简介：Background:Oneofthemostimportantdriversofforestbiodiversityisconspecificnegativedensitydependence(CNDD),areductioninperformancewhenconspecificdensitiesarehigh.WhilethemajorityofCNDDresearchhasfocusedontropicalforests,evidenceismountingthatCNDDmayalsoplayanimportantroleintemperateforests.Tofurtherexplorethepotentialreachofthisphenomenon,weinvestigatedCNDDinAmericanbeech(Fagusgrandifolia)inamaturemid-Atlanticforest.Methods:Weusedbivariatepointpatternanalysestoexaminespatialrelationshipsbetweenlargebeechtreesandconspecificsaplings,andwealsocontrastedthesepatternswithcomparablepatternsforheterospecifics.Inaddition,toaddressthepossibilityofdispersallimitationandtheassociatedeffectsonspatialpatterns,weanalyzedseedlingdensityasafunctionofadultconspecificabundance.Results:Wefoundthatbeechsaplingsweremorerepeledfromlargeconspecificsthanlargeheterospecifics,despitethefactthatbeechseedlingdensitywaspositivelycorrelatedwithbeechbasalarea.However,saplingsofothercanopytreespecieswerealsorepeledfromadultbeechtrees,suggestingageneralsuppressiveeffect.Nonetheless,thediscrepancybetweenbeechseedlingandsaplingdensitiesbeneathadultconspecificssuggeststhatbeechseedlingsurvivalrateswerereducedinvicinityofconspecificadults.Conclusions:Regardlessoftheextenttowhichbeechinhibitsheterospecifictrees,anegativeeffectonconspecificrecruitsmaybecriticalforbiodiversitymaintenance.Withoutthisconspecificsuppression,adenselayerofshade-tolerantbeechsaplingscouldformbeneathadultbeechtrees.Ifthisweretooccur,beechwouldhaveasubstantialhead-startfolowingcanopydisturbance,andthislate-successionalspeciescouldpotentialydominateastandinperpetuity,throughrepeateddisturbancecycles.

简介：Thisstudywasonsuperiorityofthenon-negativematrixfactorization（NMF）algorithmforapplicationofinformationextractedwithaerialimages.First,NMFwasusedforaerialimageinformationextraction,andthenthisdatawascomparedwithaprincipalcomponentanalysis（PCA）inwhichr（thenumberofrowsorcolumnsofbasicmatrix）andEignum（thenumberofeigenvalues）weregivendifferentvalues.ExperimentalresultsshowedthattheruntimeofNMFwithr=20or50waslessthanthatofPCAwithanEignum=20or50.Also,therecognitionrateofNMFwithr=50washigherthanthatofanEignum=50.Theexperimentshowedthatnonnegativematrixfactorizationhadadvantagesofashorttimeperiodwithahighrecognitionrate.

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