesstreecoverfromaerialimagesandlookuptablestoassesscarbon.Quantitativemethodsarealsodescribedformaintenanceemissionsandalteredbuildingenergyuseandincludedforinformationpurposesonly.

Section Source Method

NaturalDisturbance—WildfireandPrescribedFire

Rangeofoptionsdepends onthedataavailabilityoftheentity’sforestlandincluding:FirstOrderFireEffectsModel(FOFEM)enteringmeasuredbiomass;andFOFEMmodelusingdefaultvaluesgeneratedbyvegetationtype.TheseoptionsuseReinhardtetal.(1997).

6.1.1 OverviewofManagementPracticesandResultingGHGEmissions

6.1.1.1 DescriptionofSector

ForestryactivitiesrepresentsignificantopportunitiestomanageGHGs(Caldeiraetal.,2004;PacalaandSocolow,2004).TherearemanykindsofforestryactivitiesthatmaybeconsideredbyentitiesasameanstoreduceGHGs,suchasestablishingnewforests,agroforestry,improvedforestmanagement,andavoidedforestclearing.Costisamajorfactorguidingdecisionsaboutwhichactivitiesinforestrytopursue(Lewandrowskietal.,2004;StavinsandRichards,2005;U.S.EPA,2005).IntheannualGHGinventoryreportedbytheU.S.DepartmentofAgriculture(USDA)andtheU.S.EnvironmentalProtectionAgency(EPA),forestsandforestproductssequesteranaverageof790millionmetrictonscarbondioxide(CO2)peryearon253millionhectares(ha)offorestland,makingitthemainlandcategorysequesteringcarbon(U.S.EPA,2012b;USDA,2011).Mostofthecarbonsequestered(89percent)isintheforestecosystem,withtheremainderaddedtothepoolofcarboninwoodproducts.

6.1.1.2 ResultingGHGEmissions

Forestsremovecarbonfromtheatmosphereandstoreitinvegetativetissuesuchasstems,roots,barks,andleaves.Throughphotosynthesis,allgreenvegetationremovesCO2andreleasesoxygen(O2)totheatmosphere.Theremainingcarbonisusedtocreateplanttissuesandstoreenergy.Duringrespiration,carbon‐containingcompoundsarebrokendowntoproduceenergy,releasingCO2intheprocess.AnyremainingcarbonissequestereduntilthenaturaldecompositionofdeadvegetativematterorcombustionreleasesitasCO2totheatmosphere.Thenetcarbonstockinforestsincreaseswhentheamountofcarbonwithdrawalfromtheatmosphereduringphotosynthesisexceedsthereleaseofcarbontotheatmosphereduringrespiration.Thenetcarbonstockdecreaseswhenbiomassisburned.

OtherGHGs,suchasnitrousoxide(N2O)andmethane(CH4),arealsoexchangedbyforestecosystems.N2Omaybeemittedfromsoilsunderwetconditionsorafternitrogenfertilization;itisalsoreleasedwhenbiomassisburned.CH4isoftenabsorbedbythemicrobialcommunityinforestsoilsbutmayalsobeemittedbywetlandforestsoils.Whenbiomassisburnedineitheraprescribedfire/controlburnorinawildfire,precursorpollutantsthatcancontributetoozoneandothershort‐livedclimateforcersaswellasCH4areemitted.Awildfireisanunplannedignitioncausedbylightning,volcanoes,unauthorizedactivity,accidentalhuman‐causedactions,andescapedprescribedfires.Aprescribedfire/controlburnisanyfireintentionallyignitedbymanagementunderanapprovedplantomeetspecificobjectives.

Someofthecarboninforestsisreleasedtotheatmosphereaftertheharvestoftimber.However,theamountofthecarbonreleased,andwhen,dependsonthefateoftheharvestedtimber.Ifthetimberisusedtomakewoodproducts,aportionofthesequesteredcarbonwillremainstoredforuptoseveraldecadesorlonger.Iftheharvestedtreesareburnedandusedtoproduceenergy,carbonwillbereleasedthroughcombustionbutmayalsopreventcarbonemissionsthatwouldhavebeenreleasedthroughtheburningoffossilfuels.Suchemissionsfrombiomassenergyuseare

typicallycombustedwithhigherefficiencyascomparedtoopenbiomassburningaswouldoccurinawildfiresituationnettinglowercarbonemissions.

6.1.1.3 ForestSectorSchematic

Figure6‐1isasimplifiedrepresentationofthekeyforestcarbonpools,carbontransfers,andGHGfluxesfortheforestsystem.Atthistime,CO2isthemainGHGrepresentedcomprehensively.Emissionsofnon‐CO2GHGsinteractwithothersectors;atthistime,potentialfluxesofnon‐CO2GHGsarerepresentedinageneralmannerontheschematic.Theproportionoftotalsystemcarbonineachpoolcanvaryovertimedependingonavarietyoffactors;ratesofcarbontransferarealsovariable.

6.1.1.4 ManagementInteractions

Forestrypracticestypicallytriggerecosystemresponsesthatchangeovertime.Forexample,anewlyestablishedforestwilltakeupcarbonatalowrateinitially,andthenpassintoaperiodofrelativelyrapidcarbonaccumulation.Thecarbonuptakeratewillthentypicallydeclineasheterotrophicandautotrophicrespirationincreaseandgrowthisbalancedagainstmortalityintheolderforest.Fromthispointintime,standinglivetreebiomassmaynotincrease,butevidencesuggeststhatcarbonmaycontinuetoflowintootherforestcarbonpoolsuntiltheforestisremovedbyharvestoranaturaldisturbanceevent.

Theneteffectsofmanagementactivitiesoncarbonflowsinforestecosystemsincludechangesinmanydifferentpoolsofcarbon(suchasabovegroundbiomass,belowgroundbiomass,litter,soil,etc.).Carbonaccountingshouldbecomprehensive,addressingtheneteffectsofactivitiesonallcarbonflows.Forestryactivitiescausecarbontomovebetweenthevariouspoolsandto/fromtheatmosphere.Forexample,forestmanagementmaybeveryeffectiveatincreasingtheaccumulationofbiomassincommerciallyvaluableforms—thatis,inthetrunksofcommercialtreespecies.Thisincreasedgrowthmaysimplyresultfromreducingcompetitionfromothertypesoftrees,causingatransferofcarbonuptakefromonegroupoftreestoanother.Forestryactivitiescanalsohaveeffectsonforestsoils,woodydebris,andtheamountofcarboninwoodproducts.Thenetcarbonfloweffectsofanyactivitywillbethesumofalltheindividualeffectsonthedifferentcarbonpools.

Inaddition,theremaybeinteractionsbetweenbiologicalandphysicalprocessesthatareaffectedbyforestmanagementtreatmentsornaturaldisturbances(e.g.,changesinalbedoduringforestregeneration,afterwildfires).Whiletheseinteractionsoccur,researchinthisfieldisintheearlystagesandsuchinteractionsarebeyondthescopeofthisguidance.

6.1.1.5 RiskofReversals

Carbonthatissequesteredinsoils,vegetation,orwoodproductsisnotnecessarilypermanentlyremovedfromtheatmosphere.Forestryactivitiesintendedforonepurposemaybechangedbyadifferentlandownerorachangeinmanagementobjectives.Landownersmaychangetheirpractices,causingthereleaseofstoredcarbon,ornaturaldisturbancesmaycausethelossofstoredcarbontotheatmosphere.Insectepidemics,drought,orwildfiremayhappenatanytimeandmayaffectalloronlyaportionofthelandareawithinactivityorentityboundaries.Naturaldisturbancesmayberareevents,inwhichcasetheeffectsonestimatedcarbonflowsmaybesmallwhenaveragedoverlargeforestedareasorlongperiodsoftime.Catastrophicdisturbancessuchaswindstormsmaycauseobviousandeasilyestimatedchangesincarbonstocks,whileinothercases,suchasaone‐yearperiodofinsectdefoliation,itmaybedifficultafterafewyearstoseparatetheeffectsofthenaturaldisturbancefromotherfactors.ItshouldbenotedthatGHGregistriesgenerallyrequireentitiestocalculatecarbonstocksandfluxesandgenerallyrequireentitiestoconductanassessmentofriskofreversalofprojectedcarbonvalues.Suchassessmentsgenerally

Figure6‐1:Schem

aticofForestCarbonPools,CarbonTransfers,andGreenhouseGasFlux

includeriskofnaturaldisturbancessuchasfire,drought,insectanddiseasemortality,windthrow(hurricane,tornado,highwindevents),aswellasfinancialrisks,managementrisks,andsocialpoliticalrisks.Theseriskassessmentsarecommonlyusedtogenerateavaluethatdiscountstheprojectedcarbonvalueofmanagementactivitiesandtoprovidean“insurancepolicy”againstreversalsthatmaybeusedtoensurethataprogram’sclimatebenefitsarerealized.Manyforestmanagementpracticescanreducethesenaturalhazardrisks(suchasfuelhazardreduction,forestthinningforgrowthorresiliencetodroughts,climatechange,insectordiseaseagents,anduseofprescribedfiretoreduceriskoffires).Reducingtheriskofreversalthroughmanagementmayleadtoreducedemissions,long‐termnetincreaseincarbonstocks,andimprovedresultsinariskassessment.

6.1.2 SystemBoundariesandTemporalScale

Forthisreport,thenominalsystemboundariesaretheextentofthelandowner’sproperty.Estimationmethodspresentedinthissectionarefortheforestsector;however,wheretheforestsectormayinteractwiththeanimalagricultureorcroplandsandgrazinglandssectors,theseinstancesarenotedandlandownersshouldrefertotherelevantsectorguidance.AlandownermayneedtouseestimationmethodsforseveralsectorstoachieveacomprehensivereportofGHGsourcesandsinksfortheirproperty,ensuringthatdoublecountingdoesnotoccur.Inaddition,ifland‐usetransitionsoccurwithintheproperty,thesemustbeaccountedforsothatapparentchangesincarbonstocksorfluxesare“real”andnottheresultofanunrecordedtransferfromonesectortoanother.WhileGHGfluxeswilloccuracrossthesystemboundary,thesearegenerallynotestimatedexceptintheinstanceofharvestedwoodproducts(HWPs).

Theforestsectorpresentsanaccountingchallengerelatedtotemporalscalethatmaynotoccurinothersectors.Whilemanyfarmsoperateonanannualcycle,forestryoperations,bytheirnature,occurovermultipleyearsanddecades.Whileannualestimationandreportingarerequired,annualmeasurementsofforestcarbonpoolsarenoteconomicallyfeasible,norarechangesincarbonstocksgenerallydetectablewithinacceptableerrorlevelsonanannualbasis.ThisnecessitatestheuseofmodelsandprojectionstoassessthecarbonconsequencesofmanagementpracticesandevaluatethepossibleGHGbenefitsofachangeinmanagementpractices.Throughouttheforestguidance,referenceswillbemadetoseveraltypesofestimatesthatmaybegenerated.ATypeIestimateistheestimateofthecarbonstockinthecurrentyear(orarecentpastyear)basedonfieldmeasurementsandotherdata.Toassessthecarbonimpactsofapracticeovertime,anecessarysteptogenerateanannualestimate,projectionsoffuturecarbonstocksmustbemade.ThiswillbereferredtoasaTypeIIestimateandwillrequiretheuseoflookuptables,simulationmodels,orothertools.ATypeIIIestimateisusedtoassessthechangeintheGHGfootprintasaresultofachangeinmanagementpractice.TogenerateaTypeIIIestimate,alandownerwillneedtoproduceTypeIIestimatesforthecurrentpracticeandthepracticeunderconsiderationandcomparethetwo.Whilesomelandownersmayrequireonlyanestimateofcurrentcarbonstocks(TypeIestimate),manywillbeinterestedingeneratingestimatesoftherateofcarbonstorageovertime(TypeIIestimate),whichnecessitatestheuseofmodelstoprojectforestgrowth.TheoverallgoalofthisguidanceistoenablealandownertodevelopanestimateoftheirGHGfootprintandtoassessthepotentialeffectsofchangesinmanagementpracticesorlanduseonthisfootprint(forforestsystems,thiswillbedominatedbycarbon).TypeIIestimatescanbegeneratedandcomparedforthecurrentmanagementschemeandmultiplealternatives(whichmayincludea“noaction”scenario).Comparingtheestimatespermitslandownerstoevaluatethepotentialimpactsofawiderangeofpossiblefactors,includingforegonegrowth,land‐usechange,andchangesinmanagementpractices.

Generally,entitiesreportannuallyforthelifeofaproject.Sinceforestsmaylastindefinitely,thereisnobiologicalending,althougheventssuchasland‐usechange,anaturaldisturbance,orbiome

shiftfromclimatechangemayeffectivelyendthelifeofaspecificforestorforesttype.Variousprogramsmayimposetimelimitsforreporting,ortheentitymaychooseaprojectlengththatisconsistentwithmanagementobjectives.Theaccountingmethodsarenotaffectedbyprojectorreportingperiodlength;thereforenospecificrecommendationsaremadeinthisguidance.

6.1.3 SummaryofSelectedMethods/Models

6.1.3.1 FieldMeasurementsofCarbonPoolsandFluxes

Methodsforestimatingthekeyforestcarbonpoolsarewelldevelopedandfairlystandard.PoolsaredefinedinSection6.2,althoughdetailedmethodsarenotgiven.Methodsformeasuringforestcarbonstocksaredescribedinavarietyofpublications,includingtheIPCCGoodPracticeGuidanceforLandUse,LandUseChange,andForestry(IPCC,2003),Pearsonetal.(2007),andHoover(2008),amongothers.AstheForestInventoryandAnalysis(FIA)programoftheUSDAForestServiceistheFederalprogramtaskedwithprovidingnational‐scaleestimatesoftheU.S.forestcarbonstocks/flux(Heathetal.,2011),documentedinventoryproceduresfromthisprogram(USDAForestService,2010a;2010b)serveasabasisformanyfacetsofentitylevelcarbonreportingprescribedinthisdocument.

6.1.3.2 LookupTablesandRegionalEstimates

ThemostcomprehensivecollectionoftablesofcarbonstockestimatesisSmithetal.(2006).Estimationmethodsaredescribed,andestimatesforeachcarbonpoolareprovidedbyforesttypeforeachregionoftheconterminousUnitedStates.ThevolumeincludesmethodsandtablestoestimatecarboninHWPs.

6.1.3.3 Models

Avarietyofmodelsmaybeusedtoassistintheestimationofforestcarbonstocksandstockchanges.Modelswillbedescribedinmoredetailinthesectionsthatfollow,butforreferencepurposes,briefsummariesofthemostcommonlyusedmodelsareprovidedbelow.Someofthesemodelsarecomplexandmayrequireasubstantialtimeinvestment.Interactingwithsomeofthesemodelsoftenrequiresspecialistknowledgeortrainingorboth.Forsuchmodels,anonlineestimationtoolcouldbedevelopedsothatlandownerswouldnotneedtolearneachindividualmodel,butwouldinteractwiththemthroughtheinterfaceofanestimationtool,whilethecomponentsoperateinthebackground.Whileallmodelshavestrengthsandlimitations,themodelsrecommendedforuseineachsectionofthisreportwereselectedbecauseoftheirnationwidecoverage,historyofperformance,andsuitabilityforthistask.

ForestVegetationSimulatorandFireandFuelsExtensionCarbonReports.TheForestVegetationSimulator(FVS)isanationalsystemofgrowthandyieldmodels,withmultipleregionalvariants,thatcanbeusedtosimulategrowthandyieldforU.S.forests.FVSisastand‐levelmodelandcansimulatenearlyanytypeofforestmanagementpractice.TheFireandFuelsExtension(FFE)toFVScanbeusedtogeneratereportsofallcarbonpoolsexceptsoilbutincludingHWPs;nonCO2GHGsarenotincluded.1Anumberofgeographicvariantsareavailable,eachwithregionallyspecificequationsanddefaultvalues.2

i‐Tree.Twoofthetoolsini‐Treeestimatecarbonstoragewithinurbantrees,annualcarbonsequestration,andcarbonemissionsavoidedthroughenergyconservationduetourbantrees.Onetool,theUrbanForestEffects(UFORE)model,focusesonanentireurbanforest.Theothertool,

1Seehttp://www.fs.fed.us/fmsc/fvs/index.shtml2Suggestedvariantsmaybefoundhere:http://www.fs.fed.us/fmsc/fvs/whatis/index.shtml

STRATUM,focusesonstreettreepopulations.Treesample(e.g.,fromrandomfieldplots)orinventorydataarerequiredtorunthemodel.Modelstoestimatefuturecarboneffectsbasedonlocalfielddataanduser‐definedmortalityandplantingrateshavealsobeendeveloped.3

FirstOrderFireEffectModel.TheFirstOrderFireEffectsModel(FOFEM)isanationallevelmodelwithgeographicvariants,designedtopredicttreemortality,fuelconsumption,smokeproduction,andsoilheatingcausedbyprescribedfireorwildfire.4

COMSUME.CONSUMEisadecision‐makingtooldesignedtoassistresourcemanagersinplanningforprescribedfireandimpactsofwildfire.CONSUMEpredictsfuelconsumption,pollutantemissions,andheatreleasebasedonfuelloadings,fuelmoisture,andotherenvironmentalfactors.5ItallowsestimationofGHGemissionsandconsumptionfrompost‐harvestandthinningactivities.

6.1.4 SourcesofData

SourcesofavailabledatathatmaybeappropriateforuseindevelopingestimatesofGHGemissionsandcarbonsequestrationvarybycarbonpool(orflux).Inallcases,fieldcollectionofdataispossible,andmaybetheonlyavailableapproachforthoseinstanceswherecredibledefaultvalueshavenotbeendevelopedand/orlookuptablesarenotavailable;thismaybeparticularlyrelevantforagroforestryandurbanforestryapplications.Inthecaseofmanyofthenon‐livingforestcarbonpools,regionaldefaultvaluesareavailablefordowndeadwood(DDW),forestfloor,andstandingdeadwoodthroughtheFIAprogram,aswellasanumberofdocumentsdevelopedinsupportofofficialU.S.governmentestimates.AllFIAdataareavailablethroughanumberofportals,includingtheFIAdatabasetools—ForestInventoryDateOnline(FIDO)andEVALIDator—andtheCarbonOnLineEstimator(COLE),6whichinteractsdirectlywiththeFIAdatabase.SeeTable6‐2forapartiallistofpotentialdatasources.

Currently,valuesforsoilorganiccarbon(SOC)stocksaredrawnfromtheStateSoilGeographic(STATSGO)database,andareofcoarsespatialresolution.Alimitedamountoffield‐sampledSOCdataarealsoavailablethroughtheFIAdatabaseaspartoftheForestHealthMonitoringportionoftheinventoryprocess.CarboninlivetreebiomassisalsoavailablefromFIAandlikeothervariablescanberetrievedatthecountylevel.TheFIAsamplingdesignisintendedtomeetaspecifiederrortargetatlargeareasofforestland;soFIAdatamaynotbeappropriateforuseatsmallerspatialscales.Estimatesbasedonasmallnumberofplotsmaypresentanunacceptableerrorlevel.COLEandEVALIDatorprovideerrorestimatesforallvariables;thesevaluesshouldbecarefullyconsideredbeforethedataareusedtodevelopestimatesforaparticularsite.

DataforemissionsofotherGHGsfromforestsarenotwidelyavailable,althoughestimatesandcalculationmethodsarebetterdevelopedforN2OthanCH4.TheU.S.EPAandIPCCprovideestimationmethodsandemissionsfactorsforbothgasesfromwildfires,andforN2Ofromforestfertilization(IPCC,2006;U.S.EPA,2011).TheU.S.EPApublishesaNationalEmissionsInventoryeverythreeyears,whichprovidesestimatesforwildfireaswellasprescribedfireforcriteriapollutantsaswellashazardousairpollutants,includingsomeGHGspecies(U.S.EPA,2012a).

3Seehttp://www.itreetools.org/4Seehttp://www.firelab.org/science‐applications/fire‐fuel/111‐fofem5Seehttp://www.fs.fed.us/pnw/fera/research/smoke/consume/index.shtml6Seehttp://www.ncasi2.org/COLE/index.html.COLEwasdevelopedthroughUSDAForestServicefinancialsupport,butiscurrentlyhostedbyNCASI.

6.1.5 OrganizationofChapter/Roadmap

ThischapterprovidesguidanceonestimatingcarbonsequestrationandGHGemissionsfortheforestsector.Incaseswherealandowner’sholdingsinvolvemultiplelanduses,guidancefortheothersectorsshouldbeconsulted.Inthischapter,attemptstonoteareaswherecross‐sectorinteractionsarelikelytooccurhavebeenmade.Wetlandsandhydrologicallymanagedsoilsareimportantinseveralsectors,andforthisreasonguidanceforestimatingGHGemissionsandsequestrationfromwetlandsystemsiscoveredinaseparatesection,outsideofthecroplands/grazinglandsandforestsectors.

Thechapterisorganizedtoprovideanoverviewoftheelementsofforestcarbonaccounting,includingdefinitionsofthekeycarbonpoolsandbasicmethodsfortheirestimation.Nextisasectionrelatingtoestimationmethodsincaseswhereforestshavebeenestablished,re‐established,and/orcleared.TheforestmanagementsectionconsiderstheGHGimplicationsofavarietyofcommonlyemployedmanagementpractices,andisfollowedbyguidanceontheestimationofcarboninHWPs.Whileagroforestrysystemsandurbanforestsmaynotbeconsideredastraditionalforestlandscapes,theworkinggrouprecognizestheimportanceoftreeslocatedoutsideofforests.Sincethemostimportantcomponentinthesesystemsisoftenthelivebiomass,urbansystemshavebeenincludedintheforestsector.Agroforestryisacomplextopic,combiningaspectsofforestry,croplandagriculture,andanimalagriculture.Sinceagroforestryismostlikelytobepracticedonlandsprimarilyusedforagriculture,theestimationguidanceisprovidedinthecroplandsandgrazinglandssectionofthedocument.Itisimportanttonotethatagroforestryhasmanycross‐sectorlinkages,andacompleteestimateoftheGHGimplicationsofagroforestrypracticesmaynecessitateconsultationoftheforestmethodsprovidedhere.Asnotedabove,naturaldisturbanceisoneoftheimportantrisksofreversalintheforestsector,andthefinalsectionprovidesguidanceonestimatingtheimpactsfromnaturaldisturbanceinforestedsystems.

Theremainderofthischapterisorganizedasfollows:

Section6.2:ForestCarbonAccounting

Section6.3:Establishing,Re‐establishing,andClearingForest

Section6.4:ForestManagement

Section6.5:HarvestedWoodProducts

Section6.6:UrbanForests

Section6.7:NaturalDisturbances

Table6‐2showsinternetsitesavailableforinformationoncarbonestimation.Figure6‐2showsadecisiontreefortheforestsectorshowingwhichforestchaptersections(i.e.,sourcecategories)arerelevantdependingonwhichforestactivitiesaretakingplaceforanentity.

Table6‐2:InternetSitesAvailableforInformationonCEstimation

Internetsite Organization RelevantContent

http://fia.fs.fed.us/ USDAForestService,ForestInventoryandAnalysis

Foreststatisticsbystate,includingcarbonestimates

Sampleplotandtreedata Forestinventorymethodsandbasicdefinitions

http://www.fhm.fs.fed.us/

USDAForestService,ForestHealthMonitoring

Foresthealthstatus Regionaldataonsoilsanddeadwoodstocks Foresthealthmonitoringmethods

http://www.usda.gov/oce/climate_change/greenhouse.htm

USDAGHGInventory State‐by‐Stateforestcarbonestimates

http://unfccc.int/http://www.ipcc.ch/

UNFCCCandIPCC Internationalguidanceoncarbonaccounting

andestimationhttp://soildatamart.nrcs.usda.gov/

USDANaturalResourcesConservationService

SoilDataMart:accesstoavarietyofsoildata

http://www.nrs.fs.fed.us/carbon/tools/

USDAForestService,NorthernResearchStation

Accountingandreportingprocedures Softwaretoolsforcarbonestimation

http://www.eia.gov/oiaf/1605/gdlins.html

U.S.EnergyInformationAdministration,VoluntaryGHGReporting

Methodsandinformationforcalculatingsequestrationandemissionsfromforestry;seePartI,Appendix

http://www.epa.gov/climatechange/emissions/usinventoryreport.html

U.S.EnvironmentalProtectionAgency

MethodsandestimatesforGHGemissionsandsequestration

http://www.comet2.colostate.edu/

USDANaturalResourcesConservationServiceandColoradoStateUniversityNaturalResourcesEcologyLab

Web‐basedtoolforestimatingcarbonsequestrationandnetGHGemissionsfromsoilsandbiomassforU.S.farmsandranches

Figure6‐2:DecisionTreeforForestSectorShowingRelevantChapterSectionsDependingonApplicableSourceCategories

See Section 6.7:Natural Disturbances

Chapter 6 is not applicable for your

entity.

Did you have any natural disturbances

(e.g., fires, pests, storms) in your forest

stands?

Did you establish new,

re‐establish, or clear forest stands on your

Did you initiateany improved forest

management practices on your forest stands?

Did youharvest any wood for

products from your forest stands?

Do you have forest stands that are located

in an urban area?

See Section 6.3:Establishing,

Re‐establishing, and Clearing Forest

See Section 6.4:Forest Management

See Section 6.2:Forest Carbon Accounting

See Section 6.6:Urban Forestry

See Section 6.5: Harvested Wood

Products

Do you have forest stands on your

Do you have additional forest

stands ?

Did you useagroforestry: e.g.,

windbreaks, riparian forest buffers, alley cropping,

silvopastures?

See Section 3.4: Agroforestry

6.2 ForestCarbonAccounting

6.2.1 DescriptionofForestCarbonAccounting

Thebasicquestioninherentwithinthebroadercontextofforestcarbonestimationis:“Howmuchcarbonisinthisforest?”AnydiscussionofforestsorforestryactivitiesinthecontextofGHGsdependsonquantifyingforestcarbon.Forestecosystemsaregenerallyrecognizedassignificantstocksofcarbon,andaggrading,orgrowing,forestscanbestrongcarbonsinks.Disturbancesandforestmanagementinfluencethesizeandratesofchangeofthesestocks.Itisimportanttonotethatforestcarbongenerallyisnotmeasureddirectly(e.g.,collectingforestbiomasssamplesforlaboratorydeterminationofcarboncontent).Itisusuallyquantifiedindirectlyfromstandardforestinventoriesandassociatedcarbonmodels(e.g.,littercarbondependentonforesttypeandstandage).Forlivetreepools,forestinventoriesoftenonlymeasurelimiteddimensionalattributes(e.g.,diameterandheight)ofindividualtreesandusebiomasscomponentmodels(e.g.,boleandcrowns)andwooddensityvaluestoconvertthesevaluesintoanestimateoftotaltreebiomass.Onceanestimateofbiomassisattained,astandardcarbonconversionconstantisappliedtoproduceacarbonstockestimate.Carbonconversionsvaryslightly,but50percentofdryweightisausefulroundvalueapplicabletoallvegetationandsoundwood(IPCC,2006).Forotherpools,suchaslitterlayersandsoilorganicmatter,specificcarboncontentperunitvolumedependsondecayandcompositionofthematerialandisgenerallylessthan50percentcarbon.Giventhediversityofestimationproceduresandcarbonpooldefinitions,areasonableselectionofmethodologiesshouldbeavailableforentitieswishingtoassesstheirforestcarbon.

Amajorattributeofcarbon“accounting”istoexplicitlydocumentanddefineaccountingproceduressuchthatforestcarbonreportsarecomparableacrossownershipsandforestecosystems.Absolutequantitiesofcarbon,orcarbonmass,arenotonlyafunctionofaspecificforestbutalsodependentonhowpoolsaredefinedandhowthemassofcarbonwithinthepoolisestimated.Forexample,bothremotelysensedimagesandground‐basedtreemeasurementscanprovideseparateestimatesofthesameforest.Thesetwotechniquesareunlikelytoprovideidenticalestimatesduetomethodologicaldifferences,includingthefactthateachapproachmaydefinedifferentpopulationsofinterestandthusaccountfordifferentsetsoftrees.Identifyingandresolvingsuchissuesisanobjectiveofforestcarbonresearch.Notallforestcarbonassessmentsormanagementplansneedtoencompassallcarbon(orGHGs)poolsifthecarbonisproperlyidentified.Measuringthecurrentstateofaforest’scarbonstocksandrecentchangesisapartof

MethodsforForestCarbonAccountingUtilizedinthisGuidance

Rangeofoptionsdependentonthesizeoftheentities’forestlandincluding:

− FVS‐FFEmodule(entitiesthatfitthelargelandownerdefinition),and

− Defaultlookuptables(entitiesfittingthesmalllandownerdefinition).

Theseoptionsuse:

− AllometricequationsfromJenkinsetal.(2003a),and

− DefaultlookuptablesfromSmithetal.(2006;GTRNE‐343)—defaultregionalvaluesbasedonforesttypeandageclassdevelopedfromFIAdata.

Thesemethodswereselectedbecausetheyprovidearangeofoptionsdependentonthesizeoftheentities'forestland.

developingabaseline,whichcanthenbeusedforadditionalanalysis.Abaselineofpastcarbonstocksandchangecanbeconstructedandusedwithmodelingtodetermineprojectionsoflikelyfuturecarbon.Similarly,abaselineisnecessaryforanalysisofalternatemanagementoptionstoevaluatepotentialforsequestration/emission.Thetechnicalspecificationsofbaselines(e.g.,startingyearandincludedstockcategories)areoftenasocial/politicaldecision,andarebeyondthepurviewofthisdocument.However,tostandardizeforestcarbonaccountingoptionsforthepurposeofentityreporting(e.g.,woodlandowners),thisdocumentwillproposeasinglesetofforestcarbonpooldefinitions.Thespecificrecommendationsincludedhereareintendedtodirectlandownerstotoolsanddatasourcesspeciallydevelopedforquantifyingforestcarbon.Notethattheselistedprocessesarenotintendedtoexcludealternativedatasummariesthatmaybeavailabletoentities.Detailsarediscussedbelowinthediscussionoftherespectiveforestcarbonpools,butthegeneraloptionslistedindecreasingaccuracy(andcost)includethefollowing:

(1) Measure/sampleyourforestandestimatecarbonfromthesedata(reducesampledatasoastothenapplyavailablebiomassequationsorothercarbonconversionfactors);

(2) Characterizeyourforestaccordingtoclassifications(i.e.,lookuptables)basedonstandorsiteattributesderivedfromrecordsinthenation’sforestinventorydatabase(FIADB)(Woodalletal.,2010;Woudenbergetal.,2010);or

(3) Useassociatedmodels(FIDO,COLE,etc.),whichbaseyourforest’scarbonestimatesonrepresentativedatasampledbyotherswithcriticaldependentuservariableinput(e.g.,standage).

Notethattheabovethreeoptionsarenotnecessarilymutuallyexclusive.Forexample,FIADBdataorsimilarmodels(Option2)arebasedonpermanentinventoryplotsamplingandcarbonconversion(Option1),andlookuptables(Option3)arebasedontheFIADB(Option2).Therecommendedforestcarboninventoryoptionsinvolvetradeoffsincostsandlevelofinformationuniquetotheentities’forestland.

Theprocessofobtainingforestcarbonestimatesdependsoncircumstancesuniquetoeachentity,butmostlydependsontheintendedaudienceandtheresourcesavailableforforestinventory.Forthisguidance,atwo‐tiersystemisinplace.Thegoalistobeasinclusiveaspossiblewhilenotcreatingameasurementburden.Smallerholdingsthatarenotactivelymanagedareunlikelytobeinventoried;atwo‐tierapproachpermitsownersofsuchholdingstoestimatetheirfootprintandthepotentialchangesfromchangesinpracticesappliedwithoutincurringthecostsofmeasurement.Smallerlandownerswhohaveinventorydataorwhowishtoacquireitshouldusethetoolsandprotocolsdescribedforlargelandowners.

Landownersizeclassesaredefinedasfollows:

Landownerswhohold200ormoreacres(80.9hectares[ha])offorestlandshouldfollowthemethodsforlargelandowners.Also,landownerswhoholdlessthan200acres(80.9ha)offorestlandshouldfollowthemethodsforlargelandownersifthreeormoreofthefollowingaretrue:

Landownerownsormanagesmorethan50forestedacres(20.2ha)

Landowner’sforestiscertified

Landownerhasdevelopedaforestmanagementplan

Landowner’sforestedpropertyhasahistoryoftimberharvesting

LandownerparticipatesinStateforesttaxabatementprograms

Landownersnotmeetingthedefinitionoflargelandownershouldfollowthemethodsforsmalllandowners.

Recommendedmethodsdependonforestlandownersize.Smalllandownersmayusegeneralizedlookuptablesbasedonregion,foresttype,andageclasstoestimatecarbonstocks.LargelandownersshouldcollectstandardforestinventorydataandusetheFVS‐FFEmodulewithJenkinsetal.(2003a)allometricequations.ItshouldbenotedthatFVSandtheFFEarelargeandcomplicatedmodels;anytoolthatimplementsthesemethodswillrequiredevelopmentofasimplifieduserinterfacethatinteractswithFVSandFFE.

Atthistime,theJenkinsetal.(2003a)equationsarespecifiedsincetheyarenationallyconsistent.FuturedevelopmentislikelytoincludetheimplementationofamorerecentFIAbiomassestimationmethodinFVS,enablingtheproductionofestimatesthatmatchtheofficialU.S.forestcarbonestimates.Whilelocalvolumeorbiomassequationsmaybemoreaccurateforagivenlocation,useofsuchequationswillresultinadditionalinconsistenciesinresults,sonootherequationsareapprovedforuseatthistimeunderthismethodology.

Althoughcarbonreportingbeyondthatoftheentitylevel(e.g.,majortimberlandownerornationalforest)mayuserefinedmeasurementprotocols,expandedcarbonpooldefinitions,and/orancillarydata(e.g.,remotelysensedimagery),theproposedpoolsandinventorymethodologiesinthisdocumentserveasastartingpoint.Classificationofcarbonestimateswithinmulti‐tieredsystems,andlinkstomodelstoprojectfuturechangeunderalternatescenariosareaddressedattheendofSection6.2.

Tofacilitateaccounting,forestcarbonistypicallyclassifiedintoafewdiscretepools,whichshouldbecomprehensive(allorganiccarbon)withnogapsandnooverlap.Thepurposeofestablishingtheseseparatepools,orbins,offorestcarbonistwofold:(1)toalignappropriatedatawithecosystem/productcomponents(e.g.,treeinventoriesandlivetreecarbonpool),oralternativelytoidentifygaps;and(2)asapartoftheaccountingprocess,notallreportedstockorchangenecessarilyneedstoincludeallofthecarbonpools,butwhatisincludedmustbeunambiguouslyidentified.Notethatthecarbonpools(orbinsorclassifications)focusoncarbonfromphytomass.Strictlyspeaking,totalcarbonstockswithinaforestincludeanon‐plant(notoriginatingfromtheplantkingdom)percentage,butsuchpoolsarenotdefinedbecausethisisgenerallyaninsignificantproportion.Exceptionsaretheforestfloorandsoilpools,whichincludedecomposersandsoilfauna.Asometimessignificantamountofcarbonisremovedfromforestsaswoodisharvestedandusedinwoodproducts.Someofthatcarbonremainssequesteredforlongperiodsoftime,dependingontheproducts.Thus,harvestedwoodshouldbeincludedinforestcarbonestimates.

Figure6‐3isadecisiontreefortheforestcarbonaccountingsourcecategoryshowingwhichcarbonaccountingassumptions(e.g.,simulationmodels,allometricequations,biomassexpansionfactors,lookuptables)arerecommendedforanentitydependingonthetypeofactivitydataavailable.However,itshouldbenotedthatfornationalreporting—i.e.,theannualGHGinventoryreportedbyUSDAandU.S.EPA—whereindividualtreemeasurementsfromFIA’sinventoryplotsareavailable,thecomponentratiomethod(CRM)forestimatingbiomass(Woodalletal.,2011)iscurrentlyused.Again,futuredevelopmentwilllikelybringthesemethodsintoalignment.

Figure6‐3:DecisionTreeforForestCarbonAccountingShowingMethodsAppropriateforEstimatingForestCarbonStocks

1Smalllandowners(asdefinedinSection6.2.1)mayusegeneralizedlookuptablesbasedonregion,foresttype,andageclasstoestimatecarbonstocks.Largelandownersshouldcollectstandardforestinventorydataanduseallometricequationstoestimatelivetreebiomasscarbon(othercarbonpoolsmaybeobtainedfromlookuptables).2Jenkinsetal.(2003a).3Notethatvolumeequationsusedbylandownersshouldalignwith“meanvolume”specifications(e.g.,rotten/culldeductions)ofSmithetal.(2006).Differentvolumeequationsanddeductionswillproducevolumeestimatesthatdifferfromthoseusedinthetables.4Smithetal.(2006).

Anotheraspectofacarbonaccountingframeworkisconsistentorcomparablerepresentationofchange,whichgoesbeyondtheidentificationofcarbonpools.Changeisaffectedbyprocessesofrecruitmentandgrowthaswellasdisturbance,mortality,andharvest.Inthemostbasicsense,changecanbethedifferencebetweentwosuccessivestockestimates.ThisiscommonforGHGreportingbasedonstandardforestinventories.Somecomponentsofchangecanbemeasuredwithintensivesamplingatsmallscales,butingeneralchangeisestimatedfrommeasurementsattwosuccessiveinventorytimes(e.g.,totalstockchange,orgrowth/removals/mortalityestimates,orremotelysenseddata),orbasedonmodelsofecosystemorbiogeochemicalchange.Abasicapproachtoquantifyingchangeinforestcarbonisbasedonthequantitiesdefinedforforestcarbonstocks.Netannualcarbonstockchangesarecalculatedbytakingthedifferencebetweentheinventoriesanddividingbythenumberofyearsbetweentheinventoriesforaselectedforestorforestarea(e.g.,Δstock=(stock2–stock1)/time).Thisstock‐changeapproach(IPCC,2006)isthechangemethodappliedtoFIAstrategic‐scaleinventoriesforthestock‐changevaluesreportedintheU.S.NationalGHGInventories(e.g.,U.S.EPA,2011).

SixStepstoForestEntityCarbonEstimation

Theapproachtoestimationofcarbonstocksandfluxesintheforestsectorisasfollows:

Step1:Determinelandownersizeclassbasedonforestarea.Basedontheacreageunderconsideration,landownersaredividedintotwogroups:“small”landownersand“large”landownersasdefinedinSection6.2.1.

Step2:Collectforestdata.Forbothsizeclassesoflandowners,somelevelofforestinventory(i.e.,fieldsurvey)dataisrequired.However,therearedifferingdatarequirementsforsmalllandownersandlargelandowners.

Smalllandownersshouldcollectbasicdataonspeciesmix(i.e.,typeofforest)andstandage(ortimesincelastmajordisturbance)withintheirforest.Greaterinventorydetailcanleadtomorepreciseestimatesofcarbon,butevenbroadgeneralizationsabouttheregion,age(and/ormeanvolume),andtypeofforestcanleadtoacarbonestimate.Theobjectiveistoobtainreasonableandconsistentestimatesovertimeatthelowestcost.Ifasmalllandownerwishestoconductaninventoryandfollowtherecommendedguidanceforlargelandowners,theyarefreetochoosethisoption.Theprincipaltradeoffisbetweencostandaccuracy;collectinginventorydataincreasesthecostofdevelopingestimatesbutincreasesaccuracy.

Largelandownersshouldgathermoreextensivedataaboutforestandstandcharacteristics.AthoroughforestinventoryiscreatedusingindustrystandardsandpracticesofthetypedescribedinGTRNRS‐18:MeasurementGuidelinesfortheSequestrationofForestCarbon.Variablesconsideredmustincludedominantspecies,dominantageclass,standdensity,andsiteclass.Inclusionofadditionalvariables,whilenotrequired,willimproveaccuracyofcarbonestimates.

Step3:Estimateinitialforestcarbonstockandannualfluxes.Quantitiesofcarbonchangeovertime.Forestcarbonestimatesaredividedintosixdiscrete,mutuallyexclusivepools,includinglivetrees,standingdeadtrees,understoryvegetation,downdeadwood,forestfloor,andsoilorganiccarbon.Anumberofpool‐specificcarbonconversionmethodsareavailable;thesemethodsusetheinventorydatagatheredinStep2toquantifycarbonforeachpool.However,thespecificmethodstobeuseddifferdependingonthelandownersizeclass.

(Continued)

Smalllandowners,aftercollectingobservationaldata,canuselookuptablesfromSmithetal.(2006)(alsoknownasGTR‐NE‐343:MethodsforcalculatingforestecosystemandharvestedcarbonwithstandardestimatesforforesttypesoftheUnitedStates)toestimatecarbonstocksandcarbonstockchanges.Thelookuptablesarecategorizedbyregion,foresttype,previouslanduse,andinsomecases,managementactivity.Usersmustidentifythecategoriesfortheirforestsandestimatetheareaofforestland.TofacilitateuseofthedatafromGTR‐NE‐343,atoolcouldincorporatethedatasuchthat,inmostcases,landownerswouldbeabletoselecttheirstandcharacteristicsfromadrop‐downmenuofdefaults.Basedonthelandowner’sselectionsfromthedefaultmenus,thetoolwouldproduceestimatesofcarbonstocksineachofthesixcarbonpools.

LargelandownersshouldusethedatacollectedintheirforestsurveystoperformmodelrunsusingtheFVSmodel.FVSwillusethesite‐andstand‐specificdatatoprovidemoreaccurateestimatesofcarbonstocksineachofthecarbonpools(excludingsoilcarbon,whichFVSdoesnotestimate).Soilcarbonestimatescanbedeterminedfromarangeofmethodsincludingsamplingorexistingforestsoilcarbonestimatedatasetsdependingonaspecificentity’scircumstances.

Thoughthemethodsdifferforsmalllandownersandlargelandowners,bothcalculateinitialcarbonstocksandexpectedannualratesofaccumulationunderaverageconditions(repeatingthefieldsurveyatprescribedintervalswillhelpcalibrateorvalidatethestockchangeestimates).

ThemethodsalsoallowforadjustmentsduetoHWPs(Step4),forestmanagementpractices(Step5),andnaturaldisturbances(Step6).

Step4:AdjustcarbonestimatesduetoHWPs.Harvestingactivitiescanhaveconsiderableimpactoncarbonquantityacrossthesixforestcarbonpools.Intermsofemissions,thefateoftheharvestedmaterialmustbeconsideredaswell,includingwhetherthematerialisusedinHWPsorforenergy.Asabove,themethodsforestimatingtheseimpactsdifferdependingonthelandownersizeclass.

ForHWPs,smalllandownersshouldrelyondataprovidedinlookuptablesinGTR‐NE‐343,whichprovidesfactorsforcalculationofcarboninHWPsbasedonregion,timbertype,andindustrialroundwoodcategory.Thelookuptablesdividetheharvestedforestmaterialspoolintofourdistinctfates:productsinuse,landfill,emittedwithenergycapture,andemittedwithoutenergycapture.Carbonemissionsdifferdependingonthefate,whichinturndependsontheregionandharvestmaterialcharacteristics.Byusingthelookuptables,landownerscanadjustcarbonestimatesaccordingly.

LargelandownersshouldrelyonFVStomodelforestmanagementpractices,resultinginestimatesofthecarbonimpactofthesepractices(e.g.,harvesting).Forexample,FVScanconsiderthetypeofharvest(e.g.,clearcutversusstrategicthinning)andprojecttheresultsofthisharvestoncarbonstocks,thusallowinguserstoquantifythecarbonimpactofvariousharvestingactivities,aswellasadjustingfortheultimatefateofharvestedmaterials.TheharvestedforestmaterialpoolisdividedbyFVSintothesamefourdistinctfatesasforGTR‐NE‐343:productsinuse,landfill,emittedwithenergycapture,andemittedwithoutenergycapture.Harvestsalsoimpactforestgrowthovertime,whichismodeledbyFVS.

(Continued)

6.2.1.1 ForestCarbonPools

Carbonreporting—suchasfortheU.S.reportingcommitmenttotheUnitedNationsFrameworkConventiononClimateChange(UNFCCC),whichismetbytheU.S.EPA’sofficialGHGinventory(e.g.,

(Continued)

Step5:Adjustcarbonestimatesduetoimprovedforestmanagement.Forestmanagementpractices,suchasthinningorfertilization,mayimpactcarbonfluxesaswell.Asabove,themethodsforestimatingtheseimpactsdifferdependingonthelandownersizeclass.

FVSallowslargelandownerstoquantifytheimpactofvariousforestmanagementpractices.Forexample,usingkeywords(orcombinationsofkeywords)providedbyFVS,userscangenerateestimatesfortheimpactofstanddensitymanagement,sitepreparationmethods,vegetationcontrols,variousdensitiesofplantingstock,fertilization,rotationlengthmanagement,prescribedfire/controlburnsandfuelloadmanagement,andpestanddiseasecontrol.Withgivenstandandtree‐listdata,userscandevelopabaseline,whichcanthenbecomparedtoalternativemanagementstrategies.Thisallowsforassessmentofcarbonimpactofimplementingthosemanagementpractices.ItshouldbenotedthatFVSistherecommendedmethod,evenifalargelandownerhasitsowncustominventoryandmodelingsystem,whichmightbeconsideredsuperiortoregionalmodelssuchasFVS.Theadoptionofasingle,recommendedmethodforlandownersallowsfortransparent,consistent,comparable,andcompleteestimatesacrosslandownersappreciatingthattherewillbealikelytradeoffintheaccuracy,costeffectiveness,andeaseofuseofthemethodforthoselandownerswithcustomsystems.Futuredevelopmentmayincludeameansforlargelandownerstousecustommodelsinthisframework,butthisoptionisnotavailableatthistime.

Unfortunately,thelookuptablesdonotallowforestimatesassociatedwithimprovedforestmanagement.Ifprescribedfire/controlburningisusedbyeitherlandownertype,itisrecommendedthattheemissionsfortheactivitybecalculatedasguidedinStep6.

Step6:Adjustcarbonestimatesduetoforestfiresandothernaturaldisturbances.Naturaldisturbances,suchasforestfires,storms,wind,drought,orpest/insectinfestation,canalsohaveconsiderableimpactoncarbonquantitiesacrossthesixforestcarbonpools.Landownersshouldestimatethecarbonimpactofnaturaldisturbances.

Forforestfires,wildfires,andprescribed/controlledburns,bothsmallandlargelandownersshouldrelyonFOFEMtogeneratecarbonestimates.FOFEMinputrequirementsincludebasicforesttype,sitelocation,anddominantspeciesdata,butalsoallowsuserstoinputadditionalinformation,dependingonaspecificentity’scircumstances,onamountofduff,moisturecontent,andothervariablesassociatedwithfire.Theseverityofthefirecanbecategorizedbypercentofthelandaffected.Theresultingoutputincludesestimatesofcarbonemissions.

Themethodsassumesmalllandownerscanprovideobservationalestimatesfortheimpactsofnaturaldisturbancessuchaspests,basedonthepercentageofforestlandaffectedbythedisturbance.LargelandownersmaymodelimpactsofpeststhroughavailablekeywordsandextensionsprovidedbyFVS.

Thephilosophybehindthesesixstepsisthattheyallowtheentitytoassesswhatcarbonstockstheyhaveunderanypresentconditionsandwhatstockstheymightexpectgivenimplementationofaparticularharvestingregime,changeinforestmanagementpractices,and/oravarietyofnaturaldisturbances.

U.S.EPA,2011)—providesaframeworkforthepoolsdescribedhere.However,thepoolsaremodifiedtomorecloselycorrespondtotypesofforestinventorydata.Forexample,forestcarboncanbeeasilycategorizedaccordingtoabovegroundversusbelowground,orlivingversusdeadplantmaterial.Inpractice,classificationsofcarbonpoolsdependontheforestdataandhowtheyareused.Assuch,thepoolsdescribedbelowarejointlydefinedbyUNFCCCreportingrequirementsandtheuseofFIAforestinventoryastheprimarydatasource.Inotherwords,thepoolsdefinedbelowareaconvenientset,butdefinitionsandboundariesaroundpoolscanvaryaccordingtospecificcarbonestimationprocedures/capabilitiesandreportingneeds(seeFigure6‐4).

Figure6‐4:ForestCarbonPoolHierarchyShowingHowForestCarbonPoolsCanBeDelineatedintoEvenSmallerPoolsDependentontheEntityNeedsandInventoryCapabilities

Livetrees:Alargewoodyperennialplant(capableofreachingatleast15feet(4.6m)inheight)withadiameteratbreastheight(DBH)oratrootcollar(ifmultistemmedwoodlandspecies)greaterthan1inch(2.5centimeters[cm]).Includesthecarbonmassinroots(i.e.,livebelowgroundbiomass)withdiametersgreaterthan0.08in(2millimeters[mm],stems,branches,andfoliage.

Understory:Roots,stems,branches,andfoliageoftreeseedlings,shrubs,herbs,forbs,andgrasses.

Standingdeadtrees:Deadtreesofatleast1inch(2.5cm)DBHthathavenotyetfallen,includingcarbonmassofcoarseroots,stems,andbranches,butthatdonotleanmorethan45degreesfromvertical(Woudenbergetal.,2010),includingcoarsenonlivingrootsmorethan0.08in(2mm)indiameter.

Downdeadwood(alsoknownascoarsewoodydebris):Allnonlivingwoodybiomasswithadiameterofatleast3inches(7.6cm)attransectintersection,lyingontheground.Thispoolalso

includessomeless‐than‐obviouscomponentsofDDW:(1)debrispiles,usuallyfrompastlogging;and(2)previouslystandingdeadtreesthathavelostenoughheightorvolume,orleangreaterthan45degreesfromvertical,sotheydonotqualifyasstandingdeadtrees.

Forestfloor:Thelitter,fulvic,andhumiclayers,andallfinewoodydebriswithadiameterlessthan3inches(7.6cm)attransectintersection,lyingonthegroundabovethemineralsoil.

SoilorganicC:Allorganicmaterialinsoiltoadepthofgenerally3.3feet(1meter[m]),includingthefineroots(e.g.,lessthan0.08in(2mm)indiameter)oftheliveandstandingdeadtreepools,butexcludingthecoarserootsofthepoolsmentionedearlier.

Harvestedwood:Woodremovedfromtheforestecosystemforprocessingintoproducts,notincludingloggingdebris(slash)leftintheforestafterharvesting.

Thesepooldefinitionsaredevelopedaroundacommonsetinusebyanumberofpublications(e.g.,Smithetal.,2006)andattheforeststandlevel,whichinturndifferfromstockdefinitionsusedbytheUnitedStatestomeetUNFCCCnationalreportingrequirements.

Alsonotable(inthereportinglist)istheinclusionofHWP(coveredindetailinSection6.5),whichassumesthatameasurableportionofwoodremovedatharvestremainssequesteredfromreemissiontotheatmosphereforaperiodoftimethatcanbeestimated.PoolsandestimationofstocksareorganizedprimarilyaccordingtodatacollectionandestimationwithFIA’spermanentinventoryplots(phasetwo(P2),thestandardinventorymeasurements;andphasethree(P3),theforesthealthmeasurements).Notethatpooldefinitionsarenotindependentofrelatedestimators;detailsrelatedtoestimationarenotaddresseduntilsubsequentsectionsofthisguidance.

6.2.2 DataCollectionforForestCarbonAccounting

Forestcarbonistypicallyestimatedindirectly,throughapplyingconversionconstantstoastandardforestinventory,usingalocalizedbiogeochemicalmodel,orsimplylookingupspecificforestattributes(e.g.,standage,foresttype)inalookuptable(e.g.,Smithetal.,2006).Forthepurposesofthisdocumentation,astandardsetofcarbonpooldefinitionsthatarepartofFIA’snationalinventoryaredelineatedthatcorrespondtoavailablelookuptables(Smithetal.,2006).

6.2.2.1 LiveTrees

Thetreecarbonpoolsincludeabovegroundandbelowground(coarseroot)carbonmassoflivetrees.Separateestimatesaremadeforfull‐treeandaboveground‐onlybiomasstoestimatethebelowgroundcomponent.TreecarbonestimateswithintheFIADB(USDAForestService,2012;Woudenbergetal.,2010)arebasedonWoodalletal.(2011)andJenkinsetal.(2003a).Theper‐treecarbonestimatesareafunctionoftreespecies,diameter,height,andvolumeofwood.Belowgroundbiomassiscalculatedasavaryingproportionofabovegroundbiomass.Again,thisisdependentonspeciesandsizeofindividualtrees.ThepooloflivetreeswithintheFIADBisdefinedastrees,orwoodybiomasswithgreaterorequalto1inch(2.5cm)DBH.However,treeslessthan5inches(12.7cm)DBHaresampleddifferentlythanthosethatare5inches(12.7cm)ormore.Thesedifferencesshouldnotaffectprecisionintheoverallamountoftreecarbonorstandleveldensity.Saplingsaretreesatleast1inch(2.5cm)butlessthan5inches(12.7cm)DBH.The“sapling”versuslargertreedistinctionisbasedonsamplingdifferencesontheFIAplots.Thisillustratesthatpoolclassificationisdependentonboththeobviousphysicalandspatialseparationinastandaswellasdatasources.

6.2.2.2 Understory

Understoryvegetationisaminorcomponentofbiomassortheliveplantcomponent.Understoryvegetationisdefinedasallbiomassofundergrowthplantsinaforest,includingwoodyshrubsand

treeslessthan1inch(2.5cm)DBH.InFIADB‐basedcarboninventory,itisassumedthat10percentofunderstorycarbonmassisbelowground.Thisgeneralroot‐to‐shootratio(0.11)isnearthelowerrangeoftemperateforestvaluesprovidedinIPCC(2006)andwasselectedbasedontwogeneralassumptions:ratiosarelikelytobelowerforlight‐limitedunderstoryvegetationcomparedwithlargertrees,andagreaterproportionofallrootmasswillbelessthan0.08in(2mm)indiameter.EstimatesofcarbondensityarebasedoninformationinBirdsey(1996),whichwasappliedtoFIApermanentplots.

6.2.2.3 StandingDead

Thestandingdeadtreecarbonpoolsincludeabovegroundandbelowground(coarseroot)mass.Estimatesandallometryareessentiallysimilartothoseforlivetrees,withsomeadditionalconsiderationsfordecayandmechanical/structuraldamage(Domkeetal.,2011;Harmonetal.,2011).Carbonconversionsvaryslightly,but50percentisausefulroundvaluefordeadwood.However,specificcarboncontentislessforthelitterandorganiclayersoftheforestfloor.Thereisnotadeadplantmaterialpoolcorrespondingtounderstory;itisassumedtheseveryquicklybecomelitterorsmallwoodydebris.Pairingpooldefinitions(boundaries)withdatasourcesisalsoveryimportantwiththepoolsofdeadplantmaterial,becausemeasurementsspecifictoestimatesaremuchlesslikelyforDDW,forestfloor,etc.IntheFIADBthedistinctionbetween“standing”and“down”deadwoodisbasedonangleofleanandisappliedtoP2(phasetwo,“standard”forestinventoryplot)andP3(phasethree,asmallernumberofplotsthatincludeadditionalmeasurementssuchassoilsandforestfloor)data;otherdefinitionsmayvary.Forsmalldiameterstandingdeadtrees,estimatesexistbutareproblematic:FIAdataonlyprovidesamplesofstandingdeadtreesat5inches(12.7cm)DBHorlarger.Estimatesofsaplings(1–5inch(2.5—12.7cm)DBHtrees)necessarilywillbemodeled(Woodalletal.,2012).

6.2.2.4 DownDeadWood

DDWisdefinedaspiecesofdeadwoodnolongerapartofstandingdeadorsnags,yetdistinctfromsmalleroradvanceddecayedwoodoftheforestfloor.ThedefinitionlargelycorrespondstotheP3downwoodymaterialpool,andrepresentsaslightchangefromthepastdefinition.Thispoolalsoincludessomeless‐than‐obviouscomponentsofDDW:(1)debrispiles,usuallyfrompastlogging;(2)previouslystandingdeadtreesthathavelostenoughheightorvolumeorleangreaterthan45degreesfromverticalsotheydonotqualifyasstandingdead;(3)stumpswithcoarseroots(aspreviouslydefined);and(4)nonlivingvegetationthatotherwisewouldfallunderthedefinitionofunderstory.

6.2.2.5 ForestFloororLitter

Theforestflooristhelayersoflitter,oftenclassifiedasthefibric(Oi),hemic(Oe),andsapric(Oa)organiclayersabovethemineralsoilandsmallerthanDDW.Thisclassificationrepresentsachangefromthepastdefinition,whichalsoincludedthesmallwoodydebrisfromtheDDWpool.Organicsoilspresentadditionalchallengeswhendelimitingthispool.

6.2.2.6 ForestSoilOrganicCarbon(SOC)

Thispoolisorganiccarbonwithinthesoilbutexcludingcoarserootsasdefinedforlivetrees,understory,standingdeadtrees,andstumps—allasdefinedabove.Byconvention,largepiecesofwoodymaterialthatareseparatelyandindependentlyestimatedthroughsamplingandallometryareexcluded.Depthisarbitraryandsofarhasbeendefinedbythedatasetinuse.Thedatasetshouldrepresentsamplesofasmuchoftheorganiccarbonaspossible,althoughpeatlandspresentauniqueproblem.Acommonsamplingdepthis1m,althoughthisisnotanIPCCstandard.Adequatesamplingdepthmaybeascertainedthroughlocalknowledge;3.9to7.9inches(10to20

cm)maybeadequateforsomeforestecosystems,whileothersrequiregreaterdepths.Datasetsofsoilmapsfromsurveysareanothersourceofdata(inadditiontoP3plots).SOCvariabilityextendstorelativelylarge‐scalemapssuchaslocationssurroundingP2/P3plots.Thatis,soilsmapsarebasedondatawiththesamevariabilityasseenintheP3subplot‐to‐subplotprecision.

NotethatthepooldefinitionsusedbyFVSdonotmatchdefinitionsusedbyFIAinallcases.Whilethemaincategoriesofliveanddeadbiomasswillincludethesameelements,theFIAdefinitionofforestfloorincludesfinewoodydebris,whiletheFVS‐FFEdefinitionplacesfinewoodydebrisintheDDWcategory.FIAconsiderstreesunder1inch(2.5cm)DBHtobepartoftheunderstorypool,whileFVStrackstheseastreesregardlessofsize.FutureworkislikelytoincludethecapabilityofFVS‐FFEtogenerateacarbonreportwithpoolscorrespondingtothedefinitionsusedbyFIAinnationalaccounting.

6.2.3 EstimationMethods

Theflexibilityinusingthebestobtainabledatabalancedwiththeneedsandresourcesofeachindividualforestownercanprovidegood/validforestcarbonestimatesifsomebasicguidelinesarefollowed:

Carbonpoolsshouldbeexplicitlyidentifiedtomakeitpossibletoidentifypossiblegapsoroverlapsbetweenpools.Identifyingandrecognizingthatagapexists(forexample,therearenoseedlingdata,orstandingdeadtreeswerenotmeasured)ismoreusefulthanfuzzyboundariesbetweenpools.

Consistentpooldefinitionsandmethodsforcarbonestimationwithinthosepoolsarerequiredforvalidestimatesofchange.Thatis,changeshouldbebasedonthesamepoolsandmethodsatbothtime1andtime2.

6.2.3.1 LiveTrees

Variousapproachesareusedforestimatesoftreebiomassorcarboncontent;ultimately,eachreliesonallometricrelationshipsdevelopedfromacharacteristicsubsetoftrees.Here,livetreesincludestemswithDBHofatleast1inch(2.5cm).Allometrycanincorporatewholetreesorcomponentssuchascoarseroots(greaterthan0.08to0.20inches(0.2to0.5cm);publisheddistinctionsbetweenfineandcoarserootsarenotalwaysclear),stems,branches,andfoliage.Livetreebelowgroundcarbonestimatescanbetroublesome,butoverallaccuracyisbestiftheboundaryissettoconformtoavailabledataratherthanapredefinedthreshold.

Recommendedoptionsforobtainingestimatesofcarbonstockoflivetreesare:

Smalllandowners(asdefinedinSection6.2.1):Valuesobtainedfromlookuptables(e.g.,eitherthoseinSmithetal.,2006,orasotherwiseprovided)categorizedbygeographicregion,foresttype,andageclass.

Largelandowners(asdefinedinSection6.2.1):Standardforestinventory,estimatescalculatedusingindividualtreemeasurement(diameter)andtheFVS‐FFEmodulewiththeJenkinsbiomassequations(Jenkinsetal.,2003a).

Biomassequationsmustbeappliedappropriately;usingequationsoutsidethediameterorgeographicrangesforwhichtheyweredevelopedwillintroduceadditionalerrortotheestimates.GiventhehundredsofdifferenttreespeciesgrowingindiversehabitatsacrosstheUnitedStates,itisbeyondthescopeofthisdocumenttosuggestthemagnitudeoftheeffectofalternativetreevolumemodelsbeyondthenational‐scalemodelssuggestedherein.Regardlessoftheestimationapproachselected,itiscriticaltousethatmethodconsistentlyovertime.Estimatesproducedfromdifferentmethodswillvary;changingestimationmethodsovertimewillintroduceadditionalerror.

AlthoughwearecurrentlyspecifyingonlytheuseofbiomassequationsbyJenkinsetal.(2003a),itisunderstoodthattheseequationsmaynotbethemostappropriateinallcircumstances.Forexample,usingequationsoutsidethediameterorgeographicrangesforwhichtheyweredevelopedwillintroduceadditionalerrortotheestimates.SomeJenkinsequationshavelimitstotheallowablediameters.SpecificguidancewillbedevelopedinthefuturetofacilitatetheuseofdifferentbiomassequationssuchasthoseusedbyFIAbasedontheCRMandlocally‐specificequations.RefertoFigure6‐3foradecisiontreefortheforestcarbonaccountingsourcecategoryshowingwhichcarbonaccountingassumptions(e.g.,simulationmodel,allometricequations,andlookuptables)arerecommendedforanentitydependingonthesizeclassandtypeofactivitydataavailable.

SamplingandAllometry.Recommendedapproachesarebasedontheapplicationofallometricrelationshiptosampledinventorydata.TheFIADB‐basedestimatesoflivetreecarbonarebasedontheplotdata–P2dataandCRMbiomassestimation(Woodalletal.,2011).Inaddition,alargenumberofotherallometricrelationshipshavebeendevelopedfortreebiomass(biomassregressionequations).Manybiomassequationsareavailableforavarietyofforesttypes;forexample,possibleoldercitationsareTer‐MikaelinandKorzukhin(1997);seealsocitationsinJenkinsetal.(2003b).TheequationsrecommendedinthisreportaretheJenkinsetal.(2003a)equations,whicharenationallyconsistentandstraightforwardtoapply.FuturedevelopmentorintegrationofthismethodintoasoftwaretoolshouldconsiderimplementationoftheCRMbiomassestimationmethodinordertobetteralignwiththemethodsusedforU.S.GHGinventoryreporting.TheCRMapproachiscomputationallycomplex,andisnotincludedatthistime.

Inventorydesignsandprotocolsarewelldocumentedbyavarietyofauthorsandwillnotbediscussedfurtherhere.AgoodexampleisPearsonetal.(2007),whichiswrittenspecificallyforcarboninventories.

LookupTables.Publishedsummaryvaluesofsimilarorrepresentativeforestsprovidequickandinexpensivemeansofroughlyassessinglikelyforestcarbon.Agoodexampleofsuchlookupvaluesarethepastrevised1605(b)guidelines,withtheforesttablespublishedasSmithetal.(2006).AlternativeversionsofrepresentativevaluesincludeFIAonlineapplicationssuchasFIDOorEVALIDator,FIA‐relatedapplicationssuchasCOLE,ormodelsfromspatialdatasuchastheFIAbiomassmaportheNationalLandCoverDatasetlayers.

Simulations/Modeling.Notonlydoforestbiometricalmodelsprovideaplatformforestimatingfuturescenariosofforestcarbonstocks,buttheycanalsobearapidmethodologyforentity‐levelcalculationofcurrentforestcarbonstocks.TheFVSisonesuchsimulationtoolthatcanprovideestimatesofcurrentforestcarbonstocksgivenanelementaryforestinventorywasconducted(e.g.,numberoftrees,size,andspecies).Inaddition,andperhapsamorepowerfulaspectofsuchatool,isthatprojectionsoffuturestandattributescanbeacquired(e.g.,forestcarbonstocks50yearsfrompresent)asdescribedinDixon(2002)andHooverandRebain(2008;2011).

6.2.3.2 Understory

Estimationproceduresanddatasourcesarelimitedforthispool.Unlessanentityhasthecapabilitytodeveloplocalizedunderstorymodelsandallometricrelationships,thedevelopmentofcarbonestimatesforthesepoolswillbelimitedtolookuptablesandsimulations/modeling.ValuesareprovidedintheSmithetal.(2006)lookuptables,whicharebasedonBirdsey(1996)andmodifiedtoapplytoFIAdata;seeU.S.EPAAnnex3.12(2010)foradditionaldetails.TheFIADBconditiontableincludesestimatesbasedonthismodel,soestimatesbasedonsimilarstandscanbeobtainedfromtheFIADB.UnderstoryvaluesareprovidedinthecarbonreportsinFVSandareregionaldefaultvaluessetwithinthemodel.

6.2.3.3 StandingDead

Theprevailingdifferenceinvolume/biomass/carbonestimationofstandingdeadtreesfromlivetreesistheincorporationofdecayreductionfactorsandrotting/missing/cullcomponents(Domkeetal.,2011;Harmonetal.,2011).

SamplingandAllometry.FIAinventory‐basedestimationforstandingdeadtreesisfromP2plot,condition,andtreerecords.TreemassintheFIADBiscalculatedaccordingtoCRMmethods(Woodalletal.,2011)withrefinementstotheCRMapproachspecifictostandingdeadtreesproposedbyDomkeetal.(2011).Duringastandardforestinventory,standingdeadtreesaremeasuredandtallied,andlargelandownerscanusethisinformationwithFVStoproduceestimatesofthebiomassandcarboninthispool.

LookupTables.Publishedsummaryvaluesofsimilarorrepresentativeforestsprovidequickandinexpensivemeansofroughlyassessinglikelyforestcarbon.Agoodexampleofsuchlookupvaluesarethepastrevised1605(b)guidelines,withtheforesttablespublishedasSmithetal.(2006).AlternativeversionsofrepresentativevaluesincludeFIAonlineapplicationssuchasFIDOorEVALIDATOR,andFIA‐relatedapplicationssuchasCOLE.Notethatsomedifferencesmayappearamongpoolestimatescomparedtothesampleestimates,becausesomeorallarebasedonempiricalmodels(regressions)andnotthedirectplot‐levelmeasurementsthatarenowavailablewithintheFIADB.SmalllandownerscanobtainestimatesofthestandingdeadpoolusingtheSmithetal.(2006)lookuptables.

6.2.3.4 DownDeadWood

TherecommendedmethodforobtainingestimatesofcarbonstockofDDWforlargelandownersisestimationfromtransectdatacollectedduringtheinventory.CareshouldbetakentoadheretotheboundsbetweentheDDWandforestfloorpools(notingthatfinewoodydebrisisconsideredpartoftheforestfloorpoolinthisguidance).Smalllandownersmayrefertothelookuptablesforpoolestimates.

SamplingandAllometry.AvarietyofsamplingandestimationprotocolsisavailablefortheDDWpool;astraightforwardandcommonlyusedapproachcanbefoundinPearsonetal.(2007).

LookupTables.RegionalaveragesbyforesttypeareasdescribedinSmithetal.(2006),orestimatescanbesummarizedandextractedfromtheFIADBconditiontabletocorrespondtotheentity’sforest.However,notethatthecurrentFIADB’sDDWfromtheconditiontableisamodelindependentofP3sampling.SeeSmithetal.(2006),U.S.EPAAnnex3.12(2010),Woodalletal.(2013),andDomkeetal.(2013)fordetails.

Simulations/Modeling.DDWcarbonvaluesareprovidedinthecarbonreportsinFVS.Valuesmaybesuppliedbythelandowner;ifthesedataarenotavailable,regionaldefaultvaluesbasedonP3dataoravailabledatafortheregionandforesttypeareautomaticallyinputbythemodel.

6.2.3.5 ForestFloororLitter

Recommendedoptionsforobtainingestimatesofcarbonstockofforestfloorforalllandownersistheuseoflookuptablesbasedonforesttype,region,andstandage.Largelandownerswhoarechanginglandusesfromnon‐foresttoforestmaywishtocollectdataforthispool.

SamplingandAllometry.LandownerswishingtoestimatethesepoolsfromfielddatacanusefinewoodydebrissamplingandcarbonconversionaccordingtoWoodallandMonleon(2008),andforestfloorusingtheapproachdescribedbyPearsonetal.(2007).NotethatwhilePearsonetal.(2007)applyamasstocarbonconversionfactorof0.5(Smithetal.,2006)),othersuseaconversion

factorof0.37.Landownerswhoareestimatingtheforestfloorpoolusingfielddatashouldapplythe0.37conversionfactor.

LookupTables.RegionalaveragesbyforesttypeareasdescribedinSmithetal.(2006);estimatescanalsobesummarizedandextractedfromtheFIADBconditiontabletocorrespondtotheentity’sforest.TheseestimatesarebasedonsimulationsdescribedinSmithandHeath(2002).NotethatthecurrentFIADBconditiontableestimatesofforestfloorarethesemodeledvaluesindependentoftheP3sampling.

Simulations/Modeling.ForestfloorcarbonvaluesareprovidedinthecarbonreportsinFVS.Valuesmaybesuppliedbythelandowner;ifthesedataarenotavailable,regionaldefaultvaluesbasedonP3dataoravailabledatafortheregionandforesttypeareautomaticallyinputbythemodel(FVSemploysthe0.37masstocarbonconversionfactorwhenestimatingthispool).

6.2.3.6 SoilOrganicCarbon

PossibleoptionsforobtainingestimatesofSOCstocksare:

Sampling,followingstandardfieldmethods;

DatasetssuchastheSoilSurveyGeographic(SSURGO)Database,StateSoilGeographic(STATSGO)Database,ortheDigitalGeneralSoilMapoftheUnitedStates(STATSGO2);and

Stand/forestclassification:extractrangeofmodeledestimatesfromFIADBconditiontable.

SamplingandAllometry.SoilsamplingandcarbonestimationaccordingtoFIAP3plotprotocolscanbefoundattheUSDAForestServiceFIALibrary:FieldGuidesforStandards(Phase3)Measurements;7methodsarealsoavailableinPearsonetal.(2007),Hoover(2008),andothers.

Soilsdataaregenerallyconsidereddifficulttomeasureandspatiallyquitevariable.Theconsequenceisthatthecostsarehighandthepayoffislikelylow.Ourrecommendationisthatsamplingisonlyusefulifthereisanimportantreasontodoso,suchasachangefromnon‐foresttoforestorviceversa.Ifawildfireoccursandthereissignificantconsumptionofpeatlands,samplingshouldbeconductedandemissionscalculatedusingFOFEMand/orCONSUMEmodels.ThissituationismostlikelytobefoundintheSoutheastorNorthCentralStates.

LookupTables.Forestsoilorganiccarbonestimates—representativevaluesorlookuptables.DatasetssuchasSTATSGOorSSURGOarepossiblesources.EstimatescanbesummarizedandextractedfromtheFIADBconditiontabletocorrespondtotheentity’sforest;thesearebasedonaSTATSGO/P2overlay(Smithetal.,2006;U.S.EPA,2010).

6.2.4 Limitations,Uncertainty,andResearchGaps

Thereisoftentremendousuncertaintyassociatedwithestimatesofforestcarbonbaselines,suchthatevenatlargescales(e.g.,state‐level)thepowertodetectstatisticallysignificantchangesinforestcarbonstocksislimitedtomajordisturbances(Westfalletal.,2013).Compoundingthesamplingerroroftenassociatedwithforestinventories,thereismeasurementandmodelerrorthatmaynotbeacknowledged.Usersofanyinventories,lookuptables,ormodelsshouldremainawareofthesepotentialerrorsduringtheirapplicationofinformation.

Thereisalevelofuncertaintyassociatedwithnotonlytreevolume/biomassequations,butalsowiththevariousforestcarbonpools(e.g.,belowgroundtoforestfloor)foundacrossadiversityofforestecosystems(e.g.,tropicaltoboreal)intheUnitedStates.Researchtorefineapproachestoforestcarbonaccountingandrefinementsofassociatedmodelsiscurrentlyinprogress.Perhaps7http://fia.fs.fed.us/library/field‐guides‐methods‐proc/

someofthemostneededimprovementsareforindividualtreevolume/biomassequations,especiallyfortraditionallynon‐commercialspecies.Anotherforestcarbonpoolthatisbeinginvestigatedissoilorganiccarbon.Althoughthesoilcarbonpoolisnotexpectedtochangequicklyincomparisontolivetreepools,inmanyareasoftheUnitedStatesitisthelargestcarbonstock(e.g.,northernMinnesota).Beyondreducingtheuncertaintyassociatedwithestimatesofcarbonpools,researchisbeingconductedtorefineunderstandingoftheeffectsofdisturbanceandclimatechangeoncarbonpools.

6.3 Establishing,Re‐establishing,andClearingForests

6.3.1 Description

Conventionalparlanceattributeschangesofcarbononasiteundergoingland‐usechangeintothreedirectionalprocesses:establishing(i.e.,afforestation),re‐establishing(i.e.,reforestation),andclearingforest(i.e.,deforestation).Inrecentyears,thetermforestdegradationhasbeenusedtoacknowledgethatanexistingforestcanbesignificantlyreducedincarbonstocksandcanbeconsideredasourceofemissions,aslongasthereductionincarbonstocksisnotanaspectofnormalforestmanagement.However,thisisnotaformofland‐usechangebecausethelandremainsinforests.Thisisanimportantconsiderationunderforestmanagement,butmayalsobeimportantwhenhumanuseandremovalsofforeststockstakeplaceevenwhennotprescribedbyamanagementregime.ThemostimportantsourceofGHGemissionsfromforestsisassociatedwithforestclearing(IPCC,2007).Theconversionofforeststootherlandusesimmediatelyreducesthestockofcarboninabovegroundbiomassandsoilorganicmatter,andislikelytoreducethelong‐termcarbonstoragepotentialoftheland.Thecarbonthatwasoncestoredinforestbiomassandsoilisreducedthroughrapidoxidationbyfireorslowlyovertimebymicrobialdecomposition.Someofthebiomasscanalsoberemovedfromthesiteandconvertedtoforestproductssuchaslumber,paper,pulp,andotherproductsthathavelongertermbutvariabledecompositionrates—andhencelongertermandvariableemissionsovertime.Allofthesecomponentsofland‐usechangeneedtobeaccountedforwhendeterminingthechangesinsitecarbonstocksduetoland‐usechange.

Aparceloflandcanbeconvertedtoforest,plantation,orothertreedlandscapeeitherthroughintentionalplantingorthenaturalprocessofsecondarysuccession.Landthathadoncebeeninforestisreturnedtoforestthroughre‐establishment.Notethatthisappliestolandthatisnotcurrentlyinforest,nottoforestlandthatisregeneratedaspartofforestmanagement.Landthathadnotbeeninforest,suchasgrasslands,canbeconvertedtoforeststhroughestablishment.In

MethodsforEstablishing,Re‐establishing,andClearingForest

IPCCalgorithmsdevelopedbyAaldeetal.(2006).

Theseoptionsuse:

− AllometricequationsfromJenkinsetal.(2003a),orFVSwiththeJenkinsetal.equationswhereapplicable;and

− DefaultlookuptablesfromSmithetal.(2006;GTRNE‐343)—defaultregionalvaluesbasedonforesttypeandageclassdevelopedfromFIAdata.

Thesemethodswereselectedbecausetheyprovidearangeofoptionsdependentonthesizeofanentity'sforestland.

eithercase,generallyspeaking,thestockofcarboninbiomassandsoilorganicmatterwillincreaseovertimeasaresultofthistypeofland‐usechange.Biomassincreasespredictablyastreesandothervegetationareestablishedonthesite.Soilorganicmatteralsochanges,butinlesspredictableways.Forinstance,theestablishmentofaforestplantationongrasslandincooltemperateregionsmayresultinatemporarylossofcarboninsoilorganicmatterbeforeitbuildsupagainaftertheplantationisfullyestablished.Forbothaccountingandplanningpurposes,thesechangesinstocksofcarbonmustbeestimatedandaccountedforwhenassessingtheeffectsofland‐usechange.

Currentinternationaldefinitionsarepresentedbelowanddrawadistinctionbetweenlandsthathaveneverbeenunderforestcoverandthosewhichwereinforestcoverinthepastbuthavenotbeenforestedrecently(e.g.,forthelast50years).Thesedefinitionsarepresentedherebecausetheyarecommonlyusedintheliterature;however,intermsofcarbonaccountingforlivebiomass,thereisnopracticaldifferencebetweenthetwocategories.Thegreatestimpactisonthesoilcarbonpool.Wheretheaimistoestimateentity‐levelGHGfluxes,thesetwocategorieswillbetreatedtogetherandtermed“establishingforest”inthisguidance.

6.3.1.1 EstablishingForest

Establishmentistheconversionofanon‐forestsitethatisnotnaturallyaforestedortreedecosystemorhadneverbeeninforesttoaforestorsimilartree‐dominatedlandcover.Examplesofestablishmentincludetheconversionofbarelandtoaforestandconversionofgrasslandstoforestsorplantation.Inpracticalterms,andforthesakeofthisguidance,landthathadbeeninagricultureorothernon‐forestlandcoverforalongtime(e.g.,morethan50years)thatisconvertedtotreecovercanalsobeviewedasestablishment.Hence,establishedforestlandisthatwhichhasnotbeendominatedbytreesformorethan50years.

6.3.1.2 Re‐establishingForest

Re‐establishmentisthereversionofforestsortreecoveronsitesthathadformerlyandrecentlybeen(e.g.,lessthan50years)inforestordominatedbytreecover.Examplesofre‐establishmentincludenaturalregenerationofadisturbedorclearedparcelofforesttoasecondaryforest,conversionofagriculturallandtoaforest,andestablishmentofaplantationonasitethathadoncebeenforestbutisnowinanotherlanduse(suchascropland).Itisimportanttodistinguishbetweenre‐establishmentasaland‐usechangeandforestregrowthaspartofforestmanagementortheresultofanaturaldisturbance.Forexample,aland‐usechangefromagriculturetoforestisconsideredhereasre‐establishment,whereforestregenerationfollowingawindthroworclear‐cuttingisnotconsideredaland‐usechangeresultinginre‐establishment.

Intheinternationalconventions,theIPCCSpecialReportonLandUse,Land‐UseChange,andForestry(IPCC,2000),whichwasdevelopedexplicitlyforcarboninventory,definesre‐establishmentas"theestablishmentoftreesonlandthathasbeenclearedofforestwithintherelativelyrecentpast;theplantingofforestsonlandswhichhave,historically,previouslycontainedforestsbutwhichhavebeenconvertedtosomeotheruse." Establishmentandre‐establishmentbothrefertoestablishmentoftreesonnon‐treedland.Re‐establishmentreferstocreationofforestonlandthathadrecenttreecover,whereasestablishmentreferstolandthathasbeenwithoutforestformuchlonger.Avarietyofdefinitionsdifferentiatebetweenthesetwoprocesses.Somedefinitionsofestablishmentarebasedonphrasessuchas"hasnotsupportedforestinhistoricaltime;"othersrefertoaspecificperiodofyears,andsomemakereferencetootherprocesses,suchas"undercurrentclimateconditions."TheIPCCGuidelinesdefineestablishmentasthe"plantingofnewforestsonlandswhich,historically,havenotcontainedforests"(IPCC,2000).

Asnotedabove,forthepracticalpurposesofreportingunderthesemethods,achangefromnon‐foresttoforestcoverwillbetermedestablishingforest,andthe50yeartimehorizonwillnotapply.

6.3.1.3 ClearingForest

Clearingistheconversionofaforestortree‐dominatedsitetoanotherlanduseotherthanforestoratree‐dominatedsite.Oftenclearingresultsinthecompleteremovalofabovegroundlivebiomass.Examplesofclearingincludetheconversionofaforestwoodlottocroplandorpasture,conversionofaforestwoodlottocommercialorresidentialuse,andconversionofanaturalforesttoagriculture.

6.3.1.4 OtherImportantConsiderations

DistinctionbetweenLand‐UseChangeandLand‐CoverChange.Itisveryimportanttounderstandanddelineatethedifferencebetweenland‐coverchangeandland‐usechange.Becausetheterms“landuse”and“landmanagement”areoftenconfusedorusedinterchangeablythedistinctionisdefinedhere.Abasicdefinitionoflandcoveris“theobservedphysicalandbiologicalcoveroftheEarth’slandasvegetationorhuman‐madefeatures.”Abasicdefinitionoflanduseis“thetotalofarrangements,activities,andinputsundertakeninacertainland‐covertype(asetofhumanactions).Thesocialandeconomicpurposesforwhichlandismanaged(e.g.,grazing,timberextraction,conservation).”Theconventionsfoundintheliterature—Turneretal.(1994),Skole(1994),andLambinetal.(2006)—arefollowedandwereadoptedbytheIPCCin2000.Itisrecognizedthatinadoptionoftheterminologyoflanduse,land‐usechange,andforestry,theIPCCGoodPracticeGuidancedocument(IPCC,2006)generalizedtheuseoftermstoincludethesixbroadland‐usecategoriesdefinedinIPCC(2003)Chapter2andrecognizedthattheseland‐usecategoriesareamixtureoflandcover(e.g.,forest,grassland,wetlands)andlanduse(e.g.,cropland,settlements)classes.Forconvenience,theyareherereferredtoasland‐usecategories.

Werecognizeherethatthetermland‐usechangecanbeadoptedtoincludeland‐coverchanges,aswellasland‐usechanges.Thus,forthisguidance,aswithIPCC,land‐usechangewillbetheconversionofthe“typeofvegetation”fromonecovertype,suchasaforestdominatedbytrees,toacompletelydifferentcovertype,suchascroplanddominatedbynon‐woodyfoodcrops.Thedirectionofcoverchangedeterminesthenatureofthechangeincarbonstocks(e.g.,forestclearingversusestablishment).Generallyspeaking,land‐usechangeisthemostimportantconsiderationforalandowner,sincethisprocessusuallyresultsinthelargestchangeinonsitecarbon.

However,wealsorecognizethatlandownerswillhaveimportantchangestotheirlandsthroughthemanagementactivitiesthattheydeploy,andtheseactivitiescanhaveimportantimplicationsforcarbonstocksandGHGemissionsandremovals.Thus,wealsorecognizetheconceptandterminologyofland‐managementchange,whichisachangeinthetypeofactivitybeingcarriedoutonaunitofland,andthushowitismanagedorused,suchaschangingthemanagementpracticeswithinaforestfromselectiveharvesttoprotection.Land‐managementchangemayormaynothaveasignificantimpactoncarbonandotherGHGs.

Landmanagementexplicitlyreferstohowthelandisbeingmanagedorused,whilelandusereferstowhatisontheland.Anexampleoflandmanagementisatree‐dominatedsitethatisusedasaworkingforestorwoodlot.Assuch,alandownercanchangethemanagementplanforthesite—forinstance,changingitsusetoaforestreserve—withoutradicallychangingitscover.Nonetheless,evensuchchangeinusecanaffecttheamountofcarbonstoredonthesiteandinthesoils.Typically,whenaforeststandlandmanagementischangedwithoutaffectingitscovertypeitisconsideredamanagedforest,anditsaccountingprotocolsfollowthoseforforestmanagementratherthanforestablishingforests.Thusitisimportanttodetermineanddocumentboththeland‐useandland‐managementchangesthatoccuronthesite,andexplicitlyassociatethecarbonestimationapproachtoeitherestablishing/clearingforests(Section6.3)orforestmanagement(Section6.4),butnotboth.

EstablishingandClearingForestversusForestManagement.Forreasonsoforderandconsistency,establishingandclearingforestisdistinguishedfrommanagement,whichisaddressedinSection6.4.Forestryoperationssuchasthinning,artificialregeneration,andharvestingareassociatedwithmanagedforestsystems.Unlessforestryactivitiesleadtoachangefromonelandusetoanotherland‐use,theseactivitiesarenottreatedusingestablishingandclearingforestaccountingprinciples.Theinitialconversionfromforesttoagriculture,forexample,wouldusetheestablishingandclearingforestrules,followedbytheapplicationofrulesforagriculture.Similarly,whenanon‐forestlandcoverisconvertedtoamanagedforesttheinitialconversionwouldbetreatedasestablishingforestandusethesemethods,butsubsequentmanagementofthestandwouldfollowforestmanagement(e.g.,forestcarbonaccountingandforestmanagement)methods.

TypesofForest.Fromastrictcarbonaccountingpointofview,theland‐coverdesignationdoesnotmatter,nordoesitschangeincovertypeaslongasonehasgoodestimatesofcarbonstocks,andcanmeasureorestimatetheirchanges.However,datausedtoestimatechangesincarbonareoftenreportedandorganizedbyforesttype,sothecompositionandstructureoftheforestoftencomesintothecomputationmethods.Moreover,toavoiddoublecounting,itisimportanttodefinewhattypeoflandscapescanbeconsideredasaforestforestablishingandclearingforest.Therearetwoelementsofadefinitionofforeststhatarewarranted.Thefirstisabasicdefinitionofaforest.Therearearangeofconditionsoftreedlandscapeswhereestablishingandclearingforestactivitiescantakeplace,frompreservedforeststowoodlotstoopenandwidelyspacedtreelandscapesandurbantreedlandscapes.Therearehundredsofvariationsofdefinitionsofforest(Lund,1999)andforeachofthesetherearesubtypes.Examiningtheimplicationsofeachvariantwouldnotbefruitful;theresultwouldbegreaterconfusion,ratherthantheclaritysought.Inastrictsense,aforestisdefinedhereusingtheU.S.‐specificdefinitionofforestland(Smithetal.,2009).Thesearelandswithtreecrowncover(orequivalentstockinglevel)ofmorethan10percent,widthofatleast120feet(36.6m),andareaof1acre(0.4ha).Treesshouldbeabletoreachaminimumheightof6.6–16.4feet(2–5m)atmaturityinsitu.Aforest‐landunitmayconsistofclosedforestformationswheretreesofvariousstoriesandundergrowthcoverahighproportionofground,oropenforestformationswithacontinuousvegetationcoverinwhichtreecrowncoverexceeds10percent.

Second,landownersmayhaveadiverselandbasethatisaffectedbydifferentforestryactivities,managedatdifferentintensities,orthathasavarietyofexistingdata.Oneofthefirststepsinpreparingentity‐wideorsub‐entityestimatesofcarbonfluxesfromforestsistoorganizetheunderlyingdataonlandconditionsintomanageableunits,referredtohereasforeststrata.Landshouldbegroupedintoforeststratausingalogicalframeworkthataggregatessimilarlandunits.Forexample,landcouldbepartitionedbyaveragetreeage,foresttype,productivityclass,andmanagementintensity.Inmanycasesforeststratawillbecontiguous,althoughthisisnotanecessarycondition.Thelandownercanselectthetypeofstratificationschemetoemploy;andthereareseveralguidesavailabletodothis.Thebetterthestratification,themoreaccurateandprecisearethecarbonestimationswiththeminimalamountofdatacollection.

Thedefinitionofaforestisusefulforconsistencyinreportingandcoversawiderangeofconditions.However,notethatthetechnicalmethodscanapplytoanytreedlandscape.Theadoptionoftheinternationalnomenclatureforforestsallowstheconsiderationofarangeofsiteconditionsandsituations.ForestsintheUnitedStatesarevaried,fromscrubwoodlandsinsemi‐aridzonestomaturedeciduousandconiferouscomplexesinthehumidzones.Inaddition,humanmanagedsystems,suchaswoodlotsandplantations,areconsideredasforests.

SimilarModalitiesandVariantsofEstablishing,Re‐establishing,andClearingForest.Thissectionrecognizesthatestablishingandclearingforestaresimilartoandindeedconceptuallyrelatedtoseveralotherland‐coverchangemodalities,whicharetreatedinotherprotocols.Theseincludebutarenotlimitedtoagro‐forestry,whichinvolvestheuseoftreesonfarms;urbanforests

andwidelyspacedtreecomplexes;treesonlandscapesoutsideofforests;woodlandsandsavannasystems;orchards;andpalmandhorticulturecomplexes.Althoughthemeasurementandestimationmethodsdescribedheremaybeeasilyadaptedtotheselandcoversandlanduses,theyarenottreatedinthissection.

6.3.2 ActivityDataCollection

Activitydataaremeasurementsorestimationsofmagnitudeofhumanactivityresultinginemissionsorremovalstakingplaceduringagivenperiodoftime.Mostoftentheareaoflandthatisconvertedfromonelandusetoanotheristhemostimportanttypeofactivitydata.Dataonareaburned,managementpractices,andlimeandfertilizeruseareotherexamplesofactivitydata.Forestablishingandclearingforest,activitydataconsistsmostlyofinformation,preferablyinmapformwithdelineatedboundaries.Forsmalllandowners,itispossibletodelineateanareaofland‐coverchangebyfootusingsimpledistancemeasurementsorwiththeaidofaGPS.Alandownermayhavedifferentactivitiesoccurringonasingleproperty,andthuseachoftheforeststratashouldbemappedandhaveseparatelydelineatedactivities.Remotesensingoraerialphotographycanbeusefulforanylandownerwithaccesstothesedata,butareespeciallyusefulforlargerlandunits.Historicalinformationonchangesintheareasoflandusesonapropertyisalsoimportant,andthesedataarefrequentlyfoundinairphotoarchivesorothermaprecords.Inadditiontotheareasandratesofclearingand/orestablishment,itisnecessarytocollectdataonspecificaspectsanddetailsoftheseactivities.Thismayincludedataontreetypes,biomass,clearingintensity,woodremovals,treeplantingdensities,andotherfactorsthatdescribedthemodalityoftheestablishingandclearingforestactivities.

6.3.2.1 EstablishingForest

Foranestablishmentactivity,itisimportanttogatherbasicinformationontheareaandlocationofeachstratumoflandusethatisbeingestablished.Forthemostpartanestablishmentactivitywillbeaplantationorsimilartypeofestablishment/forestationactivity.Thus,basicinformationonsitepreparation,speciesselection,anddensitiesofplantingscanbeusedwithaprojectionofthelong‐termplanforthesitetomakeareasonableex‐antecalculation.Ifnaturalregenerationistheprimarymeansofestablishment,estimatesofseedlingcountscanbeusedtodevelopagrowthprojection.Alternatively,regionalyieldtablesmaybeusedtoestimateprojectedstocks.Theprioruseandmanagementofthestratumorlanduseshouldalsobedocumented,sincethehistoricaluseofthelandinfluencescarbonstockandstockchangeestimates.Forinstanceestablishmentofaforeststandongrasslandwillhaveadifferentresultintermsofcarbonthanestablishmentonarowcropagriculturalfield.Onceaforestiswellestablished,forallpracticalpurposesitbecomesamanagedforestandshouldbetreatedusingthemethodsinthenextsectiononforestmanagement.Weconsidertheland‐usestratumtobeaforestwhenthecharacteristicsofthestandmeetthedefinitionofaforest.Mostoftenthiswillbewhenthesiteiswellstockedtothedefinitionalcrowncoverandheightoftrees.

6.3.2.2 ClearingForest

Themostimportantactivitydatatocollectaretheareaandratesofforestclearingforeachstratumorparcelintheprojectarea.Itisalsoimportanttoknowtheintensityofclearingandifthereareremainingtreesorothervegetationleftonsiteafterclearing.Toestimateemissions,itisnecessarytoknowalsothecharacteristicsofthestratumthatistobecleared,includingthebiomassandsoilorganicmatterofthesite.Theprocessofclearingasiteisanactivitythatcanalsobecharacterized.Informationneededincludesthefractionoftheabovegroundbiomassthatwouldbeburned,thefractionthatisleftbehindonsiteasslashanddebris,thefractionthatwouldberemovedintheformofwoodproducts,andthefractionthatisremovedintheformofotherproducts.

Thissectionlaysouttheminimumnecessarypartsofacomputationschemeforestimatingcarbonstocksandcarbonemissionsinbiomassandsoilassociatedwithestablishingandclearingforest.Thedescriptionslaidoutherearegeneralized.Thebasicconceptbehindthemissimple:thestock,ormass,ofcarbononasitechanges,andthetaskofestimationistocomputethedifferenceinstocksbetweenthelandusebeforeandaftertheinterventionordisturbance.Whenasiteiscleared,stocksgodownandthisresultsinemissionstotheatmosphere.Whenasiteisestablished,stocksgoupandthisresultsinremovalsfromtheatmosphere.

6.3.3.1 UnitsofMeasurement

Allstockcomputationsareperformedintermsofmassofcarboninkilogramsormetrictonsperunitareainmetricsystemunits(carbonperhectareorCha−1).Ratedataarereportedintermsofchangeincarbonperhaovertime,asincarbonperhectareperyear(Cha−1year−1).Allcarbonbiomassisreferencedtoitsdryweightbasisandthefractionofbiomassincarbon.Forthepurposeofthisguidance,thefractionofdrybiomassthatiscarbonis0.5.Anexamplestockis100metrictonsCha−1,andanexamplestockchangeis100metrictonsCha−1year−1.ItisimportanttodifferentiatebetweenunitsofcarbonandCO2equivalents(CO2‐eq)andreporttheappropriateunitstothereportingentity.Forexample,somereportingprograms(e.g.,carbonmarkets)requiretheconversionofmetrictonsofcarbontometrictonsCO2‐eq.ThisconventionplacesallcarbonmassestimatesintounitsofCO2,whichcanbederivedbymultiplyingthecarbonmassby44/12.

6.3.3.2 StocksandFluxes

Thestockofcarbonistheamountofcarboninbiomassandsoilonasite.Thestockchangeisthedifferenceinthestocksfromonetimeperiodtothenext.Thischangecanbepositiveornegative,dependingonwhetherthesiteisexperiencingclearing,degradation,restoration,orestablishment.Decliningstocksovertimefromclearingordegradationresultinemissions,whileaccumulatingstocksovertimefromestablishmentorrestorationarereferredtoassequestration.

6.3.3.3 DelineatingandCharacterizingtheSiteUsedinComputation

Toestimatecarbonstocksandfluxes,itisnecessarytodefinethemappedextentandthefeaturesofthesite.Forsmallareas,suchasafarmwoodlotorforeststand,theboundariesaredefinedgeographicallyusingaGPSdevice.Ifsurveyors’reportsorotherformsofmapsandphotossuchasaerialimageryareavailable,theycanbeused.Thereareagrowingnumberofonlinetoolsthatareavailable(e.g.,GoogleMaps)thatprovidedetailedimageryoflandthatcanbeusedtodrawboundariesoftheproposedsites.Afterdefiningthepreciseboundaries,aland‐coverclassificationshouldbeperformedtodefinethevariousvegetation,cover,orsoilstratawithinthesite.Forinstance,are‐establishmentprojectwithtwozoneswithintheboundaries,oneforacommercialplantationandtheotherfornaturalregeneration,wouldbestratifiedintotwostands.Iftheprojectorpropertyistobeasinglecover,suchasanaturalregenerationforestoraplantationforest,theprojectsitecanbeasinglestratum;butotherfactorsmaybeimportant,suchaslandslopeorsoilconditions.Iftherewillbeafuturemanagementactivityassociatedwiththeproject,thisstratumshouldalsobedelineated.Inshort,anyareawithintheprojectboundarythatwouldhavedifferentcoverorcarboncharacteristicsshouldbeseparatelydelineated.Standardmappingcoordinates,projections,andgeodeticdatumsshouldbeused.

6.3.3.4 CarbonPoolsunderConsideration

Generally,IPCCandothersourcesreferencefivepoolsofcarbontomeasure—abovegroundlivebiomass,belowgroundlivebiomass,standingdeadanddowneddebris,litter,andsoilorganic

carbon.Thelandownerorprojectdevelopershouldidentifyfromthebeginningthepoolsthatwillbeaccounted.Allpoolsshouldbeincluded,unlessonecanshowthatapool’sstockchangesaresmallandunimportant—thedeminimisassumption(lessthan10percentofthetotalbaselinestock,seemorebelow)—orcanshowthatapoolwouldnothavestocklossesoremissions(e.g.,forestclearing).Inthesecases,thelandownerischoosingtobeconservativeinestimationoftheimpactoftheestablishingandclearingforestontheatmosphereforthatpool.Forinstance,inanestablishmentprojectwheretheestimationofsoilcarbonchangemaybedifficult,timeconsuming,orcostly,andthesoilcarbonchangeisassumedtobedeminimisinmagnitude,itmaybeeliminated.Or,ifitcanbedemonstratedthatthesoilpoolwillbeaccumulatingcarbon,thelandownermayselecttonotcountthatpoolandthusbeconservativeinthesequestrationpotentialoftheproject.Woodproductsthatareremovedfromthesitethroughharvestarenotbythemselvesconsideredaseparatepool,butthelandownerisadvisedtodocumentthisamountanditsfate,wherebyfatecanbe,forexamplehardwoodproducts,paperproducts,orfirewood(seeSection6.5).

6.3.3.5 InitialCarbonStockMeasurement

Thecarbonstocksinthemeasuredpoolsthataretobereportedneedtobedeterminedatthebeginningoftheprojectinordertodefineareferencecarbonamounttowhichfuturechangeswillbecompared.Whetherthesiteisaforestbeforeitsconversionoragriculturallandbeforere‐establishmentoftreecover,theinitialconditionsintermsofcarbonmustbereported.Theinitialcarbonstocksinallstrataareindividuallydeterminedfromlookuptables,satelliteimagery,orFIAdatabase,oraremeasuredandreportedaccordingtothedetailedmeasurementmethodsgivenbelow.Thereportingofthebaselinecangetcomplicatedinsomecases.Typicallythebaselineisthecurrentcarbonstocks.However,insituationswherethecarbonstocksarechanging,thebaselineiscomputedovertimeastheforwardlookingcarbonstocksthatwouldoccurintheabsenceoftheprojectorintervention.

6.3.3.6 TheEx‐AnteComputation

Onceinitialcarbonstocksaredetermined(theTypeIestimate),theprojectdeveloperneedstomakeaforwardprojectionoftheexpectedcarbonstockchanges,anditsdeviationfromwhatwouldhaveoccurredonthesitewithouttheinterventionofaprojectorland‐coverchange(TypeIIandIIIestimates).Thisissomewhatproblematicsinceitisnotpossibletopredictthefuturewithcertainty.However,anumberoftoolsandmethodsareavailabletomaketheseprojectionswithreasonablecertainty(seeTable6‐3).Animportantreasonformakingthiscomputationisthatthecarbonstockwouldchangeovertimeintheabsenceoftheproject’sintervention.Forexample,anabandonedfarmfieldcouldbeexpectedtonaturallygothroughold‐fieldsuccessionevenwithoutareestablishmentproject.Hence,theproject‐relatedcarbonchangesneedtobecomparedwiththenointervention/noactionestimateovertime,notjustfromthestartoftheproject,togetatrueaccountingofnetcarbonbenefits.Landownerswouldwanttomaketheex‐antecomputationsothattheycanevaluatearangeoffutureestablishment,clearing,ormanagementoptionstoselecttheonethatbestsuitstheircarbonandotheroutcomeneeds.

6.3.3.7 MeasurementandMonitoring

Aftertheinitiationoftheprojectintervention(e.g.,treeplanting),ongoingmeasurementsofactualcarbonstockchangesneedtooccur.Thisisoftenreferredtoasthemonitoringphaseoftheproject.Methodsforongoingmeasurementaredescribedbelow.Theprojectdevelopershouldkeeporganizedrecordsofthemeasurementsmadeoveraroutineandstandardtimeframe.Annualmeasurementsareusuallyeithernotlogisticallypossibleortootime‐consumingandexpensive.

Thus,itisrecommendedthataftertheinitialmeasurement,thesemeasurementsarerepeatedevery5years.

6.3.3.8 PermanentSamplePlots

Forsmallprojectssuchasfarmwoodlots,ortreeandforeststands,acompleteinventoryofcarboninthereportingpools,strata,andprojectlandcanbeperformed.However,forlargeareas,installinganddelineatinganumberofsampleplotsisrequired.Thesesampleplotsareestablishedintheprojectareaonastratifiedbasis,laidoutrandomlyorsystematically—i.e.,eachlandcoverstratumhasanestablishednumberofsystematicallyorrandomlyplacedplots.Methodsforforestinventoryarewelldescribedandavailablefromavarietyofsourcesandwillnotbefurtherdescribedhere(e.g.,Pearsonetal.,2007).Boththenumberandlocationoftheplotsneedtobeconsidered.Itisimportanttorememberthattheplotsareestablishedforthepurposeofsamplingaforeststandorprojectstratum.Thesampleestimatewillbeasaccurateasthenumberandlocationofthesampleplotspermit.Thenumberofplotswillrelatetotheaccuracyoftheestimates;insimplestratasuchasplantations,thenumberofsampleplotscanbeextremelylow,butincomplexnaturalstandsthenumberwillhavetobegreater.Agoodstratificationwillreducethenecessarynumberofplots.Thelocationoftheplotsisimportanttocapturethespatialheterogeneityofthestand.Theplotsaretobewellmarkedandmadepermanentforrepeatmeasurementsovermanyyears.Forforestclearingcomputations,itisnotnecessarytomakepermanentplotsunlesstheprocessofclearingisselectivedegradationoveralongperiodoftime.Forforestclearing,lotsonlyneedtobemeasuredoncebeforetheinterventionandonceaftertheinterventionhasbeencompleted.

6.3.3.9 MeasurementversusEstimation

Insomecases,itwillnotbepossibletomeasuretheinitialcarbonstocksorpost‐interventioncarbondirectly.Forinstance,aforestclearingeventmayoccurwithouttheopportunitytoestablishplotsintheforest,oritmaynotbepossibletomeasurealarge‐areaestablishmentevent.Inthesecases,regionalsummaryvaluesoftheforestcarbonstocksmaybeofuse(Smithetal.,2006).

6.3.3.10 Allometry,BiomassExpansionFactors,andStandardValues

Theconventionalapproachtobiomassestimationistouseallometricequationsbasedonspecies‐specificinformation(Jenkinsetal.,2003b;2003a).AnallometricapproachcanbebasedonDBHoracombinationofDBH,canopyheight(H),andwooddensityonanindividualtreebasisfortheentirestandorfortreesinthepermanentplots.Theallometricequationpredictseithervolumeofwoodinthemainstemorwholetreebiomassorcarbon.Intheformercase,itisthennecessarytoestimateawholetreebiomassexpansionfactor(Smithetal.,2003).Alternatively,theentitycanusestandardvaluesforstocksandgrowthratesbasedonlookuptables(DOE,1992;Smithetal.,2006).Forlargeareasofforestsconvertedthroughclearing,itmaybeacceptabletousestandardvaluesforstocksperunitarea,suchasthosepublishedbyIPCC(2003;2006).

6.3.3.11 StocksversusChangeinStocksoverTime

Forestimationofforestestablishmentitisnecessarytocomputethechangeinstocksovertime,whichwillbeameasurementofnetsinksofcarbonthroughsequestration.Forestclearingcomputationisessentiallythesamebutwiththeoppositesigntoindicateemissions.Thesubtledifferenceisthatestablishmentrequiressomemeanstoestimatetheaccumulationofcarbonontheprojectsiteovertime.Thisisaccomplishedusingeitherdirectmeasuresoryieldmodels.Forforestclearing,itisnecessarytoknowtheinitialstockofcarbonintheforeststand,andhowitthenchangeswithdisturbance.Thelatterrequiresdataonthepartitioningofpost‐disturbancecarboncomponents,asremovals,andslashanddebrisleftonsite.

6.3.3.12 ForestClearingRemovalsandDeadMaterialonSite

Thedifferenceofcarbonstocksbeforeandafterforestclearingisthecarbonthathasbeenremovedbyharvestaswoodproductsorotherproducts(e.g.,energyfeedstocks),andthatleftbehindonthesiteasslashanddebris(Skog,2008).Ifthesemassamountsareknown,theycanbeincludeddirectlyintothecomputations.Iftheyarenotknown,theycanbeestimatedandrepresentedasfractionsoftheoriginalstandingstockspriortodisturbance.Allremovalssuchastheseconstituteimmediateandfutureemissionsources,astheydecayoverdifferenttimescales.Therefore,itisnecessarytoassignmassamountstofourlong‐termdecaypoolswithturnovertimesof1,10,100,and1,000years.Theemissionsarecomputedalonganexponentialdecayfunctionrelatedtotheturnovertimeofthepool.Forexample,carbonlostduetoimmediateoxidationbyfireisplacedintothe1‐yearpool,andthecharcoalcomponentisplacedintothe1,000‐yearpool.Otherremovalsareplacedintothe10‐and100‐yearpools.

6.3.4 SpecificProtocolforComputation

6.3.4.1 ActualCarbonRemovalsbySinksinEstablishingForest

Thebasicapproachtoestimationofemissionsto,orremovalsfrom,theatmosphereistomultiplytheactivitydatabyemissionfactorsor,inthiscase,multiplytheland‐usechangeareabysitebiomasscarbonandsoilorganicmattercarbon.Theseproceduresdescribetherecommendedmethodofestimatingcarbon—usingallometricequationstoestimatebiomassdirectlyfromDBHusingtheequationsofJenkinsetal.(2003a).

Stratificationoftheprojectareamaybecarriedouttoimprovetheaccuracyandtheprecisionofthecarbonestimates.Whererequired,stratificationcouldbemadeaccordingtotreespecies,ageclasses,orforestmanagementpractices.Figure6‐5showsadecisiontreeindicatingwhichmethodismoreapplicableforaparticularlandowner.

Thisprotocolwillfollowthetwo‐tierapproachdescribedearlierinthedocument.Smalllandownerscanusedefaulttables(i.e.,Smithetal.,2006)andequationsfortheappropriateregionandforesttypegrouptoestimatebiomassoftheirforestsystems.Largelandownersshouldusebasicforestdatacollectedinthefieldonsampleplotswithallometricequations(Jenkinsetal.,2003a)toestimatethebiomassofindividualtreesandentirestands.Ifsmalllandownerswanttousesampleplotsandallometricequations,theyarefreetodoso.Smalllandownersshouldcontactaconsultingforesterorperhapsauniversityextensionpersontobestunderstandrequirementsforfieldsampling.

Whilemostofthefluxesfromanestablishmentprojectareremovalsfromtheatmosphere,theremaybesomeemissionsassociatedwithsomeaspectsoftheproject.TheactualnetCO2removalsbysinkscanbeestimatedusingtheequationsinthissection.Whenapplyingtheseequationsforex‐antecalculationsofnetanthropogenicCO2removalsbysinks,landownerswillprovideestimatesofthevaluesofthoseparametersthatarenotavailablebeforethestartoftheprojectperiodandcommencementofthemonitoringactivities.Participantsshouldretainaconservativeapproachinapplyingtheseestimates.

Figure6‐5:DecisionTreeforEstablishing,Re‐establishing,andClearingForestsShowingMethodsAppropriateforEstimatingForestCarbonStocks

1Smalllandowners(seeSection6.2fordefinition)mayusegeneralizedlookuptablesbasedonregion,foresttype,andageclasstoestimatecarbonstocks.Largelandowners(seeSection6.2fordefinition)shouldcollectstandardforestinventorydataanduseallometricequationstoestimatelivetreebiomasscarbon(othercarbonpoolsmaybeobtainedfromlookuptables).However,largelandownerswhodonotengageinanymanagementactivitiesorplantomanagetheirholdingsmayuselookuptablesforallpools;butifactivemanagementoccurs,theinventoryapproachshouldbeused.2Jenkinsetal.(2003a).3Smithetal.(2006).

TheactualnetCO2removalsbysinksinyeartareequalto:

EstimationofCarbonStockinLivingBiomassofTreesattheStratumLevel.Thecarbonstockinlivingbiomassoftreesforstratumi(Ctrees,i,t)isestimatedusingthefollowingapproach:Themeancarbonstockinabovegroundbiomassperunitareaisestimatedbasedonfieldmeasurementsinpermanentsampleplots.

Step1:Determinebasedonmeasurements(expost),theDBHattypically4.3feet(1.3m)abovegroundlevel,andalsopreferablyheight(H),ofallthetreesabovesomeminimumDBHinthepermanentsampleplots.

Step2:Calculatetheabovegroundbiomassforeachindividualtreeofaspecies,usingallometricequationsappropriatetothetreespecies(orgroupsofthemifseveraltreespecieshavesimilargrowthhabits)inthestratum.

Step3:Estimatecarbonstockinabovegroundbiomassforeachindividualtreelofspeciesjinthesampleplotlocatedinstratumiusingtheselectedordevelopedallometricequationappliedtothe

Equation6‐1:TheActualNetCO2 RemovalsbySinksinYeart

ΔCACTUAL,t=ΔCPJ,t

Where:

ΔCACTUAL,t =ActualnetCO2removalsbysinksinyeart(metrictonsCO2eqyear−1)

ΔCPJ,t =ProjectCO2removalsbysinksinyeart(metrictonsCO2eqyear−1)

Equation6‐2:ProjectCO2RemovalsbySinksareCalculatedasFollows(betweentwodatesforatimeperiodoft)

tΔCPJ,t=ΣΔCproject,i,t×44/12

ΔCproject,i,t=[(Ctrees,i,t2–Ctrees,i,t1)/T]+ΔCsoil,i,t

Where:

ΔCPJ,t =ProjectCO2removalsbysinksinyeart(metrictonsCO2eqyear−1)

ΔCproject,i,t =AverageCO2removalsbylivingbiomassoftreesandsoilforstratumi,foryeart(metrictonscarbonyear−1)

Ctrees,i,t =Carbonstockinlivingbiomassoftreesforstratumi,inyeart(metrictonscarbon)

ΔCsoil,t =Averageannualchangeincarbonstockinsoilorganicmatterforstratumi,foryeart(metrictonscarbonyear−1)

T =Numberofyearsbetweenyearst2andt1(years)

treedimensionsresultingfromStep1,ormultiplytheresultofStep2by0.5(i.e.,thefractionofdrybiomasstocarbonconversionfactor),andsumthecarbonstocksinthesampleplot.

Step4:ConvertthecarbonstockinabovegroundbiomasstothecarbonstockinbelowgroundbiomassusingtheequationsprovidedinJenkinsetal.(2003a)orbymultiplyingtheresultofStep3by0.26(i.e.,theroot‐to‐shootratio).Sumtheabovegroundcarbonstockandbelowgroundcarbonstocks.

Step5:Calculatetotalcarbonstockinthelivingbiomassofalltreespresentinthesampleplotspinstratumiattimet.

Step6:Calculatethemeancarbonstockinlivingbiomassoftreesforeachstratum,asperEquation6‐6.

Equation6‐3:EstimateCarbonStockinAbovegroundBiomassforEachIndividualTree

CAB,i,sp,j,t=ΣCFj×ƒj(DBH,H)t=1

Where:

CAB,i,sp,j,t =Carbonstockinabovegroundbiomassoftreesofspeciesj,onsampleplotsp,forstratumi(metrictonscarbon)

CFj =Carbonfractionofdrymatter(dm)forspeciesorgroupofspeciestypej(metrictonscarbon(metrictondm)‐1)

fj(DBH,H)=Anallometricequationlinkingabovegroundbiomassofalivingtree(metrictonsdm)toDBHandpossiblytreeheight(H)forspeciesj,inyeart(metrictonsdm)

Note:Forex‐anteestimations,meanDBHandHvaluesshouldbeestimatedforstratumi,inyeartusingagrowthmodeloryieldtablethatgivestheexpectedtreedimensionsasafunctionoftreeage.TheallometricrelationshipbetweenabovegroundbiomassandDBHandpossiblyHisafunctionofthespeciesconsidered.AlternativelythereareestimatorsandtoolsthatprojectcarbongrowthratesdirectlywithoutinputofDBH.

i=1,2,3,…MPSstrataintheprojectscenario

j=1,2,3,…SPStreespeciesintheprojectscenario

l=1,2,3,…Nj,spsequencenumberofindividualtreesofspeciesj,insampleplotsp

t=1,2,3,…t*yearselapsedsincethestartoftheprojectactivity

Equation6‐4:ConverttheCarbonStockinAbovegroundBiomasstotheCarbonStockinBelowgroundBiomass

CBB,i,sp,j,t=CAB,i,sp,j,t×Rj

Where:

CBB,i,sp,j,t =Carbonstockinbelowgroundbiomass(BB)oftreesofspeciesj,inplotsp,instratumi,foryeart(metrictonscarbon)

CAB,i,sp,j,t =Carbonstockinabovegroundbiomass(AB)oftreesofspeciesj,inplotsp,instratumi,foryeart(metrictonscarbon)

Rj =Root:shootratioappropriateforbiomassstock,forspeciesj(dimensionless)

Equation6‐5:CalculateTotalCarbonStockintheLivingBiomassofAllTreesPresentintheSamplePlot

Ctree,i,sp,t=Σ(CAB,i,sp,j,t+CBB,i,sp,j,t)

Where:

Ctree,i,sp,t =Carbonstockinlivingbiomassoftreesonplotspofstratumi,foryeart(metrictonscarbon)

CAB,i,sp,j,t =Carbonstockinabovegroundbiomass(AB)oftreesofspeciesj,inplotsp,instratumi,foryeart(metrictonscarbontree−1)

CBB,i,sp,j,t =Carbonstockinbelowgroundbiomass(BB)oftreesofspeciesj,inplotsp,instratumi,foryeart(metrictonscarbontree−1)

i =1,2,3,…MPSstrataintheprojectscenario(PS)

j =1,2,3,…SPStreespeciesintheprojectscenario(PS)

t =1,2,3,…t*yearselapsedsincethestartoftheprojectactivity

SoilOrganicCarbon.Forstratathatcontainonlymineralsoils,ex‐anteandex‐postΔCsoil,i,tchangeisestimatedfromEquation6‐7.

ThedefaultvalueofΔCforesti=0.5metrictonsCha−1year−1,andatequilibriumof20years,ishallbeused.

Changesincarbonstockinsoilorganicmatterarenotmonitoredex‐post(i.e.,measuredbeforeandaftertheequilibriumperiod),butareinsteadestimatedex‐ante(i.e.,predictedbasedonthespecifieddefaultvalueandequilibriumperiod).

OtherPools.Sampleplotsneedtobesetupinsuchawaysthatthesmallherbsandbushes,aswellasforestfloorlitterisalsomeasured.Todothis,establishseveralsmallcollectionplotsmeasuring3.3feetby3.3feet(1mby1m)ontheforestfloor.Collectallliter,herbs,andsmalldebrisinthesubplotandweighitusingafieldscale,anddrysmallsampletogetthedryweightfraction.

Equation6‐6:CalculateMeanCarbonStockinTreeBiomassforEachStratum

Ctree,i,t=(Ai/Aspi)ΣCtree,i,sp,t sp=1

Where:

Ctree,i,t =Carbonstockinlivingbiomassoftreesinstratumi,foryeart(metrictonscarbon)

Ctree,i,sp,t =Carbonstockinlivingbiomassoftreesonplotsp,ofstratumi,foryeart(metrictonscarbon)

Aspi =Totalareaofallsampleplotsinstratumi(ha)

Ai =Areaofstratumi(ha)

sp=1,2,3,… =Pisampleplotsinstratumiintheprojectscenario

i=1,2,3,… =MPSstrataintheprojectscenario(PS)

t=1,2,3,… =t*yearselapsedsincethestartoftheprojectactivity

Equation6‐7:EstimatingChangeinCarbonStocksforStrataThatContainOnlyMineralSoils

ΔCsoil,i,t=Ai*ΔCforest,ifort≤tequilibrium,i

ΔCsoil,i,t=0fort>tequilibrium,i

Where:

ΔCsoil,i,t =Averageannualchangeincarbonstockinsoilorganicmatterforstratumi,foryeart(metrictonsCyear−1)

Ai =Areaofstratumi;hectare(ha)

ΔCforest,i =Averageannualincreaseincarbonstockinsoilorganiccarbonpoolforforestsysteminstratumi(metrictonsCha−1year−1)

tequilibrium,i=Timefromstartoftheprojectactivityuntilanewequilibriumincarbonstockinsoilorganicmatterisreachedforforestsysteminstratumi(years)

Multiplytheaveragedryweightoflitterby0.37tocomputetheplotlittercarbon,andby0.5tocomputetheplotherbsandseedlingcarbon.Forsmalltreesandbushesestablishafewsmallplotsmeasuring16.4feetby16.4feet(5mby5m)inthesampleplot.Cutandweighallsmalltreesandbushes.Establishadryweightbasisandmultiplythedryweightby0.5tocomputeasubsamplecarbonvalue.Standingdeadwoodalsoneedstobeestimated.Mostpublishedstudiessuggestthispoolissmallandcanbeignored.

Non‐CO2GHGs.Non‐CO2GHGs,includingCH4andN2Oarecalculatedbasedonemissionfactorsappliedtotheparcelbiomass.Thus,theparcelbiomassismultipliedbyafactorfromdefaultvaluesforthattimeofstandorplantingactivity.Theseemissionsandremovalswillvarydependingonthemanagementpractice,e.g.,naturalsuccession,plantations,fertilization.

6.3.5 ActualGHGRemovalsandEmissionsbySourcesandSinksfromForestClearing

Theabovesuiteofequationscanbeusedtoestimatethesourcesandsinksofcarbonfromforestclearing,withtheresultshavingadifferentsignthanestablishmentandre‐establishment.ThefundamentalcomputationisinEquation6‐8.

TheprecisecomputationinEquation6‐9requiresthemeasurementorestimationofthedifferencesincarbonstocksintheforestsystemandtheland‐coversystemthatitisconvertedto.Italsorequiresanunderstandingacomputationofthepartitioningoftheproductsthatwereremovedfromthesiteorleftasslashanddebris.Formaterialleftonsiteandburned,GHGemissionsshouldbecalculatedusingtheCONSUMEmodel.Hence,Cfisestimatedfromstandardper‐areaforesttypecarbonstocksorfromplotdata.Thefractionsfyanddyareestimatedordirectlymeasured(forsimplicityitispossibletoassumethatdyisthefractionoftheturnovertime,asin1/1,1/10,1/100or1/1,000).Esisthesoilfluxthatisrepresentedinlookuptables,andbasedonthetime‐varyingrateofcarbonlossasapercentageoftheoriginalforestsoilcarbon.

Equation6‐8:ComputingEmissionsofCarbonfromaForestClearing

Ed=f(D×C/ha)

Where:

Ed =Emissionsofcarbonfromforestclearing,D(metrictonscarbonyear‐1)

D =Therateofforestclearing(hayear‐1)

C/ha =Thestockofcarbonintheforestsystempriortoclearing(metrictonscarbonha‐1)

6.3.6 LimitationsandUncertainty

Therearepublishedmethodsforformallyestimatinguncertaintyoftheestimation,generallybasedonthenumberanddistributionofthepermanentplots,andhowtheyareappliedtothewholestratum.Theseuncertaintyestimatescanbeusedaprioritoestablishthenumberofplotsneededtoachievealevelofaccuracy.Theycanalsobeusedtoattachanuncertaintyvaluetothefinalestimate.Butperhapsthemostchallengingcomponentofuncertaintyliesintheuseofvariousexpansionfactorswhereprecisefieldestimatesarenotknown.Inparticular,theestimationofnon‐CO2GHGfluxesisveryuncertain,andmustbeusedwithsomedegreeofcaution.ThisisespeciallytrueforN2OinallactivitiesandCH4incasesofforestestablishment.Considerablymoreresearchisnecessarytomaketheseestimates.

Anotheruncertaintyinmostestimatesisthefractionofstandingdeadbiomass.Basedonsomework(WoodallandMonleon,2008),itisbelievedtobesmall,butthevariationwithforesttypes,standage,conditions,andactivitiesislarge.Whenusingdefaultvaluesthismaybeachallengetothefinalestimation.Inthecasewheredirectmeasurementsaretobemadeonsite,thestandingdeadcanbemeasuredalongwithstandinglivebiomass.Thismaybeanapproachthathasspecialbenefitifthesitebeingclearedhasbeenintenselydamagedbypestsordisease.

Perhapsthemostproblematicareaisthecomputationofwholetreebiomassfromallometry.ThereisaverygoodNorthAmericanliteratureonallometryforstemvolumesandbiomassbutlessonwholetreevolumeandbiomass.Mostallometryisbasedonvolumesratherthanwholetreebiomassorcarbon.Frequentlyalimitednumberofsimpleexpansionfactorsaredeployedtoexpandthevolumeofthemainstemtothebiomassofthewholetreeincludingitsbranches.Thesemodelsneedtoberefinedtobettermaketheestimation.Thismaybeimportantsincemostlandownerswillnothavetheabilityorinteresttoconducttheirowndestructivetreesamplingtoextractlocalwholetreebiomassallometry(i.e.,aTier3approach).

Equation6‐9:ComputingthePartitioningoftheProductsThatWereRemovedfromtheSiteorLeftasSlashorDebrisin1Year

Ed=D[(Cf–Cc)×∑ ]+Es

Where:

Ed=Emissionsofcarbonfromforestclearing,D(metrictonscarbonyear‐1)

D=Therateofforestclearing(hayear‐1)

Cf=Thecarbonstockpriortoforestclearing(metrictonscarbonha‐1)

Cc=Thecarbonstockafterforestclearing(metrictonscarbonha‐1)

fy=Thefractionoforiginalcarbonstockinlong‐termdecaypooly

dy=Thedecayfunctionforthemassquantitiesindecaypooly (long‐termdecaypoolsare1‐,10‐,100‐and1,000‐yearturnovertimes)

Es=Emissionsfromsoil(metrictonscarbonyear‐1)

Table6‐3:ExamplesofForestCarbonCalculators

Developer WebsiteUSDAForestServicetoolsforcarboninventory,management,andreporting

http://www.nrs.fs.fed.us/carbon/tools/

FAOExACT http://www.fao.org/tc/exact/en/TARAM(BioCFandCATIE) http://wbcarbonfinance.org/Router.cfm?Page=DocLib&Catalog

ID=31252CO2Fix http://www.efi.int/projects/casfor/models.htmGORCAM http://www.joanneum.at/gorcam.htmCASS http://www.steverox.info/software_downloads.htmFullCam http://www.ieabioenergy‐

task38.org/workshops/canberra01/cansession1.pdfCOLE http://www.ncasi2.org/COLE/Reforestation/AfforestationProjectCarbonOnlineEstimator

http://ecoserver.env.duke.edu/RAPCOEv1/

WinrockAFOLUCalculator http://winrock.stage.datarg.net/CarbonReporting/Welcome

6.4 ForestManagement

6.4.1 Description

Forestmanagementisconcernedwithmeetinglandownerobjectivesforaforestwhilesatisfyingbiological,economic,andsocialconstraints.Forestmanagersuseawidevarietyofsilviculturaltechniquestoachievemanagementobjectives,mostofwhichwillhaveimpactsonthecarbondynamics(seeTable6‐4).Theprimaryimpactsofsilviculturalpracticesonforestcarbonincludeenhancementofforestgrowth(whichincreasestherateofcarbonsequestration)andforestharvestingpractices(whichtransferscarbonfromstandingtreesintowoodproductsandresidues,whicheventuallydecay).Someforestmanagementactivitieswillresultinacceleratedlossofforestcarbon,suchaswhensoildisturbanceincreasestheoxidationofsoilorganicmatter,orwhenprescribedburningreleasesCO2.Furthermore,someforestmanagementactivitiesresultinfossilfuelemissions(e.g.,fromtheutilizationofmechanizedequipment,transportation).However,recentevidencesuggeststheseemissionsarefairlyminor.Markewitz(2006)estimatedthatfossilemissionsfromsilviculturalactivitiesinintensivelymanagedpineplantationswereabout3MgCha−1overa25‐yearrotation.Theseemissionswereverylowrelativetothesubsequent

MethodsforForestManagement

Rangeofoptionsdependentonthesize/managementintensity/dataavailabilityoftheentity’sforestlandincluding:

− FVS‐FFEwithJenkins(2003a)allometricequations;

− Defaultlookuptablesofmanagementpracticescenarios;and

− FVSmaybeusedtodevelopasupportingproductprovidingdefaultlookuptablesofcarbonstocksovertimebyregion;foresttypecategories,includingspeciesgroup(e.g.,hardwood,softwood,mixed);regeneration(e.g.,planted,naturallyregenerated);managementintensity(e.g.,low,moderate,high,veryhigh);andsiteproductivity(e.g.,low,high).

Themethodswereselectedbecausetheyprovideaconsistentandcomparablesetofcarbonstocksovertimeundermanagementscenarioscommontotheforesttypesandmanagementintensities.

sequestrationofcarbonintheforestandinwoodproducts.Côtéetal.(2002)reportemissionsfromsilviculturalactivitiestotaledabout9percentoftotalemissionsfromapulpandpaperoperationandabout4percentofgrossforestsequestration.Inalife‐cycleanalysisfromthePacificNorthwest,Johnsonetal.(2005)reportedfossilemissionsofCO2fromforestryoperationsamountedto8.02to8.12kgCO2‐eqm−3ofharvestedlogs,orlessthan1percentofthe935kgCO2‐eqcontainedinacubicmeterofaDouglas‐firlog.InthedryPonderosapineforestsofArizona,athinningtreatmentresultedinCO2emissionsfromfossilfuelsof334kgCO2‐eqha−1,about1.1percentofthe30,213kgCO2‐eqha−1offirewoodremovedinthethinningoperation(FinkralandEvans,2008).

Thissectiondescribesgeneralcategoriesofforestmanagementactivitiesandtheirimpactsoncarbonstorage.ThedetailsvarywidelyacrosstheUnitedStateswithdifferentforesttypes,ownershipobjectives,andforeststandconditions.Itisimportanttoengageprofessionalforesterswhenconsideringharvestsorothersilviculturalpractices.Animportantdistinctiontobemadeattheoutsetisbetweenplantedforests,orplantations,andforeststhathavebeennaturallyregenerated.Productivityrates,silviculturalpractices,andmanagementobjectivesmaybemarkedlydifferentforplantedversusnaturalforests.Inplantedforests,conditionsaretypicallyoptimizedforincreasedgrowth,whichincreasescarbonsequestrationoverslowergrowing,naturallyregeneratedforests.However,methodsforinventorying,monitoring,andassessingcarbonstorageinbothplantedandnaturalforestsarethesame;variabilitymaybelessinsingle‐speciesplantations,butapproachesareidentical.SmalllandownerswillusetheregionaldefaulttablestoestimatethepotentialchangesinGHGfluxesfromchangesinforestmanagement,whilelargelandownerswillusestandardforestinventorydataincombinationwiththesimulationfeatureoftheFVS‐FFEtoassesschangesinsequestrationandemissionsfromchangesinpractice.

Table6‐4:CommonForestManagementPractices

Practice Description Benefits

Standdensitymanagement

Controllingthenumbersoftreesperunitareainastandthroughavarietyoftechniques,suchasunderplanting,precommercialthinning,andcommercialthinning

Maintainsstandatatreedensitythatprovidesoptimalgrowingspacepertreeforbestutilizationofsiteresources

Allowsconcentrationofsiteresourceson“crop”trees

Sitepreparation Preparinganareaoflandforforestestablishmentbyremovingdebris,removingcompetingvegetation,and/orscarifyingsoilwhenneeded

Improvessurvivalandinitialgrowthofplantedornaturallyregeneratedseedlingsorsprouts

Enhancesregenerationofdesiredspecies Providesconditionsfavorableforplanting

ofseedlingsVegetationcontrol

Removing,throughchemicalormechanicalmeans,undesirablevegetationthatwouldcompetewiththedesiredspeciesbeingregenerated

Improvessurvivalandgrowthofdesiredtrees/species

Planting Plantingofseedlingsbyhandormachinetoestablishanewforeststand

Controlsspeciescompositionandgeneticsofnewlyestablishedstand

Controlsstocking(density)oftreesperunitareaforoptimalgrowth/survival

Practice Description Benefits

Naturalregeneration

Establishinganewforeststandbyallowing/enhancingnaturalseedingorsprouting

Resultsinmixofspecies Speciesthatsproutfromstumpsand

rootswillrapidlyrecapturethesite Lowcostrelativetoplanting Mayinvolvelesssoildisturbancethereby

reducingerosionFertilization Augmentingsitenutrientsthroughthe

applicationofnitrogen,phosphorous,orotherelementsessentialtotreegrowth

Enhancesgrowthoftrees Reducesthetimefortreestoreach

merchantablesize Eliminatesorreducesnutrient

deficienciesthatwouldimpairforestgrowth/survival

Selectionofrotationlength

Choosingthetimingoffinalharvestsoastooptimizethemixofforestproductsthatcanbeobtainedfromthestand

Controlstherelativeamountsofpulpwoodandsawtimberproducts

Allowslandownertorespondtowoodproductsmarketsbyoptimizingproductmix

Harvestingandutilization

Removaloftreesfromtheforest,andcuttingandseparatinglogsforforestproductsmarkets

Selectionofappropriateharvestingsystemscanprovidelogsformarketswhileminimizingdamagetoresidualtreesordisturbanceofsoil

Choiceofharvestingandsilviculturalcuttingsystemwillimpactsubsequentregenerationofthestand;systemscanbechosentoinfluencethespeciescompositionoftheregeneratedstand

Fireandfuelloadmanagement

Reducingtheriskoflosstowildfirebycontrollingthequantityoffuelsinaforeststandbycontrolledfireormechanicaltreatments

Reducesthedamagecausedbyseverewildfiresbyeliminatingexcessivelyhighfuelloads

Mayinfluencethespeciescompositionoftheunderstory

Reducingriskofemissionsfrompestsanddisease

Recoveringvalueoftimberafterdamagingeventsand/orpreventingfurtherdamagebyinterruptingspreadofpests/diseases

Salvageharvestsrecoversvalueindamagedtimberbyremovingitbeforeitisunusable

Sanitationharvestspreventspreadofpests/diseases

Short‐rotationwoodycrops

Producingmerchantabletreesinveryshorttimeperiodsthroughintensivemanagement(genetics,herbicide,fertilization)

Reducesthetimefortreestoreachmerchantablesize

Theremainderofthissectiondescribestheseforestmanagementpracticesandtheirimpactoncarbonstocks.

6.4.1.1 StandDensityManagement

Managementofforeststanddensity(numberoftreesperunitarea)isimportanttoachieveoptimalgrowth.Overstockedstands(toomanytrees)orunderstockedstands(toofewtrees)willgrowlessfiber,andthereforestorelesscarbon,thanmightbedesirable.Inoverstockedstands,treescompetewitheachotherforscarceresources(nutrients,water,andlight),andsuchstandsmayhavehighnumbersoftreesofpoorsizeandqualityandarehighlysusceptibletowildfireorotherreversaldisturbances.Reducingthestockinginoverstockedstandswillconcentrategrowthintreesofmore

desirablespeciesandquality.Understockedstandsdonotfullyutilizetheresourcesofthesiteandthereforedonotachievethegrowthpotentialofafullystockedstand.Standdensitymanagementseekstomaintainafullystockedstand.

Densityofanexistingforeststandmaybeincreasedbyunderplanting,whichinvolvesplantingadditionaltrees(possiblyofdifferentspecies)beneathanexistingtreecanopy.Thistreatmentmaybedesirableforstandsinwhichadequateadvancedregenerationofdesiredspeciesislacking.Underplantingisdesignedtoincreasethelikelihoodofsuccessfulregenerationfollowingtheeventualharvestoftheoverstory.Thus,whiletheimmediatecarbonimpactofthistreatmentislow,theremaybesubstantialeventualimprovementincarbonstockscomparedwithastandwithoutunderplanting.

Decreasingthedensityofaforeststandisaccomplishedthroughthinning,orcuttingsomeproportionofthetreesinastand.Thismaybedoneasprecommercialthinning,inwhichcasemostofthetreestobecutaretoosmalltoeconomicallyjustifytheirremovalfromtheforest,andtheyareleftinthestandtodecaynaturally.Whileprecommercialthinningprovidesnoimmediateeconomicbenefits,itmaybeusedtoimprovethestockinglevel,speciescomposition,andoverallhealthofastand;itrepresentsaninvestmentincreatingamorevaluable,productiveforest.Precommercialthinningandstanddensitymanagementalsocanreducetheriskofreversalfromdrought,insects,disease,andpossiblyfire.Fromacarbonstandpoint,precommercialthinningwillremovecarbonfromthelivetreepoolandincreasethecarboninthedeadwoodpool.Iftheslashisburned,theGHGemissionsshouldbeaccountedforusingtheCONSUMEmodelwhentheburnoccurred.

Iftreestobethinnedareofproperspecies,size,andquality,commercialthinningmaybeperformed.Incommercialthinning,treesaretargetedforremovalbasedontheirspecies,size,andthemanagementobjectives.Thinnedtreesareremovedfromthestandandsoldtoappropriateforestproductsmarkets.Thus,commercialthinningwillshiftcarbonfromthelivetreepoolandintodeadwoodandlitter(branches,foliage,andstumpsremaininginthestandafterharvest),andHWPpools.

6.4.1.2 SitePreparationTechniques

Regeneratingaforeststandafterharvestmayrequiretreatmentstocreatethemostdesirableconditionsfordevelopmentofthenewstand.Thismayinvolveremovingdebrisfromthepriorstand,removingundesirablecompetingvegetation,scarifyingordisturbingthesoilforenhancedregenerationofspeciesthatrequiresuchconditions,andcreatingspaceorproperconditionsforplantingtrees.

Awidevarietyoftechniquesareavailabletomeetthespecificregenerationobjectives;theyvaryconsiderablyacrossgeographicregions,topography,siteconditions,andforestspeciesundermanagement.Generalcategoriesofsitepreparationtechniquesincludemechanicalmethods,chemicalapplications,andprescribedfire.

Mechanicalmethodsdisplaceunwantedvegetation,moveorbreakdownloggingresidues,and/orcultivatethesoil(Nyland,2002).Mechanicalsitepreparationusesavarietyofmachinesandequipment,andmaybelimitedbysitefactorssuchasterrainandsoilconditions.Becausemechanicalsitepreparationinvolvessoildisturbance,thereisincreasedoxidationandemissionofCO2fromthesoilorganicmatterforaperiodoftimeaftersitepreparation.

Chemicalapplicationsinvolvetheuseofherbicidestargetedatcontrollingundesirablevegetationsothatthepreferredspeciesoftreeshaveimprovedsurvival.Chemicalsmaybeappliedthroughgroundorairsprayingorinjectionintoindividualtrees.Chemicalsitepreparationinvolveslittletonosoildisturbanceandhasminimaleffectonsoilcarbonemissions.

Prescribedburningmaybeusedtoreducetheamountofdebris(limbs,tops,andfoliage)frompriorharvests,killadvancedregenerationoftreesofundesirablespecies,andcontrolpeststhatinhabitdecayingwoodleftfromthepriorstand.Somefire‐adaptedspeciesrequireburningtoopenconesanddisperseseedforthenewstand.Clearly,prescribedfireforsitepreparationwillresultincombustionandemissionofCO2fromwoodymaterialsleftonthesite,butwillavoidthesoildisturbanceofmechanicaltechniques.TheFOFEMmodelfornaturalfuelsandtheCOMSUMEmodelforactivitygeneratedfuelscanbeusedtoaddressthistypeofburningandallowsestimationofGHGemissionsandconsumption.

6.4.1.3 VegetationControl

Controlofcompetingvegetationisonemeansofenhancingthegrowthofdesirabletreesinaforest.Forexample,inapineplantation,wherepinetreesarethespeciesofprimaryinterest,growthofpinesisincreasedwhenhardwoodcompetitionisremoved.Vegetationcontrolmaybeaccomplishedmechanically(suchasgirdlingundesirabletrees)orchemically.Vegetationcontrolisespeciallyimportantattwostagesinthelifeofastand:atestablishment(plantingorregeneration)andlaterintherotationbutbeforetreesarepastthesaplingstage.

Atestablishment(e.g.,ofaplantation),theprimarycompetitionmaycomefromherbaceousvegetationthatcanquicklyoutgrowtheplantedtreesandsuppresstheirgrowthorincreasemortality.Herbicidesmaybeeffectiveatcontrollingherbaceouscompetitionandprovidingthenewlyplantedtreesachancetogrowsufficientlytocapturethesite.Mid‐rotationreleaseoftreesmayrequireanadditionalapplicationofchemicalcontroltoreducecompetitionandfocusgrowthondesirabletrees.

Vegetationcontrolhasbeenestimatedtohavecontributed35percentofthesubstantialgaininplantationproductivityrelativetounimprovedplantations(Stanturfetal.,2003).Theprimarycarbonstockimpactofvegetationcontrolisatransferofcarbonstockfromthelivetreetostandingdeadbiomasspool.Treesreleasedfromcompetitionwillusuallyexhibitagrowthresponsetobalancethelossofgrowthonthevegetationremoved(i.e.,overallforestproductivityandsequestrationwillremainunchanged).

6.4.1.4 Planting

Onepopularformofregeneratingaforeststandfollowingclearcuttingistoestablishaplantationbyplantingtreesofadesirable,fast‐growingspecies,potentiallyutilizinganimprovedgeneticsource,ataconsistentspacingselectedtooptimizegrowth.Plantationmanagementpracticesincludecombinationsoftreatmentstocontrolcompetingvegetationandmanagetreenutritionthroughfertilization,thinning,anduseofgeneticallyimprovedstock(Vanceetal.,2010).Becauseoftheseefforts,plantationsmaybeuptosixtimesmoreproductivethannaturallyregeneratedstandsofthesamespecies(CarterandFoster,2006).Successfulplantationestablishmententailscarefulselectionofspecies,genetics,andspacing(plantingdensity).

Speciesusedinplantedstandstypicallyareselectedforhighgrowthrates,lowsusceptibilitytodamagefrominsectsanddisease,andqualityandvalue.Forexample,intheU.S.South,loblollypineisthemostwidelyplantedtreespeciesbecauseitisnativetothearea,fast‐growingrelativetootherpines,andresistanttodisease(Schultz,1997).Longstandinggeneticimprovementprogramshaveledtotheproductionofimprovedgeneticsourcesforforestplantationspecies.Geneticallyimprovedseedlingsareavailablefromcommercialandstatetreenurseries;essentiallyallofthe1.2billionloblollypineseedlingsplantedannuallyintheU.S.Southaretheresultoftreeimprovementprograms(McKeandetal.,2003).InthePacificNorthwest,geneticimprovementinDouglasfirtreeshasledtoincreasesinproductivity(volumeproduction)inexcessof25percent(St.Clairetal.,2004).Finally,selectionofplantingdensity(treesperunitarea)canaffectoverallstand

productivity,necessityforthinning,abilitytoaccessthestandwithequipmenttoconductsilviculturaloperations,andtimerequireduntiltreesreachmerchantablediameters.Allofthesefactorscombinetodeterminethelikelysurvivalandgrowthratesofaforestplantation.Plantationproductivityisdirectlyrelatedtorateofforestsequestration.Anyactivityincreasingproductivitywillimprovesequestrationrates.

6.4.1.5 NaturalRegeneration

Certainforesttypesareregeneratedmostefficientlyusingnaturalregeneration,inwhichseedlingsandsproutsfromarecentlyharvestedordisturbedforestwillgrowquicklyafterremovalofaportionoralloftheforestoverstory.Inthiscase,thespecieswillbepredictablebasedonthespeciescompositionofadvancedregenerationfromthepreviousstand,orifspeciespresentinthepreviousstandareprolificinsprouting.Thespeciescanalsobepredictedbasedonpost‐harvestregenerationofseedlingsfromresidualoverstorytreesorfromsurroundingstands.Densitywillnotbecontrolledduringtheregenerationprocess;frequentlynaturalregenerationresultsinverydensevegetationthatthengoesthroughanaturalprocessofcompetition.

Becauseneitherthegeneticsourcenordensityarecontrolledduringnaturalregeneration,thesestandsarefrequentlylessproductivethanplantationsbutmaybemoredesirablebasedontheobjectivesofthelandowner(e.g.,forrecreation,wildlife,ordifferentproductsthanplantationswouldprovide).Theprocessofnaturalregenerationmayentailminimal(ifany)sitepreparationandlesssoildisturbanceandcostthanwouldplantations.Dependingonthelevelofsoildisturbancefromtheharvestofthepreviousstand,earlysoilCO2emissionsmaybelowerthaninplantedstands.

6.4.1.6 Fertilization

Fertilizationhasbeenshowntodramaticallyimprovetheproductivityofforeststandsinwhichnutrientsarelimitingplantgrowth.Forexample,intheU.S.South,nitrogenandphosphorusarecommonlydeficientinpineplantations(Foxetal.,2007).Intheseareas,phosphorusfertilizationmayincreasevolumeproductionbymorethan100percent(Jokelaetal.,1991).Nitrogenandphosphorusfertilizationhasbeenshowntoincreasegrowthby1.6tonsacre−1year−1(Foxetal.,2007).

ThetwoprimarytypesofforestfertilizationcurrentlypracticedintheSoutharephosphorus‐fertilizationondeficientsites(usuallyatorneartimeofplanting),andnitrogenandphosphorusfertilizationinmid‐rotationstands(e.g.,ages8to12).Volumegainsvary,withhighestgainswherestandsaremostnutrient‐limited.

Thedirectcarbonimpactoffertilizationofforestsistheobservableincreaseingrowthandthereforesequestration.Otherimpactshavebeennotedinagriculturalsettings,includingincreasedemissionsofotherGHGssuchasNOxandN2O.Resultsfromagriculturalfertilizerapplicationsmaynotbedirectlyapplicabletoforestryoperations.RecentresearchinwesternCanadianforestsshowedsoilGHGfluxeswereneutralfollowingfertilization(Basilikoetal.,2009).InananalysisoffertilizationofpineplantationsinthesoutheasternUnitedStates,Albaughetal.(2012)foundthatcarbonsequestrationinforestgrowthfarexceededtheemissionsassociatedwithfertilizerproduction,transport,andapplication(8.70Tgyear−1CO2sequestrationversus0.36Tgyear−1emissions).Thus,forestfertilizationwhenappliedappropriatelycandramaticallyincreasecarbonsequestrationwhencomparedtounfertilizedstands.

6.4.1.7 SelectionofRotationLength

Onesignificantdecisionthatforestmanagersmakeistheselectionoftherotationlength,ortargetageatwhicharegenerationharvest(finalharvest;oftenbutnotnecessarilyaclearcut)willoccur.

Thedecisionaffectsthetimingofotherstandtreatments.Forexample,thinningsandsomefertilizationtreatmentsaretargetedforacertaintimebeforefinalharvest.Italsoaffectsthemixofforestproductsthatmightbeexpectedfromtheharvestedstand.Standsharvestedatrelativelyyoungageswillyieldprimarilytreessuitableforpulpwoodmarkets,whilelongerrotationsmayinvolvemorethinningsandwillincreasetheproportionofsawtimber‐sizedtreesinthestand.Becausethesedifferentproductshavedifferentlongevities(seeSection6.5),therotationlengthwillhaveasignificantimpactontheoverallcarbondynamicsofaforest(anditssubsequentpoolofcarboninHWPs).Furthermore,longerrotationsresultingreateraveragecarbonstorageintheforest,withresultinghigherlevelsofsequestration(StainbackandAlavalapati,2002).Itiswidelyrecognizedthatincreasingrotationsfromharvestingatfinancialmaturitytoharvestingclosertoagesatwhichstandsreachasteadystatebetweengrowthandmortalitycanbebeneficialforcarbonstorage(vanKootenetal.,1995).

Avarietyofdecisioncriteriaareavailableforidentifyingtheoptimalrotationlengthfordifferentsetsofobjectives.Ifcarbonstorageisoneoftheimportantobjectives,longerrotationswillbebeneficial(Liskietal.,2001).

6.4.1.8 HarvestingandUtilizationTechniques

Regenerationharvests(alsocalledrotationharvestsorfinalharvests)areconductedtoharvesttreesforforestproductsmarketsandtopromotetheregenerationofdesirablespeciesforthenextstand.Tomeetthetwinobjectivesofregenerationandproductionofmerchantabletimber,forestmanagersmaychoosefromawidearrayoftechniquesandoperationalapproaches.Thesilviculturalsystemwillbechosentodeterminewhichtreesaretoberemovedfromthestand,andaharvestingsystemwillbechosentodeterminethebestloggingapproachtodoso.

Thesilviculturalsystemdetermineswhatproportionoftheforeststandistoberemovedintheharvest,andwilldictatewhethertheresultingstandwillbeeven‐aged(astandoftreesofasingleageclass)oruneven‐aged(astandoftreeswiththreeormoreageclasses)(Helms,1998).Harvestsrangefromclearcuts,inwhichmostoralloftheoverstoryisremoved,toavarietyofpartialharvests.Partialharvestsincludesystemssuchasseed‐tree,shelterwood,groupselection,individualtreeselection,diameter‐limit,andothers.Harvesttechniquesthatopenmostorallofthecanopy(suchasclearcuttingorseed‐treeharvests)willpromotetheregenerationofspeciesthatthriveinsunlightanddonottolerateshade.Clearcuttingisalsothepreferredtechniquewhenthenextstandistobeestablishedbyplantingratherthannaturalregeneration.

Afterselectionofasilviculturalsystemforregeneration,forestmanagerswillselectaharvestingsystemforthefellingandextractionoftreesfromthesite.Againawidevarietyofsystemsareavailable,fromindividualtree‐fellingbychainsawwithextractionbyhorseteams,tohighlymechanizedsystemsinvolvingskidders,feller‐bunchers,forwarders,andothertypesofequipment.Whenterrainconditionspreventground‐basedvehicularextractionoffelledtrees,itmaybedoneusingcableyardingsystemsorhelicopters.Loggingsystemsthatminimizesoildisturbanceandimpactsonunharvestedtreesandunderstorymayreducetheseharvest‐associatedemissions.

Whentreesareharvestedfromaforest,theymayproduceavarietyofproductsforspecificmarkets.Forexample,large‐diametertreesofcertainspeciesarepreferredforsawtimbermarkets,whilepulpwoodmarketsacceptroundwoodwithsmallerdiametersorevenchips.Thus,aharvestingoperationwillofteninvolvemerchandising—thesorting,cutting,andseparatingoflogsfordeliverytodifferentmarkets.Dependingonthesilviculturalsystemchosen,treeswithoutmarketvalue(e.g.,toosmall,poorform,orundesirablespecies)maybecutandleftonsitetodecay.Inaddition,agreatdealoflogging“slash”maybeproduced;thismaterialmayconsistofbranches,portionsoftreesbeyondmerchantabilitylimits(tops),roots,andfoliage.Wherebiomassenergymarketsexist,someofthismaterialmayberemovedandusedtoreplacefossilenergyGHGsources;

otherwiseitmaybeleftonsitetodecayorbeburnedduringsitepreparationwithassociatedGHGemissions.Theproportionofwoodymaterialremovedfromaharvestingoperationistermedutilization;highlevelsofutilizationmeanmorewoodybiomassisremovedandlessremainsonsite.

Therearemanycarbonconsequencestotheselectionofasilviculturalandharvestsystem.Partialharvestswillleavesubstantialcarboninlivetreesonthesite,whereasclearcutharvestwillleaveverylittle.Oncertainsoils,mechanizedsystemsforfellingandextractingtreeswillresultinmoresoildisturbanceandsubsequentCO2emissionsthanlow‐impactsystems(Naveetal.,2010).Theharvestingimpactonsoilcarbonisgreaterfortheforestfloorthanforcarboninthemineralsoil,buttheseeffectsareshorterlivedandmaybemodestoverlongertimeintervals(Naveetal.,2010).Theavailabilityofmarketsforsmaller‐diametermaterialortreesofnonmerchantablespecieswillaffecthowmuchresidue(slash)isleftonthesite.Availabilityofstrongmarketswillgenerallyleadtohigherutilizationandlessresidue.Itisimportanttokeepaccountingboundariesinmindtoensurethatthereisnoomissionordoublecountingofemissionsorremovals.TheIPCCmethodologieshaveadoptedtheconventionthatemissionsfromburningbiomassforenergyshouldnotbeaccountedintheenergysector,butshouldbeaccountedintheland‐usesector.Weconformtothisconvention.If,forexample,forestresiduesareburnedforenergy,theCO2emissionsarenotcountedintheenergysector,andthereshouldbeareductionintheamountoffossilfuelburned.ButtheCO2emissionsfromtheburnedresiduewillbeaccountedasadecreaseincarbonstocksintheland‐usesector,andemissionswillbenodifferentthaniftheresidueshadbeenpiledandburnedintheforest.Thatis,acompleteaccountingofemissionswhenresiduesareburnedforenergywillshowemissionssavedintheenergysectorbutnochangeintheland‐usesector.

6.4.1.9 FireandFuelLoadManagement

Manyforesttypeshaveanaturaldependenceondisturbancefromfire.Asmentionedpreviously,itmayplayaroleinnaturalregeneration,butithasmanyotherfunctionsincludingnutrientrelease,naturalthinningandpruning,aswellasmodifyingfuelstructureandloading.Withoutprescribedfire,manyforesttypesmaybeatamuchhigherriskofreversalofgrowingcarbonstock.Inregionsofthecountrywherewildfireisaconcern,forestmanagersmaytakeamoreactiveroleinmanagingthelevelsofpotentialfuelsinaforest.Fuelmanagementcannotpreventignitionsofwildfires,butcandecreaselevelsofintensity,severity,andspread.Twocommonapproachestofuelloadmanagementareprescribedburningandmechanicalfueltreatments.

Prescribedfireisanyfireintentionallyignitedbymanagementunderanapprovedplantomeetspecificobjectives.Whenforestfuelsareburnedundercarefullyselectedconditions(weather,fuel,moisture,etc.),fuelscanbereducedtolevelsthatdecreasetheriskofdamagingwildfires.Otherobjectivesforuseoffireandcontrolledburnmaybetoreducethreatfromnon‐nativeinvasivespeciesandmaintenanceofmanyendangeredspeciesthroughouttheUnitedStates.

Mechanicalfueltreatmentsaresimilartoharvestingoperations,inthatspecificclassesoftreesarecutandremoved.Forexample,alltreesbelowathresholddiametermayberemovedinathinning(Johnsonetal.,2007).Theresultshouldbedecreasedavailabilityoffuelsthatwouldincreasewildfireseverity.

Thecarbonimpactoffueltreatmentsistwo‐fold.First,itinevitablyresultsinemissionsofCO2fromthematerialremovedorburned.However,second,itsgoalistoreducethepotentialformuchlargerfutureemissions(andincreasedenvironmentaldamage)fromwildfiresinareaswheretheyareathreat.Awildfirecouldresultinareversalofthepreviousgainsincarbononthesite.Wildfireintensityandresultantlossofcarbonishighlyvariableanddependsuponsitespecificconditionsandeffects.Wildfirecanoccuratlowtomoderateintensity,whichlikeaprescribedfiremayresultinamoreresilientandproductivesiteoverthelongterm.ThechallengeisthattheimmediateCO2

emissionsfromawildfireorprescribedfire/controlburnarereadilyquantifiable,whereastheavoidedemissionsfrompotentialwildfiresarenotand,becausetreatmentsmaynottakeplaceintheareaswherewildfireoccurs,theycouldcreateextraemissionsthatwouldnototherwisehavehappened.Recentresearchindicatesthatprescribedburninghasaminimalimpactonforestcarbonbudgets,especiallyintheeasternUnitedStates.Impactsobservedfrommechanicalandfiretreatmentswerealsofairlyshort‐lived(Boerneretal.,2008).DispositionofremovedmaterialsisakeyfactortoconsiderwhenassessingtheGHGimplicationsoffuelmanagementtreatments.Prescribedfirecanhavesignificanteffectsonreducingtheriskofreversalthatcouldresultfromawildfire.

6.4.1.10 ReducingRiskofEmissionsfromPestsandDisease

Silviculturalinterventionmayalsobecalledforwhenforestsaredamagedbyweather,insects,ordisease.Forexample,wheninsectoutbreakssuchaspinebeetleinfestationskillpatchesoftrees,removaloftreesatorneartheinfestationsitemaypreventpopulationsofharmfulinsectsfromspreadingfurther.Whenharvestsaredesignedtorespondtopestanddiseaseproblems,theymaybecalledsanitationharvests.

Whenweathereventssuchasicestorms,hurricanes,orseverewinds(orawildfire)causeextensivedamagetoforeststands,quickremovalofthedownedtimbermayprovideanopportunitytorecoversomeofthefinancialvalueofthetimberandmaypreventthebuildupofverylargefuelloads.Wheneconomicvalueiscapturedfromaharvestofdamagedtimber,itistermedasalvageharvest.

Bothsalvageandsanitationharvestsremovetrees,sometimeswithmarketvalueandsometimeswithout.Thecarbonimpactsarereflectedintheamountofwoodymaterialremovedfromtheforestandwhetherthematerialremovedentersmarketsforwoodproductsorforenergy.Similartowildfiretreatments,inbothsanitationandsalvageharvests,however,theremovalofbiomassmaybecomparedwiththealternativeofleavingthematerialintheforesttodecayorburn,resultinginCO2emissions.Forsomecarbonaccountingsystems,thisdifferenceiscrucial;theassumptionthatemissionswouldhaveoccurredwithouttheactivityaffectsbaselineassumptionsagainstwhichcarbonsequestrationismeasured.

6.4.1.11 Short‐RotationWoodyCrops

Short‐rotationwoodycrops,alsocalledbiomassplantationsorbiomassenergyplantations,aretreeplantationsmanagedwithaveryhighintensitytoproducefibercropsinarelativelyshorttimeframe(e.g.,5–10years).Theseplantationsaremorelikeagriculturalcropsinthelevelofintensityoftreatments(e.g.,fertilization,weedcontrol,andsometimesirrigation).Woodgrowninthismannerisusuallysuitableforusebybiomassenergyfacilitiesorpossiblypulpmills,butthecosttoproducethiswoodisveryhighcomparedwithtraditionalplantations.Forsomespecies,itispossibletoregeneratethesestandsbycoppicing,orcuttingtopromotesproutingfromintactrootsystems,whichavoidsthecostofplantingnewtrees.Regenerationbysproutscanresultindensestandsexhibitingveryfastgrowth.

Thecarbondynamicsinashort‐rotationwoodycropsystemaresimilartoconventionalplantations,exceptfortheacceleratedgrowthandreducedrotationlength.Insomeshort‐rotationwoodycropsystems,covercropsmaybegrowntopreventerosionandmaintainsoilfertility.Covercropswouldalsoservetoincreasecarbonstorageonsite.

6.4.2 ActivityData

Carbonstoragefromforestmanagementactivitiesisestimatedapplyingthreedifferenttypesofestimates.EstimateTypeIfocusesontheeffectsofmanagementactivitiesoncarbonstocksfora

givenyear.EstimateTypeIIfocusesontheeffectsofmanagementactivitiesoncarbonstocksoveraperiodofyearsinthefutureandmustbebasedonprojections.EstimateTypeIIIexaminesthedifferenceinprojectedcarbonstocksbetweensetsofalternativescenariosofpotentialmanagement.Thissectionwilldiscusstheactivitydataneedsforeachofthetypesofestimatesforthevariousforestmanagementactivities.Ingeneral,however,theestimationapproachesanddataneedswillbeoftwotypes:(1)forestinventorydata;and(2)standprojectionmodels.

ForTypeI,incaseswhereamanagementactivityhasalteredthecarbonstockinspecificpools,thebestestimatesmaybeobtainedbyhavingforestinventorydatabeforeandafterthetreatment,suchthatthedifferencecanbeattributedtothemanagementactivity.Forestinventorydatashouldincludemeasurementsobtainedintheforestataseriesofplots,withlistsofthetreesineachplot.Usuallyforeachtreeitisnecessarytoknowthespecies,diameter,andsometimesheight.Fromthesemeasurements,stand‐levelestimatesoftreedensity(treesperunitarea),basalarea(cross‐sectionalboleareaat4.5feet(1.4m)fromtheground),speciescomposition,andtreevolumeandbiomasscanbecomputed.

Anotherapproach,usedforTypeIIandTypeIIIestimates,requirestheuseofstandprojectionmodelstoestimatetheresponsesoftheforesttomanagementactivities.Suchmodelshavebeencreatedforawidevarietyofforesttypesandtreatments;anexampleistheFVSfamilyofmodelsdiscussedearlier.Projectionmodelsforforecastingforestconditions(andcarbonstocks)typicallyrequiremeasuresorindicesofforestproductivity.Acommonlyusedmeasureofforestproductivityissiteindex,whichrepresentstheheightthattreesonasitewillreachbyacertainbaseage.Forexample,onlandwithasiteindexof65(baseage25),theaverageheightofdominantandco‐dominanttreesinastandwillbe65feet(19.8m)whenthetreesreachage25.

ThemostaccurateTypeIIandTypeIIIestimatesarefrommodelsdevelopedspecificallyforagivenplantationspeciesornarrowlydefinedforesttype.Forexample,therearemanymodelsavailabletoestimateeffectsofmanagementoncommonlyplantedandhighlyresearchedspeciessuchasDouglasfirorloblollypine(e.g.,AmateisandBurkhart,2005;Burkhart,2008;Carlsonetal.,2008;Lietal.,2007;Sucreetal.,2008).Atthistime,theFVSfamilyofmodelsistherecommendedmethodforestimatingforestcarbonstocks.Inincorporatingthismethodintoanysoftwaretool,adataportalthatallowstheusertoloadtheirexistingstanddataandmanagementactivitydatafortranslationintotheFVSformatisrecommendedandwouldproveuseful.Futuredevelopmentmayalsopermitcustommodelstointerfacewithanestimationtool.Atthistime,however,suchcapabilityisnotavailable.Incaseswheresuchmodelsarenotavailable,itmaybenecessarytogeneralizebyaggregatingforesttypesandmanagementactivitiesandperformprojectionsbasedoncategoriesofmanagementintensityforgeneralforesttypes.ManagementintensitycategoriesaredefinedinSection6.4.3.

Theremainderofthissectionisorganizedasfollows:

StandDensityManagement

SitePreparationTechniques

VegetationControl

Planting

NaturalRegeneration

Fertilization

SelectionofRotationLength

HarvestingandUtilizationTechniques

FireandFuelLoadManagement

ReducingRiskofEmissionsfromPestsandDisease

Short‐RotationWoodyCrops

Standdensitymanagementactivitiesincludeunderplanting,precommercialthinning,andcommercialthinning.Ineachcase,theprimarydatarequirementsforTypeIestimatesaretreeinventoriesbeforeandafterthetreatment,whichcanindicatethechangeinstockinglevelsandthequantityofbiomassremovedduringthinnings.Inthecaseofthinnings,itisimportanttoknowthevolumeorbiomassdirectedtodifferentwoodproductsmarkets(e.g.,pulpwood,sawtimber,orenergy)toproperlyaccountforthecarboninHWPs.

ForTypeIIandIIIestimatesofthefuturecarbondynamicsofthestandafterthesetreatments,standprojectionmodelswillrequireameasureofsiteindexinadditiontotheinventoryinformationcollectedforTypeIestimates.

6.4.2.2 SitePreparation

Theprimaryinformationrequirementforestimatesofstockchangesduetositepreparationiswhethersoildisturbancehasoccurredduringsitepreparation.Mechanicalsitepreparationtechniquesthatinvolvesoildisturbancewillbeassumedtoleadtoashort‐termlossofsoilcarbonstoragefollowedbyarecovery.Chemicalorothertreatmentsthatdon’tinvolvesoildisturbancewillnotresultinsoilCO2emissionsbeyondwhatmayhaveoccurredduringharvesting.ForTypeIIandIIIestimates,thesitepreparationtechniqueshouldberecordedintheeventthatmodelsmaydifferentiatebetweengrowthratescorrespondingtovarioussitepreparationtechniques.

ForTypeIestimates,itisnecessarytohaveinventoryinformationbeforeandaftervegetationcontroltreatmentsifthevegetationcontrolinvolveswoodymaterial.(Carbonstocksarenotexpectedtobesubstantiallydifferentforherbaceouscontroltreatmentsneartimeofplanting.)Whenvegetationiskilledbutnotremoved,thecarbonstockimpactsinvolveprimarilytheredirectionofstockfromonepool(livetrees)toanother(standingdeadtrees).

ForTypeIIandIIIestimates,somemodelsmayprojectstandgrowthdifferentlyifcompetingvegetationisremoved.Insuchcases,similarinventoryinformationbeforeandaftertreatmentwillbenecessary.

6.4.2.4 Planting

Theactofplantingitselfinvolvesanegligiblecarbonstockchangefortheyearofplanting.Thus,aTypeIestimatewouldshownocarbonstockchangefollowingaplanting.

Forallsubsequentyears,however,criticalparametersarethespeciesplanted,theoriginalplantingdensity(treesperacre),andthesurvivalrate(inpercent)afteronegrowingseason.Becausemostearlymortalityoccurswithinoneyearofplanting,thepercentageoftreessurvivingatyearoneprovidesarobustestimateofstanddensityforgrowthprojections.ItwillalsobeimportantforTypeIIandIIIestimatestorecordthegeneticstockused(e.g.,firstgeneration,open‐pollinated,mass‐controlledpollinated,clonal)intheeventthatprojectionmodelsaredevelopedforspecificgeneticsources.Somemeasureofsiteproductivity(e.g.,siteindex)willbeneededaswell.

Asinthecaseofplantationestablishment,carbonstockchangesatthetimeofnaturalregenerationarenegligible.

TypeIIandIIIestimateswillrequireinformationonspeciesmix,standdensity,andsomeinformationonstandproductivity.Incasesinwhichstandproductivitycannotbemeasureddirectly(bymeasuringexistingtreesforsiteindex),someestimatescanbederivedfromsoilsdatabasessuchasSSURGO,orfromfieldcharacterizationofsoilseriesandreferencetosoilmapsandmanuals.

6.4.2.6 Fertilization

TypeIestimateswillshownoimmediatecarbonstockchangesrelativetofertilizationfortheyearinwhichtheactivityoccurred.N2Oemissionswilloccurattimeoffertilization;activitydatashouldincludenumberofacresfertilized,applicationrate,andtypeofnitrogenapplied.

TypeIIandIIIestimatesinvolvingstandprojectionmaymakeuseofmodelswhichincorporateinformationaboutthefertilizationtreatment.Applicationrates(poundsperacre)andelementalcomposition(nitrogen,phosphorus,potassium)shouldberecorded.

6.4.2.7 SelectionofRotationLength

TypeIestimatesarenotapplicabletoselectionofrotationlength.TypeIIandIIIestimatesmayentailexperimentationwithrotationlengthsinmodelingexercisestotestthecarbonstockimplicationsofdifferentrotationlengthstrategies.Suchexperimentationwillsimplyinvolvethecomparisonofmodelsrunwithallparametersheldconstantexceptforrotationlength.

6.4.2.8 HarvestingandUtilizationTechniques

Harvestinghasthelargestimmediateimpactonforestcarbonstocks.Consequently,forTypeIestimates,thelandownerneedstocollectaccurateandsufficientlydetailedforestinventoryinformationbeforeharvestandafterharvestinthecaseofpartialcutting.Becauseongoingsequestrationofcarbonstocksfollowsdifferentpathwaysfordifferentforestproducts,thedispositionoftheharvestedmaterialintodifferentproductpools(e.g.,pulpwood,sawtimber)needstoberecorded.Thisinformationshouldbereadilyavailableaspartofsalesrecords.Defaultfactorsareavailabletoestimatecarboninharvestingresidues(slash).

Inthecaseofpartialharvests(wherethereisaresidualstandtoproject),orprojectionsofimpactsofdifferentharvestingorsilviculturalsystems,completeinventorydataandproductivityestimates(e.g.,siteindex)forthestandareneeded.

ForTypeIestimates,pre‐treatmentdataonfuelloadingwithfocusonthematerialtoberemovedinthetreatmentneedstobecollected.AnexampleofdatacollectionprotocolsforfueldatacanbefoundinBrown(1974).Post‐treatmentassessmentofresidualmaterialwillindicatetheamountremovedinthetreatment.Thetypeoftreatment(burnormechanical)andthedispositionoffuel(consumed,leftonsite,removed)shouldberecorded.Ifconsumed,FOFEMorCONSUMEcanbeusedtocalculatetheGHGemissionsfromaprescribedburn.

TypeIIandIIIestimatesofthecarbonstockimpactsoffueltreatmentswillrequirespecializedfiremodelsthatcouldindicatelikelyoutcomesofthefueltreatmentrelativetonotreatmentandasubsequentwildfire;availabletoolsincludemodelssuchasCONSUME(JointFireScienceProgram,2009)andtheFVS‐FFEmodule(ReinhardtandCrookston,2003).SeeTable6‐13wherealow‐severityfirecouldbecomparedtothecrownfireeffectbasedonFOFEMoutputs.

Forestimatesofcarbonstockimpactsofsanitationandsalvageharvests,pretreatmentandpost‐

treatmentinventoriesarerequired.Inthepretreatmentinventory,theextentandnatureofdamageareneededtoestimatethecarbonstockthathasshiftedfromlivetodeadbiomasspriortotreatment.

ModelingforTypeIIandIIIestimatesmayentailsimplyprojectingtheresidual(post‐treatment)stand.Tofullyevaluatethecarbonstockimpactsofthetreatment,modelsorassumptionsareneededforestimatingthespreadoftheinsectordiseaseabsentthetreatment.Toolsforsuchmodelingorassumptionsmaybehardtoobtain.

Estimationofcarbonstockimpactsfromplantationsofshort‐rotationwoodycropswouldfollowthesamegeneralprocedureasotherplantationestimates.Nostockchangeswouldbeexpectedattimeofplanting(carboninseedlingsorplantingstockisnegligible).ProjectionsforTypeIIandIIIestimatesrequiretheavailabilityofmodelstoprojectgrowthandyieldofthespeciesplantedunderthemanagementscenariosenvisioned.

6.4.3 ManagementIntensityCategories

Intheprevioussection,theuseofmodelstopredictforestresponsestomanagementactivitieswasdiscussed.Manysuchmodelsareavailableforspecificmanagementpracticesinplantationsofcertainspeciesorinspecificforesttypes.Thesemodelsarevariedintheirinputrequirementsandtheirapplications.Todevelopanationallyconsistentapproach,theinfinitecombinationsofsequencesofspecificmanagementactivitiesandforesttypesneedtobegeneralized.Usingasinglemodelingframework,suchasFVS(Dixon,2002)andcategoriesofmanagementintensities,allowsforthesimulationofsuitesofmanagementactivitiesinawidevarietyofforesttypesandconditionswithasinglesetofinputs.ThisapproachtodefiningmanagementintensitycategoriesissimilartothatusedbySiry(2002).

Therefore,inthissectioncategoriesofforesttypesandmanagementintensitiesthatrepresentbroadcombinationsofcommonlyappliedactivitiesintheforesttypesoftheUnitedStatesaredefined.Defaulttablesofcarbonstocksforthesecategoriescouldthenbedevelopedtoprovideconsistentandusefulinformationaboutlikelycarbonstockimplicationsofforestmanagementactivitiesacrossthecountry.

6.4.3.1 DefiningForestTypeCategories

Thefirstdistinctionindefiningmanagementintensitycategoriesistheidentificationofthebroadspeciesgrouping:hardwood,softwood,ormixed.Hardwoodforesttypesaredominatedbyhardwoodtreespeciessuchasoak,maple,cottonwood,birch.Softwoodtypesaredominatedbysoftwoodtreespeciessuchaspine,spruce,orDouglasfir.Mixedtypesexhibitnocleardominanceofonespeciesgroup.Thesecondmajordistinctioniswhetherthestandwasplantedornaturallyregenerated.Certainmanagementactivitiesarefarmorelikelytobeappliedtoplantationsthannaturalstands.Mostplantationsaresoftwoods,withtheexceptionofsomeshort‐rotationwoodycropsofhardwoodtypessuchascottonwood,willow,hybridpoplar,oraspen.

6.4.3.2 DefiningCategoriesofManagementIntensity

Fourcategoriesofmanagementintensityaredefinedbasedoncommonlyencounteredpractices.Forexample,almostallforestfertilizationisappliedtoplantationsratherthannaturallyregeneratedstands,sofertilizationwillbeconsideredpartofmanagementintensitiesrelatedonlytoplantations.Similarly,standsthatarefertilizedareusuallyalsotreatedwithherbicidetocontrolcompetingvegetationsothatthefertilizationbenefitaccruestothedesiredcropspecies.

Thefourcategoriesofmanagementintensityarelow,moderate,high,andveryhigh.Lowintensitygenerallyreferstominimalmanagementintervention(e.g.,naturalregenerationoroldersoftwoodplantationswithoutgeneticallyimprovedstock).Moderateintensityincorporatessomelevelofactivemanagementsuchasintermediateharvests(e.g.,thinnings).Highintensityappliesonlytoplantationsandincorporatestheuseofsuperiorgeneticstockandvegetationcontrol.Veryhighintensitymanagementappliestoaggressivelymanagedsoftwoodorhardwoodplantationsinwhichsubstantialeffortismadetomaximizegrowthusinggenetics,vegetationcontrol,andfertilization.Theresultingcombinationsofforesttypes,intensities,andmanagementpracticesaresummarizedinTable6‐5.

Table6‐5:ManagementIntensityCategories

ForestTypea/ManagementIntensityb

StandDensityMgmt

Planting SuperiorGenetics

VegetationControl

Fertilization

Hardwood/low

Hardwood/moderate X Mixed/low Mixed/moderate X Softwood(Nat)/low Softwood(Nat)/moderate X Softwood(Plt)/low X Softwood(Plt)/moderate X X X Softwood(Plt)/high X X X XSoftwood(Plt)/veryhigh X X X X XHardwood(Plt)/veryhighc X X X X XaForesttypereferstothecombinationofspeciesgroupandregeneration(Nat=naturallyregenerated;Plt=Planted).bAnXindicatesthatthepracticeindicatedisappliedforthemanagementintensitycategory.cVeryhighintensityhardwoodplantationsareusuallyencounteredinthecontextofshort‐rotationwoodcropsorbiomassplantations.

Figure6‐6showsthespecificregions(e.g.,PacificNorthwest,West;PacificNorthwest,East;PacificSouthwest;RockyMountainNorth;RockyMountainSouth;GreatPlains;NorthernLakeStates;Central;SouthCentral;Northeast;andSoutheast)forwhichsilviculturaloptionsbythemostcommonlymanagedforesttypeweredeveloped.

Figure6‐6:MapofSpecificRegionsofForestManagement

ForthemanagementintensitycategoriesillustratedinTable6‐5,commonsilviculturaloptionsbythemostcommonlymanagedforesttypesforspecificregionsofforestmanagement(seeTable6‐6)aredescribed.Thislistisnotexhaustive,sincesilviculturalprescriptionsmayoftenbetailoredtositespecificconditions;however,thelistprovidesthepracticesfrequentlyappliedincommonlymanagedforesttypes.Themanagementobjectivemaynotnecessarilybetimberproduction;insomeregionsandtypeshabitatrestoration,rangelands,orforesthealthmaybetheprimarymanagementobjectives.Table6‐6providesalistofcommonlyusedsilviculturalprescriptionsforcommonforesttypesineachregion.

Table6‐6:CommonSilviculturalOptionsbyMostCommonlyManagedForestType

Region ForestType GeneralizedPractice

Northeasta

Northernhardwoods:beech,sugarmaple,yellowbirch,andassociates

Singletreeselection:harvest40–50ft2peracreevery20yearsacrossarangeofsizeclassesinstandswith120–130ft2basalarea(BA)Clearcut:when120–130ft2,thencommercialthinningCommercialthin:Atage90–100(120ft2)thinto70–80ft2

Standardshelterwood:Harvest40–50ft2frombelow,leaving80ft2inoverstory;removeoverstoryin10–15years

Spruce–fir:red/whitespruce,balsamfir

Shelterwood:Harvest60ft2 frombelow(leave100ft2);harvestremainderin10–15yearsSingletreeselection:At160ft2,remove50ft2inallsizes,every20years

Commercialthinning:Atage50–60,thinfrom150downto100ft2

Centralb

Oak–hickory

ClearcutShelterwood: followinglocalguidelinesGroupselectionwithcommercialthinningtoB‐levelstockingonGingrichGuide(Gingrich,1967)Precommercial/commercialthinningtoB‐levelstockingonGingrichGuideDiameterlimitcut:To12inchesDBHPrescribedfire:topromoteoakregenerationorwoodlandrestoration

Elm–ash–cottonwoodClearcutIndividualtreeselection: followinglocalguidanceDiameterlimitcut:To12inchesDBH

Maple–beech–birch

ClearcutShelterwood: followinglocalguidanceGroupselectionwithcommercialthinningtoB‐levelstockingonGingrichGuideIndividualtreeselection:CommercialthinningtoB‐levelstockingonGingrichGuideDiameterlimitcut:To12inchesDBH

Oak–pine

Clearcut:Shelterwood:GroupselectionwithcommercialthinningtoB‐levelstockingonGingrichGuideDiameterlimitcut:To12inchesDBHPrescribedfire:Topromote woodlandrestoration

RockyMountainSouthc

Drymontane:ponderosapine,Douglasfir

Selectioncutting:Harvest20–30ft2peracreevery20–30yearsacrosssizeclassesinstandsto40–80ft2BACommercialthinning:Atage60–80thinto50–60ft2 BAShelterwood:Harvest60–80ft2 BAfrombelow;leave30ft2inoverstory;removeoverstoryin5–10years

Aspen Coppice: Atage100Lodgepolepine Clearcut: Atage120–150

Spruce–firSingletreeselection:Harvest20–30ft2peracreevery20–30yearsacrosssizeclassesinstandsto80–120ft2BA

Woodlandtypes:pinyon–juniper,Gambreloak Selectioncutting:Harvestto40–60ft2BA

Southeastd

UplandhardwoodClearcut:Atage35–50Singletreeselection:Harvest40–60ft2peracreinstandswith100–140ft2peracre

BottomlandhardwoodSingletreeselection:Harvest40–60ft2peracreinstandswith100–140ft2peracre

Pineplantation–lowintensity

Plantwithnon‐improvedseedlings600–700peracre,thinto60–70ft2peracreatage18–24,clearcutatage25–35

Pineplantation–mediumintensity

Plantwithimprovedseedlings600–700peracre,thinto60–70ft2peracreatage18–22,fertilizeafterthinningwithnitrogenandphosphorus(ifneeded),clearcut5–7yearsafterthinning

Pineplantation–highintensity

Plantwithimprovedseedlings600–700peracre,herbaceousweedcontrolage2–4,thinto60–70ft2peracreatage16–20,fertilizeafterthinningwithnitrogenandphosphorus(ifneeded),clearcut5–7yearsafterthinning

SouthCentrald

UplandhardwoodClearcut:Atage35–50Singletreeselection:Harvest40–60ft2peracreinstandswith100–140ft2peracre

Bottomlandhardwood Singletreeselection:Harvest40–60ft2peracreinstandswith100–140ft2peracre

Pineplantation–lowintensity

Plantwithnon‐improvedseedlings450–700peracre, onlowerqualitysites,thinto60–70ft2peracreatage18–20;onhigherqualitysites,thinto60–70ft2peracreatage12–16,onhigherqualitysites,thinagainatage20–24,clearcut5–7yearsafterthinning

Pineplantation–mediumintensity

Plantwithimprovedseedlings600–700peracre,onlowerqualitysites,thinto60–70ft2peracreatage18–20;onhigherqualitysites,thinto60–70ft2peracreatage12–16,fertilizeafterthinningwithnitrogenandphosphorus(ifneeded),onhigherqualitysites,thinagainage20–24,clearcut5–7yearsafterthinning

Pineplantation–highintensity

Plantwithimprovedseedlings600–700peracre,herbaceousweedcontrolage2–4,onlowerqualitysites,thinto60–70ft2peracreatage18–20;onhigherqualitysites,thinto60–70ft2peracreatage12–16,fertilizeafterthinningwithnitrogenandphosphorus(ifneeded),onhigherqualitysites,thinagainatage20–24,clearcut5–7yearsafterthinning

NorthernLakeStatese

Aspen–birch

Clearcut:50–60yearrotationShelterwood:Whenbirchismaincomponent:twocutsystem,commercialthinningatage40–50onhighqualitysites

NorthernhardwoodsShelterwood:twostage;firstcut20yearspriortorotationage;commercialthinningasrequiredSingletree/groupselectionwith10–20yearcuttingcycle

Clearcut:Onlowerqualitysites,andonhighqualitysiteswhereadequateadvancedregenerationispresent;commercialthinningasrequiredShelterwood:Onhighqualitysiteswhenadequateadvancedregenerationisnotpresent;commercialthinningasrequired

JackpineClearcut:50–60yearrotation (notethatjackpinemanagedforKirtland’swarblerhabitatwillhaveadditionalmanagementrequirements)

Redpine

Clearcut:Commonlyfollowedbysitepreparationandplanting900peracre,commercialthinningbeginningatage25–40Shelterwood:Wherediseaseriskislow;oftenusedwithprescribedfire;commercialthinningbeginningatage25–40

WhitepineShelterwood:Twostagesystem;commercialthinningbeginningatage40

Whitespruce/balsamfirClearcut:WhenadequateregenerationispresentShelterwood:Twostagesystem,whenadequateregenerationisnotpresent

Lowlandconifer

Clearcut:Whenadequateregenerationispresent; patchandstripclearcutsmaybeusedinsomecasesShelterwood:Twostagesystem,whenadequateregenerationisnotpresent

GreatPlainsf Ponderosapine

Two‐cutShelterwood:reducebasalareatobelow60ft2peracre,thenremoveremainingoverstoryafteradequateregenerationispresentPrecommercialthinningasnecessarytomaintaindesireddensitiesArtificialregenerationmayberequiredaftercatastrophicdisturbancesortoestablishforestsonpreviouslyunforestedland;thismaybedonethroughbroadcastseedingorplanting

RockyMountainNorthg

PonderosapinePlant400–500trees peracre,precommercialthinto200–300treesperacre,commercialthinto150–200treesperacreatage30–40;clearcutharvestatage60–80

LodgepolepineSitepreparetoexposemineralsoilseedbed,naturalregenerationbyseeding,precommercialthinto200–400treesperacre,patchclearcutharvestatage80–100

PacificSouthwesth

Mixedconifer:ponderosapine,sugarpine,Douglasfir,incensecedar,whitefir,Jeffreypine,andCaliforniablackoak

Commercialthin:Startingatagesnear40andcontinuingatvariousperiodiccyclesuntilregeneration;post‐thinningstockinggenerallyrangesbetween150–250ft2;variablerotationlength,dependingonobjectivesCommercialthinningwithbothpatchregenerationandreservedareas:Similartoabove,butwithhigherlevelsofvariationinpost‐thinningstockinglevels,smallpatchesofregeneration,primarilytoincreasepinespecies,andsmallareasreservedfromharvest,maintaininglarger/oldertreesprovidingrelativelyuniquewildlifehabitats;variablerotationlength,dependingonobjectives

PacificNorthwest,Easti

Douglasfir/Ponderosapine–lowintensity

Sitepreparationbysitescarificationinsmallspots,naturalregeneration,precommercialthinatage20–25yearsto100–250treesperacre,patchclearcutorseed‐treeharvestatage50–70

Douglasfir/Ponderosapine–mediumintensity(onmoreproductivesites)

Mechanicalsitepreparationtoscarifysoilandremovecompetingvegetation,plantwithimprovedseedlingsatapprox.400–500peracre,precommercialthinatage15–20,commercialthinatage30–40,patchclearcutorseed‐treeharvestatage50–70

PacificNorthwest,Westj

Douglasfir

Sitepreparestandwithpre‐emergentherbicides,plantwithimprovedseedlingsatapprox.450peracre,commercialthinningasneededatage20–30,fertilizeasneededatage30–40,clearcutharvestatage40–50

DBH=DiameteratbreastheightaPersonalcommunication:BillLeak.bPersonalcommunication:SteveShifley.cPersonalcommunication:JamesYoutz,JimThinnes.dPersonalcommunication:StevePrisley.ePlanningdocumentsandsilvicultureguides,andpersonalcommunicationwithstaffontheHuron‐Manistee,Ottawa,and

HiawathaNationalForests.fSeeShepperdandBattaglia(2002).gSeeYoungblood(2005).hPersonalcommunication:JoeSherlock.iSeeBriggs(2007).jSeeHanleyandBaumgartner(2005).

6.4.3.3 ApplyingDefaultTablesofManagementPracticeScenarios

Oncethegeneralcategoriesofforesttypesandmanagementintensitiesaredefined,amodelingframeworksuchasFVScouldbeusedtodevelopsetsofdefaulttablesofcarbonstocksinvariouspoolsovertimeundermanagementscenarioscommontotheforesttypesandmanagementintensities.Notethatatthistime,theselookuptablesarenotavailable;developingdefaultcarbonstockvaluesforforestmanagementpracticesisataskrequiringasignificantleveloftimeandeffort.Intheabsenceofsuchtables,smalllandownerswishingtoestimatetheeffectsofchangingmanagementpractices(aTypeIIIestimate)willneedtousethemethodsdescribedforlargelandowners.

Table6‐7showsanunpopulatedexampleforthedefaultlookuptablesofmanagementpracticescenarios.Thedefaulttableswouldprovideregionalestimatesoftimbervolumeandcarbonstocksforaspecificforesttypegroup(e.g.,loblolly‐shortleafpinestands)underaspecific(e.g.,Softwood(planted)/veryhigh)managementintensityonforestlandafterclearcutharvestinaspecificregion(e.g.,theSoutheast)forlowproductivityandhighproductivitysites.

Table6‐7:RegionalEstimatesofTimberVolumeandCarbonStocksforaSpecificForestTypeGroup(e.g.,Loblolly‐ShortleafPineStands)UnderaSpecific(e.g.,Softwood(Planted)/VeryHigh)ManagementIntensityonForestLandafterClearcutHarvestinaSpecificRegion(e.g.,theSoutheast)forLowProductivityandHighProductivitySites

Note:Atthistime,populatedtablesarenotavailable;developmentofsuchtablesisnotcertain.

AgeMeanVolume

MeanCarbonDensity

LiveTree StandingDeadTree

DownDeadWood

ForestFloororLitter

TotalNonsoil

Years m3ha−1 ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐MetricTonsCha−1(LowProductivity)‐‐‐‐‐‐‐‐‐‐‐‐‐0 ‐ ‐ ‐ ‐ ‐ ‐5 ‐ ‐ ‐ ‐ ‐ ‐10 ‐ ‐ ‐ ‐ ‐ ‐15 ‐ ‐ ‐ ‐ ‐ ‐20 ‐ ‐ ‐ ‐ ‐ ‐25 ‐ ‐ ‐ ‐ ‐ ‐30 ‐ ‐ ‐ ‐ ‐ ‐35 ‐ ‐ ‐ ‐ ‐ ‐40 ‐ ‐ ‐ ‐ ‐ ‐45 ‐ ‐ ‐ ‐ ‐ ‐50 ‐ ‐ ‐ ‐ ‐ ‐55 ‐ ‐ ‐ ‐ ‐ ‐60 ‐ ‐ ‐ ‐ ‐ ‐65 ‐ ‐ ‐ ‐ ‐ ‐70 ‐ ‐ ‐ ‐ ‐ ‐75 ‐ ‐ ‐ ‐ ‐ ‐80 ‐ ‐ ‐ ‐ ‐ ‐85 ‐ ‐ ‐ ‐ ‐ ‐90 ‐ ‐ ‐ ‐ ‐ ‐

AgeMeanVolume

MeanCarbonDensity

LiveTree StandingDeadTree

DownDeadWood

ForestFloororLitter

TotalNonsoil

Years m3ha−1 ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐MetrictonsCha−1(highproductivity)‐‐‐‐‐‐‐‐‐‐‐‐ 0 ‐ ‐ ‐ ‐ ‐ ‐5 ‐ ‐ ‐ ‐ ‐ ‐10 ‐ ‐ ‐ ‐ ‐ ‐15 ‐ ‐ ‐ ‐ ‐ ‐20 ‐ ‐ ‐ ‐ ‐ ‐25 ‐ ‐ ‐ ‐ ‐ ‐30 ‐ ‐ ‐ ‐ ‐ ‐35 ‐ ‐ ‐ ‐ ‐ ‐40 ‐ ‐ ‐ ‐ ‐ ‐45 ‐ ‐ ‐ ‐ ‐ ‐50 ‐ ‐ ‐ ‐ ‐ ‐55 ‐ ‐ ‐ ‐ ‐ ‐60 ‐ ‐ ‐ ‐ ‐ ‐65 ‐ ‐ ‐ ‐ ‐ ‐70 ‐ ‐ ‐ ‐ ‐ ‐75 ‐ ‐ ‐ ‐ ‐ ‐80 ‐ ‐ ‐ ‐ ‐ ‐85 ‐ ‐ ‐ ‐ ‐ ‐90 ‐ ‐ ‐ ‐ ‐ ‐

TypeIestimatesmaybedevelopedforstanddensitymanagement.Forunderplanting,carbonstocksareessentiallyunchangedimmediatelyafterthetreatment.Forprecommercialthinnings,carbonismovedfromthelivetreepooltothestandingdeadpooland/orforestfloorpool;quantitieswillbelowandessentiallyjustacceleratethenaturalmortalityofthesesmallertrees,thusaccountingforthisactivitymaybeunnecessary.Forcommercialthinning,thelivetreecarbonstockisreducedandcarbonismovedintoHWPs,sothesepoolsneedtobeestimatedusingproceduresoutlinedinSection6.2andSection6.5.

TypeIIandIIIestimatesmaybedevelopedusingforestgrowthmodels(i.e.,FVS)specifictotheforesttypeandpracticesused.

6.4.4.2 SitePreparationTechniques

Carbonstockchangesthatareduetomechanicalsitepreparationtechniqueswillconsistofsomeoxidationofsoilorganiccarbonthatwillbereplacedovertimebyforestgrowth.Forlong‐termmonitoring,itmaybeassumedthatsoilcarbonstockswillbestableundersustainableforestmanagement(Smithetal.,2006).Thus,TypeIestimatescouldreflectshort‐termlossesofsoilcarbonstocksbasedonassumptionsappropriatetotheforesttypeandregion.

Controlofwoodyvegetationwillexhibitpatternssimilartoprecommercialthinning:transferofcarbonstocksfromlivetreetodeadtreepools.Quantitieswilllikelybesmallandtheeffectofshortduration;henceaccountingfortheseimpactsusingTypeIestimatesmaybeunnecessary.

ForTypeIIandIIIestimates,vegetationcontrolmaybeexpectedtohaveabeneficialimpactonthe

growthoftheresidualstandthatshouldbemodeledaccordingly.

6.4.4.4 Planting

Negligiblecarbonstockchangesareexpectedatthetimeofestablishmentofanewplantation,soTypeIestimateswillshownostockchanges.ForTypeIIandIIIestimates,theplantationactivityestablishesanewstandthatcanthenbemodeledbasedonspecies,siteindex,andinitialstocking(plantingdensitytimesyear1survivalpercent).

Asinthecaseofplantationestablishment,carbonstockchangesatthetimeofnaturalregenerationarenegligible.ForTypeIIandIIIestimatesinvolvingprojectionsofstandgrowthovertime,initialstocking,speciesmix,andsiteproductivitywilldefinethestandparametersforgrowthprojections.

6.4.4.6 HarvestingandUtilization

Dependingontheharvestingandsilviculturalsystemused,multiplestockchangesoccurwitharotationharvest.Livetreebiomassstocksarereducedbytheamountofharvestedwood(upto100percentofthelivetreebiomasspool).TheseremovalsshouldbebalancedbyadditionstoHWPpoolsandslash/residueintheforestflooranddeadwoodpools.Becauselossestosoilorganiccarbonpoolsfromdisturbancebymechanizedharvestingsystemsareofrelativelyshortduration,itiscommontoconsiderthelossandrecaptureasasteadystate(e.g.,Smithetal.,2006),thoughthismaydifferdependingonsoilcharacteristics.

Inthecaseofpartialharvests,thereisaresidualstandforwhichcarbonstocksremaintobeprojectedovertime.Post‐harvestinventoryinformationprovidesthecriticalstandparameterstobeinputintogrowthmodels.Intheabsenceofapost‐harvestinventory,pre‐harvestinventorydatacanbeadjustedtoreflectthelossoftreesremovedbytheharvest(e.g.,bydecreasingthenumbersoftreesbyspeciesanddiameterclassbasedonharvestrecords).

TypeIestimatesofcarbonstockchangesduetofueltreatmentsorprescribedfireshouldreflectlossestolivetreebiomassaccordingtothematerialburned,killed,orremoved(frompreandpost‐treatmentinventorydata).Foraprescribedfire,emissionscanbecalculatedusingFOFEM.Ifslashisleftfromthefueltreatment,CONSUMEmayalsobeused.

TypeIIandIIIestimatessimplyinvolveprojectingthestandbasedoninformationfromthepost‐treatmentinventory.

TypeIcarbonstockestimateswillinvolvecomputationoflossestolivetreebiomassfromthesanitationorsalvageharvest,withadditionstoHWPpoolsasappropriate.

TypeIIandIIIestimatessimplyinvolveprojectingthestandbasedoninformationfromthepost‐treatmentinventory.

Negligiblecarbonstockchangesareexpectedatthetimeofestablishmentofanewplantation,soTypeIestimateswillshownostockchanges.ForTypeIIandIIIestimates,theplantationactivityestablishesanewstandthatcanthenbemodeledbasedonspecies,siteindex,andinitialstocking(plantingdensitytimesyear1survivalpercent).

6.4.5.1 MeasurementUncertainties

Forestinventorydata,fromwhichmostestimatesinthissectionarederived,containuncertaintyasaresultofsamplingandmeasurementerror.Furthermore,equationsareusedtoestimatebiomassfromtreemeasurements(species,diameters,heights),andtheseequationsintroduceadditionalerrors.Theseuncertainties,however,arewelldocumentedandcanbequantified.

6.4.5.2 ModelUncertainties

ForthedevelopmentofTypeIIandTypeIIIestimates,modelsareusedtoprojectcurrentconditionsintothefuture.Thesetypesofestimatesarebasedinitiallyoninventorydataandaresubjecttothemeasurementuncertaintiesdiscussedabove,butarealsosubjecttomodelingerror.Modelingerrorcanbedocumentedinpartbasedonthediagnosticsreported(ifany)fromthemodeldevelopmentprocess.Greateruncertaintiesareintroducedwhenmodelsareappliedbeyondtheconditionsforwhichtheyweredeveloped(e.g.,biomassequationsappliedtospeciesforwhichnobiomassdatawerecollected,forestgrowthmodelsappliedtostandsreceivingdifferentmanagementthanthestandsusedformodeldevelopment,etc.).Modeluncertaintiesalsoincreasewiththeprojectionperiod(thedistanceintothefutureforwhichestimatesareobtained).Someofthemodeluncertaintiesarecancelledoutwhenresultsfromtwosimilarmodelrunsarecompared(i.e.,aTypeIIIestimate).Forexample,ifamodelslightlyoverestimatescarbonstockinaforestwithandwithoutsometreatment,thedifferencebetweenthetwomodelestimatesmaybeaccurateeveniftheindividualestimatesarenot.

6.4.5.3 GeneralizationUncertainties

ForthepurposeofapplyingnationallyconsistentestimationmethodstoTypeIIandIIIestimates,itisnecessarytogeneralizesituationsintobroadforesttypesandmanagementintensities.Thus,someprecisionislostinapplyingageneralized,aggregatedestimatetoaparticularsetofmanagementactivities.

6.5 HarvestedWoodProducts

6.5.1 GeneralAccountingIssues

Whenforestlandownersharvestwoodforproducts,aportionofthewoodcarbonendsupinsolidwoodorpaperproductsinenduses,andeventuallyinlandfills,andcanremainstoredforyearsordecades.Thisreportsuggestsaspecificmeasure,alongwithestimationmethods,that

MethodforHarvestedWoodProducts

MethodusesU.S.‐specificHWPstables.

TheHWPstablesarebasedonWOODCARBIImodelusedtoestimateannualchangeincarbonstoredinproductsandlandfills(Skog,2008).

TheentityusesthesetablestoestimatetheaverageamountofHWPcarbonfromthecurrentyear’sharvestthatremainsstoredinendusesandlandfillsoverthenext100years.

Thismethodwasselectedbecauseitissuitabletorepresenttheamountofcarbonstoredinproductsinuseandinlandfills.

forestlandownerscanusetoreportcarbonadditionstothestockofHWPsfromwoodtheyharvest.TheaccountingframeworkusedtotrackHWPcarbonissimilartotheframeworkthattheUnitedStatesusestoreportnational‐levelannualchangesinHWPcarbonstocksunderUNFCCC.

Thenationalaccountingframeworkandthesemethodsadopttheproductionapproach,whichentailsthefollowing:(1)estimatingtheannualcarbonadditionstoandremovalsfromthestockofcarbonheldinwoodproductsinuseandinlandfills,(2)trackingonlycarboninwoodthatwasharvestedintheUnitedStates(U.S.EPA,2011),and(3)providingestimatesthattrackwoodcarbonheldinproducts,evenifistheproductsareexportedtoothercountries.

EstimatesoftheannualcontributionofHWPstocarbonstocksmaybemadeforTypeI,TypeII,andTypeIIIestimatesofforestcarbonchangeasoutlinedinSection6.2:

ForTypeIestimates,thefocusisonestimatingtheannualcontributionofHWPstocarbonstocksforagivencurrentyearorrecentpastyears.

ForTypeIIestimates,thefocusisonestimatingtheannualcontributionofHWPstocarbonstocksforaprojectedperiodofyearsinthefuture.

ForTypeIIIestimates,thefocusisonestimatingthechangeintheannualcontributionofHWPstocarbonstocksbetween:(1)abasecasewithonescenarioforforestmanagement(andharvest);and(2)asecondscenarioforforestmanagement(andharvest)thatisintendedtochangecarbonflux.

ForeachoftheTypeI,II,orIIIestimates,thesemethodsrecommendthatforestlandownersreporttheannualcontributionofHWPstocarbonstocksusingaspecificmeasureintendedtoapproximatetheclimatemitigationbenefitassociatedwithstoringcarboninHWPsovertime.TherecommendedmeasureistheestimatedaverageamountofHWPcarbonfromthecurrentyear’sharvestthatremainsstoredinendusesandlandfillsoverthesubsequent100years.

Theintentofthismeasureistoapproximatetheaverageannualclimatebenefitofwithholdingcarbonfromtheatmospherebyacertainamounteachyearfor100yearsasdescribedbya“decay”curve.Thisaveragebenefitisonethatcanbecreditedintheyearofharvest.ThisestimateofaverageeffectisconceptuallysimilartothemeasureoftheradiativeforcingimpactofacurrentyearemissionofCO2,CH4,orotherGHG.OnetonofCO2emissions—inGHGaccounting—isequatedtotheradiativeforcingitcausesoverthe100yearsfollowingtheemission.Theradiativeforcingcausedineachyearisweightedthesameovereachofthe100years.Wearesuggestingthesameconventioninweightingthecarbonstorageinwoodproductsequallyforeachof100years.

AnestimateofaveragefractionofHWPcarbonstoredover100years(averageamountstoredover100yearsdividedbytheoriginalproductcarbonproduced)isnotexactlythesameasthefractionofradiativeforcingavoidedbystoringwoodproductscarbon(andemittingcarbonslowly)over100years.FordecaycurveswhereaconstantfractionofremainingHWPcarbonisemittedeachyearthefractionofradiativeforcingavoidedover100yearscanbe0to14percentlessthantheaveragefractionofHWPcarbonstoredover100yearsdependingonthedecayrate.8Estimatesofthefractionofradiativeforcingavoidedover100yearscouldbeusedinplaceoftheaveragecarbonstorage.Giventheuncertaintyindecayratesasaninfluenceonestimatesandthegreatercomplexityoftheradiativeforcingmeasure,werecommendthemeasureofaveragecarbonstoredasanadequateproxyfortheeffectofwoodproductsproducedinthecurrentyearandstoredover

8Thefractionofradiativeforcingavoidedover100yearswasestimated(andcomparedtoaveragecarbonstoredover100years)assumingarangeofdecayratesforfirstorderdecaycurvesforwoodproductsandusingtheCO2radiativeforcingresponsecurvefromtheIPCCWorkingI4thAssessmentReport(footnotea,p.213)(IPCC,2007).

100years.

Themeasure—averagecarbonstoredinHWPover100years(withvariationsonhowlandfillcarbonisincluded)—isusedintheClimateActionReserve(2010)ForestProjectProtocolsadoptedbytheCaliforniaAirResourcesBoard.Theprotocolsindicatehowtocalculatethelevelofannualcarboncreditsthatmaybesoldbyforestlandownerswhoentercarboncontracts.

Notethatuseoftheproductionapproachtoaccountingisnotalife‐cycleassessmentaccountingapproachthatcouldtakeintoaccounthowcarbonemissionsfromincreasedwoodburningorincreaseduseofwoodproductsmightoffsetfossilfuelemissionsoremissionsfrommakingnon‐woodproductsovertime.TheestimatesofannualchangeincarboninHWPsarenotintendedtoindicatethetotalimpactonGHGlevelsintheatmosphereofusingHWPs(includinguseofwoodforenergy),noraretheyintendedtoindicatethattheemissiontotheatmospheretookplaceintheUnitedStatesversusothercountrieswhereproductswereexported.EstimationofTypeIIIsecondaryGHGreductioneffectsofsubstitutionofwoodforfossilfuelsornon‐woodconstructionproductsarecomplexandwouldrequirespecificationofabaselinefromwhichchangeismeasuredandotherassumptionsthatarebeyondthescopeofthesemethods.

Theproductionapproachisusedtoacknowledgethatharvestingofforestsdoesnotimmediatelyreleaseallofthecontainedcarbontotheatmosphere;theaccountingcountsonlythecarbonchangeinHWPsinordertoallowannualcarbonchangesinHWPstobedeductedoraddedtoannualemissionsintheenergyandmanufacturingsectorsandcarbonchangesinforests,sotherewillbenoomissionordoublecountingofsequestrationoremissionstotheatmosphere.Inthenationalaccountingframework,theannualemissionsfromwoodenergyareaccountedforaspartoftheaggregatedannualchangeinforestplusHWPcarbon.

6.5.2.1 WoodProductsFate/Longevity

ToallowforestlandownerstoestimatecarbonadditionstoHWPstocks—usingaveragecarbonstoredinHWPover100years—lookuptablesareprovidedthatgiveestimatesofcarbonremainingstoredafterharvestoutto100years.

Therearetwotypesoflookuptables:a“roundwood”typeanda“primaryproduct”type.

Fortheroundwoodtype,thelandownerneedsestimatesofthecarboninharvestedamountsofindustrialroundwood:hardwood(HW)orsoftwood(SW),sawlogs(SL),orpulpwood(PW).Industrialroundwoodiswoodusedforsolidwoodorpaperproductsandexcludesbarkandfuelwood.Thelandownercanbeginwithestimatesincubicunitsandconvertthemtocarbonweightorwoodweightunitsthenconvertthemtocarbonweight(assuming0.5metrictonscarbonpermetrictondrywood).Separatelookup“decay”tablesareprovidedbymajorU.S.regionandroundwoodtype(HWorSW,SL,orPW)thatshowthefractionofcarboninwoodtypicallystoredinwoodproductsinuseandinlandfills,outto100yearsaftertheyearofharvest,andtheaveragefractionstoredover100years.

Fortheprimaryproducttypeoflookuptables,thelandownerneedsestimatesoftheprimarywoodproductsmadefromthewoodharvested;i.e.,SWorHWlumber,SWorHWplywood,orientedstrandboard,orpaper(inconventionalproductunits).Thelandownerthenconvertstheseamountstocarbonweight.Foreachprimaryproduct,thelookup“decay”tablesshowthefractionofwoodcarbonthatistypicallystoredinwoodproductsinuseandinlandfills,fromtheyearofharvestoutto100years,andtheaveragefractionofcarbonstoredover100years.

6.5.3.1 PrimaryProductDecayTables

Inordertoconstructtheprimaryproducttypedecaytables,dataareusedforeachU.S.regionon:

Thedispositionofeachprimaryproduct(e.g.,lumber,structuralpanels)tomajorenduses(e.g.,percentageofproductgoingtoresidentialhousing,non‐residentialhousing,manufacturing(furniture)),andpercentagegoingtoexports;

Thedecayfunctionsindicatinghowquicklyproductsgooutofuseforeachenduse;

Thefractionofmaterialgoingoutofusethatgoestolandfills;and

Thefractionofmaterialinlandfillsthatdoesnotdecay,andthedecayrateformaterialinlandfillsthatdoesdecay.

ItisassumedthatthereisanationalmarketforprimaryproductsandthepercentageofprimaryproductsgoingtoeachendusewillbethesameforeachU.S.region.ItisalsoassumedthatprimaryproductsexportedfromtheUnitedStatesareusedinthesamewayasdomesticproducts.Thatis,thereisanationalmarketforeachoftheprimarywoodandpaperproducts.Dataforitems(1)through(4)comefromtheWOODCARBIImodelusedtoestimateannualchangeincarbonstoredinproductsandlandfillsfortheU.S.InventoryofGHGEmissionsandSinksreport(Skog,2008;U.S.EPA,2010).

Ifalandownerknowsthetraditionalnumberofunitsofprimaryproducts(e.g.,thousandboardfeetoflumber)thatweremadefromthetimberharvestedfromtheirlandinagivenyear,theycanuseTables6‐A‐1,6‐A‐2,and6‐A‐3toestimatethecarboncontentsintheseproducts(Table6‐A‐1)andestimatetheamountofcarbonstoredintheseproducts(inuseandinlandfills)outto100yearsandtheaverageamountofcarbonstoredover100years(Table6‐A‐2[inuse]andTable6‐A‐3[inlandfills]).

Theaverageamountofcarbonstoredover100yearsforaparticularprimaryproductisthetotaloftheaveragesforproductsinuseandproductsinlandfillsshowninTables6‐A‐2(inuse)andTable6‐A‐3(inlandfills).

6.5.3.2 RoundwoodDecayTables

Inordertoconstructtheroundwoodtypeofdecaytables,dataareneededforeachregiononthepercentageofHWorSW,SL,orPWthatgoestovariousprimarywoodproducts;forexample,thefractionofSWSLsintheSouththatgoestolumber,panels,andpaper.Aftertheamountsofprimarywoodproductsareestimated,theprimaryproductstypedecaytablescanbeusedtoconstructroundwooddecaytables.DataneededtodivideroundwoodintoprimaryproductsforeachregionincludeForestServiceFIAtimberproductoutputdataandnationaldataonprimarywoodproductsproduction(Howard,2012;Smithetal.,2007).

Ifalandownerknowsthecubicfeetofroundwood,intheformofHWorSWSLsorPWthatisharvestedfromtheirlandinagivenyear,theycanuseTable6‐A‐4and6‐A‐5to(1)estimatetheweightofwoodharvested;(2)convertweightofwoodtocarbonbymultiplyingby0.5(i.e.,thefractionofdrybiomasstocarbonconversionfactor);and(3)estimatethetotalamountofcarbonstoredintheproducts(thesumofamountsinuseandinlandfills)eachyearoutto100years,andtheaveragestoredover100years.

Ifthelandownerknowstheweightofroundwoodharvestedratherthancubicfeet,itwouldusesteps2and3above.

AnnualHWPcarbon(averagestoredover100years)isgivenforeachregionandroundwoodtype

inTable6‐A‐5.

Ifthelandownerismakingforestgrowthandharvestprojections(TypeIIandTypeIIIestimates)andonlyknowsthecubicfeet(orweight)ofgrowingstockofHWandSWSLsandPWthatwillbeharvestedingivenfutureyears,thenTable6‐A‐6canbeusedtoestimatethetotalamountofroundwoodthatcanexpectedtobeharvested(growingstockandnon‐growingstock).Thesetotalamountsofroundwood(HWandSWSLsandPWmaythenconvertedtocarbonandtocarbonstored(andaveragecarbonstoredover100years)usingTable6‐A‐4andTable6‐A‐5,asdiscussedabove.Toconvert1cubicfootofdrywoodtopoundsmultiplydensityby62.4lbsft−3.Toconvert1cubicfoottokilogramsmultiplydensityby28.3kgft−3.

Aspreadsheetisavailableshowingalltheparametersandcalculationsthatproducethecarbonstoragetablesthatstartwithprimaryproductsorroundwoodharvest(Skog,2013).

6.5.4 Limitations,Uncertainty,andResearchGaps

6.5.4.1 UncertaintyinCchangeestimate

Generalestimatesofuncertainty,givenasthe95percentconfidenceintervals,canbemadeforHWPmeasureusedinTypeIcarbonchangeestimates(currentyearorrecentpastyears).Theseestimatesofuncertaintycouldbeprovidedwitheachofthetwotypesoflookuptables,andcanbemadeusingMonteCarlosimulationsandassumptionsaboutHWPuncertaintythatareusedfortheInventoryofU.S.GreenhouseGasEmissionsandSinksreport(U.S.EPA,2011).Uncertaintycouldbespecifiedforkeyvariablesincluding:(1)fractionsofSLsPWgoingtovariousprimaryproducts;(2)fractionsofprimaryproductsgoingtovariousenduses;(3)rateatwhichproductsarediscardedfromeachenduse;(4)fractionofdiscardedwoodorpaperthatgoestolandfills;(5)fractionofwoodorpapersettolandfillsthatissubjecttodecay;and(6)rateofdecayinlandfillsofdegradablewood/papercarbon.

AspreadsheetisavailablethecouldbeusedasabasisforMonteCarlosimulationstoestimateoveralluncertaintyforestimatesofaveragecarbonstoredover100years(Skog,2013).

ItwouldbepossiblebutmorecomplextomakeuncertaintyestimatesforTypeIIandTypeIIIcarbonchangeestimatesbyaddingestimatesofuncertaintyinparametersusedtomakeprojectionsofharvest.

Additionalresearchisneededtoimprovedifferentiationofthevariousratesatwhichsolidwoodproductsarediscardedfromusessuchaspallets,railroad,railcars,andfurniturethatarecurrentlygroupedintoonecategory.Thisfurtherdifferentiationwouldrefineestimatesofaveragecarbonstoredwhenthelandownerknowswhichprimarywoodproductsaremadefromthewoodthatisharvestedontheirland.Alternatecurvesfordiscardratesfromenduses,particularlydiscardsfromhousing,ifempiricallyverified,couldimproveestimatesofaveragecarbonstored.Estimatesofuncertaintyinparametersover100yearprojectionsareneededtogiveasoundestimateoftheuncertaintyinaveragecarbonstoredover100years.

6.6 UrbanForests

6.6.1 Description

6.6.1.1 DefiningUrbanAreasandForests

Urbanforestsarecomposedofapopulationofalltreeswithinanurbanarea.Todelimittheextentofanurbanforest,theboundariesoftheurbanareamustbedrawn.Thisboundaryissuecanbeproblematic,aspeoplemayconceiveordefine“urban”differently.TodelimiturbanareasintheUnitedStates,U.S.Censusbureaudefinitionsareused.ThesedefinitionsdifferfromthoseusedintheNationalResourcesInventory,whichaimstoidentifyareasthatareremovedfromtherurallandbaseandincludeslandusessuchastransportationcorridors.

TheU.S.CensusBureau(2007)definesurbanasallterritory,population,andhousingunitslocatedwithinurbanizedareasorurbanclusters.Urbanizedareaandurbanclusterboundariesencompassdenselysettledterritories,whicharedescribedbyoneofthefollowing:(1)oneormoreblockgroupsorcensusblockswithapopulationdensityofatleast386.1peoplekm−2

Figure6‐7:UrbanandCommunityLandinConnecticut

Source:U.S.CensusBureau(2007).

MethodsforUrbanForests

Rangeofoptionsdependsondataavailabilityoftheentity’surbanforestland.

Theseoptionsuse:

− i‐TreeEcomodel(http://www.itreetools.org)toassesscarbonfromfielddataontreepopulations;and

− i‐TreeCanopymodel(http://www.itreetools.org/canopy/index.php)toassesstreecoverfromaerialimagesandlookuptablestoassesscarbon.

Quantitativemethodsarealsodescribedformaintenanceemissionsandalteredbuildingenergyuseandincludedforinformationpurposesonly.

Themethodswereselectedbecausetheyprovidearangeofoptionsdependentonthedataavailabilityfortheentity'surbanforestland.

(1,000peoplemile−2);(2)surroundingblockgroupsandcensusblockswithapopulationdensityof193.1peoplekm−2(500peoplemile−2);and(3)lessdenselysettledblocksthatformenclavesorindentationsorareusedtoconnectdiscontinuousareas.Morespecifically,urbanizedareasconsistofterritoriesof50,000ormorepeople.Urbanclusters,aconceptnewtothe2000Census,consistofterritorieswithatleast2,500peoplebutfewerthan50,000people.

Inadditiontourbanland,theCensusBureaudesignatesplacesthatdelimitpopulationconcentrationsbasedonincorporatedorunincorporatedplaces,suchasacity,town,village,andcensus‐designatedplace.Theseplaces,or“communities,”alsodefineareaswherepeoplereside,butoftenwithalowerpopulationdensity.Thegeographicareasofurbanandcommunitiesoverlap(seeFigure6‐7),andeitherorbothcouldbeusedtodefineurbanforests.Theurbanlanddesignationdelimitshigherpopulationdensities,butdoesnotfollowtheboundariesofcitiesortownsthatmostpeoplecanrelateto.Theplaceorcommunityboundariesfollowthesepoliticalboundaries,butoftenincludebothruralandurbanland.

Urbanlandisdefinedbasedonpopulationdensity,andcommunitylandisoftenbasedonpoliticalboundaries.Thus,urbanforestlandoverlapswithforestlands.Thatis,forestedstandsthataremeasuredaspartofotherprogramscanexistwithinurbanorcommunityboundaries.Assessmentsofurbanforesteffectsthushavethepotentialtodouble‐counteffectsfoundinforestswithinregionalornationalscaleassessments.Theamountofthisoverlapisestimatedas13.8percentofurbanareaor1.5percentofforestareaintheconterminousUnitedStates(Nowaketal.,2013)andisanimportantconsiderationforlargerscaleassessments.ThissectionfocusesonassessingthecarboneffectsofurbanorcommunitytreesandforestsintheUnitedStates.

Urbanorcommunityforests(hereafterreferredtoasurbanforests)affectthecarboncyclebydirectlystoringatmosphericcarbonwithinthewoodyvegetation,butalsobyaffectingthelocalclimateandtherebyalteringcarbonemissionsaffectedbylocalclimaticconditions.Urbantreemaintenanceactivitiesalsoaffectcarbonemissionsinurbanareas.Foratrueaccountingofcarboneffects,allofthesefactorsneedtobeconsidered.Thisreportfocusesontrees(definedaswoodyvegetationwithadiameterofatleast1inch(2.5cm)DBH),butsimilaraccountingcouldbeconductedforallurbanvegetation.

6.6.1.2 AccountingforPrimaryUrbanForestCarbonEffects

Treessequesterandstorecarbonintheirtissueatdifferingratesandamounts,basedonsuchfactorsastreesize,lifespan,andgrowthrate.Afteratreeisremoved,thetreecandecomposewiththecarbonstoredinthattreeemittedbacktotheatmosphere,orthecarbonmaybestoredinwoodproductsorthesoil.Thus,inordertoaccountforthetotalcarboninthesystematonetime,oneneedstounderstandhowmanytreesthereareinthesystemalongwithinformationsuchasspeciesandsize(e.g.,NowakandCrane,2002).Toaccountforhowthecarbonstockwillchangethroughtime,onemustalsoaccountforgrowthrates,treemortalityandremovals,andthedispositionofthewoodafterremoval(e.g.,chipping,burning,products),whichaffectdecompositionratesandcarbonemissions.Inaddition,thenumberofnewtreesenteringthesystemthroughtreeplantingandnaturalregenerationmustbeconsidered.

6.6.1.3 AccountingforSecondaryEffects

Inadditiontothecarbonstoredintrees,theurbanforesthassecondaryimpactsonatmosphericcarbonbyaffectingcarbonemissionsfromurbanareas.Treecareandmaintenancepracticesoftenreleasecarbonbacktotheatmosphereviafossil‐fuelemissionsfrommaintenanceequipment(e.g.,chainsaws,trucks,chippers).Thus,someofthecarbongainsfromtreegrowthareoffsetbycarbonlossestotheatmosphereviafossilfuelsusedinmaintenanceactivities(Nowaketal.,2002).Treesstrategicallylocatedaroundbuildingscanreducebuildingenergyuse(e.g.,Heisler,1986),and

consequentlyreducecarbonemissionsfromfossil‐fuel‐burningpowerplants.Theseenergyeffectsarecausedprimarilybytreetranspiration(loweringofairtemperatures),blockingofwinds,andshadingofbuildingsandothersurfaces.Treestypicallylowerbuildingenergyuseinsummer,butcaneitherlowerorincreasebuildingenergyuseinthewinterdependinguponthetree’slocationrelativetoabuilding.

“Alteredbuildingenergyuse”and“maintenanceemissions”forurbantreesaredescribedinSection6.6.3.1.However,whilequantitativemethodsaredescribedforestimatingalteredbuildingenergyuseandmaintenanceemissionsforurbanforestry,theyareincludedforinformationpurposesonly,sincetheyhavealreadybeendevelopedaspartofthei‐Treesoftwaresuite.However,aspreviouslymentionedinChapter1,thescopeofthisguidancedoesnotincludeotherenergy‐relatedsourcecategoriesthatareassociatedwithmanagementactivitiesrelatedtocertainagricultureandforestryactivities(e.g.,transportation,fueluse,heatingfueluse).

Toestimatecarbonstorage,annualsequestration,andlong‐termcarbonchanges,twogeneralapproachescouldbeused.Thefirstmethodisbasedoncollectingdataontreesintheurbanareaofinterest;thesecondmethodinvolvescollectingaerialdataontreecoverinthearea,andusingtablestoestimateeffectsbasedonfielddatafromotherareas.Thefirstmethod,usinglocalfielddata,willproducethemostaccurateestimatesforthelocalarea,butatincreasedcostsandtimespentbythelandowner.Thesecondmethodismorecost‐effectiveandmorestraightforward,butitsaccuracyismorelimited(seeTable6‐8).

Table6‐8:Comparisonofthe“FieldData”and“Aerial”MethodsforEstimatingtheChangesinCarbonStocksforUrbanForests

FieldDataMethod AerialMethod

Requiressignificanttimecommitmenttotakefieldmeasurements

Requireslesstimetoextractnecessaryaerialdatafromanexistingdatabase

Requiresaccesstoseveralsampleplotsacrossanarea

Doesnotrequirefieldmeasurements,onlyacomputerwithinternetaccess

Increasesspecificityandaccuracy ReturnsamoreapproximateestimateProvidesavarietyofoutputdataincludingcurrentcarbonstock,annualcarbonsequestration,andlongtermeffects

Providesonlyinformationontotalcarbonstoredandannualcarbonsequestration

Theoutputdatafromthefielddatamethodincludescurrentcarbonstock(existingcarbonstorage),annualcarbonsequestrationbytrees,andlongtermeffectsoftheforest(accountingforchangesintreepopulationanddispositionofcarbonfromtrees).Forthefielddatamethod(orforproducingthedefaulttablesthatareusedintheaerialapproach)thefollowingitemsneedtobemeasuredandinputbythelandowner:

CurrentStock:

− Numberoftreesbyspeciesandsizeclass(species,DBH,height,condition,competitionfactor)

AnnualSequestration:

− Annualgrowthratesforeachtreebasedontreeandsiteconditions(inchesperyear)

LongTermEffects:

− Annualgrowthratesforeachtreebasedontreeandsiteconditions(inchesperyear)

− Changesintreepopulationduetotreedeathandremovals,andnewtreesplantedornaturallyregenerated(numbersoftreesdyingbyspeciesandsizeclass,numberofnewtreesbyspeciesandsizeclass)(numberperyear)

Proportionofremovedtreebiomassthatis:

− Chipped/mulched

− Burned

− Burnedtoproduceenergy(e.g.,heatbuildings)

− Belowthegroundinroots

− Usedforlong‐termwoodproducts

− Leftonthegroundtodecomposenaturally

− Putinlandfills

Decomposed;decompositionratesforwoodfromremovedtrees:

− Percentageofbiomassperyeardecomposedperremovalclassabove

MaintenanceEmissions:

− Amount(numberandhoursperyear)ofmaintenanceequipmentused(e.g.,vehicles,chippers,chainsaws)forvegetationmaintenance(e.g.,planting,maintenance,treeremoval)

− Emissionfactors(gChr−1)foreachmaintenanceequipmentused

AlteredBuildingEnergyUse:

− Numberoftreesbyspeciesandsizeclasswithin60feet(18.3m)ofresidentialbuildingbycardinalandordinaldirection

Forestimatingtreecoverusingtheaerialapproach,onewouldneedtoknowtheextent(ha)oftheurbanareaandthepercentageoftreecoverwithinthearea,anduseadefaulttableofvaluestoconverthaoftreecovertoprimaryandsecondarytreeeffectsinacity.Toestimatechangeinthepopulation,thetreecoverwouldneedtobere‐measuredthroughtime.

Aspreviouslymentioned,alteredbuildingenergyuseandmaintenanceemissionsforurbantreesaredescribedinSection6.6.3.1.However,whilequantitativemethodsaredescribedforestimatingalteredbuildingenergyuseandmaintenanceemissionsforurbanforestry,theyareincludedforinformationpurposesonly,astheyarepartofthei‐Treesoftwaresuiteorcanbecalculatedfromi‐Treedata.

Themethodsforestimatingcarboneffectsinanurbanforestwillbedetailedforthefielddataandaerialapproachesseparately.ThefielddatamethodandaerialmethodforurbanforestsaredescribedinSection6.6.3.1andSection6.6.3.2.Figure6‐8showsadecisiontreeindicatingwhichmethodismoreapplicableforeachtypeofactivitydata.

Figure6‐8:DecisionTreeforUrbanForestsShowingMethodsAppropriateforEstimatingUrbanForestCarbonStocks

1TheU.S.CensusBureau(2007)definesurbanasallterritory,population,andhousingunitslocatedwithinurbanizedareasorurbanclusters.Urbanizedareaandurbanclusterboundariesencompassdenselysettledterritories,whicharedescribedbyoneofthefollowing:(1)oneormoreblockgroupsorcensusblockswithapopulationdensityofatleast386.1peoplekm−1(1,000peoplemile−2);(2)surroundingblockgroupsandcensusblockswithapopulationdensityof193.1peoplekm−2(500peoplemile−2);and(3)lessdenselysettledblocksthatformenclavesorindentations,orareusedtoconnectdiscontinuousareas.Morespecifically,urbanizedareasconsistofterritoriesof50,000ormorepeople.Urbanclusters,aconceptnewtothe2000Census,consistofterritorywithatleast2,500peoplebutfewerthan50,000people.

6.6.3.1 FieldDataMethodforEstimatingCarbonStorageandAnnualSequestration

Thefielddatamethodinvolvesusingfieldmeasurementsofurbantrees(i.e.,a“treelist”)tobuildatailored,accurateestimateofcarbonstorageandsequestrationinanurbanforest.Thevariousstepsforestimatingcarbon(andalteredbuildingenergyuse)effectsfromanurbanforestare:

(1)Delimitboundaryofurbanareatobeanalyzed.Thisinformationisessentialtosettheboundaryoftheanalysis.U.S.Censusboundaryfilesofurbanareasorplacescanbeusedtodelimittheboundaries(U.S.CensusBureau,2011).Informationontheseboundariescanbeusedtodetermineareasofpotentialoverlapwithothercarbonestimates(e.g.,non‐urbanforests),andtohelpsetupa

samplingdesigntocollectnecessaryfielddataasdesiredbythelandowner.

(2)Measurealltreeswithintheurbanareaorsamplethetreepopulation.Withinthedefinedgeography,alltreescanbemeasured,orarandomdistributionoffieldplotscanbemeasuredtoquantifytheurbantreepopulationasdesiredbythelandowner.Toconductthisfieldsamplingandanalysis,thei‐TreeEcomodel(formerlyUFOREmodel)isavailablefreeofchargeatwww.itreetools.org.Fieldmanualsexistonhowtorandomlyselectplotslocationsandcollecttheneededfielddata(http://www.itreetools.org/resources/manuals.php).Detailsonmodelmethodsalsoexist(e.g.,NowakandCrane,2002;Nowaketal.,2008).

Thebasicfielddataprocedureistorecordinformationonalltreeswithinthefieldplots.Thisinformationincludes:

Treespecies

Treeheight

Dieback

Crownlightexposure

Distanceanddirectiontobuildings

Thesevariablesareneededtoassesscarboneffects,butothertreevariables(e.g.,crownwidth,percentageofcrownmissing)canalsobecollectedtoassessotherecosystemservices(e.g.,airpollutionremoval,volatileorganiccompoundemissions,effectsonbuildingenergyuse,rainfallinterception,andrunoff).

(3)Enterdataintoi‐Treeandrunanalyses.Afterfielddataarecollected(viapaperformsoronamobiledevice),dataareenteredintoi‐Tree,andtheprogramproducesstandardtables,graphs,andreportsthatdetailcarbonandotherecosystemserviceinformation.Inrelationtocarbon,resultsalongwithsamplingstandarderrorsarespecificallyproducedbyspeciesandlanduseregarding:

Carbonstorage:amountofcarboncurrentlyintheexistingtreestock;

Grossannualcarbonsequestration:one‐yearestimateassequestrationbasedonestimatedannualtreegrowth,whichvariesbylocation,treecondition,andcrowncompetition;and

Netannualcarbonsequestration:grosssequestrationminusestimatedcarbonlostfromdeadorremovedtreesduetodecomposition.

AlteredBuildingEnergyUse.Inadditiontothecarboneffectsestimatedbythefielddatamethod,thei‐TreeprogramcanestimatetreeeffectsonresidentialbuildingenergyuseandconsequentcarbonemissionsusingmethodsdetailedinMcPhersonandSimpson(1999).

MaintenanceEmissions.Forestimatingmaintenanceemissioneffects,thefollowingstepsaresuggested:

(1)Determinevehicleuserelatedtotreemaintenance.Determinethenumberofmilesdrivenbyvariousvehicletypes.

(2)Calculatecarbonemissionsfromvehicles.Toestimatecarbonemissionsfromvehicles,thelatestfuelefficiencyinformation(mpg)willbeneededforeachvehicleclass.Dividethemilesdrivenbythevehicleclassmpgtodeterminethetotalgallonsofgasoline(orotherfuel)used.Multiplytotalgallons(orotherunits)usedbytheemissionsfactorinTable6‐9toestimatecarbonemissionsfromvehicleuse(Nowaketal.,2002).

Table6‐9:EmissionFactorsforCommonTransportationFuels

Fuel Emissions(lbsCO2perunitvolume)

B20biodiesel 17.71 pergallonB10biodiesel 19.93 pergallonDieselfuel(No.1andNo.2) 22.15 pergallonE85ethanol 2.9 pergallonE10ethanol 17.41 pergallonGasoline 19.36 pergallonNaturalgas 119.90 perMcfPropane 5.74 pergallonSource:Table1.D.1,U.S.DOE(2007).

(3)Determinemaintenanceequipmentuse.Estimatethenumberofrunhoursusedforallfossil‐fuel‐basedmaintenanceequipmentusedontrees(e.g.,chainsaws,chippers,aeriallifts,backhoes,andstumpgrinders).EstimatesofruntimeforvariouspruningandremovalequipmentaregiveninTable6‐10.

Table6‐10:TotalHoursofEquipmentRun‐TimebyDBHClassforTreePruningandRemoval

Pruning Removal2.3hp

BucketChipperb

Saw Saw Trucka Saw Saw Saw Trucka Grinderb

1–6 0.05 NA NA 0.05 0.3 NA NA 0.2 0.1 0.257–12 0.1 NA 0.2 0.1 0.3 0.2 NA 0.4 0.25 0.3313–18 0.2 NA 0.5 0.2 0.5 0.5 0.1 0.75 0.4 0.519–24 0.5 NA 1.0 0.3 1.5 1.0 0.5 2.2 0.75 0.725–30 1.0 NA 2.0 0.35 1.8 1.5 0.8 3.0 1.0 1.031–36 1.5 0.2 3.0 0.4 2.2 1.8 1.0 5.5 2.0 1.5+36+ 1.5 0.2 4.0 0.4 2.2 2.3 1.5 7.5 2.5 2.0

Note:TableisbasedonACRTdata(WadeandDubish,1995)andassumesthatcrewsworkefficientlyandequipmentisnotrunidle(Nowaketal.,2002).hp = Horsepower DBH = Diameter at breast height a Mean hp = 43 (U.S. EPA, 1991) b Mean hp = 99 (U.S. EPA, 1991)

(4)Calculatecarbonemissionsfrommaintenanceequipment.Calculationsforemissionsfromequipmentarebasedontheformula:

TypicalloadfactorsandaveragecarbonemissionsforequipmentaregiveninTable6‐11.

Table6‐11:TypicalLoadFactors(U.S.EPA,1991),AverageCarbonEmissions,andTotalCarbonEmissionsforVariousMaintenanceEquipment(fromNowaketal.,2002)

Equipment TypicalLoadFactora

Average CarbonEmission

(ghp−1hr−1)b

TotalCarbonEmission(kghr−1)c

Aeriallift 0.505 147.2 3.2dBackhoe 0.465 147.3 5.3eChainsaw<4hp 0.500 1,264.4 1.5fChainsaw>4hp 0.500 847.5 3.2gChipper/stumpgrinder 0.370 146.4 5.4h

aAveragevaluefromtwoinventories(conservativeloadfactorof0.5frominventoryBwasusedforchainsaws>4hpduetodisparateinventoryestimates;inventoryaverageforthischainsawtypewas0.71).bCalculatedfromestimatesofcarbonmonoxide(U.S.EPA,1991),hydrocarboncrankcaseandexhaust(U.S.EPA,1991),andcarbondioxideemissions(Charmley,1995),adjustedforin‐useeffects.Totalcarbonemissionswerecalculatedbasedontheproportionofcarbonofthetotalatomicweightofthechemicalemission.Multiplyby0.0022toconverttolbshp−1hr−1.cMultiplyby2.2toconverttolbshr−1.dMeanhp=43(U.S.EPA,1991).eMeanhp=77(U.S.EPA,1991).fhp=2.3.ghp=7.5.hMeanhp=99(U.S.EPA,1991).

(5)Calculatetotalmaintenancecarbonemissions.Addresultsofcarbonemissionsfromvehiclesandmaintenanceequipment.

CombinedCarbonSequestration,AlteredBuildingEnergyUse,andMaintenanceEmissions.Todeterminecurrentnetannualurbanforesteffectoncarbon,thecarbonemissionsfromtreemaintenanceshouldbecontrastedtonetcarbonsequestrationfromtreesandalteredcarbonemissionsfromalteredbuildingenergyuseeffects.

ChangesinCarbonSequestration,AlteredBuildingEnergyUse,andMaintenanceEmissions.Todeterminehowtreeandmaintenanceeffectsoncarbonchangethroughtime,thefieldplotsortreesinventoriedcanbere‐measured,andresultsbetweentheyearscontrastedtoestimatechangesincarbonstock,netannualcarboneffects,andalteredbuildingenergyuseeffects.In

Equation6‐10:CalculateCarbon EmissionsfromMaintenanceEquipment

C=N×HRS×HP×LF×E

Where:

C =Carbonemissions(g)

N =Numberofunits(dimensionless)

HRS =Hoursused(hr)

HP =Averageratedhorsepower(hp)

LF =Typicalloadfactor(dimensionless)

E =Averagecarbonemissionsperunitofuse(ghp−1hr−1)(U.S.EPA1991)

addition,maintenanceactivityestimatesshouldbeupdatedwhenthere‐measurementoccurs.

6.6.3.2 AerialDataMethod

Theaerialdatamethodusesaerialtreecoverestimatesandlookuptablestoprovideamoreapproximate(i.e.,higherdegreeofuncertainty),butlessresourceintensiveestimateofannualcarbonsequestrationinanurbanforestcomparedtothefielddatamethod.Thevariousstepsforestimatingcarboneffectsfromanurbanforestare:

(1)Delimitboundaryofurbanareatobeanalyzed.Thisinformationisessentialtosettheboundaryoftheanalysis.U.S.Censusboundaryfilesofurbanorplacescanbeusedtodelimittheboundaries(U.S.CensusBureau,2011).Informationontheseboundariescanbeusedtodetermineareasofpotentialoverlapwithothercarbonestimates(e.g.,non‐urbanforests).

(2)Conductphotointerpretationoftreecoverinurbanarea.Todeterminepercentageoftreecover,theurbanareacanbephotointerpretedusingi‐TreeCanopy(http://www.itreetools.org/canopy/index.php).Thiswebtoolallowsuserstoimportashapefileof,ormanuallydelimittheirarea,andthenrandomlylocatepointswithintheareaonGoogle®aerialimagery.Theuserthenclassifieseachpointaccordingtoitscoverclass(e.g.,treeornon‐tree).Theprogramproducesestimatesofpercentagecoverandassociatedstandarderrorforthecoverclasses.ThissametypeofanalysiscouldalsobeperformedwithdigitalaerialimagesusingaGeographicInformationSystem.

(3)Estimatetotaltreecoverinurbanarea.Multiplythepercentageoftreecoverandstandarderrorbyurbanarea(ha)toproduceanestimateoftotaltreecoverandstandarderror(ha).Notethati‐TreeCanopywillmakethesecalculations.

(4)Estimatecarboneffects.Multiplytotaltreecover(ha)byaveragecarbonstorageorannualsequestrationperhaoftreecoverinplacesorurbanareas(Table6‐12).i‐TreeCanopywillmakethesecalculationsbasedonaveragestateornationaldata.

Notethattoestimateeffectsformaintenanceemissionsandalteredbuildingenergyusebasedontotaltreecover,atablesimilartoTable6‐12wouldneedtobedevelopedcontainingemissionratesforthesesourcecategories.

Table6‐12:MetricTonsCarbonStorageandAnnualSequestrationperHectareofTreeCoverinSelectedCitiesandUrbanAreasofSelectedStates(fromNowaketal.,2013)

City,StateStorage Sequestration

MetrictonsCha−2 StandardError

MetrictonsCha−2year−1

StandardError

Arlington,TXa 63.7 7.3 2.9 0.28Atlanta,GAa 66.3 5.4 2.3 0.17Baltimore,MDa 87.6 10.9 2.8 0.36Boston,MAa 70.2 9.6 2.3 0.25Casper,WYb 69.7 15.0 2.2 0.39Chicago,ILc 60.3 6.4 2.1 0.21Freehold,NJa 115.0 17.8 3.1 0.45Gainesville,FLd 63.3 9.9 2.2 0.32Golden,COa 58.8 13.3 2.3 0.45Hartford,CTa 108.9 16.2 3.3 0.46JerseyCity,NJa 43.7 8.8 1.8 0.34Lincoln,NEa 106.4 17.4 4.1 0.63LosAngeles,CAe 45.9 5.1 1.8 0.17Milwaukee,WIa 72.6 11.8 2.6 0.33

City,StateStorage Sequestration

MetrictonsCha−2 StandardError

MetrictonsCha−2year−1

StandardError

Minneapolis,MNf 44.1 7.4 1.6 0.23Moorestown,NJa 99.5 9.3 3.2 0.30Morgantown,WVg 95.2 11.6 3.0 0.37NewYork,NYh 73.3 10.1 2.3 0.29Oakland,CAi 52.4 1.9 na naOmaha,NEa 141.4 22.9 5.1 0.81Philadelphia,PAj 67.7 9.0 2.1 0.27Roanoke,VIa 92.0 13.3 4.0 0.58Sacramento,CAk 78.2 15.7 3.8 0.64SanFrancisco,CAl 91.8 22.5 2.4 0.50Scranton,PAm 92.4 12.8 4.0 0.52Syracuse,NYa 85.9 10.4 2.9 0.30Washington,DCn 85.2 10.4 2.6 0.30Woodbridge,NJa 81.9 8.2 2.9 0.28Indianao 88.0 26.8 2.9 0.77Kansasp 74.2 13.0 2.8 0.48Nebraskap 66.7 18.6 2.7 0.74NorthDakotap 77.8 24.7 2.8 0.79SouthDakotap 30.6 6.6 1.3 0.26Tennesseeq 64.7 5.0 3.4 0.21Average 76.9 13.6 2.8 0.45aUnpublisheddataanalyzedusingtheUFOREmodel.bNowaketal.(2006a).cNowaketal.(2011).dEscobedoetal.(2009).eNowaketal.(2011).fNowaketal.(2006c).gNowaketal.(2012c).hNowaketal.(2007d).iNowak(1991).

j Nowaketal.(2007c).kNowaketal.(Inreview).lNowaketal.(2007b).mNowaketal.(2010).nNowaketal.(2006b).oNowaketal.(2007a).pNowaketal.(2012b).qNowaketal(2012a).

CombinedCarbonSequestration,AlteredBuildingEnergyUse,andMaintenanceEmissions.Todeterminecurrentnetannualurbanforesteffectoncarbon,thecarbonemissionsfromtreemaintenance,ifavailable,shouldbecontrastedtothenetcarbonsequestrationfromtreesandalteredcarbonemissionsfromalteredbuildingenergyuseeffects.

ChangesinCarbonSequestration,AlteredBuildingEnergyUse,andMaintenanceEmissions.Todeterminetreeeffectsoncarbonchangethroughtime,thephoto‐interpretationpointscanbere‐measuredwhennewerphotosbecomeavailabletoassesschangeintreecover(e.g.,NowakandGreenfield,2012).Thei‐TreeCanopyprogramsavesthegeographiccoordinatesofeachpointsothepointscanbere‐measuredinthefuture.Changesintreecoverandassociatedcarboneffectsbetweentheyearscanbecontrastedtoestimatechangesincarbonstockandnetannualcarboneffects.Changesinalteredbuildingenergyuseeffectsandmaintenanceeffectscouldalsobeestimatediftheappropriatetablesaredeveloped.

Fielddatacollectionestimateshavefewerlimitationsthantheaerialapproach,butsomelimitationsexist(Nowaketal.,2008).Themainadvantageofcarbonestimationusingthefielddata

approachandi‐Treeishavingaccurateestimatesofthetreepopulation(e.g.,species,size,distribution)withacalculatedlevelofprecision.Themodeledcarbonvaluesareestimatesbasedonforest‐derivedallometricequations(Nowak,1994;NowakandCrane,2002).Thecarbonestimatesyieldastandarderroroftheestimatebasedonsamplingerror,ratherthanerrorofestimation.Estimationerrorisunknown,andlikelylargerthanthereportedsamplingerror.Estimationerrorincludestheuncertaintyofusingbiomassequationsandconversionfactors,whichmaybelarge,aswellasmeasurementerror,whichistypicallysmall.Thestandardizedcarbonvalues(e.g.,kgCha−1orlbsC(acreoftreecover)−1)fallinlinewithvaluesforforests(BirdseyandHeath,1995),butvaluesforcities(places)canbehigher(Table6‐12),likelyduetoalargerproportionoflargetreesincityenvironmentsandrelativelyfastgrowthratesduetoamoreopenurbanforeststructure(NowakandCrane,2002).

Therearevariousmeanstohelpimprovethecarbonstorageandsequestrationestimatesforurbantrees.Carbonestimatesforopen‐grownurbantreesareadjusteddownwardbasedonfieldmeasurementsoftreesintheChicagoarea(Nowak,1994).Thisadjustmentmayleadtoconservativeestimatesofcarbon.Moreresearchisneededontheapplicabilityofforest‐derivedequationstourbantrees.Inaddition,moreurbantreegrowthdataareneededtobetterunderstandregionalvariabilityofurbantreegrowthunderdifferingsiteconditions(e.g.,treecompetition)forbetterannualsequestrationestimates.Averageregionalgrowthestimatesareusedbasedonlimitedmeasuredurbantreegrowthdatastandardizedtolengthofgrowingseasonandcrowncompetition.

Therearecurrentlyaverylimitednumberofbiomassequationsfortropicaltreesini‐Tree.Themodelneedstobeupdatedwithtropicaltreebiomassequationsformoreaccurateestimatesintropicalcities.Futureresearchisneededtoobtainbiomassequationsforurbanorornamentaltreespecies.Estimatesoftreedecayandnetannualsequestrationini‐Treearequiterudimentary(Nowaketal.,2010),andcanbeimprovedwithfutureresearch.Thedegreeofuncertaintyofthenetcarbonsequestrationestimatesisunknown.

Estimatesofmaintenanceemissionsandalteredbuildingenergyuseeffectsarealsorathercrude.Accuratemaintenanceemissionsestimatesrequiregoodestimatesofvehicleandmaintenanceequipmentuse;thentheyrelyonanaveragemultiplierforemissionsfromtheliterature.Energyeffectsestimatesarebasedonsamplingproximityoftreesnearbuildingswithinvarioustreesize,distance,anddirectionclassesfromabuilding.Energyfactors,convertedtocarbonemissionfactorsbasedonstateaverageenergydistribution(e.g.,electricity,oil)areappliedtotreesineachbuildinglocationclassbasedonU.S.climatezoneandaveragebuildingtypesinastatetoestimateenergyeffects(seeMcPhersonandSimpson,1999).Thoughtheseestimatesarecrude,withanunknowncertainty,theyarebasedonreasonableapproachesthatprovidefirst‐orderestimatesofeffects.Itshouldbenotedthatemissionreductionsfromalteredbuildingenergyuseeffectsmightalsobeimplicitlyincludedinanyemissionestimationanentitymightperformbasedonactualenergyusedata(e.g.,meterreadings)forthebuildinginquestion.

Estimatesbasedonaerialtreecanopyeffectshavethesamelimitationsasfielddataapproaches,plussomeadditionallimitationsandadvantages.Theadvantagesincludeasimple,quick,andaccuratemeanstoassesstheamountofcanopycoverinanarea,withmeasuresthatarerepeatablethroughtime.Thedisadvantagesarethattheusermustusealookupvaluefromatable(e.g.,meanvalueperunitofcanopycover)toestimatecarboneffects.Thoughthetreecoverestimatewillbeaccuratewithknownuncertainty(i.e.,standarderror),thecarbonmultipliersmaybeoffdependingupontheurbanforestcharacteristics.Ifaveragemultipliersareused,theaccuracyofthoseestimateswilldeclineasthedifferenceincreasesbetweenthelocalurbancharacteristicsandthevaluesoftheaveragemultipliers.Iflocalfielddataarenotcollected,thenthediscrepancybetweentheurbanforest’scharacteristicsandthoseofaveragevaluesisunknown.Iftheaveragevaluesin

Table6‐12trulyrepresentaverages,theestimatesoveralargepopulationofurbanareasshouldbereliable.However,localestimatesmaybeinaccuratedependingupontheextenttowhichcharacteristicsofthelocalurbanforestdivergefromtheaveragevalues.

Bothapproachescanprovidecarbonestimatesforurbanareas,withdifferingdegreesofuncertaintyandworkrequired.Bothapproachescanalsobeimprovedwithmorefielddatacollectioninurbanareas,andwithmodelandmethodimprovementsrelatedtocarbonestimation.

6.7 NaturalDisturbance–WildfireandPrescribedFire

6.7.1 Description

FireproducesGHGemissionsdirectlythroughfuelconsumption.Emissionsproducedaredirectlyproportionaltofuelconsumed.Fuelconsumptionisinturninfluencedbyfuelquantityandfuelcharacteristicssuchassize,moisturecontent,fireweather,andfireseverity.Algorithmsexistforestimatingfuelconsumptionforavarietyoffueltypesandconditions.Fireandotherdisturbancesalsoconvertlivevegetationtodead,alteringsubsequentcarbondynamicsonthesitebyreducingcarboncapturedbyphotosynthesisintheshortrunduetoreducedvegetativecover,andincreasingemissionsfromdecompositionofdeadvegetation.Fireseverity,whichisdrivenbytheonsitefactorsthatdriveconsumptionaswellasotherphysicalfactors,willdrivethesubsequentcarbondynamicsandareawherereversalofcarbonretentionmayoccur.

Foralldisturbances,keyactivitydataistheareaaffected.Asimpledescriptorisusedtocharacterizetheseverityoftheevent.Forbothwildfireandprescribedfire/controlburns,descriptorsofseverityincludecrownfire,stand‐replacementunderburn,mixed‐severityunderburn(sometreemortality),andlow‐severityunderburn.Typicallywildfirewillbemoreweightedtowardscrownfireandhigherseverityversuslowerseverityfromprescribedfire.Forotherdisturbances,thepercentageoflivetreeskilled(orpercentagebasalareamortality)andthepercentageofkilledtreesthatarestillstandingaswascoveredpreviouslyinSection6.4.2.10andSection6.4.4.8areused.

FOFEM9(Reinhardtetal.,1997)isrecommendedforestimatingGHGemissions,becauseitisapplicablenationally,computercodeisavailablethatcanbelinkedtoorincorporatedintoother

9http://www.firelab.org/science‐applications/fire‐fuel/111‐fofem

MethodsforEmissionsfromNaturalDisturbances

Rangeofoptionsdependsonthedataavailabilityoftheentity’sforestlandincluding:

− FOFEMmodelenteringmeasuredbiomass;and

− FOFEMmodelusingdefaultvaluesgeneratedbyvegetationtype.

TheseoptionsuseReinhardtetal.(1997).

Themethodswereselectedbecausetheyprovidearangeofoptionsdependentonthedataavailabilityoftheentity'sdisturbedforestland.

code,andinputsaredefinedsothatmeasuredbiomasscanbeenteredordefaultvaluesgeneratedbyvegetationtype.FOFEMproducesdirectestimatesoftotalCO2,CO,CH4,andNOxemitted,aswellasestimatesoffuelconsumptionbycomponent,whichcanbeusedtodetermineresidualfuelquantitiesforestimatingsubsequentdecomposition.FOFEMand/orCONSUME(JointFireScienceProgram,2009)canalsobeuseddirectlytocomputeemissionsandconsumptionfromfire.FOFEMalgorithmscanalsobeusedtocomputetreemortalityinordertoupdateestimatesofliveanddeadbiomass.AlthoughanotheroptionistouseFVS‐FFE10(Rebain,2010;ReinhardtandCrookston,2003),itisnottherecommendedapproachforwildfireGHGcalculation.FVS‐FFEusesmanyofthesameinternalalgorithmsforestimatingtreemortality,fuelconsumption,andemissionsasFOFEM,butalsosimulatesstand,fuel,andcarbondynamicsovertime.Itisamorepowerfulpredictivetool,butsubstantiallymoreworkisinvolvedinunderstandingthemodelingframework,settingupmodelrunsanddatapreparation.Alternatively,lookuptablescanbebuiltusingthesetoolsforarangeofvegetationtypes,fuelloadingsfromnaturaland/ormanagementprocesses,andfireseverities,orasimplifiedalgorithmcanbedevelopedasinthe2006IPCCGuidelinesforNationalGHGInventories(IPCC,2006).

10http://www.fs.fed.us/fmsc/fvs/whatis/index.shtml

Figure6‐9:DecisionTreeforNaturalDisturbancesShowingMethodsAppropriateforEstimatingEmissionsfromForestFiresDependingontheDataAvailable

6.7.3.1 EstimationofGreenhouseGasEmissionsfromFire

ThecalculationofGHGemissionsfromfirescanbeseeninEquation6‐11below.

Inordertousethisalgorithm,anestimateofAbyfireseverityisused.ForMB,theunderstory,DDW,andforestfloorareassumedtobeavailableforcombustion.Inaddition,anestimateofwhatportionofthelivetreebiomassisavailableforcombustion(typicallyonlyfoliageandfinebranchwood)isused.ForCf,IPCC(2006)protocolsuse0.45fortemperateforests.SeparatevaluesforCfforbiomasspoolsforcrownfire,stand‐replacementunderburn,mixed‐severityunderburn,andlow‐severityunderburn,byforesttype,usingFOFEMareprovided(seeTable6‐13).ForGefemissionfactorsfromUrbanskietal.(2009)arerecommended:1619g(kgdrymatterburntforCO2)−1,89.6g(kgdrymatterburntforCO)−1,3.4g(kgdrymatterburntforCH4)−1,andfromAkagietal.(2011),2.5g(kgdrymatterburntforNOx)−1.Notethatnotallbiomassisavailableforcombustion;inparticular,standinglivetreebolesarenotavailable.

Forsubsequenteffects,theGHGestimationmethodsadoptedshouldmatchascloselyaspossiblethoseusedinothersections(e.g.,HWPs).Decompositionofdeadmaterialovertimewillbeprojectedusingafixedannuallossrate.Theconversionofstandingdeadtodead‐and‐downshouldalsobeprojectedusingafixedrateandapproximatingthemethodsinFVS‐FFE.

GHGemissionsfromnaturaldisturbancewildfiresandprescribedfiresusedforsitemaintenanceandrestorationshouldbereportedseparatelyfromemissionsresultingfrommanagement(siteswiththinningslash,machineorhandpiles,orloggingslash)tofacilitatetheuseoftheestimatesindecisionmakingregardingmanagementpractices.

Table6‐13showsanexampleforthedefaultlookuptablesforconsumptionfraction(Cf).RegionsarethoseshowninTable6‐13,withtheexceptionoftheWestregion,whichrepresentsanaverageofallwesternregions.

Table6‐13:CfConsumptionFraction

Region ForestTypeCfCrownFire

Cf StandReplacementUnderburn

CfMixedSeverity

Cf LowSeverity

Underburn

Northeast

Aspen–birch 84 69 59 45Elm–ash–cottonwood 74 47 35 20Maple–beech–birch 77 60 44 35Oak–hickory 63 49 41 32Oak–pine 80 61 50 38Spruce–fir 73 73 69 62White–red–jackpine 55 45 37 26

Equation6‐11:CalculateGHGEmissionsfromFire

Lfire=A×MB×Cf×Gef×10−3

Where:

Lfire =Amountofgreenhousegasemissionsfromfire(metrictonsofeachGHG,i.e.,CH4,N2O,etc.)

A =Areaburned(ha)

MB =Massoffuelavailableforcombustion(metrictonsha−1)

Cf =Combustionfactor(dimensionless)

Gef =Emissionfactor(g(kgdrymatterburnt)−1)

Region ForestTypeCfCrownFire

Cf StandReplacementUnderburn

CfMixedSeverity

Cf LowSeverity

Underburn

NorthernLakeStates

Aspen–birch 84 69 59 45Elm–ash–cottonwood 74 47 35 20Maple–beech–birch 77 60 44 35Oak–hickory 80 61 50 38Spruce–fir 73 73 69 62White–red–jackpine 55 45 37 26

NorthernPrairieStates

Elm–ash–cottonwood 74 47 35 20Maple–beech–birch 77 60 44 35Oak–hickory 80 61 50 38Ponderosapine 60 53 47 37

PacificNorthwest,East

Douglasfir 85 79 72 60Fir–spruce–m.hemlock 67 64 58 44Lodgepolepine 77 72 64 52Ponderosapine 78 53 41 27

PacificNorthwest,West

Alder–maple 82 67 48 42Douglasfir 71 62 55 43Fir–spruce–m.hemlock 67 64 58 44Hemlock–Sitkaspruce 85 77 69 55

PacificSouthwest

Mixedconifer 79 69 50 46Douglasfir 66 42 30 17Fir–spruce–m.hemlock 67 64 58 44PonderosaPine 78 53 41 27Redwood 82 76 69 56

RockyMountain,NorthandSouth

Aspen–birch 80 61 50 35Douglasfir 85 79 72 60Fir–spruce–m.hemlock 67 64 58 44Lodgepolepine 77 72 64 52Ponderosapine 78 53 41 27Mixedconifer 79 69 50 46

Southeast

Elm–ash–cottonwood 76 45 29 19Loblolly–shortleafpine 66 52 44 35Oak–hickory 61 50 44 36Oak–pine 62 55 51 45

SouthCentral

Elm–ash–cottonwood 76 45 29 19Loblolly–shortleafpine 66 52 44 35Longleaf–slashpine 69 63 57 47Oak–hickory 61 50 44 36Oak–pine 62 55 51 45

Pinyon–juniper 64 55 49 41Tanoak–laurel 70 52 43 32Westernlarch 76 68 60 47Westernoak 65 62 56 48Westernwhitepine 68 56 47 33

aRepresentsanaverageoverallwesternregionsforthespecifiedforesttypes(PNW‐W,PNW‐E,PSW,RMN,RMS).

6.7.3.2 EstimationofGreenhouseGasEmissionsfromOtherDisturbances

Forotherdisturbances,theprimaryeffectsareindirect:byconvertinglivebiomasstodead—andinsomecasesstandingtreestodead,downtrees—decompositionisaccelerated.Currentlygroupingnon‐firedisturbanceintotwocategoriesissuggested:disturbancesthatleavedeadtreesstanding(insectanddisease‐causedmortality)anddisturbancethatleavesthetreesontheground(windoricestorms).Thelandownerwillhavetoestimatemortality(Section6.7.2);thenasindecompositionoffire‐killedtrees,afixeddecompositionrate(defaultvalue0.015)willbeusedtosimulatesubsequentdecomposition.

Forinsectorpathogen‐causedmortality,thetreesareassumedtobeinitiallystandingafterdeath.Conversionofstandingdeadtodead‐and‐downwillbeprojectedusingafixedrateandapproximatingthemethodsinFVS‐FEE.Oncedown,thedefaultdecompositionratefromFVS‐FFEof0.015fordeadanddownwoodwillbeusedtosimulatedecomposition.Forblowdownsoricestorms,theimpactedtreesareassumedtobedeadanddown.Inthiscasedecompositionbeginsimmediately.

Amajorsourceofuncertaintyinpredictingfireemissionsisthepreburnfuelquantities.Iflandownersaredoingsomekindofinventoryofliveanddeadbiomass(seeSection6.7.2)theywillhaverelativelyrobustestimatesofavailablefuel.Iftheyareusinglookuptablevaluesbyforesttype,therewillbemoreuncertaintyassociatedwiththeestimatessincefuelquantitiesvarygreatlywithinforesttype.

Arelatedchallengeisdeterminingtheappropriatedegreeofspecificityfortrackingbiomassbypools(e.g.,live,dead).Anykindofmanagementordisturbancechangesbiomassatthetimeofoccurrence,andalsothesubsequenttrajectory.Subsequentmanagementordisturbanceshouldbeappliedtothechangedandchangingvalues,nottheoriginalvalues.ThiscanresultinacomplicatedsimulationmodellikeFVS,ratherthanacalculator.Sinceprefirefuelquantityisthestrongestpredictoroffuelconsumption,determiningtheappropriatedegreeofspecificityfortrackingbiomassbypoolsisnotacompletelyacademicquestion.

Appendix6‐A:HarvestedWoodProductsLookupTables

Table6‐A‐1:FactorstoConvertPrimaryWoodProductstoCarbonMassfromtheUnitsCharacteristicofEachProduct

SolidwoodProductorPaper UnitFactortoConvertUnitstoTons(2,000lbs)C

FactortoConvertUnitstoMetricTonsC

Softwoodlumber/laminatedveneerlumber/glulamlumber/I‐joists

Thousandboardfeet 0.488 0.443

Hardwoodlumber Thousandboardfeet 0.844 0.765

Softwoodplywood Thousandsquarefeet,3/8‐inchbasis

0.260 0.236

Orientedstrandboard Thousandsquarefeet,3/8‐inchbasis

0.303 0.275

Non‐structuralpanels(average)Thousandsquarefeet,3/8‐inchbasis 0.319 0.289

Hardwoodveneer/plywoodThousandsquarefeet,3/8‐inchbasis 0.315 0.286

Particleboard/mediumdensityfiberboard

Thousandsquarefeet,3/4‐inchbasis 0.647 0.587

HardboardThousandsquarefeet,1/8‐inchbasis

0.152 0.138

InsulationboardThousandsquarefeet,1/2‐inchbasis

0.242 0.220

Otherindustrialproducts Thousandcubicfeet 8.250 7.484Paper Tons,airdry 0.450 0.496

Table6‐A‐2:FractionofCarboninPrimaryWoodProductsRemaininginEndUsesupto100YearsAfterProduction(year0indicatesfractionattimeofproduction)

YearafterProduction

SoftwoodLumber

HardwoodLumber

SoftwoodPlywood

OrientedStrandboard

Non‐StructuralPanels

Misc.Products Paper

0 1.000 1.000 1.000 1.000 1.000 1.000 1.0001 0.908 0.909 0.908 0.908 0.908 0.903 0.8802 0.892 0.893 0.893 0.896 0.892 0.887 0.7753 0.877 0.877 0.878 0.884 0.876 0.871 0.6824 0.863 0.861 0.863 0.872 0.861 0.855 0.6005 0.848 0.845 0.848 0.860 0.845 0.840 0.5286 0.834 0.830 0.834 0.848 0.830 0.825 0.4657 0.820 0.815 0.820 0.837 0.816 0.810 0.3548 0.806 0.801 0.807 0.826 0.801 0.795 0.2699 0.793 0.786 0.794 0.815 0.787 0.781 0.20510 0.780 0.772 0.781 0.804 0.774 0.767 0.15615 0.718 0.705 0.719 0.753 0.708 0.700 0.04020 0.662 0.644 0.663 0.706 0.649 0.639 0.01025 0.611 0.589 0.613 0.662 0.595 0.583 0.00330 0.565 0.538 0.567 0.622 0.546 0.532 0.00135 0.523 0.492 0.525 0.585 0.501 0.486 0.00040 0.485 0.450 0.487 0.551 0.460 0.444 0.00045 0.450 0.411 0.452 0.519 0.423 0.405 0.00050 0.418 0.376 0.420 0.490 0.389 0.370 0.00055 0.389 0.344 0.391 0.462 0.358 0.338 0.00060 0.362 0.315 0.364 0.437 0.329 0.308 0.00065 0.338 0.288 0.340 0.413 0.303 0.281 0.00070 0.315 0.264 0.317 0.391 0.280 0.257 0.00075 0.294 0.242 0.296 0.370 0.258 0.234 0.00080 0.276 0.221 0.277 0.351 0.238 0.214 0.00085 0.258 0.203 0.260 0.333 0.220 0.195 0.00090 0.242 0.186 0.244 0.316 0.203 0.178 0.00095 0.227 0.170 0.229 0.300 0.188 0.163 0.000100 0.213 0.156 0.215 0.285 0.174 0.149 0.000Average 0.466 0.430 0.468 0.526 0.441 0.424 0.059

Table6‐A‐3:FractionofCarboninPrimaryWoodProductsRemaininginLandfillsupto100YearsafterProduction(year0indicatesfractionattimeofproduction)

YearafterProductio

Softwood

Lumber

HardwoodLumber

SoftwoodPlywood

OrientedStrandboar

Non‐StructuralPanels

Misc.Products Paper

0 0.000 0.000 0.000 0.000 0.000 0.000 0.0001 0.061 0.060 0.061 0.061 0.061 0.064 0.0402 0.071 0.070 0.071 0.068 0.071 0.074 0.0733 0.080 0.080 0.080 0.076 0.081 0.084 0.1024 0.089 0.090 0.089 0.083 0.090 0.094 0.1275 0.098 0.099 0.097 0.090 0.099 0.103 0.1476 0.106 0.109 0.106 0.097 0.108 0.112 0.1647 0.114 0.117 0.114 0.103 0.117 0.121 0.1978 0.122 0.126 0.122 0.110 0.125 0.129 0.2209 0.130 0.134 0.130 0.116 0.134 0.138 0.23610 0.138 0.143 0.137 0.122 0.142 0.146 0.24715 0.173 0.181 0.172 0.151 0.179 0.184 0.25620 0.203 0.214 0.202 0.176 0.211 0.217 0.24125 0.230 0.243 0.229 0.199 0.239 0.246 0.22330 0.253 0.269 0.252 0.220 0.265 0.272 0.20735 0.274 0.292 0.273 0.238 0.287 0.296 0.19540 0.293 0.313 0.292 0.255 0.307 0.316 0.18545 0.310 0.332 0.308 0.271 0.325 0.335 0.17750 0.325 0.348 0.324 0.285 0.341 0.352 0.17155 0.338 0.363 0.337 0.298 0.356 0.367 0.16660 0.351 0.377 0.349 0.310 0.369 0.380 0.16365 0.362 0.389 0.361 0.321 0.381 0.393 0.16070 0.372 0.400 0.371 0.331 0.391 0.404 0.15875 0.381 0.410 0.380 0.341 0.401 0.414 0.15680 0.390 0.419 0.389 0.350 0.410 0.423 0.15485 0.398 0.427 0.397 0.359 0.418 0.431 0.15390 0.405 0.435 0.404 0.366 0.426 0.439 0.15395 0.412 0.442 0.411 0.374 0.432 0.446 0.152100 0.418 0.448 0.417 0.381 0.438 0.452 0.151Average 0.297 0.317 0.296 0.264 0.311 0.321 0.178

Table6‐A‐4:DensityofSoftwoodandHardwoodSawlogs/VeneerLogsandPulpwoodbyRegionandForestTypeGroupa

Region ForesttypeSpecific Gravitydof

SoftwoodsSpecificGravitydof

Hardwoods

Northeast

Aspen–birch 0.353 0.428Elm–ash–cottonwood 0.358 0.470Maple–beech–birch 0.369 0.518Oak–hickory 0.388 0.534Oak–pine 0.371 0.516Spruce–fir 0.353 0.481White–red–jackpine 0.361 0.510

NorthernLakeStates

Aspen–birch 0.351 0.397Elm–ash–cottonwood 0.335 0.460Maple–beech–birch 0.356 0.496Oak–hickory 0.369 0.534Spruce–fir 0.344 0.444White–red–jackpine 0.389 0.473

NorthernPrairieStates

Elm–ash–cottonwood 0.424 0.453Loblolly–shortleafpine 0.468 0.544Maple–beech–birch 0.437 0.508Oak–hickory 0.448 0.565Oak–pine 0.451 0.566Ponderosapine 0.381 0.473

PacificNorthwest,East

Douglasfir 0.429 0.391Fir–spruce–m.hemlock 0.370 0.361Lodgepolepine 0.380 0.345Ponderosapine 0.385 0.513

PacificNorthwest,West

Alder–maple 0.402 0.385Douglasfir 0.440 0.426Fir–spruce–m.hemlock 0.399 0.417Hemlock–Sitkaspruce 0.405 0.380

PacificSouthwest

Mixedconifer 0.394 0.521Douglasfir 0.429 0.483Fir–spruce–m.hemlock 0.372 0.510PonderosaPine 0.380 0.510Redwood 0.376 0.449

RockyMountain,North

Douglasfir 0.428 0.370Fir–spruce–m.hemlock 0.355 0.457Hemlock–sitkaspruce 0.375 0.441Lodgepolepine 0.383 0.391Ponderosapine 0.391 0.374

RockyMountain,South

Aspen–birch 0.355 0.350Douglasfir 0.431 0.350Fir–spruce–m.hemlock 0.342 0.350Lodgepolepine 0.377 0.350Ponderosapine 0.383 0.386

Region ForesttypeSpecific Gravitydof

SoftwoodsSpecificGravitydof

Hardwoods

Southeast

Elm–ash–cottonwood 0.433 0.499Loblolly–shortleafpine 0.469 0.494Longleaf–slashpine 0.536 0.503Oak–gum–cypress 0.441 0.484Oak–hickory 0.438 0.524Oak–pine 0.462 0.516

SouthCentral

Elm–ash–cottonwood 0.427 0.494Loblolly–shortleafpine 0.470 0.516Longleaf–slashpine 0.531 0.504Oak–gum–cypress 0.440 0.513Oak–hickory 0.451 0.544Oak–pine 0.467 0.537

Pinyon–juniper 0.422 0.620Tanoak–laurel 0.430 0.459Westernlarch 0.433 0.430Westernoak 0.416 0.590Westernwhitepine 0.376 ‐‐

‐‐=Nohardwoodtreesinthistypeinthisregion.aEstimatesbasedonsurveydatafortheconterminousUnitedStatesfromUSDAForestService,FIAProgram’sdatabaseofforestsurveys(FIADB)(USDAForestService,2005)andincludegrowingstockontimberlandstandsclassifiedasmedium‐orlarge‐diameterstands.Proportionsarebasedonvolumeofgrowingstocktrees.dAveragewoodspecificgravityisthedensityofwooddividedbythedensityofwaterbasedonwooddrymassassociatedwithgreentreevolume.eWestrepresentsanaverageoverallwesternregionsfortheseforesttypes.

Table6‐A‐5:AverageDispositionPatternsofCarbon asFractions inRoundwoodby RegionandRoundwoodCategory;FactorsAssumeNoBarkonRoundwoodandExcludeFuelwood

YearafterProduction

Northeast,Softwood

SawlogTotal

Emissions InUse

PulpwoodTotal

EmissionsInLandfills

TotalStored

InLandfills

TotalStored

0 0.569 0.000 0.569 0.431 0.513 0.000 0.513 0.4871 0.521 0.029 0.550 0.450 0.452 0.021 0.473 0.5272 0.505 0.037 0.542 0.458 0.400 0.038 0.438 0.5623 0.491 0.044 0.535 0.465 0.355 0.052 0.407 0.5934 0.478 0.050 0.528 0.472 0.315 0.064 0.379 0.6215 0.465 0.056 0.522 0.478 0.279 0.074 0.354 0.6466 0.453 0.062 0.516 0.484 0.248 0.083 0.331 0.6697 0.438 0.069 0.507 0.493 0.193 0.099 0.293 0.7078 0.425 0.075 0.500 0.500 0.152 0.111 0.263 0.7379 0.414 0.080 0.494 0.506 0.120 0.119 0.239 0.76110 0.403 0.085 0.489 0.511 0.096 0.124 0.220 0.78015 0.363 0.105 0.468 0.532 0.038 0.130 0.168 0.83220 0.332 0.121 0.453 0.547 0.022 0.124 0.146 0.85425 0.306 0.134 0.440 0.560 0.017 0.116 0.133 0.86730 0.282 0.146 0.428 0.572 0.015 0.109 0.124 0.87635 0.260 0.156 0.417 0.583 0.014 0.103 0.117 0.88340 0.240 0.166 0.406 0.594 0.013 0.099 0.111 0.88945 0.222 0.174 0.397 0.603 0.012 0.095 0.107 0.89350 0.206 0.182 0.388 0.612 0.011 0.093 0.104 0.89655 0.191 0.189 0.380 0.620 0.010 0.091 0.101 0.89960 0.177 0.195 0.372 0.628 0.009 0.089 0.099 0.90165 0.165 0.201 0.365 0.635 0.009 0.088 0.097 0.90370 0.153 0.206 0.359 0.641 0.008 0.087 0.095 0.90575 0.143 0.210 0.353 0.647 0.008 0.086 0.094 0.90680 0.133 0.214 0.347 0.653 0.007 0.086 0.093 0.90785 0.124 0.218 0.342 0.658 0.007 0.085 0.092 0.90890 0.116 0.221 0.337 0.663 0.006 0.085 0.091 0.90995 0.108 0.224 0.332 0.668 0.006 0.085 0.091 0.909100 0.101 0.227 0.328 0.672 0.006 0.085 0.090 0.910Average 0.235 0.166 0.402 0.041 0.095 0.136

Table6‐A‐5—continued

YearafterProduction

Northeast,Hardwood

InUseSawlog

TotalEmissions

PulpwoodTotal

TotalStored

InLandfills

TotalStored

0 0.614 0.000 0.614 0.386 0.650 0.000 0.650 0.3501 0.559 0.034 0.594 0.406 0.580 0.032 0.613 0.3872 0.544 0.042 0.586 0.414 0.540 0.046 0.586 0.4143 0.530 0.049 0.579 0.421 0.503 0.059 0.562 0.4384 0.516 0.056 0.573 0.427 0.471 0.070 0.541 0.4595 0.504 0.063 0.567 0.433 0.443 0.079 0.522 0.4786 0.491 0.069 0.561 0.439 0.417 0.087 0.504 0.4967 0.477 0.076 0.553 0.447 0.374 0.101 0.475 0.5258 0.463 0.083 0.546 0.454 0.341 0.111 0.453 0.5479 0.452 0.089 0.540 0.460 0.316 0.119 0.434 0.56610 0.441 0.094 0.535 0.465 0.295 0.125 0.420 0.58015 0.397 0.117 0.514 0.486 0.239 0.137 0.376 0.62420 0.361 0.136 0.497 0.503 0.215 0.140 0.355 0.64525 0.330 0.152 0.482 0.518 0.199 0.141 0.340 0.66030 0.301 0.167 0.468 0.532 0.186 0.142 0.328 0.67235 0.275 0.180 0.455 0.545 0.175 0.144 0.319 0.68140 0.252 0.192 0.444 0.556 0.164 0.146 0.310 0.69045 0.230 0.202 0.432 0.568 0.155 0.148 0.302 0.69850 0.211 0.211 0.422 0.578 0.146 0.150 0.296 0.70455 0.193 0.220 0.412 0.588 0.138 0.152 0.290 0.71060 0.176 0.227 0.403 0.597 0.130 0.154 0.285 0.71565 0.162 0.234 0.395 0.605 0.123 0.157 0.280 0.72070 0.148 0.240 0.388 0.612 0.116 0.159 0.275 0.72575 0.136 0.245 0.380 0.620 0.110 0.161 0.271 0.72980 0.124 0.250 0.374 0.626 0.104 0.163 0.268 0.73285 0.114 0.254 0.368 0.632 0.099 0.165 0.264 0.73690 0.104 0.258 0.362 0.638 0.094 0.167 0.261 0.73995 0.096 0.261 0.357 0.643 0.089 0.169 0.258 0.742100 0.088 0.264 0.352 0.648 0.085 0.171 0.255 0.745Average 0.244 0.192 0.437 0.178 0.145 0.323

YearafterProduction

NorthCentral,Softwood

Sawlog

TotalEmissions

Pulpwood

TotalEmissionsIn

LandfillsTotalStored

InLandfills

TotalStored

0 0.630 0.000 0.630 0.370 0.514 0.000 0.514 0.4861 0.579 0.031 0.610 0.390 0.454 0.021 0.475 0.5252 0.561 0.039 0.601 0.399 0.402 0.038 0.440 0.5603 0.545 0.047 0.592 0.408 0.357 0.052 0.409 0.5914 0.530 0.055 0.585 0.415 0.317 0.064 0.381 0.6195 0.516 0.062 0.577 0.423 0.281 0.074 0.356 0.6446 0.502 0.068 0.570 0.430 0.250 0.083 0.333 0.6677 0.485 0.076 0.561 0.439 0.196 0.099 0.295 0.7058 0.470 0.083 0.553 0.447 0.154 0.111 0.265 0.7359 0.457 0.089 0.546 0.454 0.123 0.119 0.241 0.75910 0.446 0.094 0.540 0.460 0.098 0.124 0.223 0.77715 0.401 0.116 0.517 0.483 0.041 0.130 0.171 0.82920 0.366 0.133 0.500 0.500 0.025 0.124 0.148 0.85225 0.336 0.148 0.485 0.515 0.020 0.116 0.135 0.86530 0.310 0.162 0.471 0.529 0.018 0.109 0.126 0.87435 0.286 0.173 0.459 0.541 0.016 0.103 0.120 0.88040 0.264 0.184 0.447 0.553 0.015 0.099 0.114 0.88645 0.243 0.193 0.437 0.563 0.014 0.096 0.110 0.89050 0.225 0.202 0.427 0.573 0.013 0.093 0.106 0.89455 0.208 0.209 0.418 0.582 0.012 0.091 0.103 0.89760 0.193 0.216 0.409 0.591 0.012 0.089 0.101 0.89965 0.179 0.222 0.401 0.599 0.011 0.088 0.099 0.90170 0.166 0.228 0.394 0.606 0.010 0.087 0.098 0.90275 0.154 0.233 0.387 0.613 0.010 0.087 0.097 0.90380 0.144 0.237 0.381 0.619 0.009 0.086 0.095 0.90585 0.134 0.242 0.375 0.625 0.009 0.086 0.095 0.90590 0.125 0.245 0.370 0.630 0.008 0.086 0.094 0.90695 0.116 0.249 0.365 0.635 0.008 0.086 0.093 0.907100 0.108 0.252 0.360 0.640 0.007 0.086 0.093 0.907Average 0.258 0.184 0.442 0.043 0.095 0.138

YearafterProduction

NorthCentral,Hardwood

InUseSawlog

TotalEmissions

PulpwoodTotal

TotalStored

InLandfills

TotalStored

0 0.585 0.000 0.585 0.415 0.685 0.000 0.685 0.3151 0.533 0.032 0.565 0.435 0.613 0.035 0.648 0.3522 0.518 0.040 0.558 0.442 0.575 0.049 0.624 0.3763 0.504 0.047 0.550 0.450 0.541 0.061 0.602 0.3984 0.490 0.054 0.544 0.456 0.511 0.071 0.582 0.4185 0.477 0.060 0.537 0.463 0.484 0.080 0.565 0.4356 0.465 0.066 0.531 0.469 0.460 0.089 0.548 0.4527 0.450 0.073 0.523 0.477 0.421 0.101 0.522 0.4788 0.437 0.080 0.517 0.483 0.390 0.111 0.501 0.4999 0.425 0.085 0.511 0.489 0.365 0.119 0.484 0.51610 0.415 0.090 0.505 0.495 0.346 0.125 0.471 0.52915 0.372 0.112 0.484 0.516 0.290 0.139 0.429 0.57120 0.339 0.130 0.468 0.532 0.263 0.144 0.408 0.59225 0.309 0.145 0.454 0.546 0.245 0.148 0.393 0.60730 0.282 0.158 0.441 0.559 0.229 0.151 0.380 0.62035 0.258 0.170 0.428 0.572 0.216 0.154 0.370 0.63040 0.236 0.181 0.417 0.583 0.203 0.158 0.360 0.64045 0.216 0.191 0.407 0.593 0.191 0.161 0.352 0.64850 0.197 0.199 0.397 0.603 0.180 0.165 0.345 0.65555 0.181 0.207 0.388 0.612 0.170 0.168 0.338 0.66260 0.165 0.214 0.379 0.621 0.160 0.171 0.332 0.66865 0.151 0.220 0.372 0.628 0.152 0.174 0.326 0.67470 0.138 0.226 0.364 0.636 0.143 0.178 0.321 0.67975 0.127 0.231 0.358 0.642 0.136 0.180 0.316 0.68480 0.116 0.235 0.351 0.649 0.129 0.183 0.312 0.68885 0.106 0.239 0.346 0.654 0.122 0.186 0.308 0.69290 0.098 0.243 0.340 0.660 0.116 0.188 0.304 0.69695 0.089 0.246 0.336 0.664 0.110 0.191 0.300 0.700100 0.082 0.249 0.331 0.669 0.104 0.193 0.297 0.703Average 0.229 0.182 0.411 0.212 0.158 0.370

YearafterProduction

PacificNorthwest,East,Softwood

AllTotal

Emissions

InLandfills

TotalStored

0 0.637 0.000 0.637 0.363 1 0.574 0.036 0.610 0.390 2 0.551 0.046 0.597 0.403 3 0.530 0.055 0.585 0.415 4 0.511 0.063 0.574 0.426 5 0.494 0.070 0.564 0.436 6 0.478 0.077 0.555 0.445 7 0.455 0.086 0.541 0.459 8 0.436 0.093 0.529 0.471 9 0.420 0.100 0.520 0.480 10 0.406 0.105 0.512 0.488 15 0.359 0.125 0.484 0.516 20 0.327 0.139 0.466 0.534 25 0.301 0.150 0.451 0.549 30 0.278 0.160 0.438 0.562 35 0.258 0.169 0.427 0.573 40 0.239 0.177 0.416 0.584 45 0.222 0.185 0.406 0.594 50 0.206 0.191 0.397 0.603 55 0.191 0.198 0.389 0.611 60 0.178 0.203 0.381 0.619 65 0.166 0.208 0.374 0.626 70 0.155 0.213 0.368 0.632 75 0.145 0.217 0.362 0.638 80 0.136 0.221 0.356 0.644 85 0.127 0.224 0.351 0.649 90 0.119 0.227 0.347 0.653 95 0.112 0.230 0.342 0.658 100 0.105 0.233 0.338 0.662 Average 0.238 0.177 0.415

YearafterProduction

PacificNorthwest,West,Softwoods

SawlogTotal

Emissions InUse

PulpwoodTotal

TotalStored

InLandfills

TotalStored

0 0.740 0.000 0.740 0.260 0.500 0.000 0.500 0.500

1 0.674 0.039 0.713 0.287 0.440 0.020 0.460 0.540

2 0.652 0.049 0.702 0.298 0.387 0.037 0.424 0.576

3 0.632 0.059 0.691 0.309 0.341 0.051 0.392 0.608

4 0.613 0.068 0.681 0.319 0.300 0.063 0.364 0.636

5 0.596 0.076 0.672 0.328 0.264 0.074 0.338 0.662

6 0.579 0.083 0.663 0.337 0.233 0.082 0.315 0.685

7 0.558 0.093 0.651 0.349 0.177 0.099 0.276 0.724

8 0.539 0.101 0.640 0.360 0.134 0.111 0.245 0.755

9 0.524 0.108 0.631 0.369 0.102 0.119 0.221 0.779

10 0.510 0.114 0.624 0.376 0.078 0.124 0.202 0.798

15 0.457 0.139 0.596 0.404 0.020 0.129 0.149 0.851

20 0.418 0.158 0.576 0.424 0.005 0.122 0.127 0.873

25 0.384 0.174 0.558 0.442 0.001 0.113 0.114 0.886

30 0.355 0.188 0.543 0.457 0 0.105 0.105 0.895

35 0.328 0.201 0.529 0.471 0 0.098 0.099 0.901

40 0.303 0.213 0.516 0.484 0 0.093 0.093 0.907

45 0.281 0.223 0.504 0.496 0 0.090 0.090 0.910

50 0.260 0.232 0.493 0.507 0 0.086 0.086 0.914

55 0.242 0.241 0.482 0.518 0 0.084 0.084 0.916

60 0.224 0.248 0.473 0.527 0 0.082 0.082 0.918

65 0.209 0.255 0.464 0.536 0 0.080 0.080 0.920

70 0.194 0.261 0.456 0.544 0 0.079 0.079 0.921

75 0.181 0.267 0.448 0.552 0 0.078 0.078 0.922

80 0.169 0.272 0.441 0.559 0 0.078 0.078 0.922

85 0.158 0.276 0.434 0.566 0 0.077 0.077 0.923

90 0.148 0.281 0.428 0.572 0 0.077 0.077 0.923

95 0.138 0.285 0.423 0.577 0 0.076 0.076 0.924

100 0.129 0.288 0.417 0.583 0 0.076 0.076 0.924

Average 0.298 0.213 0.511 0.030 0.090 0.119

YearafterProduction

PacificNorthwest,West,Hardwood PacificSouthwest,Softwood

InUseAll

TotalEmissions

AllTotal

TotalStored

InLandfills

TotalStored

0 0.531 0.000 0.531 0.469 0.675 0.000 0.675 0.325

1 0.476 0.027 0.503 0.497 0.611 0.036 0.647 0.353

2 0.447 0.038 0.485 0.515 0.587 0.047 0.634 0.366

3 0.421 0.048 0.469 0.531 0.566 0.056 0.622 0.378

4 0.397 0.057 0.454 0.546 0.546 0.065 0.611 0.389

5 0.376 0.064 0.440 0.560 0.528 0.072 0.600 0.400

6 0.357 0.071 0.428 0.572 0.511 0.080 0.591 0.409

7 0.327 0.081 0.408 0.592 0.488 0.089 0.577 0.423

8 0.303 0.089 0.393 0.607 0.468 0.097 0.565 0.435

9 0.284 0.096 0.380 0.620 0.451 0.104 0.555 0.445

10 0.269 0.101 0.369 0.631 0.437 0.110 0.547 0.453

15 0.222 0.115 0.337 0.663 0.387 0.131 0.518 0.482

20 0.197 0.122 0.319 0.681 0.353 0.146 0.499 0.501

25 0.179 0.127 0.306 0.694 0.324 0.159 0.483 0.517

30 0.164 0.132 0.295 0.705 0.299 0.170 0.469 0.531

35 0.150 0.136 0.286 0.714 0.276 0.180 0.457 0.543

40 0.137 0.140 0.278 0.722 0.256 0.190 0.445 0.555

45 0.126 0.144 0.270 0.730 0.237 0.198 0.435 0.565

50 0.115 0.148 0.263 0.737 0.220 0.205 0.425 0.575

55 0.106 0.151 0.257 0.743 0.204 0.212 0.416 0.584

60 0.097 0.155 0.252 0.748 0.189 0.218 0.408 0.592

65 0.089 0.157 0.247 0.753 0.176 0.224 0.400 0.600

70 0.082 0.160 0.242 0.758 0.164 0.229 0.393 0.607

75 0.075 0.163 0.238 0.762 0.153 0.233 0.387 0.613

80 0.069 0.165 0.234 0.766 0.143 0.238 0.381 0.619

85 0.064 0.167 0.231 0.769 0.133 0.241 0.375 0.625

90 0.059 0.169 0.227 0.773 0.125 0.245 0.370 0.630

95 0.054 0.171 0.224 0.776 0.117 0.248 0.365 0.635

100 0.050 0.172 0.222 0.778 0.109 0.251 0.361 0.639

Average 0.145 0.139 0.284 0.254 0.190 0.444

YearafterProduction

RockyMountain,Softwood

All Total

Emissions

0 0.704 0.000 0.704 0.296 1 0.640 0.037 0.677 0.323 2 0.615 0.048 0.663 0.337 3 0.592 0.057 0.650 0.350 4 0.572 0.066 0.638 0.362 5 0.552 0.075 0.627 0.373 6 0.535 0.082 0.617 0.383 7 0.510 0.092 0.602 0.398 8 0.489 0.101 0.590 0.410 9 0.472 0.108 0.579 0.421 10 0.457 0.114 0.571 0.429 15 0.404 0.136 0.540 0.460 20 0.368 0.152 0.520 0.480 25 0.338 0.166 0.504 0.496 30 0.312 0.177 0.489 0.511 35 0.288 0.188 0.476 0.524 40 0.266 0.198 0.464 0.536 45 0.247 0.206 0.453 0.547 50 0.229 0.214 0.443 0.557 55 0.212 0.221 0.433 0.567 60 0.197 0.228 0.425 0.575 65 0.183 0.234 0.417 0.583 70 0.170 0.239 0.409 0.591 75 0.159 0.244 0.403 0.597 80 0.148 0.248 0.396 0.604 85 0.138 0.252 0.390 0.610 90 0.129 0.256 0.385 0.615 95 0.121 0.259 0.380 0.620 100 0.113 0.262 0.375 0.625 Average 0.265 0.198 0.463

YearafterProduction

Southeast,Softwood

InUseSawlog

TotalEmissions

PulpwoodTotal

TotalStored

InLandfills

TotalStored

0 0.636 0.000 0.636 0.364 0.553 0.000 0.553 0.447

1 0.578 0.034 0.612 0.388 0.490 0.024 0.514 0.486

2 0.557 0.043 0.600 0.400 0.442 0.040 0.482 0.518

3 0.537 0.052 0.589 0.411 0.399 0.054 0.453 0.547

4 0.519 0.060 0.578 0.422 0.361 0.066 0.427 0.573

5 0.502 0.067 0.569 0.431 0.328 0.076 0.403 0.597

6 0.486 0.074 0.560 0.440 0.298 0.084 0.382 0.618

7 0.465 0.083 0.547 0.453 0.247 0.100 0.347 0.653

8 0.447 0.090 0.537 0.463 0.208 0.111 0.319 0.681

9 0.432 0.096 0.528 0.472 0.178 0.119 0.297 0.703

10 0.418 0.102 0.520 0.480 0.155 0.124 0.279 0.721

15 0.371 0.122 0.494 0.506 0.098 0.132 0.230 0.770

20 0.339 0.137 0.476 0.524 0.079 0.128 0.208 0.792

25 0.311 0.150 0.461 0.539 0.071 0.123 0.194 0.806

30 0.287 0.161 0.448 0.552 0.066 0.118 0.184 0.816

35 0.265 0.171 0.436 0.564 0.062 0.115 0.177 0.823

40 0.245 0.180 0.425 0.575 0.058 0.112 0.170 0.830

45 0.227 0.188 0.415 0.585 0.055 0.110 0.165 0.835

50 0.210 0.195 0.405 0.595 0.052 0.109 0.161 0.839

55 0.195 0.202 0.397 0.603 0.049 0.108 0.157 0.843

60 0.181 0.208 0.389 0.611 0.046 0.108 0.154 0.846

65 0.169 0.213 0.382 0.618 0.044 0.108 0.151 0.849

70 0.157 0.218 0.375 0.625 0.041 0.108 0.149 0.851

75 0.146 0.222 0.369 0.631 0.039 0.108 0.147 0.853

80 0.137 0.226 0.363 0.637 0.037 0.108 0.145 0.855

85 0.127 0.230 0.358 0.642 0.035 0.108 0.143 0.857

90 0.119 0.233 0.353 0.647 0.033 0.109 0.142 0.858

95 0.111 0.236 0.348 0.652 0.031 0.109 0.141 0.859

100 0.104 0.239 0.344 0.656 0.030 0.110 0.140 0.860

Average 0.243 0.180 0.423 0.082 0.109 0.191

YearafterProduction

Southeast,Hardwood

SawlogTotal

Emissions InUse

PulpwoodTotal

TotalStored

InLandfills

TotalStored

0 0.609 0.000 0.609 0.391 0.591 0.000 0.591 0.409

1 0.552 0.035 0.587 0.413 0.525 0.027 0.552 0.448

2 0.534 0.043 0.577 0.423 0.480 0.043 0.522 0.478

3 0.518 0.051 0.569 0.431 0.439 0.056 0.495 0.505

4 0.503 0.058 0.561 0.439 0.404 0.067 0.471 0.529

5 0.488 0.065 0.553 0.447 0.372 0.077 0.449 0.551

6 0.475 0.071 0.546 0.454 0.344 0.085 0.430 0.570

7 0.457 0.079 0.537 0.463 0.296 0.100 0.397 0.603

8 0.442 0.086 0.528 0.472 0.260 0.111 0.371 0.629

9 0.429 0.092 0.521 0.479 0.231 0.119 0.350 0.650

10 0.418 0.097 0.515 0.485 0.209 0.124 0.334 0.666

15 0.373 0.119 0.492 0.508 0.153 0.134 0.287 0.713

20 0.338 0.136 0.475 0.525 0.132 0.133 0.265 0.735

25 0.309 0.151 0.460 0.540 0.121 0.130 0.251 0.749

30 0.282 0.164 0.446 0.554 0.113 0.127 0.240 0.760

35 0.258 0.176 0.434 0.566 0.106 0.126 0.232 0.768

40 0.236 0.186 0.422 0.578 0.100 0.125 0.225 0.775

45 0.216 0.196 0.412 0.588 0.094 0.125 0.218 0.782

50 0.198 0.204 0.402 0.598 0.089 0.125 0.213 0.787

55 0.181 0.212 0.393 0.607 0.084 0.125 0.209 0.791

60 0.166 0.218 0.384 0.616 0.079 0.126 0.205 0.795

65 0.152 0.224 0.376 0.624 0.075 0.126 0.201 0.799

70 0.139 0.230 0.369 0.631 0.071 0.127 0.198 0.802

75 0.127 0.235 0.362 0.638 0.067 0.128 0.195 0.805

80 0.117 0.239 0.356 0.644 0.063 0.129 0.193 0.807

85 0.107 0.243 0.350 0.650 0.060 0.130 0.190 0.810

90 0.098 0.247 0.345 0.655 0.057 0.131 0.188 0.812

95 0.090 0.250 0.340 0.660 0.054 0.132 0.186 0.814

100 0.083 0.253 0.336 0.664 0.051 0.133 0.185 0.815

Average 0.231 0.187 0.417 0.119 0.123 0.242

YearafterProduction

SouthCentral,Softwood

InUseSawlog

TotalEmissions

PulpwoodTotal

TotalStored

InLandfills

TotalStored

0 0.629 0.000 0.629 0.371 0.570 0.000 0.570 0.430

1 0.569 0.035 0.603 0.397 0.506 0.026 0.532 0.468

2 0.547 0.044 0.591 0.409 0.459 0.041 0.500 0.500

3 0.527 0.053 0.580 0.420 0.417 0.055 0.472 0.528

4 0.509 0.061 0.569 0.431 0.380 0.066 0.447 0.553

5 0.492 0.068 0.560 0.440 0.348 0.076 0.424 0.576

6 0.477 0.075 0.551 0.449 0.319 0.085 0.404 0.596

7 0.455 0.083 0.538 0.462 0.270 0.100 0.370 0.630

8 0.437 0.091 0.527 0.473 0.232 0.111 0.343 0.657

9 0.421 0.097 0.518 0.482 0.202 0.119 0.321 0.679

10 0.408 0.102 0.510 0.490 0.180 0.124 0.304 0.696

15 0.362 0.122 0.484 0.516 0.123 0.133 0.256 0.744

20 0.330 0.136 0.466 0.534 0.103 0.130 0.234 0.766

25 0.303 0.148 0.451 0.549 0.094 0.126 0.220 0.780

30 0.280 0.158 0.439 0.561 0.087 0.122 0.210 0.790

35 0.259 0.168 0.427 0.573 0.082 0.120 0.202 0.798

40 0.240 0.176 0.416 0.584 0.077 0.118 0.195 0.805

45 0.222 0.184 0.406 0.594 0.072 0.117 0.189 0.811

50 0.206 0.191 0.397 0.603 0.068 0.116 0.185 0.815

55 0.192 0.197 0.389 0.611 0.064 0.116 0.181 0.819

60 0.178 0.203 0.381 0.619 0.061 0.116 0.177 0.823

65 0.166 0.208 0.374 0.626 0.058 0.116 0.174 0.826

70 0.155 0.213 0.368 0.632 0.054 0.117 0.171 0.829

75 0.145 0.217 0.362 0.638 0.051 0.117 0.169 0.831

80 0.135 0.221 0.356 0.644 0.049 0.118 0.167 0.833

85 0.126 0.225 0.351 0.649 0.046 0.119 0.165 0.835

90 0.118 0.228 0.346 0.654 0.044 0.119 0.163 0.837

95 0.111 0.231 0.342 0.658 0.042 0.120 0.161 0.839

100 0.104 0.234 0.338 0.662 0.039 0.121 0.160 0.840

Average 0.239 0.176 0.415 0.099 0.116 0.215

YearafterProduction

SouthCentral,Hardwood

InUseSawlog

TotalEmissions

PulpwoodTotal

TotalStored

InLandfills

TotalStored

0 0.587 0.000 0.587 0.413 0.581 0.000 0.581 0.419

1 0.531 0.033 0.564 0.436 0.516 0.027 0.542 0.458

2 0.512 0.042 0.554 0.446 0.470 0.042 0.512 0.488

3 0.495 0.050 0.545 0.455 0.429 0.055 0.484 0.516

4 0.479 0.057 0.536 0.464 0.392 0.067 0.459 0.541

5 0.464 0.064 0.528 0.472 0.360 0.077 0.437 0.563

6 0.450 0.070 0.521 0.479 0.332 0.085 0.417 0.583

7 0.432 0.078 0.510 0.490 0.283 0.100 0.383 0.617

8 0.416 0.085 0.501 0.499 0.246 0.111 0.357 0.643

9 0.403 0.091 0.493 0.507 0.217 0.119 0.336 0.664

10 0.391 0.096 0.487 0.513 0.195 0.124 0.319 0.681

15 0.347 0.116 0.463 0.537 0.138 0.133 0.272 0.728

20 0.314 0.132 0.446 0.554 0.118 0.131 0.250 0.750

25 0.286 0.145 0.432 0.568 0.108 0.128 0.236 0.764

30 0.262 0.157 0.419 0.581 0.101 0.125 0.226 0.774

35 0.239 0.168 0.407 0.593 0.095 0.123 0.217 0.783

40 0.219 0.177 0.396 0.604 0.089 0.121 0.210 0.790

45 0.200 0.186 0.386 0.614 0.084 0.121 0.204 0.796

50 0.183 0.193 0.377 0.623 0.079 0.120 0.199 0.801

55 0.168 0.200 0.368 0.632 0.075 0.121 0.195 0.805

60 0.154 0.206 0.360 0.640 0.070 0.121 0.191 0.809

65 0.141 0.212 0.353 0.647 0.067 0.121 0.188 0.812

70 0.129 0.217 0.346 0.654 0.063 0.122 0.185 0.815

75 0.118 0.222 0.340 0.660 0.060 0.123 0.182 0.818

80 0.108 0.226 0.334 0.666 0.057 0.124 0.180 0.820

85 0.099 0.229 0.329 0.671 0.054 0.124 0.178 0.822

90 0.091 0.233 0.324 0.676 0.051 0.125 0.176 0.824

95 0.084 0.236 0.319 0.681 0.048 0.126 0.174 0.826

100 0.077 0.238 0.315 0.685 0.046 0.127 0.173 0.827

Average 0.215 0.177 0.393 0.110 0.119 0.229

YearafterProduction

OtherWest,Hardwood

InUseAll

TotalEmissions

0 0.568 0.000 0.568 0.432 1 0.516 0.028 0.544 0.456 2 0.494 0.038 0.532 0.468 3 0.473 0.046 0.520 0.480 4 0.455 0.054 0.509 0.491 5 0.438 0.061 0.499 0.501 6 0.422 0.068 0.490 0.510 7 0.399 0.077 0.476 0.524 8 0.381 0.084 0.465 0.535 9 0.365 0.090 0.455 0.545 10 0.352 0.095 0.447 0.553 15 0.307 0.113 0.421 0.579 20 0.277 0.126 0.403 0.597 25 0.253 0.136 0.389 0.611 30 0.232 0.146 0.377 0.623 35 0.212 0.154 0.366 0.634 40 0.195 0.162 0.356 0.644 45 0.179 0.169 0.347 0.653 50 0.164 0.175 0.339 0.661 55 0.151 0.181 0.331 0.669 60 0.138 0.186 0.324 0.676 65 0.127 0.190 0.318 0.682 70 0.117 0.195 0.312 0.688 75 0.108 0.198 0.306 0.694 80 0.099 0.202 0.301 0.699 85 0.091 0.205 0.296 0.704 90 0.084 0.208 0.292 0.708 95 0.078 0.210 0.288 0.712 100 0.072 0.213 0.284 0.716 Average 0.195 0.161 0.357

Table6‐A‐6:RegionalFactorstoEstimateCarboninRoundwoodLogs,BarkonLogs,andFuelwood

RegionaTimberType

RoundwoodCategory

RatioofRoundwoodtoGrowing‐StockVolumethatisRoundwoodb

RatioofCarboninBarktoCarboninWoodc

FractionofGrowing‐StockVolumethatisRoundwoodd

RatioofFuelwoodtoGrowing‐StockVolumethatisRoundwoodb

NortheastSW

Sawlog 0.991 0.1820.948 0.136

Pulpwood 3.079 0.185

HWSawlog 0.927 0.199

0.879 0.547Pulpwood 2.177 0.218

NorthCentral

SWSawlog 0.985 0.182

0.931 0.066Pulpwood 1.285 0.185

0.831 0.348Pulpwood 1.387 0.218

PacificCoast

0.929 0.096Pulpwood 1.099 0.185

0.947 0.957Pulpwood 0.324 0.219

RockyMountain

0.907 0.217Pulpwood 2.413 0.185

0.755 3.165Pulpwood 1.336 0.219

0.891 0.019Pulpwood 1.246 0.185

0.752 0.301Pulpwood 1.191 0.218SW=Softwood,HW=Hardwood.aNorthCentralincludestheNorthernPrairieStatesandtheNorthernLakeStates;PacificCoastincludesthePacificNorthwest(WestandEast)andthePacificSouthwest;RockyMountainincludesRockyMountain,NorthandSouth;andSouthincludestheSoutheastandSouthCentral.bValuesandclassificationsarebasedondatainTables2.2,3.2,4.2,5.2,and6.2ofJohnson(2001).cRatiosarecalculatedfromcarbonmassbasedonbiomasscomponentequationsinJenkinsetal.(2003a),appliedtoalllivetreesidentifiedasgrowingstockontimberlandstandsclassifiedasmedium‐orlarge‐diameterstandsinthesurveydatafortheconterminousUnitedStatesfromUSDAForestService,FIAProgram’sdatabaseofforestsurveys(FIADB)(Alerichetal.,2005;USDAForestService,2005).Carbonmassiscalculatedforbolesfromstumpto4‐inch(10.2cm)top,outsidediameter.dValuesandclassificationsarebasedondatainTables2.9,3.9,4.9,5.9,and6.9ofJohnson(2001).

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