简介：EucalyptsareverypopularforrevegetationinmanypartsofsouthChinabecauseoftheircapacitytotoleratedegradedsitesandunfertilesoils,andtheirfastgrowthpotentialtocoppice.Thispaperreviewsadecadeoffieldtrialsinchina,undertakenaspartofseveralbilateralresearchprogramsinplantationforestry,concerningtheuseoffertilizers,harvestresiduemanagementandinoculationwithectomycorrhizalfungi.Oneofthekeyquestionsaddressediswhethertheproductivityofplantation...

简介：Growthofcommercialforestryishighlydependentontheavailabilityoffast-growingplantingmaterials.Consequently,theefficientutilizationoffastgrowingplantationscangreatlyimpactproductivity.Theobjectivesofthisstudyweretoevaluatevariationsinthegrowthpotentialoftwoclonesandtoestimatetheaveragestemradialgrowthadvantageofafast-growingcloneusingdataobtainedfromSappilandholdingsineasternSouthAfricaandamixedmodellingapproachthatpermitstheincorporationofcovariancestructureintothestatisticalmodel.Duringthefirst2yearsofgrowth,thestemradiusofninetreeseachoftwocloneswasmeasuredusingdendrometerattachedtothetree.Asecond-degreefractionalpolynomialmodelwaschosentoshowthefunctionalrelationshipbetweenstemradiusandtreeage.Growthofthetwohybridclonesdifferedsignificantly.TheEucalyptusgrandis9EucalyptusurophyllaclonegrewfasterthantheE.grandis9camaldulensisclone,indicatingbettergeneticpotentialforrapidgrowthandyield.Thisstudycanbeconsideredasstartingpointtofurthercomparethepotentialforrapidgrowthofseveralhybridclonesusingthelongitudinaldatamodellingapproach.

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简介：BirdcommunitiesweresurveyedinnaturaldeciduousforestofbothslopeareaandvalleyareaatMt.Gyebangsan(37°40'30"N,128°30'1"E),GangwonProvince,SouthKoreainwinter,spring,summerandautumnfromSeptember2000toNovember2001.Theinvestigatingresultsshowedthatthereexisteddifferencesinthebirdspeciescomposition,richness,birdspeciesdiversity,guildstructurebetweenslopeareaandvalleyarea,andtheverticalforeststructure,especiallycoverageofunderstory,anddiameteratbreastheight(DBH)distributionalsohadsignificantdifferencebetweenthetwostudyareas.Thedifferencesinhabitatstructurebetweentheareasareverylikelytohaveinfluencesonhowbirdsusedtheavailablehabitat.

简介：Background:Amongthemostimportantaspectsofriskandhazardstudiesrelatingtoforestecosystemsaremaximumforestdensityanddensity-dependenttreesurvival.Methods:Long-termobservationsaboutthemaximumdensityofunthinnedPinuspatulaandP.elliottiifieldplotsbasedontheCorrelatedCurveTrend(CCT)spacingstudieswhichwereestablishedalmost8decadesagobyO’Connor(ForestResearchwithSpecialReferencetoPlantingDistancesandThinning,1935)inSouthAfrica.Threespecificapproacheswereintroducedforanalysingmaximumdensityandtreesurvival,namelythe‘limitingline’,Nilson’ssparsityandtreesurvivalwiththeWeibullfunction.Results:Themainresultsare:a)Maximumdensitiesdiffergreatlyamongthetwospeciesgrownonthesamesiteandwithinthesamespeciesgrownondifferentsites;itispossibletorelatethesedifferencestositeindexinbothspecies.b)Therelationshipbetweenthequadraticmeandiameterandtheminimumaveragespacingofsurvivingtrees(knownasNilson’sSparsity)appearstobesurprisinglysimilarinbothspecies.c)AnanalysisoftreesurvivalinresponsetodifferentinitialplantingespacementsshowsthattheWeibullsurvivalfunctionparameterscanbeestimatediftheinitialplantingdensityisknown.Thisresultispresentedforeachoftheeightlargeexperimentsusedinthisstudy.Conclusions:Thisstudycontributestoabetterunderstandingoftreesurvivalandmaximumdensitywhicharethekeyfactorsrequiredforestimatingriskanduncertainty.Theriskoftreemortalityisnotconstant,butvarieswithtreespecies,plantingdensity,treeageandgrowingsite.Forestimatingthatrisk,therefore,continuouslong-termobservationondifferentsitesandwithvaryingplantingdensities,asprovidedbytheunthinnedCCTseries,areessential.

简介：Background:Wildlifeandlivestockgrazingareimportantproductsofforestecosystems,butcanbecontroversial.HerbivorybyNorthAmericanelkanddomesticcattleisacontentiousmanagementissuethroughoutwesternNorthAmerica,oftendrivingmanagementproposalstodecreasecattleandelknumbersbasedonperceivedoverutilizationofforages.Suchobservationsareoftensitelevelratherthanlandscape,andmayconfuseecologicalsustainabilitywithdesiredconditions.Methods:Weusedlinetransectstodocumentvegetationcomposition,structure,andgrazingandbrowsingutilizationfor4keyhabitattypes:mountainmeadows,aspen,thinnedconifer,andburnedconiferonLincolnNationalForest,NewMexico,USA.Wedocumentedrelativehabitatuseofthesetypesbyelk,muledeer,andcattleandmodeledrelativeuseonresidualgrassbiomassofmountainmeadowsandbrowseutilizationofforestedtypes.Wedetermineddietsanddietqualityofelkandcattletoassessdegreeofcompetition.Results:Useofgrassesinmeadowswasbelowmanagementthresholds,andcombinedelk,cattle,anddeerrelativehabitatuseaccountedfor<14%ofthevarianceinresidualstubbleheightofPoapratensis,themostabundantgrass.Palatablebrowsewaslimitedinhabitattypes(<107stems·ha~(-1)),usewasgenerallyhigh,andelkpresencewascorrelatedwiththemajorityofbrowsing.Elkandcattledietsdidnotsignificantlyoverlap(Schoener'sindex0.54–0.57);elkfedprimarilyondeciduousshrubs(34%–55%ofannualdiets)andcattleongrass(72%–77%).Digestibilityandcrudeproteinlevelsofcattledietsandbodyconditionofelkindicatedhighqualitydietsforcattleandmarginal–goodqualitydietsforelk.Conclusions:Atobservedstockinglevelsanddensities,cattleandelkwerenotcompetingforforagebasedondietsimilarity,norwerekeyhabitattypesbeingusedbeyondsustainablelevels.LowbrowseavailabilityindicatesthatopportunityexiststoincreaseforageavailabilityonLincolnNationalForest,andthusmaintainorincreasepopu

简介：ThefloraandcommunityphysiognomyofdegradedplantationecosystemsonpurplesoilwereinvestigatedinNinghuaCountyofFujianProvince,Chinatounderstandtherelationshipbetweenplantdiversityandecosystemprocesses..Fourdifferentrestorationcommunities(labeledasecologicalrestorationtreatmentI,II,IllandIV)wereselectedbyspace-timereplacementmethodaccordingtotheerosionintensityindegradedpurplesoilecosystem.Theresultsshowedthatthereweretotally86plantspeciesbelongingto78generaand43familiesinthedegradedpurplesoilecosystem.Ofthe15typesofdistributionareainspermatophytegenus,12typeswerefoundinthepurplesoilecosystem.Alongrestorationgradientfromlowtohigh,plantgrowthtypeandlifeformspectrabecameabundantmoreandmore,andthespermatophytegeneraforeachdistributionareatypeandgeneranumbersfordifferentfoliagecharactersincreasedaswell.Itisconcludedthattheplantfloraandphysiognomyinecologicalrestorationprocessbecomemorecomplexanddiverse,indicatingthattheforestecosystemonpurplesoiltendstobemorestable.

简介：Background:Tropicalforestsplayanimportantroleintheglobalcarbon(C)cycle.However,tropicalmontaneforestshavebeenstudiedlessthantropicallowlandforests,andtheirroleincarbonstorageisnotwellunderstood.Montaneforestsarehighlyendangeredduetologging,land-useandclimatechange.Ourobjectivewastoanalysehowthecarbonbalancechangesduringforestsuccession.Methods:Inthisstudy,weusedamethodtoestimatelocalcarbonbalancesthatcombinedforestinventorydatawithprocess-basedforestmodels.WeutilisedsuchaforestmodeltostudythecarbonbalanceofatropicalmontaneforestinSouthEcuador,comparingtwotopographicalslopepositions(ravinesandlowerslopesvsupperslopesandridges).Results:Thesimulationresultsshowedthattheforestactsasacarbonsinkwithamaximumnetecosystemexchange(NEE)of9.3MgC?(ha?yr)-1duringitsearlysuccessionalstage(0–100years).Inthelatesuccessionalstage,thesimulatedNEEfluctuatedaroundzeroandhadavariationof0.77MgC?(ha?yr)–1.ThesimulatedvariabilityoftheNEEwaswithintherangeofthefielddata.Wediscoveredseveralforestattributes(e.g.,basalareaortherelativeamountofpioneertrees)thatcanserveaspredictorsforNEEforyoungforeststands(0–100years)butnotforthoseinthelatesuccessionalstage(500–1,000years).Incaseofyoungforeststandsthesecorrelationsarehigh,especiallybetweenstandbasalareaandNEE.Conclusion:Inthisstudy,weusedanEcuadorianstudysiteasanexampleofhowtosuccessfullylinkaforestmodelwithforestinventorydata,forestimatingstem-diameterdistributions,biomassandabovegroundnetprimaryproductivity.Toconclude,thisstudyshowsthatprocess-basedforestmodelscanbeusedtoinvestigatethecarbonbalanceoftropicalmontaneforests.Withthismodelitispossibletofindhiddenrelationshipsbetweenforestattributesandforestcarbonfluxes.Theserelationshipspromoteabetterunderstandingoftheroleoftropicalmontaneforest

简介：为木质的植物差异，结构和新生上的读经台州的福雷斯特里的这研究，70空铅，每25?在25的m?m，用一种系统的随机的采样技术和100的间隔被选择?沿着一根横断线的m。为估计幼苗和树苗，二2??楷桴？

简介：Background:Informationonforeststructure,growth,anddisturbancehistoryisessentialforeffectiveforestmanagementinadynamiclandscape.BecausemostofourresearchconcerningtheecologyandgrowthofThujaoccidentaliscomesfromsitesinnorthernportionsofitsrange,highlycontextualbioticandabioticfactorsthataffectthespeciesinmoresouthernlocalesmaynotbefullyaccountedfor.ThisresearchcharacterizedthestructuralattributesandgrowthdynamicsofThujaoccidentalisindisjunctforeststandssouthofitscontiguousrangemargin.Methods:TheThujaoccidentalisforestsexaminedinthisresearchwerelocatedinthecentralAppalachianMountains,USA,approximately440kmsouthofthecontiguousrangemarginofthespecies.ForeststructuralattributeswerecharacterizedintwoThujaoccidentalisforeststands,whicharerareintheregion.Tree-ringchronologieswereusedtoexaminetheinfluencesofdisturbanceandclimateonthegrowthofThujaoccidentalis.Results:Theforestscontainedatotalof13treespecieswithThujaoccidentaliscontributingsubstantiallytothebasalareaofthesites.Thujaoccidentalisstemswereabsentinthesmallestsizeclass,whilehardwoodspecieswereabundantinthesmallestclasses.Thujaoccidentalisstemsalsowereabsentfromthe<70yearsageclass.Bycontrast,Thujaoccidentalissnagswereabundantwithinstands.Growth-releaseeventsweredistributedacrossthedisturbancechronologyandgenerallyaffectedasmallnumberoftrees.TheThujaoccidentalistree-ringchronologypossessedaninterseriescorrelationof0.62andmeansensitivityof0.25.ThecorrelationbetweenmeantemperatureandThujaoccidentalisgrowthwasweakandvariable.Growthandmoisturevariablesweremorestronglycorrelated,andthisrelationshipwaspredominantlypositive.Conclusions:Structuralattributesindicatetheforestsareintheunderstoryreinitiationstageofforestdevelopment.SilviculturalmanipulationsmaybenecessarytopromoteThujaoccidentalisestablishment.Thesensi

简介：Background:Overthelastdecadesinteresthasgrownonhowclimatechangeimpactsforestresources.However,oneofthemainconstraintsisthatmeteorologicalstationsarefiddledwithmissingclimaticdata.Thisstudycomparedfiveapproachesforestimatingmonthlyprecipitationrecords:inversedistanceweighting(IDW),amodificationofIDWthatincludeselevationdifferencesbetweentargetandneighboringstations(IDWm),correlationcoefficientweighting(CCW),multiplelinearregression(MLR)andartificialneuralnetworks(ANN).Methods:Acompleteseriesofmonthlyprecipitationrecords(199.5-2012)fromtwentymeteorologicalstationslocatedincentralChilewereused.Twotargetstationswereselectedandtheirneighboringstations,locatedwithinaradiusof25km(3stations)and50km(9stations),wereidentified.Cross-validationwasusedforevaluatingtheaccuracyoftheestimationapproaches.Theperformanceandpredictivecapabilityoftheapproacheswereevaluatedusingtheratiooftherootmeansquareerrortothestandarddeviationofmeasureddata(RSR),thepercentbias(PBIAS),andtheNash-Sutcliffeefficiency(NSE).Fortestingthemainandinteractiveeffectsoftheradiusofinfluenceandestimationapproaches,atwo-levelfactorialdesignconsideringthetargetstationastheblockingfactorwasused.Results:ANNandMLRshowedthebeststatisticsforallthestationsandradiusofinfluence.However,theseapproacheswerenotsignificantlydifferentwithIDWm.InclusionofelevationdifferencesintoIDWsignificantlyimprovedIDWmestimates.Intermsofprecision,similarestimateswereobtainedwhenapplyingANN,MLRorIDWm,andtheradiusofinfluencehadasignificantinfluenceontheirestimates,weconcludethatestimatesbasedonnineneighboringstationslocatedwithinaradiusof50kmareneededforcompletingmissingmonthlyprecipitationdatainregionswithcomplextopography.Conclusions:ItisconcludedthatapproachesbasedonANN,MLRandIDWmhadthebestperformanceintwosectorslocatedinso

简介：Background:Prosopisspecieshavebeenintroducedtomanyareasoutsidetheirnativerangetoprovidebenefitstolocalcommunities.SeveralProsopisspeciesandtheirhybrids(hereafter"mesquite")have,however,becomenaturalisedandinvasiveandnowgeneratesubstantialcosts.Managementoptionsarelimitedbecauseofthecomplexconflictsofinterestregardingbenefitsandcosts.Managementpoliciesandstrategiesmusttakeaccountofsuchconflicts,butfurtherinsightsareneededonthedimensionsofusesandimpactsbeforesuchinformationcanbeusefullyapplied.CurrentpolicyinSouthAfricaallowsforthegrowthanduseofmesquiteinoneprovince,butnotinotherswhereitscontrolismandatory.Wereportonastudytoquantifythedirectuseandperceptionsofnon-timberforestproducts(NTFPs)frommesquiteandnativetreesinSouthAfrica.Methods:Semi-structureshouseholdinterviewswereconductedwithvariousstakeholdergroupstoidentifywhattreeproductsareused,toascertainamountsusedaswellastogaugeperceptionsofnaturalresourceusebetweendifferenttreespeciesanduseovertime.Results:Thedirecthouseholdusevalueofnativetreeswashigherthanthatofmesquite,andlocalstakeholdersattachedgreatervaluetoproductsfromnativetreesthanfrommesquite.Therefore,nativetreesareandwillstillbepreferentiallyharvested,andmesquiteisunlikelytoofferprotectiontonativespeciesbyprovidinganalternativesourceofproducts.Mesquitepodsdo,however,providevaluableadditionalresources(fodderandmedicinalproducts).Theuseofbothnativetreesandmesquiteisdecreasingastheincomesofpoorerhouseholdsriseandasalternativeenergysourcesbecomeavailable.Thebenefitsandrelianceonmesquitearenotashighaspreviouslyassumedandtheimpactsfrommesquiteinvasionscreatelargeproblemsforlocalcommunities.Conclusion:Thisstudyprovidesfurtherevidencethattheimpactsofmesquiteexceedthebenefits,lendingsupportforapolicytoreducenegat