简介：TodateonlyonespeciesofthegenusVaticaLinn.(Dipterocarpaceae)hasbeenidentified,andasubspeciesandthreevarietieshavebeenreportedonHainanIsland,China.However,itremainedcontroversialwhetherthespecieswasVaticamangachapoioranewspeciesVaticahainanensis,andwhetherthesubspeciesorvarietiesaretaxonomicallyvalid.Weevaluatedheremorphometricvariationsof133treescollectedfromninepopulationsandherbariumspecimensofVaticaspp.using16traitsofleafandfruit.Amongthese,leaftraitsvariedmorewithinandamongpopulationsthandidfruittraits.Fourtraitsofratiosweremorestablethandirectly-measuredtraitswithinandamongpopulations.Therangesoflaminalength,laminawidthandheightofmaximumlaminawidthpointwerethegreatestamongthe16traits,whilenumberoflateralveinsvariedleastamongthe12directly-measuredtraits.Measurementsfromall9populationsoverlappedforeachmorphologicaltrait,andvariationofeachtraitwascontinuousamongbothindividualsandpopulations.TherangeofvariationdidnotdistinguishanyspecimenfromV.mangachapoiasdescribedinthefloraofSoutheastAsia.Byclusteranalysis,individualsofeachpopulationaswellasspecimensofeachvarietyformednodistinctclusters.Thepublishedvarietiesthuswerecharacterizedbynodistinguishingvariationsincomparisonwiththeninesampledpopulations.Inconclusion,thenewspeciesV.hainanensisaswellasthesubspeciesandvarietieswerenotsupportedbyourcomparisons,andonlyV.mangachapoiwithoutanysubspeciesorvarietiesoccursonHainanIsland,China.

简介：Background:Thedistributionofforestvegetationwithinurbanenvironmentsiscriticallyimportantasitinfluencesurbanenvironmentalconditionsandtheenergyexchangethroughtheabsorptionofsolarradiationandmodulationofevapotranspiration.Italsoplaysanimportantrolefilteringurbanwatersystemsandreducingstormwaterrunoff.Methods:WeinvestigatethecapacityofALSdatatoindividuallydetect,mapandcharacterizelarge(tallerthan15m)treeswithintheCityofVancouver.LargetreesarecriticalforthefunctionandcharacterofVancouver'surbanforest.WeusedanobJect-basedapproachforindividualtreedetectionandsegmentationtodeterminetreelocations(positionofthestem),todelineatetheshapeofthecrownsandtocategorizethelattereitherasconiferousordeciduous.Results:Resultsindicateadetectionrateof76.6%fortrees>15mwithapositioningerrorof2.11m(stemlocation).ExtractedtreeheightspossessedaRMSEof2.60mandabiasof-1.87m,whereascrowndiameterwasderivedwithaRMSEof3.85mandabiasof-2.06m.Missedtreesareprincipallyaresultofundetectedtreetopsoccurringindense,overlappingcanopieswithmoreaccuratedetectionanddelineationoftreesinopenareas.Conclusion:ByidentifyingkeystructuraltreesacrossVancouver'surbanforests,wecanbetterunderstandtheirroleinprovidingecosystemgoodsandservicesforcityresidents.

简介：TheimpactsofelevatedtemperatureandCO2onyoungsilverbirch(BetulapendulaRoth)saplingsafter0,25,50or75%artificialdefoliationwereassessedbymeasuringplantheightanddrymassofabovegroundcompartmentsandrootsandvariousmorphologicalandphysiologicalvariables.Defoliationeitherincreasedordecreasedplantgrowthdependingontheseverityofdamageandtheclimatictreatment.At21Cand400mgL-1CO2,defoliatedplantswerenotabletocompensateforthelostfoliage,butgrowthcompensationandadaptationtothechangedconditionsweregreater;growthofyoungdefoliatedsilverbirchsaplingsincreased,whichledtoincreasedheightandatendencytoenhancefinalabovegroundandrootbiomassandleafnitrogenandcarboncontentcomparedtothenondefoliatedcontrols.Nevertheless,theshort-termeffectofthedifferentclimaticconditionsdidnotresultinasignificantovergrowthofdefoliatedplants.AslightincreaseintemperatureandCO2werethemostacceptableconditionsfordefoliatedplants;however,a4CincreasewithcorrespondinglyhigherCO2wasmorestressfulasshownbylessgrowthinheightandbiomassallocationtoleaves,stemsandroots.Thefindingsfromthepilotexperimentaremoreapplicabletoyoungbirchtrees,butstressonyoungtreesmaybereflectedinfuturetreegrowth.

简介：Background:Forestmanagementdecisionsarebasedonexpectationsoffuturedevelopments.Forsounddecisionsitisessentialtoaccuratelypredicttheexpectedvaluesinfuturedevelopmentsandtoaccountfortheirinherentuncertainty,forexampletheimpactofclimatechangeonforests.Changingclimaticconditionsaffectforestproduaivityandaltertheriskprofileofforestsandforestenterprises.IntensifyingdroughtstressisseenasonemajorriskfactorthreateningforestmanagementinthenorthGermanlowlands.Droughtstressreducestreegrowthandvitalityandmighteventriggermortality.Butsofar,itisnotpossibletoquantifyeffectsofapersistentdryerclimateonforestproductivityatalevelsuitableforforestmanagement.Methods:Weapplyawell-establishedsingle-treeforestgrowthsimulatortoquantifytheeffectofpersistentdryerclimatesonfutureforestproductivity.WeanalysethegrowthofScotspine(PinussylvestrisL.);Europeanbeech{FagussylvoticoL.)andoak{QuercusroburL.andQuercuspetraeo(Matt.)Liebl.)intwoforestregionsinthenorthGermanlowlandsforatimeintervalof60yearsuntil2070.Thegrowthresponseunderthreedifferentclimateprojectionsiscomparedtoabaselinescenario.Results:Theresultsshowcleardifferencesinvolumeincrementtopersistentdryerclimatesbetweentreespecies.Thefindingsexhibitregionaldifferencesandtemporaltrends.WhilemeanannualincrementatbiologicalrotationageofScotspineandoakpredominantlybenefitsfromtheprojectedclimateconditionsuntil2070,beechmightsufferlossesofupto3m3-ha’-yr1dependingonclimatescenarioandregion.However,intheprojectionperiod2051to2070theuncertaintyrangescomprisepositiveaswellasnegativeclimaticeffectsforallspecies.Conclusions:Theprojectedchangesinforestgrowthserveasquantitativecontributionstoprovidedecisionsupportintheevaluationof,forexample,speciesfuturesitesuitabilityandtimbersupplyassessments.Theanalysiso

简介：在所有森林利用阶段之中，收获作为利用周期的开始的阶段起一个关键作用并且在下列阶段上有重要效果。在这研究，被记录以便关于现在、计划的操作，收获的开始的时间或切的阶段和工作流动检验费用的减小。全部操作的每个阶段的开始的时间也被记录。在收获显著的树前，适当felling方向被决定，正确方向的方位角被拿。结果显示与felling方向相比在在一棵倾斜的树的方向的差别之间没有一种有意义的关系。然而，在差别之间有一种重要关系定义并且在树倾斜和定义方向的felling方向和差别。一样的趋势在树倾斜和felling方向并且树倾斜之间被观察并且定义方向。在另一方面，在树倾斜和felling方向之间没有重要关系并且定义并且树felling方向。另外，这研究证明随树体积的增加，树切的时间升起了。而且，当树倾斜的差别和felling方向减少了时，切树的时间衰退了。回归方程是Y?=?168.9-0.14(树倾斜和felling方向之间的差别)?+?0.7(体积)。

简介：Background:LeafAreaIndex(LAI)isanimportantparameterusedinmonitoringandmodelingofforestecosystems.Theaimofthisstudywastoevaluateperformanceoftheartificialneuralnetwork(ANN)modelstopredicttheLAIbycomparingtheregressionanalysismodelsastheclassicalmethodinthesepureandeven-agedCrimeanpineforeststands.Methods:OnehundredeighttemporarysampleplotswerecollectedfromCrimeanpineforeststandstoestimatestandparameters.EachsampleplotwasimagedwithhemisphericalphotographstodetecttheLAI.ThepartialcorrelationanalysiswasusedtoassesstherelationshipsbetweenthestandLAIvaluesandstandparameters,andthemultivariatelinearregressionanalysiswasusedtopredicttheLAIfromstandparameters.DifferentartificialneuralnetworkmodelscomprisingdifferentnumberofneuronandtransferfunctionsweretrainedandusedtopredicttheLAIofforeststands.Results:ThecorrelationcoefficientsbetweenLAIandstandparameters(standnumberoftrees,basalarea,thequadraticmeandiameter,standdensityandstandage)weresignificantatthelevelof0.01.Thestandage,numberoftrees,siteindex,andbasalareawereindependentparametersinthemostsuccessfulregressionmodelpredictedLAIvaluesusingstandparameters(/?;adj=0.5431).AscorrespondingmethodtopredicttheinteractionsbetweenthestandLAIvaluesandstandparameters,theneuralnetworkarchitecturebasedontheRBF4-19-1withGaussianactivationfunctioninhiddenlayerandtheidentityactivationfunctioninoutputlayerperformedbetterinpredictingLAI(SSE(12.1040),MSE(0.1223),RM5E(0.3497),AIC(0.1040),BIC(-777310)andR2(0.6392))comparedtotheotherstudiedtechniques.Conclusion:TheANNoutperformedthemultivariateregressiontechniquesinpredictingLAIfromstandparameters.TheANNmodels,developedinthisstudy,mayaidinmakingforestmanagementplanninginstudyforeststands.