Managing boreal forests for the simultaneous production of collectable goods and timber revenues

1 SILVA FENNICA Silva Fennica vol. 50 no. 5 article id 1672 Category: research article www.silvafennica.fi ISSN-L 0037-5330 | ISSN 2242-4075 (Online) The Finnish Society of Forest Science Natural Resources Institute Finland Maiju Peura 1, María Triviño 1, Adriano Mazziotta 1,2, Dmitry Podkopaev 1,3, Artti Juutinen 4,5 and Mikko Mönkkönen 1 Managing boreal forests for the simultaneous production of collectable goods and timber revenues Peura M., Triviño M., Mazziotta A., Podkopaev D., Juutinen A., Mönkkönen M. (2016). Managing boreal forests for the simultaneous production of collectable goods and timber revenues. Silva Fennica vol. 50 no. 5 article id 1672. 17 p. http://dx.doi.org/10.14214/sf.1672 Highlights • Wefoundastrongconflictbetweenbilberryproductionandtimberrevenues,resultingin largelossesoftimberrevenueswhenincreasingbilberryproduction. • Theconflictsbetweenothercollectables(cowberry,cep)andtimberproductionwererelativelysmall. • Withcarefulforestplanning,thereispotentialtosimultaneouslyproducehighlevelsofcollectable goods and timber revenues in the landscape. Abstract Timberproductionisaneconomicallyimportantprovisioningecosystemserviceinforests,but isofteninconflictwiththeprovisionofotherecosystemservices.Inmultifunctionalforestry,the productionoftimberandnon-timberecosystemservicesshouldcoexistinthesamelandscape. Tothisend,weexploredthecapacityofaboreallandscapetosimultaneouslyproducecollectable goods −bilberry(Vaccimium myrtillus L.),cowberry(Vaccinium vitis-idaea L.) and cep (Boletus edulis Bull.) −alongsidetimberrevenues.Wealsoidentifiedoptimalforestmanagementplansto achievethis.Furthermore,weanalyzedtrade-offsbetweencollectablegoodyieldsandtimberproduction,aswellasbetweentheireconomicvalues.Weranforestgrowthsimulationsunderseven alternativemanagementregimesatalandscapelevelacross50-yearplanninghorizons.Then,we usedmulti-objectiveoptimizationtoexploretrade-offsandidentifyoptimalforestmanagement plans.Theresultsshowedthatthestrongesttrade-offwasbetweenbilberryandtimberproduction,resultinginalargelossintimberrevenuesforagaininbilberryproduction.However,the conflictsbetweenothercollectablesandtimberproductionwererelativelysmall:itwaspossible toincreasetheprovisionofcollectablegoods4–15%withsmallreductions(3−5%) from timber revenues.Withcarefulforestplanning,thereisthepotentialtosimultaneouslyproducehighlevels of collectable goods and timber revenues in the landscape. Keywordsforestmanagement;multifunctionalforestry;mushroom;trade-offs;wildberry Addresses 1UniversityofJyvaskyla,DepartmentofBiologicalandEnvironmentalSciences,P.O. Box35,FI-40014,UniversityofJyväskylä,Finland;2CenterforMacroecology,Evolutionand Climate,NaturalHistoryMuseumofDenmark,UniversityofCopenhagen,Universitetsparken 15,DK-2100Copenhagen,Denmark;3SystemsResearchInstitute,PolishAcademyofSciences, Newelska6,01-447Warsaw,Poland;4NaturalResourcesInstituteFinland(Luke),Economics andSociety,P.O.Box413,FI-90014UniversityofOulu,Finland;5UniversityofOulu,DepartmentofEconomics,P.O.Box4600,FI-90014UniversityofOulu,Finland E-mail[email protected] Received2August2016Revised10October2016Accepted12October2016 2 Silva Fennica vol. 50 no. 5 article id 1672 · Peura et al. · Managing boreal forests for the simultaneous… 1 Introduction Forestsprovidemanyvaluableecosystemservices,suchasfood,timber,andglobalclimateregulation(MillenniumEcosystemAssesment2005).Timberproductionisaneconomicallyvaluable ecosystemserviceand,duringthelastfewcenturies,manyforestshavebeenmanagedtomaximizerevenuesfromtimberharvests(SchmithüsenandRojasBriales2012).However,intensive managementthatfocusessolelyontimberproductionoftenhasanegativeeffectonotherservices, such as a decrease in thequantityofdeadwood,whichiscriticalforbiodiversity(Siitonen2001). Therefore,itiscrucialtoevaluatesuchconflictsandcarefullyplanforestmanagementtoallow theproductionofmanydifferenttypesofecosystemservices,suchastimberproductionandcollectablegoods.Recognizingmultipledemandsonforestproductsandservicesallowsprogress towardsmultifunctionalforestry,wherenon-timbervaluesandservicesofforestsaretakeninto account,alongsidetheconsiderationoftimberrevenues(Schmithüsen2007).Multifunctionalforest managementpracticestackledifferentsocialinterestsinforests,supportingalternativeforestry practices and protecting sustainable use of forests. BorealforestsextendacrossRussianSiberia,Fennoscandia,NorthernCanada,andAlaska, andcoveraboutonethirdoftheworld’sforestedarea(Burtonetal.2010).Theborealregioncontains more than one third of the terrestrial carbon stored in vegetation and soil and contains more freshwaterthananyotherbiome(Burtonetal.2010).Inaddition,borealforestsprovideimportant recreationalservices,suchashiking,naturetourism,andpickingcollectablegoods.Timberproductionisthemosteconomicallyvaluableprovisioningserviceinborealforests(Vanhanenetal. 2012).Forexample,inFinland,approximately86%(26millionha)oftotalforestareaismanaged andtheforestsectorcontributesapproximately4.8%ofFinland’sGrossDomesticProduct(Finnish statisticalyearbookofforestry2013).Manyborealforestsareintensivelymanagedtomaximize timberprovision,whileneglectingtheimportanceofmaintainingbiodiversityandotherecosystem services(Vanhanenetal.2012).Focusingonintensivetimberproductioncannegativelyaffect biodiversity(Mönkkönenetal.2014)andotherecosystemservices,suchasrecreation(Belletal. 2007),waterandsoilquality(Laudonetal.2011),climateregulationthroughcarbonsequestration andstorage(Triviñoetal.2015),aswellasgameandbilberryproduction(Gamfeldtetal.2013). Duetoeconomicimportanceoftimberproduction,forestmanagementplansthatallow thesimultaneousproductionoftimberandotherecosystemservicesareneeded.Multi-objective optimizationmethodscanbeusedtoprovideefficientoptionsforlanduseandmanagementof differentecosystemservices(Seppeltetal.2013).Forexample,previousstudieshaveshown thatitcouldbepossibletogreatlyincreasehabitatavailabilityforseveralspecies(Mönkkönenet al. 2014) or increase carbon sequestration and storage (Triviño et al. 2015) withrelativelysmall reductionsintimberharvestrevenuesbyapplyingadiversesetofforestmanagementregimesin boreal landscapes. Recent stand-scale studies have shown the importance of identifying profitable forest managementregimesforcollectablegoods.Forexample,Palahíetal.(2009) and de Miguel et al. (2014) examined the optimal economic management for both timber and mushrooms in Central PyreneesandCatalonia,respectively.Theyshowedthatthinning treatments,whichareusually unprofitable,becameaprofitablemanagementstrategywhenmushroomproductionwasincluded intheanalysis.Miinaetal.(2016)optimizedtimberandberryproduction(bilberry(Vaccinium myrtillus L.)andcowberry(Vaccinum vitis-idaea L.)) in boreal forest stands and found that joint productionallowedlongerrotationlengths,higherthinningintensitiesandmorefrequentthinning than mere timber-oriented management. These studies suggest that the economic value of collectablegoodyieldsmightevenexceedtheeconomicvalueoftimberproductioninsomeforest stands.Eventhoughthereisincreasingawarenessthatalternativelandmanagementcancritically 3 Silva Fennica vol. 50 no. 5 article id 1672 · Peura et al. · Managing boreal forests for the simultaneous… affectthecapacityoflandparcelstoprovideecosystemservices,thelong-termcapacityofentire landscapestoprovidemultipleservicesunderalternativemanagementregimeshasnotbeenwidely tackled(deGrootetal.2010).Toourknowledge,nopreviousstudyhasaddressedthequestion ofhowtoreconcilethepotentialconflictbetweentimberandcollectablegoodproductionacross alargelandscapewiththousandsofforeststands. Collectablegoodsareeconomicallyvaluableinmanypartsoftheborealzone.Forexample, Canadaistheworld’slargestproducerofwildblueberries(Vaccinium angustifolium Ait.)with exportsamountingto184M€(207M$)in2014(NaturalResourcesCanada2016).InFinland,the mostimportantwildberriescollectedarebilberryandcowberry,andthetotalvalueoftheannual harvestedwildberrycropmayreachabout100M€(Saastamoinenetal.2000).Cep(Boletus edulis Bull.)isaneconomicallyvaluablemushroomspeciesinFinland(Miinaetal.2013)andworldwide (Boa2004).Wildberryandmushroompickinghasalongtraditionand,inadditiontoitseconomic values,thisactivityalsohasrecreationalvalue(Boa2004).InmanyNordiccountries(Finland, Sweden,andNorway),everyman’srightsallowsallpeopletohavefreeaccesstoforestsandto pickberriesandmushrooms(Salo1995).Approximately60%ofFinnsparticipateinberrypicking and40%inmushroompicking(Finnishstatisticalyearbookofforestry2013).However,during thelastfewdecades,theyieldsofmanycollectablegoods,suchasbilberries,havedeclineddue tointensifiedforestmanagementfortimberproduction(Miinaetal.2009). Inthisstudy,wegobeyondpreviousstudiesbyidentifyingconflictsbetweentimberharvestrevenuesandseveralcollectablegoodsinalargeforestlandscapewithseveralthousandsof standsandoveralongtimeperiodof50years.Here,theterm“collectablegoods”referstoberries (bilberryandcowberry)andmushrooms(cep).Weestimatetheyieldsofcollectablegoodsasan indicatorofrecreationalvalues.Inaddition,werefertothecombinedpotentialeconomicvalue (netpresentvalue,NPV)ofallthreecollectableswiththeterm“economicvalueofcollectable goods”.Weusemodelsbasedonyielddata(Miinaetal.2009;Miinaetal.2013;Turtiainenetal. 2013)tostudytheeffectsofdifferentforestmanagementregimes,varyingfromcurrentrecommendedmanagementtototalprotection,onyieldsatthelandscapescaleacrossa50yearhorizon. Weusemulti-objectiveoptimization(Miettinen1999)toanalyzethetrade-offsbetweentheyields ofcollectablegoodsandtimberproduction,aswellasbetweentheeconomicvalueofcollectable goodsandtimberproduction.Weaddressthefollowingquestions:(1)Whatisthepotentialof theborealforestlandscapetosimultaneouslyproducecollectablegoodsandtimber?(2)Arethe trade-offsbetweentargetingdifferentcollectablegoodsandtimberproductionsimilar?(3)What optimalcombinationsofforestmanagementregimesmaximizetheyieldsandtheeconomicvalue ofcollectablegoodsforgivenlevelsofeconomicreturnsfromtimber,andviceversa?Answering these questions is informative in providing management recommendations to produce collectable goodsandtimbersimultaneouslyinaforestlandscapeandhowtoenhancerecreationalservices inaneconomicallysustainableway. 2 Materials and methods 2.1 Study area and data ThestudyareaislocatedinCentralFinland(62°14´N,25°43´E)andencompasses68700ha. Forestsonmineralsoilcover55%ofthetotalarea,peatlandscover13%,lakescover16%and farmland settlements cover 15%. Scots pine (Pinus sylvestris L.),Norwayspruce(Picea abies (L.)H.Karst.),birch(Betula pendulaRoth and Betula pubescens Ehrh.)andmixedstandsdominate forests.Forestsareprivatelyownedandareintensivelymanagedfortimberproduction.The 4 Silva Fennica vol. 50 no. 5 article id 1672 · Peura et al. · Managing boreal forests for the simultaneous… dataoftheforestsstudiedhereoriginatesfromtheconfidentialforestrydataadministeredbythe FinnishForestCentre,thusdetailsofindividualforestsarenotprovided.Dataarebasedonrecent fieldinventoriesandincludestandcharacteristics,suchasthebasalareaoftrees,standage,and sitetypeforeachofthe29702foreststands.Theaveragestandsizeis1.45haandthetotalarea offoreststandsis43150ha. 2.2 Forest growth simulation and timber revenues Weranthesimulatedforestgrowthfor50yearsin5yearintervals(11timesteps),usingMOTTIstand simulator (http://www.metla.fi/metinfo/motti/index-en.htm). We applied seven alternative managementregimes(Table1)thatrangedfromtherecommendedmanagementstrategy(businessasusual,BAU)−whichaimstomaximizetimberproductionthroughintensivemanagement −tonomanagementatall(setaside,SA).Extendedrotations(EXT10andEXT30)aresimilar toBAU,butthefinalharvestsarepostponedand,togetherwiththeSAregime,representactual policyinFinland,whereforestauthoritiesmakepermanentortemporaryconservationcontracts withforestowners(METSOProgramme2008–2016).Green-treeretention(GTR30)representsa conservation-orientedmanagementregime,similartotheBAUregime,but30treesperhectareare retainedatthefinalharvest,whichisabovethenormallevel.Greentreeretentionisawidelyused methodtoincreasestructuraldiversity,andconsequentlyspecieshabitats,incommercialboreal forests(Vanha-MajamaaandJalonen2001).Nothinningswithlongrotation(NTLR)represents amanagementregimewherethinningsarenotallowedbutthefinalharvestisexecutedusingthe samethresholdvalues(minimumtreediameter)asintheBAUregime,resultinginsomewhat extendedrotations.Nothinnings withshortrotation(NTSR),likewise,doesnotallowthinnings, butinthisregimethefinalharvestcriteriawereadjustedsothatrotationlengthwouldbesimilar totheBAUregime.Nothinningsregimesareagainstcurrentrecommendations,butarestillcommonlyappliedbyforestownersbecausethinningtheharvestdoesnotprovidelargeimmediate economicreturns,butmayincurextracosts.Thedevelopmentofaveragetimberbiomassforeach timestepunderalternativemanagementregimesaregiveninSupplementaryfile(Fig.S1),available at http://dx.doi.org/10.14214/sf.1672. Table 1. ThedifferentmanagementregimesappliedinourstudyareaincentralFinland(adaptedfromMönkkönenet al. 2014). Management regime Acronym Description Business as usual BAU Currentrecommendedmanagement:80yearrotationonaverage;sitepreparation,plantingorseedingtrees,1−3thinnings, finalharvestwithgreentreeretentionlevel5treesha–1 Set aside SA Nomanagement,notimberproduction Extendedrotation (10years) EXT10 BAUwithpostponedfinalharvestingby10years;lowertimber NPVduetotimediscounting;representsashorttermconservationstrategy Extendedrotation (30years) EXT30 BAUwithpostponedfinalharvestingby>30years;lower timberNPVduetotimediscounting;representsalongterm conservationstrategy Greentreeretention GTR30 BAUwith30greentreesha–1leftuncutatfinalharvest;reduced timber production; conservation oriented management used to increasestructuraldiversity Nothinningslongrotation(final harvestthresholdcriteriaasinBAU) NTLR BAUwithnothinnings;thereforeforestsgrowmoreslowly, finalharvestisdelayedandtimberNPVislower;averagerotationlength86years Nothinningsshortrotation(minimumfinalharvestthresholdcriteria) NTSR BAUwithnothinnings;finalharvestcriteriaadjustedsothat rotationsdonotprolong;averagerotationlength77years;lower timberNPVduetosmallersizeoftreesatfinalharvest 5 Silva Fennica vol. 50 no. 5 article id 1672 · Peura et al. · Managing boreal forests for the simultaneous… Weusedtimberharvestrevenues(NPVin€)foreachstandandmanagementregimeacross a50yearplanninghorizoncalculatedinapreviousstudy(Mönkkönenetal.2014).TimberNPV consistsoffourharvestrevenuecomponents:timberrevenuesfromthinnings,fromthefinalharvest,fromthestandingtimberattheendofsimulation,andthesoilexpectationvalue(thebare landvalue).Inthesecalculations,stumpagepricesforeighttimberassortments(pulpwoodand sawlogsforeachofthefourspecies:Scotspine,Norwayspruceandtwobirchspecies)were used.Theaverageamountsofharvestedpulpwoodandsawlogfromthinningsandfinalharvest underalternativemanagementregimesaregiveninSuppl.file(Fig.S2).Inaddition,timberNPV takesintoaccountcostsresultingfromfivesilviculturalactions:naturalregeneration,seedingor plantingnewtreesonclear-cuts,tendingofseedlingstands,andcleaningofsaplingstands.We useda3%interestrateindiscountingthetimberrevenuesandcostsduringthe50yearplanning horizon.ThepricesofharvestrevenuecomponentsweretakenfromtheFinnishForestCentrefor theregionofCentralFinlandandthepricesforthesilviculturalcostswerecalculatedfromFinnish forestrystatistics(fordetailedinformationaboutthepricesandcalculationsoftimberNPV,see Suppl.fileTableS1andEq.S1). 2.3 Collectable good yields Weestimatedtheaverageyieldsofcollectablegoods(kgha–1)acrosseleven5yeartimestepsfor the29702standsandsevenmanagementregimesusingready-mademodelsbasedonyielddata (Miinaetal.2009;Miinaetal.2013;Turtiainenetal.2013).Weestimatedtheyieldsofbilberry usingempiricalmodelsdevelopedbyMiinaetal.(2009).First,wepredictedthecoverageofbilberry as a function ofseveralindicatorvariables:sitetype,dominatingtreespecies,regenerationmethod, altitude,standage,andstandbasalareaoftrees(Eq.S2).Then,weconvertedbilberrycoverageinto bilberryyieldasafunction ofcoverageandstandbasalarea(Eq.S3,S4).Weestimatedtheyields ofcowberryusingmodelsdevelopedbyTurtiainenetal.(2013).First,wepredictedthecoverage ofcowberryasafunctionofsitetype,dominatingtreespecies,temperaturesum,altitude,stand age,andstandbasalarea(Eq.S5).Then,weconvertedcowberrycoverageintocowberryyieldas afunctionofcoverage,standbasalarea,altitude,andtemperaturesum(Eq.S6).Weestimatedthe yieldsofcepusingamodeldevelopedbyMiinaetal.(2013).Themodelpredictstheyieldofcep asafunctionofstandbasalareaandstandage(Eq.S7).Thedevelopmentofaverageyieldsfor eachtimestepunderalternativemanagementregimesaregiveninSuppl.file(Fig.S3).Forfurther informationaboutthecalculationsofcollectablegoodyieldsseeSuppl.file. 2.4 The economic value of collectable goods Fortheoptimizationoftheeconomicvalueofcollectablegoodsandtimberrevenues,wecalculatedthecombinedeconomicvalueofbilberry,cowberry,andcepyieldsacrossa50yearplanning horizonforeachstand,undersevenalternativemanagementregimes.First,weestimatedyields foreachyearforthe5yearperiodsandthencalculatedtheeconomicvalueofeachcollectable goodforeachyear.Weusedaveragemarketpricesofeachcollectablegoodfrom2004to2013 inCentralFinland:forbilberry,2.23€kg–1;forcowberry,1.16€kg–1; and for cep (the price of Boletusspp.used),3.36€kg–1 (MARSI2009;MARSI 2014). Finally,weaddedtheannualvalues ofeachcollectablegoodtogettheeconomicvalueofcollectablegoodsacrossthe50yearplanning horizonforeachstandas€ha–1(collectablegoodsNPV).Wecalculatedthepotentialeconomic valueofeachcollectablegoodusingthefollowingequation: 6 Silva Fennica vol. 50 no. 5 article id 1672 · Peura et al. · Managing boreal forests for the simultaneous… ∑ == − Collectable good NPVyve (1) it tirt 0 50 whereacollectablegoodwasdenotedbyi;yearsacrossthe50yearplanninghorizonbyt;yields byy;theirpricesbyv;anddiscountratebyr.Discountratewasthesame(3%)asinthecalculations of timber revenues. NPVforcollectablegoodsincludestheirvalueforthe50yearperiod only,andignoresanylateryields.However,thevalueofanylateryieldswouldbeverysmall.In addition,wedidnotincludethecostsofcollectingtheberriesandmushroomsintheNPVbecause thesevarywidelyaccordingtotheannualyieldandtheexactlocationsofthestands(traveling costs).Therefore,ourNPVestimatereflectsthepotentialofthelandscapetoprovideeconomic valuefromcollectablegoodsacrossa50yearplanninghorizon.Wecarriedoutthecalculationsin Rversion3.1.2(RDevelopmentCoreTeam2014). 2.5 Multi-objective optimization and analyses Weanalyzedalternativeforestmanagementplanstorevealtrade-offsbetweentimberrevenues andtheprovisionofcollectablegoods.Eachmanagementplanwasacombinationofmanagement regimes(Table1)selectedforallstands.Eachmanagementplanwascharacterizedbyitsoutcome, i.e.thevectorofeconomicvaluesoftimberandcollectablegoodyieldsofthelandscaperesulting fromacombinationofmanagementregimesappliedtothestands.Thefullsetofefficientmanagementplansrepresentsproductionpossibilityfrontiersamongecosystemservices,i.e.bi-dimensional planoutcomesrepresentingmaximumachievablevaluesofservices.Inordertorevealthetradeoffs,weidentifiedcombinationsofmanagementregimesthatmaximizedtheyieldofcollectable goodsatdifferentlevelsoftimberrevenues,andviceversa,i.e.Paretooptimalplans(Miettinen 1999).WecarriedoutoptimizationcalculationsbyusingIBMILOGCPLEXoptimizer(http:// www.ibm.com/software/commerce/optimization/cplex-optimizer/). For further details on the methodsofrevealingtrade-offsandoptimization,seeMönkkönenetal.(2014).Weranmulti-objective optimizationsseparatelyforeachyieldofcollectablegoodsvs.timberrevenues.Additionally,we optimizedtheeconomicvalueofcollectablegoodsvs.timberrevenues. Inordertoillustratetheoptimalcombinationofmanagementregimesthatmaximizesthe yieldsofcollectablegoods,weproducedgraphsthatshowhowtheoptimalallocationofmanagementregimesforforeststandschangeswithincreasingyieldsofcollectablesanddecreasingtimber revenues.Then,weobtainedanalogousresultsundertheconstraintthattimberrevenuedoesnot fallbelowthelevelof95%ofmaximumpossiblerevenues,i.e.whentheforestowneragreesto forego 5% of the maximum achievable timber revenues for collectable good production and recreationalvalues.Weselecteda5%leveldecreaseintimberrevenuesbecauseforestcertification rulesrequirethatatleast5%oftheforestareashouldbepermanentlysetasidefrommanagement toconservebiodiversity(ForestStewardshipCouncil2010).Italsoroughlycorrespondswiththe politicaldecisionstakeninFinlandregardingbiodiversityconservationthroughtheMETSOII program(METSOProgramme2008–2016).Thissamelevelmightbewellinvestedinsupporting theconsideredalternativeecosystemservices. 2.6 Model assumptions Themodelsavailabletoestimateyieldsofcollectablegoodsvaryintheirvalidity.Therecent studyevaluatingtheberrymodelsinFinlandshowedthatthebilberrymodelismoreaccurate thanthecowberrymodel(Kilpeläinenetal.2016).Thebilberrymodelmightunderestimatethe yieldswhilethecowberrymodelmightoverestimatetheyields.Thecepmodelhas been validated onlyforsprucedominatedforests(Miinaetal.2013)and,sincecepislivinginsymbiosiswith 7 Silva Fennica vol. 50 no. 5 article id 1672 · Peura et al. · Managing boreal forests for the simultaneous… Norwayspruce,theestimatedyieldsforotherforesttypesarelessaccurate.Inaddition,theyield modelsforbilberryandcephaveonlybeenvalidatedforNorthKarelia,easternFinland,whereas cowberryyieldmodelsandthemodelforbilberrycoveragehavebeenvalidatedforthewholeof Finland.TheforestlandscapeinCentralFinland,towhereweapplythemodel,isonly150km westofNorthKarelia,andforestconditionsinthetworegionsarefairlysimilar. Bilberrycoverandyieldaresensitivetoregenerationmethods,bothbeinglowerinartificiallyregeneratedthannaturallyregeneratedstands(Miinaetal.2009).Wedidnothavedataon thehistoryofstands,andhence,weassumedthatallstandsinitiallyoriginatedfromplantedtrees, becauseplantingisthedominantregenerationmethodafterfinalharvesting.Thus,bilberryyields areunderestimatedonstandsthatwerenaturallyregenerated. Duetopotentialbiascausedbymodellimitations,absolutepredictedyieldestimatesor theirmonetaryvaluesmaybeinaccurate(seealso2.4).Therefore,ourfocuswillbeonpotential trade-offsandontherelativeutilityofdifferentmanagementplans,ratherthanonabsolutevalues. 3 Results 3.1 Total yields Themaximumtotalcowberryyieldfromtheentirelandscapewasmorethanfourtimeshigher thanthemaximumtotalbilberryyield(Table2).Thesevaluestranslatedinto35kgha–1year–1 and7.7kgha–1year–1forcowberryandbilberry,respectively.Themaximumtotalcepyieldfrom theentirelandscapewascloseto50000kgyear–1(Table2),i.e.onaverage1.2kgha–1year–1. Themaximumeconomicvalueofthethreecollectablegoodsacrosstheentirelandscapewas approximatelyonequarterofthemaximumeconomicvalueoftimberharvestrevenues(Fig.1, Table2),i.e.32€ha–1year–1vs.116€ha–1year–1 onaverageforcollectablegoodsandtimber, respectively.Cowberryyieldsweremuchlargerthanbilberryorcepyieldsandtheproportionof cowberryfromthecombinedeconomicvalueofcollectableswasapproximately70%. Table 2. Potentialofthelandscape(43150ha)incentralFinlandtoprovideannualyieldsof collectablegoods,thecombinedeconomicvalueofcollectablegoods(NPV)acrossa50year planninghorizon,andcostsrelatedtocollectablegoodsprovision.Max and Min values representthelargestandsmallestpossibleyieldsorNPVofcollectablegoodsamongParetooptimal solutionsthatcanbeachievedwhenapplyingcombinationsofthesevenalternativemanagement regimes. Timber NPV difference isthereductionintimberNPVintheParetooptimalsets requiredtoachievemaximumyields(maxtimberNPVis250M€inallcases). Max Min TimberNPVdifference Collectable good Bilberryyield 331Mg 257 Mg 75M€ Cowberryyield 1522 Mg 1452 Mg 7M€ Cepyield 50 Mg 44 Mg 16M€ CollectablegoodsNPV 68M€ 66M€ 13M€ 8 Silva Fennica vol. 50 no. 5 article id 1672 · Peura et al. · Managing boreal forests for the simultaneous… 3.2 The potential of a landscape to produce collectable goods and timber Trade-offsbetweencollectablegoodsandtimberNPVshowednon-linearrelationshipsinthesetof outcomesofParetooptimalplansandvarieddependingonthecollectablegoodanalyzed(Fig.1). Itisnotpossibletomaximizetheyieldsofcollectablegoodsortheeconomicvalueofcollectablegoodswithoutadecreaseintimberrevenues,andviceversa.However,becausethetrade-off curveswereconvexitwaspossibletoproducesimultaneouslyhighlevelsofalternativeservices. Inthecaseofbilberry,thedifferencesbetweentheminimumandmaximumyieldsand inthereductionintimberNPVrequiredtogainthemaximumyieldwerequitelarge(Table2, Fig.1).Thismeansthatthereisthepotentialtoconsiderablyincreaseyieldsofbilberry,butthis wouldresultinlargelossesintimberrevenues.Thetrade-offcurveforbilberryversustimberNPV declinedmoresteeplythanforothercollectables(Fig.1)indicatingthataunitincrementinbilberry yieldwasmoreexpensivethanaunitincrementincowberryorcepyieldswhenapproachingtheir maximum values. Inthecaseofcowberry,therewasasmalldifferencebetweentheminimumandmaximum yields(Table2,Fig.1).Thus,thecowberryyieldwasaffectedfairlylittlebyadjustingforestmanagementplanstomaximizetimber.Moreover,thedeclineintimberNPVwhentargetingcowberry wasrelativelysmall(Table2),thusmaximizingthecowberryyieldwasrelativelyinexpensive.The trade-offcurveforcowberryversustimberNPVwasfairlyflatandshort(Fig.1),furtherindicating thattheconflictbetweentimberandcowberryisnegligible. Fig. 1. CurvesrepresentingoutcomesofPareto-optimalplansdescribingthetrade-offs betweencollectablegoodyields:bilberry,cowberry,cep,thecombinedeconomicvalue ofcollectablegoods,andtimberrevenuesinourstudylandscapeincentralFinland.The X-axisshowsthedifferencebetweenthemaximumandminimumcollectableyieldsin relativeterms.TheY-axissimilarlyshowsthereductionintimberNPVinthePareto optimalsetsrequiredtoachievemaximumcollectableyields. 9 Silva Fennica vol. 50 no. 5 article id 1672 · Peura et al. · Managing boreal forests for the simultaneous… Inthecaseofcep,thedifferencebetweentheminimumandmaximumyieldswassmaller thaninthecaseofbilberryandlargerthaninthecaseofcowberry(Table2,Fig.1).Thus,thecep yieldcanbemoderatelyaffectedbyadjustingforestmanagementplanstomaximizetimber.The declineintimberNPVwhentargetingcepwasslightlyhigherthanthatforthecowberrybutmuch lowerthanforthebilberry(Table2).Thetrade-offcurveforcepversustimberNPVwasfairlyflat (Fig.1)indicatingthatconflictbetweenthemisrelativelysmall. ForthecombinedNPVofcollectablegoods,therewasonlyasmalldifferencebetween theminimumandmaximumvaluesamongParetooptimaloutcomes(Table2).Asinthecaseof cowberry,collectablegoodNPVwasonlyslightlyaffectedbyadjustingforestmanagementplans tomaximizetimber.ThelevelofdeclineintimberNPVwhentargetingcollectablegoodNPVwas lowerthanforcowberry,buthigherthanforcep(Fig.1).Theseresultsindicatethattheconflict betweentheeconomicvalueofcollectablesandtimberwasrathersmall. 3.3 Optimal combination of management regimes Whenasingleforestmanagementregimewasappliedconsistentlyinthelandscapetherelative utilityoftheregimevariedamongdifferentcollectablegoods(Table3).Noneofthesinglemanagement regimes produced as high values as in their optimal combination selected via multi-objective optimization(cf.Table2).Thismeansthatacombinationofdifferentmanagementregimeswas alwaysneededtomaximizeyieldsofcollectablegoods.Forbilberry,EXT30wasthemostbeneficial strategyandthetworegimeswithnothinningsweretheleastbeneficialstrategies.Forcowberry, BAUwasthemostbeneficialstrategyandSAwastheleastbeneficialstrategy.Forcep,GTR30 wasthemostbeneficialstrategyandSAwastheleastbeneficialstrategy.Forthecombinedeconomicvalueofallcollectablegoods,BAUwasthemostbeneficialstrategyandSAwastheleast beneficialstrategy(Table3).However,fortheeconomicvalueofcollectablegoods,thedifferences Table 3. Annualyieldsofcollectablegoodsonaverageandtheeconomicvalueofcollectablegoodsandtimber(NPV) across50yearsforalternativemanagementregimes(BAUbusinessasusual, SAsetaside,EXT10 extended rotation 10 years,EXT30extendedrotation30years,GTR30greentreeretention,NTSR no thinnings short rotation and NTLR no thinningslongrotation)ifonlyonemanagementregimeisusedinallstandsofthestudylandscapeinCentralFinland. The largest value of alternative management regimes is given in bold. % of Max is the proportion of the values compared to the maximum value (Table 2). 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