简介：Background:Informationonabove-groundbiomass(AGB)isimportantformanagingforestresourceuseatlocallevels,landmanagementplanningatregionallevels,andcarbonemissionsreportingatnationalandinternationallevels.Inmanytropicaldevelopingcountries,thisinformationmaybeunreliableoratascaletoocoarseforuseatlocallevels.ThereisavitalneedtoprovideestimatesofAGBwithquantifiableuncertaintythatcanfacilitatelandusemanagementandpolicydevelopmentimprovements.Model-basedmethodsprovideanefficientframeworktoestimateAGB.Methods:UsingNationalForestInventory(NFI)datafora~1,000,000hastudyareainthemiomboecoregion,Zambia,weestimatedAGBusingpredictedcanopycover,environmentaldata,disturbancedata,andLandsat8OLIsatelliteimagery.Weassesseddifferentcombinationsofthesedatasetsusingthreemodels,asemiparametricgeneralizedadditivemodel(GAM)andtwononlinearmodels(sigmoidalandexponential),employingageneticalgorithmforvariableselectionthatminimizedrootmeansquarepredictionerror(RMSPE),calculatedthroughcross-validation.Wecomparedmodelfitstatisticstoanullmodelasabaselineestimationmethod.Usingbootstrapresamplingmethods,wecalculated95%confidenceintervalsforeachmodelandcomparedresultstoasimpleestimateofmeanAGBfromtheNFIgroundplotdata.Results:Canopycover,soilmoisture,andvegetationindiceswereconsistentlyselectedaspredictorvariables.ThesigmoidalmodelandtheGAMperformedsimilarly;forbothmodelstheRMSPEwas-36.8tonnesperhectare(i.e.,57%ofthemean).However,thesigmoidalmodelwasapproximately30%moreefficientthantheGAM,assessedusingbootstrappedvarianceestimatesrelativetoanullmodel.Afterselectingthesigmoidalmodel,weestimatedtotalAGBforthestudyareaat64,526,209tonnes(+/-477,730),withaconfidenceinterval20timesmoreprecisethanasimpledesignbasedestimate.Conclusions:OurfindingsdemonstratethatNFIdatamaybecombinedwithfreelyavailablesate

简介：Background:Biomassregressionequationsareclaimedtoyieldthemostaccuratebiomassestimatesthanbiomassexpansionfactors(BEFs).Yet,nationalandregionalbiomassestimatesaregenerallycalculatedbasedonBEFs,especiallywhenusingnationalforestinventorydata.ComparisonofregressionequationsbasedandBEF-basedbiomassestimatesarescarce.Thus,thisstudywasintendedtocomparethesetwocommonlyusedmethodsforestimatingtreeandforestbiomasswithregardtoerrorsandbiases.Methods:Thedatawerecollectedin2012and2014.In2012,atwo-phasesamplingdesignwasusedtofittreecomponentbiomassregressionmodelsanddeterminetreeBEFs.In2014,additionaltreeswerefelledoutsidesamplingplotstoestimatethebiasesassociatedwithregressionequationbasedandBEF-basedbiomassestimates;thoseestimateswerethencomparedintermsofthefollowingsourcesoferror:plotselectionandvariability,biomassmodel,modelparameterestimates,andresidualvariabilityaroundmodelprediaion.Results:Theregressionequationbasedbelow-,abovegroundandwholetreebiomassstockswere,approximately,7.7,8.5and8.3%largerthantheBEF-basedones.Forthewholetreebiomassstock,thepercentageofthetotalerrorattributedtofirstphase(randomplotselectionandvariability)was90and88%forregression-andBEF-basedestimates,respeaively,beingtheremainingattributedtobiomassmodels(regressionandBEFmodels,respeaively).ThepercentbiasofregressionequationbasedandBEF-basedbiomassestimatesforthewholetreebiomassstockwere-2.7and5.4%,respeaively.Theerrorsduetomodelparameterestimates,thoseduetoresidualvariabilityaroundmodelprediaion,andthepercentageofthetotalerrorattributedtobiomassmodelwerelargerforBEFmodels(thanforregressionmodels),exceptforstemandstemwoodcomponents.Conclusions:Theregressionequationbasedbiomassstockswerefoundtobeslightlylarger,associatedwithrelativelysmallererrorsandleastbiasedthantheBEF-basedones.Forstemandst

简介：Inthecontextofglobalcarboncyclemanagement,accurateknowledgeofcarboncontentinforestsisarelevantissueincontemporaryforestecology.Wemeasuredtheabove-groundandsoilcarbonpoolsinthedarkconiferousborealtaiga.Wecomparedmeasuredcarbonpoolstothosecalculatedfromtheforestinventoryrecordscontainingvolumestockandspeciescompositiondata.Theinventorydataheavilyunderestimatedthepoolsinthestudyarea(StolbyStateNatureReserve,centralKrasnoyarskTerritory,RussianFederation).Thecarbonpoolestimatedfromtheforestinventorydatavariedfrom25(tha-1)(low-densitystands)to73(tha-1)(highlystockedstands).Ourestimatesrangedfrom59(tha-1)(lowdensitystands)to147(tha-1)(highlystockedstands).Ourvaluesincludedlivingtrees,standingdeadwood,livingcover,brushwoodandlitter.Wefoundthattheproportionofbiomasscarbon(livingtrees):soilcarbonvariedfrom99:1to8:2forfullystockedandlow-densityforeststands,respectively.Thiscontradictsthecommonunderstandingthatthebiomassintheborealforestsrepresentsonly16–20%ofthetotalcarbonpool,withthebalancebeingthesoilcarbonpool.

简介：Background:Theglobalsearchfornewwaystosequestercarbonhasalreadyreachedagriculturallands.Suchlandconstitutesamajorpotentialcarbonsink.Theproductionofhighvaluetimberwithinagroforestrysystemscanfacilitateanin-situcarbonstoragefunction.Thisisfollowedbyapotentiallongtermex-situcarbonsinkwithinlonglastingproductssuchasveneerandfurniture.Forthispurposewildcherry(PrunusaviumL.)isaninterestingoptionformiddleEurope,yieldinghighpricesonthetimbermarket.Methods:Atotalnumberof39wildcherryweresampledin2012and2013toassesstheleaflessabovegroundbiomass.Thecompletetreesincludingstemandbrancheswereseparatedinto1cmdiameterclasses.Woodandbarkfromsub-sampleswereanalysedseparatelyandnutrientcontentwasderived.Modelsforbiomassestimationwereconstructedforalltreecompartments.Results:Thesmallestdiameterclassespossessthehighestproportionofbarkduetosmallercrosssectionalarea.Treeboleswithagreateramountofstemwoodabove10cmindiameterwillhaveamoreconstantbarkproportion.Totalbranchbarkproportionalsoremainsrelativelyconstantaboved_(1.3m)measurementsof8cm.Abalanceisevidentbetweentheproductionofnewbrancheswithalowdiameterandhighbarkproportionoffsetbythethickeningandarelativereductioninbarkproportioninlargerbranches.Theresultsshowthatasingletreewithanageof17and18yearscanstoreupto85kgofcarbonwithintheabovegroundbiomassportion,anamountthatwillincreaseasthetreematures.Branchesdisplaygreaternutrientcontentthanstemsectionspervolumeunitwhichcanbeattributedtoagreaterbarkproportion.Conclusions:Usingthederivedmodelsthecarbonandthenutrientcontentofabove-groundwoodybiomassofwholetreescanbecalculated.Suggestedvaluesforcarbonwithothermajorandminornutrientsheldwithinrelativelyimmaturetreesstronglysupportstheideaoftheinclusionofwildcherrywithinagroforestrysystemsasan