简介:Background:Forestmanagementstrategiessuchasthinninghavelongbeenusedtoenhanceecosystemfunctions,especiallyinplantations.Thinninginplantationswithhighdeerdensity,however,maynotyieldadesiredincreaseinunderstoryvegetationbecausedeergrazeongerminatingplantsafterthinning.Here,weexaminethechangesinunderstoryvegetationafterthinninginplantationsthathavebeenovergrazedbysikadeertoprovideinsightintotheeffectsofthinningonecosystemfunctionssuchassoilconservationandbiologicaldiversity.Methods:WeconductedoursurveyintheTanzawaMountainsofeasternJapan.Wesurveyedthechangeinunderstoryvegetationwithinandoutsideofthreedeerexclosuresonasingleslopewiththreelevelsofunderstoryvegetationcover:sparse(1%,exclosure'US'),moderate(30%,exclosure'MM'),anddense(80%,exclosure'LD')over10yearsaftera30%thinningofanold-growthcedarandcypressplantationwhichwasovergrazedbysikadeer.Results:Understoryvegetationcover,biomassandspeciesrichnessincreasedwithinandoutsidethe'US'and'MM'exclosuresafterthinning,andbiomasswasgreaterwithinthanoutsidetheexclosuresat10yearsafterthinning.Unpalatablespeciesdominatedboth'US'and'MM'exclosuresbeforethinning,andtreesandshrubsdominatedwithintheexclosuresovertimeafterthinning.Incontrast,unpalatable,grazing-tolerant,perennial,andannualspeciesincreasedoutsidethe'US'and'MM'exclosures.Nonoticeablechangeswereobservedwithinandoutsidethe'LD'exclosurewhencomparedwiththe'US'and'MM'exclosures.Conclusions:Ourresultssuggestthatthinningastandby30%basedonvolumeresultedinanincreaseinunderstoryvegetationcovermainlycomposedofbothunpalatableandgrazing-tolerantspeciesinaplantationforestwhereunderstoryvegetationissparseormoderateandsikadeerdensityishigh.Weemphasizethatestablishingdeerexclosuresorcontrollingdeerisessentialtomaintainingsimilarunderstoryvegetationbothwit