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INTRODUCTIONInwesternpartofHei1ongiiangprov-ince,scotchpine(Pinussylvestris)iswindbreak,sand-fixationandcommercialforest.It'soneofthemaintreesinthecon-structionof"threeNorth"shelterforest.ThewoodcharacterisexceI1ent.Sothedis-cussionandvaluationonScotchPineproductivityhasimportantmeaningoncommerce,windbreakandsand-fixation.Theanalysisofvolumegrowth,bio-productivityandre1ationshipsbe-tweenvo1umegrowthanddensityandbe-tweenbio-productivityanddensity,gaveevidencetostudyfastgrowingscotchpine… 相似文献
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TheprojectwassupportedbyChinaNaturalScienceFund.INTRoDUCTIoNOursocietyhascomeintoaperiodofhighdevelopedscienceandtechnology,nevertheless,it'sapitythatmankindhasn'tfreedhimselffrompassiveandblindcondi-tionthatforestfirewaspreventedandcon-trolledonlargescale.Particufarly,sofarthebasiclawsofinter-annualchangesofforestfirehasnotbeenknown.Itremainsperplexingwhyheavy-disaster-periodofforestfire(HDPFF)inacertainregionreappearseveryafewyearsandlastsforl-2yearswithgreatlossofforestresource.A1th… 相似文献
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THRESHoLDWhenthetimberswiththeho1eknotsarepassedthesystemofX-raynon-de-structiveinvestigation,thesimulatednu-meralsfigureoftheholeknotsappearinthemonitor.Thesimulatednumeralsfigureisshownintablel.Meanwhilethehistogramofthisfigurearedoublepeakcertainly.Inordertoidentifytheedgeoftheholeknotswithnakedeyeandcarryoutautomatictreatment,Wetakethebinaryva1uetreatmentforthefigure'Thechoos-ingthresholdisaveryimportantpartinthebinaryvaluetreatment.Howtochooseasuitablethreshold?Weshouldpaymuchattenti… 相似文献
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