WPC* Vt,E{t&yEYd S$/av,*Y**f<4ݻ4T#ɠnsa>645M!p^՘&L$\iɐ Us&$)̄$-֣5|uވQ}鰷ݬ*`LJ GrG!3;M‰,P{hU^={563->qAU| m^88M(Z.ْ)aVPU5_u7~N0Ķ*,>-R/j)knXxJ,{g =TF1AH5#+QUWN3W_GUlet>ҔYZudӋxpJnE'@ԑp1zū9\y_W2 D1Oc!I~T1 1GU* 0U< 0 0U< 0. 0 0 0 0 0 0A 0 0 0u 0 0 0 0U 0 0 0f~ 0 05U,- BY D3v B C 1uW 0gUN %ONU 1uWw@4   m"UN9UN 04#! $359;=?ACE1"%2A`Arial<j:Default ParaQ\  `$Arial NewRomanQ\  `$Arial NewRoman<XX:Endnote TextXXX?%2A`Arial??%2A`Arial?<m[:Endnote RefeQ\  `$Times NewRomanQ?%2A`Arial?\  `$Times NewRoman<XX:Footnote TexXXX?%2A`Arial??%2A`Arial?<m[:Footnote RefQ\  `$Times NewRomanQ?%2A`Arial?0RY.TOC 1 X X    .  44T$    5+ 4 <DL!5  08Y.TOC 2  X    T$    5+ 4 <DL!5  08Y.TOC 3  X    T$    5+ 4 <DL!5  08Y.TOC 4 ` X  <<T$    5+ 4 <DL!5  08Y.TOC 5  X  T$    5+ 4 <DL!5  0,M.TOC 6 X  44T$   5+ 4 <DL!5  0JM.TOC 7 X 2(4 4 <DL!2   5+ 4 <DL!5  0,M.TOC 8 X  44T$   5+ 4 <DL!5  0,M.TOC 9 X  44T$   5+ 4 <DL!5  48Y2Index 1  X    T$ P   5+ 4 <DL!5  48Y2Index 2  X    T$    5+ 4 <DL!5  <5:TOA Heading  T$5+ 4 <DL!54XX2Caption XXX?%2A`Arial??%2A`Arial?<j:_Equation CaQ\  `$Arial NewRomanQ2>0Footer  !>44 <DL!>' What Wildland Fire Conditions Minimize Emissions and Hazardous Air (Janice Peterson 0 .    9)  %X%X7J%  _ @ XX7J7JXX(29$ $!    %X%X/%  0^j.pbllt"A(\ Y`SymbolA"Q\  `$Times NewRomanQ(\ Y`Symbol d'dxd1 ddd$35=EMU]em2 I. A. 1) a.(1)(a) i) a)#|x(r$    %X%XW-%xhH  Z6Times New Roman Regular%X##37=CIQYag1.a.i.(1)(a)(i)1)a) D{DD)$dPU(9 Z 6Times New Roman Regular(Y Z 6Times New Roman Regular&c$""0 HP LaserJet 4,,,,,,0 $!    %X%X7J%  _      C  $#(C#84KXdd8  7J.U0 DRAFT  .X4KX.U0 -X4KXX.X4K-U0X-X4KWhat_Wildland_ԀFireConditionsMinimizeEmissionsandHazardous $ AirPollutantsandCanLandManagementGoalsStillbeMet?#-X4KX-U0 #  8 -X-X4K-X4KX-J.PetersonandB._Leenhouts_       8/20/97 Introduction -U0X-X4K r   #-X4KX-U0# 4 Thispaperisadiscussionof_wildland_Ԁconditionsandtechniquesthatminimize ^  pollutantemissionsandisintendedtoprovideinterestedreaderswithadditionalinformationonthesubject.Thispaper_was_ԀdevelopedbymembersofanEPAsponsoredworkgroupinresponsetospecificquestionsraisedaboutsmokemanagementinthedevelopmentofapolicyrecommendationtoEPA.InnowayshouldanyoftheinformationpresentedinthispaperbeconstruedasanEPArequirement. 4 Variousmanagementtechniquescanbeappliedtoreducetheemissionsproducedfrom_wildland_Ԁburning.Incidentemissionreductionscomealmostexclusivelyfromexcludingfuelsfrom_pyrolytic_Ԁdecompositionbyreducingtheareaburned,fuelloading,orfuelconsumption.Cumulativeemissionreductionsmaynotberealizedunlessthesefuelsareeitherbiologicallydecomposedorpermanentlyremovedfromthesite.Thefuelsexcludedfromoneincident(prescribedfire)maybeconsumedbysomefutureincident(wildfire).Emissionreductiontechniquesvarywidelyintheirapplicabilityandeffectivenessbyvegetationtype,burningobjective,regionofthecountry,andwhetherfuelsarenaturaloractivitygenerated.  WildfireEmissionReduction   Z  4 Littlethoughthasbeengiventoreducingemissionsfromwildfire,butmanyfire 2 managementactionsdoaffectemissionproductionfromwildfiresbecausetheyintentionallyreducewildfireoccurrence,extent,orseverity.Forexample,firepreventionefforts,aggressivesuppressionactions,andfueltreatments(mechanicalorprescribedfire)allreduceemissionsfromwildfires.Althoughfiresuppressionoftenonlydelaystheemissionsratherthaneliminatingthem.Allowingfirestoburnwithoutsuppressionearlyinthefireseasontopreventmoreseverefiresindrierperiodswouldreducefuelconsumptionandreduceemissions.Allfiremanagementplansthatallowlimitedsuppressionconsiderairqualityimpactsfrompotentialwildfiresasadecisioncriteria.So,althoughweareonlydiscussingemissionreductiontechniquesforprescribedfiresinthispaperweshouldrememberthatthereisaninextricablelinkbetweenfuelsmanagement,prescribedfire,wildfireseverity,andemissionproduction.   ,(+ PrescribedFireEmissionReduction    4 Emissionreductiontechniquesmayreduceemissionsfromagivenprescribedburnareabyasmuchasabout60percenttoaslittleasvirtuallyzero.Consideringallburningnationally,ifemissionreductiontechniqueswereoptimallyused,emissionscouldprobablybereducedbyapproximately2025percentassumingallotherfactors(vegetationtypes,acres,etc.)wereheldconstantandlandmanagementgoalswerestillmet.Individualstatesorregionsmaybeabletoachievegreateremissionreductionsthanthisormuchlessdependingonthestatesorregionsbiologicaldecompositioncapabilityorabilitytoutilizeavailablebiomass. 4 Emissionreductiontechniques(orbestavailablecontrolmeasures)arenotwithoutpotentialnegativesandmustbeprescribedandusedwithcarefulprofessionaljudgmentandfullawarenessofpossibletradeoffs.Firebehaviorisdirectlyrelatedtobothfireeffectsandfireemissions.Emissionreductiontechniquesalterfirebehaviorandfireeffectsandcanimpairorpreventaccomplishmentoflandmanagementobjectives.Inaddition,emissionreductiontechniquesdonotnecessarilyreducesmokeimpactsandsomemay,undercertaincircumstances,actuallyincreasethelikelihoodthatsmokewillimpactthepublic.Emissionreductiontechniquescancausenegativeeffectsonothervaluableresourcessuchassoilcompaction,lossofnutrients,impairedwaterquality,andincreasedtreemortality;ortheymaybemoredangerousorexpensivetoimplement. 4 Multipleresourcevaluesmustbeweighedalongwithairqualitybenefitsbeforeemissionreductiontechniquesareprescribed.Flexibilityiskeytoappropriateapplicationofemissionreductiontechniquesanduseofparticulartechniquesshouldbedecidedonacasebycasebasis.Emissionreductiongoalsmaybetargetedbuttheappropriatemixofemissionreductiontechniquestoachievethosegoalswillrequireacarefulanalysisoftheshortandlongtermecologicalandsocialcostsandbenefits.Airqualitymanagersandlandmanagersshouldworktogethertobetterunderstandtheeffectiveness,options,difficulties,applicability,andtradeoffsofemissionreductiontechniques. 4    4 Emissionsfrom_wildland_Ԁfirearecomplexandcontainmanypollutantsandtoxiccompounds.Emissionfactorsforover25compoundshavebeenidentifiedanddescribedintheliterature.Asimplifyingfindingfromthisworkisthatallpollutantsexcept_NOx_Ԁarenegativelycorrelatedwithcombustionefficiency,soactionsthatreduceonepollutantresultsinthereductionofall(except_NOx_)._NOx_ԀandCO2(notactuallyconsideredapollutant)canincreaseiftheemissionreductiontechniqueincreasescombustionefficiency. 4 _Emissionsfrom_wildland_Ԁfirearecomplexandcontainmanypollutantsandtoxiccompounds.Emissionfactorsforover25compoundshavebeenidentifiedanddescribedintheliterature.Asimplifyingfindingfromthisworkisthatallpollutantsarenegativelycorrelatedwithcombustionefficiency,soactionsthatreduceonepollutantresultsinthereductionofall;withtheexceptionofCO2(notactuallyconsideredapollutant)which h+&* increasesasothersdecrease.___  4 Itisgenerallyhelpfulduringdiscussionsofwaystominimizeincidentemissionsfrom_wildland_Ԁfiretothinkintermsofthefourmajorfactorsthatinfluencetheamountofemissionsproduced.Theseareareaburned,fuelloading,fuelconsumption,andanemissionfactor.Examplesgiveninthefollowingdiscussionarefrequentlyvegetation,region,and/orseasonspecific. T,'+  MinimizingEmissionsbyReducingtheAreaBurned     4 Perhapsthemostobviousmethodtoreduce_wildland_Ԁfireemissionsistoreducetheareaburned.Cautionmustbeappliedthoughandprogramstoreducetheareaburnedmustnotactuallyresultinjustadelayinthereleaseofemissionseitherthroughprescribedburningatalaterdateorastheresultofawildfire.Reducingtheareaburnedshouldonlybeaccomplishedbymethodsthattrulyresultinreducedemissionsovertimeratherthanadeferralofemissionstosomefuturedate. 4 Alternativestofireareleastapplicablewhenfireisneededforecosystemorhabitatmanagement,orforesthealthenhancement.Insomeareasandsomevegetationtypeswhenfireisusedtoeliminateanundesirablespeciesordisposeofbiomasswaste,alternativemethodscanbeusedtoaccomplisheffectssimilartowhatburningwouldaccomplish.Examplesofspecifictechniquesinclude:/c  /c""0 4   Mechanicaltreatments. Thisisbroadcategorythatcanincludesuchdiverse   techniquesasmechanicalremovalofloggingslashfrom_clearcuts_,useofanimalstograzeanareaandreducelivevegetationandsmalltwigs,onsitechippingorcrushingofwoodymaterialand/orbrush,andmechanicalremovaloffuelswhichmayormaynotbefollowedbyoffsiteburninginamorecontrolledenvironment.Mechanicaltreatmentsmayinterferewithlandmanagementobjectivesiftheycauseunduesoildisturbanceorcompaction,stimulatealienplantinvasion,impairwaterquality,orremovematerialneededfornutrientcyclingorsmallanimalhabitat.Adifficultywithmechanicaltreatmentsisthatmostrequiregoodroadaccesswhichisfrequentlynotavailableinremote_wildlands_.Someexamplesofmechanicaltreatmentsinclude:/c""݌4!4! Ќ  E1  <DL!XE @C  $$C  1) Wholetreeharvestingand/or_yarding_Ԁofunmerchantable(_YUM_).Mechanical  removaloffuelsmayresultinsufficienttreatmentsothatburningisnotneeded.Thistechniqueisonlyapplicableinactivityfuels(debrisgeneratedfrommanagementactivities;especiallytimberharvest).Sincethetechniqueiseffectiveinreducinglargewoodyfuels(thosegreaterthan3inchesindiameter)itisapplicableonlyinforestfueltypes(notbrushorgrass).  XXUS.,2USXX.,) Firewoodsales.Firewoodsalesmayresultinsufficientremovalofwoody  #p! debrismakingburningunnecessary.Thistechniqueisparticularlyeffectiveforpiledmaterialwherethepublichaseasyaccess.Thistechniqueisonlyapplicableinforesttypeswithlargediameter,woodybiomass. %4!$   XXUS.,3USXX.,) Otherbiomassutilization.Woodymaterialcanbeusedformany & "% miscellaneouspurposesincludingpulpforpaper,andspecialtyforestproducts(woodfurnitureorart).Thiscategoryisdifficulttodefineduetothepotentialdiversityofuses.Whenwoodisscarceandpulppricesarehigh,biomassthatpreviouslyhadnocommercialvaluecouldsuddenlybemarketable.Againthis isonlyapplicableinforesttypesthatincludelargediameterwoodybiomass. l+&*   XXUS.,4USXX.,) Hogfuelforelectricalgeneration.Woodybiomasscanalsoberemovedand   usedtoprovideelectricityinregionswith_cogeneration_Ԁfacilities.  XXUS.,5USXX.,) Ungulates.Grazingandbrowsinganimals(especiallysheep,cattle,and  goats)cansometimesbeusedtoreducelivegrassyorbrushyfuelstothe t degreethatburningis_not_Ԁlongerrequiredortoreducefuelspriortoburning ` (increasebiologicaldecomposition).Goatswillsometimesconsumeevensmall,deadwoodybiomass.Howeverungulatesareselective,favoringsomeplantsoverothers.Thecumulativeeffectofthisselectivitycansignificantlychangeplantspeciescompositionandlongtermecologicalprocessesofanarea.  L    8   ,N14 <DL!  XN @ -X-X4KC-"    1$XuXC-X4KXXXu  Chemicaltreatments. Chemicalsmayproduceeffectssimilartofirewhenthe $  objectiveistoreduceorremovelivevegetationand/orspeciesfromasite.Certainlychemicaltreatmentscancarrytheirownsetofecologicalandpublicrelationsproblems. -X-X4KC-"    3$XuXC-X4KXXXu  Concentrationburning. Sometimes,ratherthanusingfireon100percentofanarea   requiringtreatment,asubsetrepresentingconcentrationsoffuelscanbeburned.Thiscangreatlydecreasetheareaburnedalthoughthefuelloadingoftheareasreceivingtreatmentwilltendtobehigh.Thetotalareaburnedunderthesecircumstancescanbeverydifficulttoquantify.  ,H+ 4 <DL!4XHC  $$C MinimizingEmissionsbyReducingFuelLoading 8   4 Techniquesthatreducethefuelloadingpriortoburningresultinlessfuelavailabletoburnandthereforelessemissions.Reducingfuelloadingisaccomplishedbyphysicalremovaloffuelspriortoburningorschedulingburningbeforenewfuelsappear. ,E14 <DL!XE  -X-X4KC-"    a8XuXC-X4KXXXu  Mechanicalfuelremoval. Thiscategoryisbasicallythesameasthemechanical  treatmentscategoryintheprevioussectionexceptinthiscasethemechanicaltreatmentsarefollowedbyfire.Specificexamplesofthistechniqueandeffectsonlandmanagementgoalsaredescribedintheprevioussection. |    -X-X4KC-"    :XuXC-X4KXXXu  Burnmorefrequently. Frequent,lowintensityfirescanpreventunwantedvegetation h! frombecomingestablishedontheforestfloor.Iflongerfirerotationsareusedthisvegetationhastimetogrowresultingintheproductionofextrabiomassandextrafuelloadingatthetimeofburning.Thistechniquegenerallyhaspositiveeffectsonlandmanagementgoalssinceitislikelytoresultinfireregimesthatmorecloselymimicnaturalfirefrequencies. -X-X4KC-"    N=XuXC-X4KXXXu  Scheduleburningbeforenewfuelsappear. Burningcansometimesbescheduledfor '8#& timesoftheyearbeforenewfuelsappear.Thismayinterferewithlandmanagementgoalsifburningisforcedintoseasonsandmoistureconditionswhereincreased mortalityofdesirablespeciescanresult.Someexamplesofthistechniqueinclude: *&) C " $$C X,N144 <DL!4XN2Ԁ  1  )3   4 _Underburn_Ԁbeforelitterfall.Brushyvegetationdropsitsleavesinthefallandthis   littercontributesextravolumetothefuelbed.Ifburningtakesplacepriortolitterfallthereislessavailablefuelandthereforelessfuelconsumedandfeweremissions. t 2Ԁ  2  )3   4 Burnbeforegreenup.Burningincovertypeswithbrushyand/orherbaceous L  _fuelbed_Ԁcomponentscanproducefeweremissionsifburningtakesplacebeforethesefuelsgreenupfortheyear.Lessfuelisavailablethereforefeweremissionsareproduced.  `    XK+ 4 <DL!44 XKC  $$"C-- MinimizingEmissionsbyReducingFuelConsumption   8   4 Meaningfulincidentemissionreductioncanbeachievedwhensignificantamountsoffuelareatorabovethemoistureofextinction,andthereforeunavailableforcombustion.However,burningundermoisterconditionsmayleavesignificantamountsoffuelinthetreatedareaonlytobeburnedinthefuture.Longtermemissionreductionsareachievedonlyifthefuelsleftbehindcanbeexpectedtodecomposeorbeotherwisesequesteredatthetimeofsubsequentburning.Reducingfuelconsumptionreduces_fireline_Ԁintensity,crownandfoliagescorch,andcambiuminjury,thusreducingfloraandfaunamortality.Springandelevatedfuelmoistureburningisfrequentlyusedtoinitiateecosystemrestorationfollowinglongtermfireexclusion,recyclenutrients,and blackensoilstopromotesolarsoilheatingandmicroorganismgrowthwithoutsignificantvegetationmortality. 4 Intheappropriatefueltypes,theabilitytotargetandremoveonlythefuelsnecessarytomeetmanagementobjectivesisoneofthemosteffectivemethodsofreducingemissionsfromburning.Whenthecombinationofappropriatefueltypeandburningconditionscanbemet,fuelconsumptioncanbegreatlyreduced.Forexample,iftheobjectiveofburningistoreducewildfirehazard,removaloffineandintermediatediameterfuelsmaybesufficient;andtheabilitytolimitlargefuelandorganiclayerconsumptionwillsignificantlyreduceemissions.Examplesofthistechniquefollow: , E14 <DL!XE  -X-X4KC-"    6KXuXC-X4KXXXu  Highmoisturecontentinnontargetfuels. Burningwheninternalmoisturecontent 0"  offuelsishigh,effectivelylimitstheirconsumption.Intuitionmightindicatethatwetfuelsproducegreateremissionsbytendingtosmolderbutinreality,somuchlessof $d" thewetfuelisconsumedthatincidentemissionsaregreatlyreduced.Herearesomeexamples: X,N144 <DL!4XN1).23   4 High,largediameterfuel_moistures_.Burningwhenlargediameterwoodyfuels '#& (3+inchesindiameterorgreater)arewetcanresultinlowerfuelconsumptionandlesssmoldering.Whenlargefuelsarewettheywillnotsustaincombustion_ontheirownsowhenthesmalltwigsandbranchwoodfinishburning,thelargelogsareextinguishedbytheirowninternalmoisture.Thelargelogsthereforeconsumelessintotal,theydonotsmolderasmuch,andtheydonotcauseasmuchoftheorganic `,'+ layerontheforestfloortoconsume.Thiscanbeaveryeffectivetechniqueforreducingtotalemissionsfromaprescribedburnareaandcanhavesecondarybenefitsbyleavingmorelargewoodydebrisinplacefornutrientcycling.Thistechniquecanbeeffectiveinnaturalandactivityfuelsinforesttypes. t 2).Moistlitterand/orduff.Theorganiclayerthatformsfromdecayedandpartially L  decayedmaterialontheforestfloortendstoburnveryinefficiently.Consumptionofthislitterand/ordufflayercanbegreatlyreducedifthematerialisquitemoist.Thesurfacefuelscanbeburnedandtheorganiclayerleftvirtuallyintact.Theappropriateconditionsforutilizationofthistechniquegenerallyoccurinthespring(inareaswheresnowhascoveredthegroundoverthewinter)orwithinafewdaysofasoakingrain.Thistechniquecanbeveryeffectiveatreducingemissionsincertaincovertypesthattendtohavedeeporganiclayers.Thetechniquemaybemoredifficulttoutilizeincovertypeswheresurfacerootsmaybevulnerabletoinjuryfromfireunderconditionsrequiredtomakethetechniqueeffectiveorincovertypeswhereremovaloftheorganiclayerisdesired.Burninglitterand/ordufftoexposemineralsoilisoftennecessaryinfireadapted p ecosystemsforplantregenerationandbiologicalcommunityintegrity.This \ techniqueisveryeffectiveinmostnonfireadaptedforestandbrushtypes. H 3).23   4 Massignition/shortenedfireduration. Massignitioncanoccurthrougha  p combinationofdryfinefuelsandveryrapidignitionwhichcanbeachievedthroughatechniquesuchasa_helitorch_.Massignitioncanshortenthedurationofthesmolderingphaseofafireandreducethetotalamountoffuelconsumed.Whenproperlyapplied,massignitioncausesrapidconsumptionofdry,surfacefuelsandcreatesaverystrongplumeorconvectioncolumnwhichdrawsmuchoftheheatawayfromthe_fuelbed_Ԁandpreventsdryingandpreheatingoflarger,moisterfuels.(Thisstrongplumealsoresultsinimprovedsmokedispersal.)Thefirediesoutshortlyafterthefinefuelsfullyconsumeandthereislittlesmolderingorconsumptionofthelargerfuelsandduff.Theconditionsnecessarytocreateatruemassignitionsituationareonlypossibleinopenareaswithbroadcastactivityfuels(generally_clearcuts_). D! 4).23   4 Burnbeforelargefuelscure.Livingtreescontainveryhighinternalfuel_moistures_ #l! whichtakesanumberofmonthstodryafterharvest.Ifanareacanbeburnedwithin34dryingmonthsoftimberharvest,manyofthelargefuelswillstillcontainasignificantamountoflivefuelmoisture.Thistechniqueisgenerallyrestrictedtoactivitygeneratedfuelsinforesttypes. &"%  ,XQ14 <DL!44 XQ -X-X4KC-"    R]XuXC-X4KXXXu  Rapidmopup .Rapidlyextinguishingafirecanreducefuelconsumptionand (#' smolderingemissionssomewhatalthoughthistechniqueisnotparticularlyeffectiveandcanbeverycostly.Rapidmopupprimarilyeffectssmolderingconsumptionof largewoodyfuelsandduff.Rapidmopupismoreeffectiveasanavoidancetechnique t+&* byreducingresidualemissionsthattendtogetcaughtindrainageflowsandendupinsmokesensitiveareas.Thistechniquecanbeusedinforestfueltypes.   ,H+ 4 <DL!4XHC  $$C-- MinimizingEmissionsbyMinimizingtheEmissionFactor  t  4 Increasingcombustionefficiency,orshiftingthemajorityofconsumptionawayfromthesmolderingphaseandintothemoreefficientflamingphase,canreduceemissions(except_NOxNoOx_ԀandCO2).Thelandmanagementconsequencesofincreasingcombustionefficienciesareprimarilyduetoincreasing_fireline_Ԁintensity(rateofheatreleaseperunitoftimeperunitlengthofthe_fireline_).Thisincreasesfloraandfauna(primarilysoilmicroorganisms)mortality.Keepingotherfireregimecomponentsconstant(burningseason,firerotationinterval,etc.),landmanagementgoalswhichrequireincreased_fireline_intensity(i.e.,hardwoodshrubcontrol)benefit. , E14 <DL!XE  -X-X4KC-"    eXuXC-X4KXXXu  Burningfuelsinpilesorwindrows. Fuelsconcentratedintopilesorwindrows   generategreaterheatandburnmoreefficiently.Agreateramountoftheconsumptionoccursintheflamingphaseandtheemissionfactorislower.Thistechniqueisprimarilyeffectiveinforestfueltypesbutmayhavesomeapplicabilityinbrushtypesalso.Concentratingfuelsintopilesorwindrowsgenerallyrequirestheuseofheavyequipmentwhichcannegativelyimpactsoilsandwaterquality.Pilesandwindrowsalsocausetemperatureextremesinthesoilsdirectlyunderneathandcanresultinareasofsoilsterilization. -X-X4KC-"    hXuXC-X4KXXXu  Backingfires. Flamingcombustioniscleanerthansmolderingcombustion.A @ backingfiretakesadvantageofthisrelationshipbycausingmorefuelconsumptiontotakeplaceintheflamingphasethanwouldoccurifaheadingfirewereused.Inapplicablefueltypes,theflamingfrontbacksmoreslowlythroughthe_fuelbed_Ԁandbythetimeitpasses,mostavailablefuelhasbeenconsumedsothefirequicklydiesoutwithverylittlesmoldering.Inaheadingfire,theflamingfrontpassesquicklyandtheignitedfuelscontinuetosmolderuntilconsumed.Thistechniqueisonlyapplicableinnaturalfuelsandinfueltypeswheretheprimarygroundfuelisgrassand/orveryfinewoodyfuels.Withoutcontinuousfinefuels(grass,leaves,needles),backingfirespreadisimpossible.Theopportunitytousebackingfiresisverylimited,canincreaseoperationalcostssubstantially,hasotherenvironmentalconsequences,andemissionreductionsobtainedfromgrassfuelsareminorduetothecombustionpropertiesofgrass. -X-X4KC-"    mXuXC-X4KXXXu  Rapidmopup. Rapidlyextinguishingafireresultsinsomeminorreductionsin &4"% smolderingconsumptionmeaningagreateremphasisisplacedonflamingcombustionandtheaverageemissionfactorisreduced.ForamoredetaileddescriptionofthistechniqueseetheFuelConsumptionsection. -X-X4KC-"    oXuXC-X4KXXXu  Massignition/shortenedfireduration. Thistechnique,thoughdifficulttoapply,can +&* resultinagreateramountoftheconsumptionoccurringintheflamingphasewhich ,'+ reducestheeffectiveemissionfactor.ForamoredetaileddescriptionseetheFuelConsumptionsection.