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
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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.
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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.
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Section Source Method
6.7.3
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
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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
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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
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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
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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.
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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.
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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
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Figure6‐2:DecisionTreeforForestSectorShowingRelevantChapterSectionsDependingonApplicableSourceCategories
NO
NO
YES
YES
NO
See Section 6.7:Natural Disturbances
YES
YES
NO
Start
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
land?
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
YES
NO
NO
YES
NO
YES
YES
Do you have forest stands on your
land?
Do you have additional forest
stands ?
End
NO
Did you useagroforestry: e.g.,
windbreaks, riparian forest buffers, alley cropping,
silvopastures?
See Section 3.4: Agroforestry
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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.
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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.
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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.
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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).
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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)
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(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)
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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.
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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
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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
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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
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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.
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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.
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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
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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/
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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.
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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.
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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.
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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
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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.
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6.3.3 EstimationMethods
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
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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.
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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.
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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.
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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).
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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
i=1
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)
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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
Nj,sp
CAB,i,sp,j,t=ΣCFj׃j(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
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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
Sps
Ctree,i,sp,t=Σ(CAB,i,sp,j,t+CBB,i,sp,j,t)
j=1
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
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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
Pi
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)
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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)
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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)
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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.
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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
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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
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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.
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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
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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.
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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;
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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
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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
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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
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ReducingRiskofEmissionsfromPestsandDisease
Short‐RotationWoodyCrops
6.4.2.1 StandDensityManagement
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.
6.4.2.3 VegetationControl
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.
6.4.2.5 NaturalRegeneration
Asinthecaseofplantationestablishment,carbonstockchangesatthetimeofnaturalregenerationarenegligible.
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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.
6.4.2.9 FireandFuelLoadManagement
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.
6.4.2.10 ReducingRiskofEmissionsfromPestsandDisease
Forestimatesofcarbonstockimpactsofsanitationandsalvageharvests,pretreatmentandpost‐
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treatmentinventoriesarerequired.Inthepretreatmentinventory,theextentandnatureofdamageareneededtoestimatethecarbonstockthathasshiftedfromlivetodeadbiomasspriortotreatment.
ModelingforTypeIIandIIIestimatesmayentailsimplyprojectingtheresidual(post‐treatment)stand.Tofullyevaluatethecarbonstockimpactsofthetreatment,modelsorassumptionsareneededforestimatingthespreadoftheinsectordiseaseabsentthetreatment.Toolsforsuchmodelingorassumptionsmaybehardtoobtain.
6.4.2.11 Short‐RotationWoodyCrops
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.
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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.
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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
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Region ForestType GeneralizedPractice
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
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Region ForestType GeneralizedPractice
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
Oak
Clearcut:Onlowerqualitysites,andonhighqualitysiteswhereadequateadvancedregenerationispresent;commercialthinningasrequiredShelterwood:Onhighqualitysiteswhenadequateadvancedregenerationisnotpresent;commercialthinningasrequired
JackpineClearcut:50–60yearrotation (notethatjackpinemanagedforKirtland’swarblerhabitatwillhaveadditionalmanagementrequirements)
Redpine
Clearcut:Commonlyfollowedbysitepreparationandplanting900peracre,commercialthinningbeginningatage25–40Shelterwood:Wherediseaseriskislow;oftenusedwithprescribedfire;commercialthinningbeginningatage25–40
WhitepineShelterwood:Twostagesystem;commercialthinningbeginningatage40
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Region ForestType GeneralizedPractice
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
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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 ‐ ‐ ‐ ‐ ‐ ‐
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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 ‐ ‐ ‐ ‐ ‐ ‐
6.4.4 EstimationMethods
6.4.4.1 StandDensityManagement
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.
6.4.4.3 VegetationControl
Controlofwoodyvegetationwillexhibitpatternssimilartoprecommercialthinning:transferofcarbonstocksfromlivetreetodeadtreepools.Quantitieswilllikelybesmallandtheeffectofshortduration;henceaccountingfortheseimpactsusingTypeIestimatesmaybeunnecessary.
ForTypeIIandIIIestimates,vegetationcontrolmaybeexpectedtohaveabeneficialimpactonthe
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growthoftheresidualstandthatshouldbemodeledaccordingly.
6.4.4.4 Planting
Negligiblecarbonstockchangesareexpectedatthetimeofestablishmentofanewplantation,soTypeIestimateswillshownostockchanges.ForTypeIIandIIIestimates,theplantationactivityestablishesanewstandthatcanthenbemodeledbasedonspecies,siteindex,andinitialstocking(plantingdensitytimesyear1survivalpercent).
6.4.4.5 NaturalRegeneration
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).
6.4.4.7 FireandFuelLoadManagement
TypeIestimatesofcarbonstockchangesduetofueltreatmentsorprescribedfireshouldreflectlossestolivetreebiomassaccordingtothematerialburned,killed,orremoved(frompreandpost‐treatmentinventorydata).Foraprescribedfire,emissionscanbecalculatedusingFOFEM.Ifslashisleftfromthefueltreatment,CONSUMEmayalsobeused.
TypeIIandIIIestimatessimplyinvolveprojectingthestandbasedoninformationfromthepost‐treatmentinventory.
6.4.4.8 ReducingRiskofEmissionsfromPestsandDisease
TypeIcarbonstockestimateswillinvolvecomputationoflossestolivetreebiomassfromthesanitationorsalvageharvest,withadditionstoHWPpoolsasappropriate.
TypeIIandIIIestimatessimplyinvolveprojectingthestandbasedoninformationfromthepost‐treatmentinventory.
6.4.4.9 Short‐RotationWoodyCrops
Negligiblecarbonstockchangesareexpectedatthetimeofestablishmentofanewplantation,soTypeIestimateswillshownostockchanges.ForTypeIIandIIIestimates,theplantationactivityestablishesanewstandthatcanthenbemodeledbasedonspecies,siteindex,andinitialstocking(plantingdensitytimesyear1survivalpercent).
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6.4.5 LimitationsandUncertainty
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.
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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).
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100years.
Themeasure—averagecarbonstoredinHWPover100years(withvariationsonhowlandfillcarbonisincluded)—isusedintheClimateActionReserve(2010)ForestProjectProtocolsadoptedbytheCaliforniaAirResourcesBoard.Theprotocolsindicatehowtocalculatethelevelofannualcarboncreditsthatmaybesoldbyforestlandownerswhoentercarboncontracts.
Notethatuseoftheproductionapproachtoaccountingisnotalife‐cycleassessmentaccountingapproachthatcouldtakeintoaccounthowcarbonemissionsfromincreasedwoodburningorincreaseduseofwoodproductsmightoffsetfossilfuelemissionsoremissionsfrommakingnon‐woodproductsovertime.TheestimatesofannualchangeincarboninHWPsarenotintendedtoindicatethetotalimpactonGHGlevelsintheatmosphereofusingHWPs(includinguseofwoodforenergy),noraretheyintendedtoindicatethattheemissiontotheatmospheretookplaceintheUnitedStatesversusothercountrieswhereproductswereexported.EstimationofTypeIIIsecondaryGHGreductioneffectsofsubstitutionofwoodforfossilfuelsornon‐woodconstructionproductsarecomplexandwouldrequirespecificationofabaselinefromwhichchangeismeasuredandotherassumptionsthatarebeyondthescopeofthesemethods.
Theproductionapproachisusedtoacknowledgethatharvestingofforestsdoesnotimmediatelyreleaseallofthecontainedcarbontotheatmosphere;theaccountingcountsonlythecarbonchangeinHWPsinordertoallowannualcarbonchangesinHWPstobedeductedoraddedtoannualemissionsintheenergyandmanufacturingsectorsandcarbonchangesinforests,sotherewillbenoomissionordoublecountingofsequestrationoremissionstotheatmosphere.Inthenationalaccountingframework,theannualemissionsfromwoodenergyareaccountedforaspartoftheaggregatedannualchangeinforestplusHWPcarbon.
6.5.2 EstimationMethods
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.
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6.5.3 ActivityDataCollection
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
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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.
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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.
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(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
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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).
6.6.2 ActivityDataCollection
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:
− Numberoftreesbyspeciesandsizeclass(species,DBH,height,condition,competitionfactor)
− Annualgrowthratesforeachtreebasedontreeandsiteconditions(inchesperyear)
LongTermEffects:
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− Numberoftreesbyspeciesandsizeclass(species,DBH,height,condition,competitionfactor)
− 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.
6.6.3 EstimationMethods
Themethodsforestimatingcarboneffectsinanurbanforestwillbedetailedforthefielddataandaerialapproachesseparately.ThefielddatamethodandaerialmethodforurbanforestsaredescribedinSection6.6.3.1andSection6.6.3.2.Figure6‐8showsadecisiontreeindicatingwhichmethodismoreapplicableforeachtypeofactivitydata.
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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
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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
DBH
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:
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(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
DBH
Pruning Removal2.3hp
3.7hp
BucketChipperb
2.3hp
3.7hp
7.5hp
BucketChipperb
Stump
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:
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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)
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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
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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.
6.6.4 LimitationsandUncertainty
Fielddatacollectionestimateshavefewerlimitationsthantheaerialapproach,butsomelimitationsexist(Nowaketal.,2008).Themainadvantageofcarbonestimationusingthefielddata
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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
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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.
6.7.2 ActivityDataCollection
Foralldisturbances,keyactivitydataistheareaaffected.Asimpledescriptorisusedtocharacterizetheseverityoftheevent.Forbothwildfireandprescribedfire/controlburns,descriptorsofseverityincludecrownfire,stand‐replacementunderburn,mixed‐severityunderburn(sometreemortality),andlow‐severityunderburn.Typicallywildfirewillbemoreweightedtowardscrownfireandhigherseverityversuslowerseverityfromprescribedfire.Forotherdisturbances,thepercentageoflivetreeskilled(orpercentagebasalareamortality)andthepercentageofkilledtreesthatarestillstandingaswascoveredpreviouslyinSection6.4.2.10andSection6.4.4.8areused.
6.7.3 EstimationMethods
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.
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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
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Figure6‐9:DecisionTreeforNaturalDisturbancesShowingMethodsAppropriateforEstimatingEmissionsfromForestFiresDependingontheDataAvailable
6.7.3.1 EstimationofGreenhouseGasEmissionsfromFire
ThecalculationofGHGemissionsfromfirescanbeseeninEquation6‐11below.
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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)
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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
Westa
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).
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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.
6.7.4 LimitationsandUncertainty
Amajorsourceofuncertaintyinpredictingfireemissionsisthepreburnfuelquantities.Iflandownersaredoingsomekindofinventoryofliveanddeadbiomass(seeSection6.7.2)theywillhaverelativelyrobustestimatesofavailablefuel.Iftheyareusinglookuptablevaluesbyforesttype,therewillbemoreuncertaintyassociatedwiththeestimatessincefuelquantitiesvarygreatlywithinforesttype.
Arelatedchallengeisdeterminingtheappropriatedegreeofspecificityfortrackingbiomassbypools(e.g.,live,dead).Anykindofmanagementordisturbancechangesbiomassatthetimeofoccurrence,andalsothesubsequenttrajectory.Subsequentmanagementordisturbanceshouldbeappliedtothechangedandchangingvalues,nottheoriginalvalues.ThiscanresultinacomplicatedsimulationmodellikeFVS,ratherthanacalculator.Sinceprefirefuelquantityisthestrongestpredictoroffuelconsumption,determiningtheappropriatedegreeofspecificityfortrackingbiomassbypoolsisnotacompletelyacademicquestion.
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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
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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
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Table6‐A‐3:FractionofCarboninPrimaryWoodProductsRemaininginLandfillsupto100YearsafterProduction(year0indicatesfractionattimeofproduction)
YearafterProductio
n
Softwood
Lumber
HardwoodLumber
SoftwoodPlywood
OrientedStrandboar
d
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
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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
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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
Weste
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.
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Table6‐A‐5:AverageDispositionPatternsofCarbon asFractions inRoundwoodby RegionandRoundwoodCategory;FactorsAssumeNoBarkonRoundwoodandExcludeFuelwood
YearafterProduction
Northeast,Softwood
InUse
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
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Table6‐A‐5—continued
YearafterProduction
Northeast,Hardwood
InUseSawlog
TotalEmissions
InUse
PulpwoodTotal
EmissionsInLandfills
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
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Table6‐A‐5—continued
YearafterProduction
NorthCentral,Softwood
InUse
Sawlog
TotalEmissions
InUse
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
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Table6‐A‐5—continued
YearafterProduction
NorthCentral,Hardwood
InUseSawlog
TotalEmissions
InUse
PulpwoodTotal
EmissionsInLandfills
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
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Table6‐A‐5—continued
YearafterProduction
PacificNorthwest,East,Softwood
InUse
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
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Table6‐A‐5—continued
YearafterProduction
PacificNorthwest,West,Softwoods
InUse
SawlogTotal
Emissions InUse
PulpwoodTotal
EmissionsInLandfills
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
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Table6‐A‐5—continued
YearafterProduction
PacificNorthwest,West,Hardwood PacificSouthwest,Softwood
InUseAll
TotalEmissions
InUse
AllTotal
EmissionsInLandfills
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
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Table6‐A‐5—continued
YearafterProduction
RockyMountain,Softwood
InUse
All Total
Emissions
In
LandfillsTotalStored
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
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Table6‐A‐5—continued
YearafterProduction
Southeast,Softwood
InUseSawlog
TotalEmissions
InUse
PulpwoodTotal
EmissionsInLandfills
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
Chapter 6: Quantifying Greenhouse Gas Sources and Sinks in Managed Forest Systems
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Table6‐A‐5—continued
YearafterProduction
Southeast,Hardwood
InUse
SawlogTotal
Emissions InUse
PulpwoodTotal
EmissionsInLandfills
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
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Table6‐A‐5—continued
YearafterProduction
SouthCentral,Softwood
InUseSawlog
TotalEmissions
InUse
PulpwoodTotal
EmissionsInLandfills
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
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Table6‐A‐5—continued
YearafterProduction
SouthCentral,Hardwood
InUseSawlog
TotalEmissions
InUse
PulpwoodTotal
EmissionsInLandfills
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
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Table6‐A‐5—continued
YearafterProduction
OtherWest,Hardwood
InUseAll
TotalEmissions
In
LandfillsTotalStored
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
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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
HWSawlog 0.960 0.199
0.831 0.348Pulpwood 1.387 0.218
PacificCoast
SWSawlog 0.965 0.181
0.929 0.096Pulpwood 1.099 0.185
HWSawlog 0.721 0.197
0.947 0.957Pulpwood 0.324 0.219
RockyMountain
SWSawlog 0.994 0.181
0.907 0.217Pulpwood 2.413 0.185
HWSawlog 0.832 0.201
0.755 3.165Pulpwood 1.336 0.219
South
SWSawlog 0.990 0.182
0.891 0.019Pulpwood 1.246 0.185
HWSawlog 0.832 0.198
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).
Chapter 6: Quantifying Greenhouse Gas Sources and Sinks in Managed Forest Systems
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