简介：Soilwaterisoneofrenewablewaterresources.Somepropertiesofsoilwaterconcerningwithitsavailabilitytoplantarebrieflydescribed.Anequationforestimatingtheamountofsoilwaterresourceispresented.Basedontheevaporationdemandofatmosphere,theevaluationcoefficientforsoilwaterresourceissuggested.

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简介：APoissonregressionmodelandanegativebinomialregressionmodel(NBmodel)areoftenusedinareassuchasmedicineandeconomy,butrarelyinthedomesticforestrysector,especiallyintheforestfireforecasting.BasedonthedataofforestfireoccurrencesinDaxing’anlingregionin1980-2005,thispaperprofoundlyanalyzestheapplicationconditionsandtestmethodsofthetwomodels.TheAICmethodwasusedtocheckthefittinglevelofthemodelsandthecapabilityofthemodelsforforecastingforestfireswasdiscussed.ThisstudyprovidednecessarytheoreticalbasisanddatasupportfortheapplicationofthetwomodelsinthefieldofforestryinChina.

简介：在考古学的发现的底上，米饭的最早的驯服在中间和更低的Changjiang河盆被证实了，当在这个区域野米饭人口与冻结冬季寒冷在气候下面在浅沼泽地被发现时。这些调查结果铅我们覆查关于米饭的驯服和区别的过去的想法。历史上，在1930年代二亚种，indica和装饰用的梨树，在在他们之间的F1混血儿根据绝育被建议。此后不久那，二种类型被很多个遗传上独立的特点的协会分类。特点的典型协会被被假定包括一套副本的混合绝育或繁殖障碍解释了后退的致命的基因并且是内部基因机制导致品种的区别。在1980年代，在Indica和装饰用的梨树类型之间的混合绝育被分析，并且当生气时，把肥沃的混血儿给Indica和装饰用的梨树类型的Indica，装饰用的梨树，和宽相容性的类型，被证明包含等位基因，S5i，S5j和S5n，分别地在染色体6上的一个地点。并且当没有配偶子流产发生在S5i/S5n和S5j/S5n遗传型时，让S5j等位基因被发现部分是的那些配偶子在S5i/S5j的混合遗传型流产了。从那以后，基因S5n在繁殖获得在亚种之间的肥沃、精力旺盛的混血儿的混合米饭被使用了，并且混合绝育的长争论的问题被解决了。另外，在如此的研究，特点的典型协会在每品种的组发现了被创始人效果更好解释。在另一方面，米饭的很多本国的栽培变种与分子的标记在1980年代并且以后与酶多型性被调查。作为结果，深刻基因差异在栽培米饭以及在野米饭被发现。这些调查结果似乎带我们到米饭的多重独立驯服的想法。然而在得出如此的一个结论前，至少二个因素，即，一些遗传型的long-distance-dissemination和由到原始栽培变种的本地野米饭的基因渗入的可能性需要被检验。考虑二个因素以及历史的事件，在Changjiang河盆接近野米饭的长期的装饰用的�

简介：研究了木材价格的变化为一自相关过程时用材林采伐的随机决策分析问题，分析了用材林经营决策中的不确定性因素及其对经营决策的影响；建立了一个木材市场随机变动的适应价格的主伐决策模型，利用动态规划求得在一个给定决策期内的主伐最优经营策略，对应这个策略有一个最大的期望效益．并进一步分析了在价格波动情况下和不同贷款利率下的最优策略．

简介：Growthmodelisanefficientwaytostudygrowingprocessofsomefactorsofplantsquantitatively.HeightgrowthofKoreanpine(Pinuskoraiensis)wasstudiedbyusingHyperbolaequation,Logisticequation,Richardsequationwiththreeparameters,andRichardsequationwithfourparametersinthispaper.TheresultsshowedthatRichardsequationwithfourparameterswasthemostsuitableandcouldbeturnedintoothertheoreticalequationswhensomeparametersweregivendifferentvalue.ThemaximumheightoftreescouldbegiveninadvancewhenusingRichardsequationwithfourparameters,anditwasevenmorecorrespondingtoreality.Inaddition,aheightgrowthmodelwithrealheightoffixedageasaparameterwasdiscussedinthispaper.Thiskindofgrowthmodelcouldbeusedtocalculateheightgrowthofagiventreeeffectively.

简介：Thispaperfocusesontheuseofmodelsforincreasingtheprecisionofestimatorsinlarge-areaforestsurveys.Itismotivatedbytheincreasingavailabilityofremotelysenseddata,whichfacilitatesthedevelopmentofmodelspredictingthevariablesofinterestinforestsurveys.Wepresent,reviewandcomparethreedifferentestimationframeworkswheremodelsplayacorerole:model-assisted,model-based,andhybridestimation.Thefirsttwoarewellknown,whereasthethirdhasonlyrecentlybeenintroducedinforestsurveys.Hybridinferencemixesdesignbasedandmodel-basedinference,sinceitreliesonaprobabilitysampleofauxiliarydataandamodelpredictingthetargetvariablefromtheauxiliarydata.Wereviewstudiesonlarge-areaforestsurveysbasedonmodel-assisted,modelbased,andhybridestimation,anddiscussadvantagesanddisadvantagesoftheapproaches.Weconcludethatnogeneralrecommendationscanbemadeaboutwhethermodel-assisted,model-based,orhybridestimationshouldbepreferred.Thechoicedependsontheobjectiveofthesurveyandthepossibilitiestoacquireappropriatefieldandremotelysenseddata.Wealsoconcludethatmodellingapproachescanonlybesuccessfullyappliedforestimatingtargetvariablessuchasgrowingstockvolumeorbiomass,whichareadequatelyrelatedtocommonlyavailableremotelysenseddata,andthuspurelyfieldbasedsurveysremainimportantforseveralimportantforestparameters.

简介：Man-madeforest,whichistheforestecosystemofrehabilitationandreconstruction,playsasignificantroleintheprovisionofforestproductsandimprovementtheecologicalenvironment.Inthispaper,weestablishedtheAR(5)modeltopredictChina'sforestareafrom2009to2015.Thisstudyshowstheslowgrowthofthenationalplantationareatrendwithsomefluctuations,buttheoverallgrowthrateisnotlarge.WeproposedthatononehandChinashouldcontinuetoincreasetheplantationarea,ont...

简介：BPandRBFneuralnetworktopredictforeststockvolumewerestudied,butthestudyinevaluatingbothnetworks’applicationeffectswasnotconducted.Inordertofindahigherforecastprecision,morestrongapplicativemethod,thecomprehensiveanalysisandevaluationonthetwomethodswerecarriedoutinthepracticalapplication.Bythecorrelationanalysis,crowndensity,shady-slopeandsunny-slope,TM1,TM2,TM3,TM5,TM7,NDVI,TM,(4-3),TM4/3wereselectedasinputvariables,andtheforestvolumeofMiyunCountyasoutputvariables,RBFandBPneuralnetworkmodelsforforecastingtheforestvolumewereestablished.Andtheneuralnetworktrainingsteplength,trainingtime,predictionaccuracyandtheapplicabilitymodelofthetwomethodswerecomprehensivelyanalyzed.TheresultsshowthattheRBFneuralnetworkmodelissuperiortotheBPneuralnetworkmodel.

简介：ThispaperestablishedanintegratedstandgrowthmodelofMongolianoak(ISGM_oak)usingthedatafrom61permanentsampleplotsmeasuredin1997and2007.ISGM_oakisagroupofnonlinearsimultaneousequations.Themethodofnonlinearerror-in-variablesimultaneousequationsisusedtoestimatetheparametersofISGMoakwiththestatisticalsoftwareForstat2.0,sotheparameterestimationofthegroupofcorrelatedequationsinISGMoakisunbiasedandtheequationsarecompatible.Modelvalidationusingbootstrapmethodshowedthatboththeaveragerelativeerrorandsquareerrorarelessthan15percent.TheISGM_oakmodelcanbeusedtosimulatethestandgrowthwithdifferentvaluesofsiteindex,standdensityandtodrawstanddensitymanagementdiagramfordecision-making.

简介：Identificationofhigh-yieldingstablepromisingricelinesanddeterminationofsuitableareasforricelineswouldbedonebyadditivemaineffectsandmultiplicativeinteraction(AMMI)model.SevenpromisingricegenotypesplustwocheckvarietiesShiroudiand843wereanalyzedusingarandomizedcompleteblockdesignwiththreereplicationsinthreeconsecutiveyears(2012,2013and2014).Homogenouserrorvariancewasindicatedinthenineenvironmentsforgrainyield.Thecombinedanalysisofvarianceindicatedsignificanteffectsofenvironment,genotypeandgenotype×environment(GE)interactionsongrainyield.ThesignificanteffectofGEinteractionreflectedonthedifferentialresponseofgenotypesinvariousenvironmentsanddemonstratedthatGEinteractionhadremarkableeffectongenotypicperformanceindifferentenvironments.TheapplicationofAMMImodelforpartitioningtheGEinteractioneffectsshowedthatonlythefirsttwotermsofAMMIweresignificantbasedonGollob'sF-test.ThelowestAMMI-1wasobservedforG7,G2andG6.G7andG6hadhighergrainyield.Accordingtothefirsteigenvalue,whichbenefitsonlythefirstinteractionprincipalcomponentscores,G1,G6,G2andG9werethemoststablegenotypes.Thevaluesofthesumoffirsttwointeractionprincipalcomponentscorescouldbeusefulinidentifyinggenotypestability,andG6,G5andG2werethemostdynamicstablegenotypes.AMMIstabilityvalueintroducedG6asthemoststableone.AccordingtoAMMIbiplotview,G6washighyieldingandhighlystablegenotype.Inconclusion,thisstudyrevealedthatGEinteractionswereanimportantsourceofriceyieldvariation,anditsAMMIbiplotswereforcefulforvisualizingtheresponseofgenotypestoenvironments.

简介：Soilswerecollectedfrom2-year(2-y)and3-year(3-y)oldred-pineseedlingplotsintwotreenurseries,HaywardinthenorthandWilsoninthesouthwesternpartofWisconsinStaterespectively,andequilibratedwith0.01MCa(NO3)2)forsoilsolutionZnandMn(solu-ZnandMn),andwith0.01MCa(NO3)2+0.005MEDTAforsoilabsorbedZnandMn(ad-ZnandMn).BufferingcapacityofsoilZnandMn(b-ZnandMn)wasobtainedfromtheratioofad-ZnandMntothesolu-ZnandMn.Theconcernedtracesinpineseedlingneedles(ndls),stems(sts)androots(rts)weresimultaneouslymeasured.Theresultsobtainedshowthat:About60%ofsolu-andad-Znrangedfrom0.2to0.4andfrom1to2μg/gsoilrespectively.About70%ofb-Znwaswithin3-10.Thehighestcontentofsolu-Zncomparedwiththelowestshowedadiscrepanceofmorethan10-fold.ThetwoformsofsoilZnwerecommonlyhigherinWilsonthaninHaywarkNursery.About80%ofsolu-,ad-andb-Mnwerewithin3-10,5-5.8μg/gsoiland1-2respectively.Influenceoflowbufferingcapacityonsolu-ZnandMnwasabout20timesstrongerthanthatofthehigh.TheE-value,aratioofaccumulatedZnandMninneedlestothoseinthesoilsolution,isprovedtobe:E-Zn>E-Mn;E-sts>E-ndlsorE-rts;andE-2y>E-3y.Curvilinearand/orlinearcorrelationsbetweensoilsolu-,ad-andb-ZnandMnandndls-,sts-,rts-ZnandMnwereatverysignificantorsignificantlevels.Forpredictingndls-ZnandMn,tworealizableandsimplemodelsfromtworegressionequationswereestablishedthroughtheselectionofrelatedparametersanddependentvariables.BinaryregressionanalysisbasicallyeliminatedtheinfluenceofsoilpHonthepredictionofZnandMninneedles.SoilpHwasthusthoughttobeexcludedfromthemodel.

简介：Background:Capturingtheresponseofforestecosystemstointer-annualclimatevariabilityisagreatchallenge.Inthisstudy,wetestedthecapabilityofanindividual-basedforestgapmodeltodisplaycarbonfluxesatyearlyanddailytimescales.Theforestmodelwasappliedtoaspruceforesttosimulatethegrossprimaryproduction(GPP),respirationandnetecosystemexchange(NEE).Weanalyzedhowthevariabilityinclimateaffectedsimulatedcarbonfluxesatthescaleoftheforestmodel.Results:Sixyearsweresimulatedatadailytimescaleandcomparedtotheobservededdycovariance(EC)data.Ingeneral,theseasonalcycleoftheindividualcarbonfluxeswascorrectlydescribedbytheforestmodel.However,theestimatedGPPdifferedfromtheobserveddataonthedaysofextremeclimaticconditions.Twonewparameterizationsweredeveloped:oneresultingfromanumericalcalibration,andtheotherresultingfromafilteringmethod.Wesuggestnewparametervaluesandevenanewfunctionforthetemperaturelimitationofphotosynthesis.Conclusions:Theforestmodelreproducedtheobservedcarbonfluxesofaforestecosystemquitewel.Ofthethreeparameterizations,thecalibratedmodelversionperformedbest.However,thefilteringapproachshowedthatcalibratedparametervaluesdonotnecessarilycorrectlydisplaytheindividualfunctionalrelations.TheconceptofsimulatingforestdynamicsattheindividualbaseisavaluabletoolforsimulatingtheNEE,GPPandrespirationofforestecosystems.

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简介：Inthepaper,thehydraulicarchitectureparametersofPinustabulaeformisseedlings(4yearsold)weremeasuredbyimprovedflushingmethodundernormalwaterconditioninthegreenhouseandthebasictheoryofhydraulicarchitectureisusedtodiscusstherationalityofthepipemodel.Theresultsoftheexperimentandsimulationshowthatthedifferencesofhydraulicconductivity,specificconductivityandleafspecificconductivityisgreatindifferentstemsandbranchesofPinustabulaeformisseedlings.Thehydraulicconductivityofnon-constrictionareaishigherthanthatofconstrictionarea.Thedevotionoffunctionalxylemofstemtounitleafgrowthisnotaconstant,namely,theHubervalueisdiverse.Eventhoughthepipemodelhasbeenacceptedinsomeareas,itspreconditionisnotperfect,anditishelplessincorrectlyunderstandingtheessenceofwatertransportinseedlingsfromtheprospectiveofwaterphysiology.

简介：ＤｉｓｃｕｓｓｉｏｎｏｆＸｉｘｉａ’ｓＦｏｒｅｓｔｒｙＡＭｏｄｅｌｆｏｒｔｈｅＤｅｖｅｌｏｐｍｅｎｔｏｆＣｈｉｎａ’ｓＴｏｗｎｓｈｉｐＦｏｒｅｓｔｒｙ￥ｂｙＸｕＧｕｏｚｈｅｎＰｏｖｅｒｔｙｉｓｓｔｉｌｌａｓｅｒｉｏｕｓｓｏｃｉａｌａｎｄｅｃｏｎｏｍｉ...

简介：Vegetationfractionalcoverage(VFC)isoneofthekeyindicatorsofvegetationdistribution.Intheworkameasurement-basedmodelwasdevelopedtoderivetotalforestVFC(TG)aswellastheVFCoftrees(T)andshrub-grasses(G)separatelyinasubtropicalforestareainNanjing,China.Bothupwardanddownwardphotographsweretakenwithadigitalcamerain72quadrats(10m×10meach).Fifteenmodelswereestablishedandvalidated.ModelsjointlyusingbothTandGperformedbetterthanthoseusingtheTandGseparately.Thebestmodel,TG=T+G-1.134×T×G-0.025(R2=0.9115,P<0.01,rootmeansquarederror=0.0789),isrecommendedforapplication.ThismodelprovidesagoodwaytoobtaintotalforestVFCvaluesthroughtakingtreeandshrub-grassphotosongroundbelowtreecanopyratherthanabovetreecanopy.

简介：从在到喂转动的木头的水库的木材仓库的木头漂流技术被模型测试学习。模型测试与引力类似和110的比率的规则被参加。主要参数象拖船船，水疗院加速器和喂转动的结构的数量一样，是坚定的。更合适的漂流过程被提出，设计的可靠基础被供应。

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：Basedupon3widelyusedbasemodels,atotalof8ADA/GADAsiteindexmodelswerederived.Thedataforthesemodelsinthisstudywereobtainedfrom79pith-splitstemanalysisplotsandtheestimationmethodwas"indicatorvariableapproach".Weusedbothfitstatisticsandvisualanalysistoselectthebest-fitmodel,andattachedmoreimportancetothevisualanalysis.Acomprehensiveapplicationanalysiswasalsogiventotheselectedmodel.Theresultsshowed:1)GADAoutperformedADAwithrespecttopredictions.2)AGADAmodelderivedfromHossfeldⅣpresentedthebestpredictionability.Itwassuggestedthatthemodelbeusedtopredictdominantheightandtoestimatesiteindexforponderosapinestandsranging30-200yearsinBritishColumbia,Canada.3)Thebestsiteindexagewasageof100years,baseduponrelativeerrorsofpredictions.