effectofforestfragmentsizeontreediversityandpopulationstructureofhumidsubtropicalforestofmeghalaya,india

？thepresentstudywasconductedinsubtropicalhumidforestsofmeghalayatostudythedistributionalpatternofspecies,floristiccomposition,communitystructureandtreepopulationstructure.forestfragmentsofvaryingsizes(0.5ha,1ha,2haand5ha)wereusedinthestudy.alloftheforestfragmentsaredistributedwithinthesamealtitudinalrange,andhadsimilarrainfallandtemperatureregimes.fourforestfragmentsweresampledusingrandomquadratstoanalyzetheimpactoffragmentsizeontreediversityandpopulationstructure.indiceswereusedtocomparethedispersionpatternofplantspecies,speciesdiversityamongfragments,andtheheterogeneityandhomogeneityofthefragments.atotalof45treespecieswererecordedfromallthefragmentsandsimplecorrelationshowedthatthespeciesrichnesswaspositivelyrelatedtofragmentsize(n=4,p<0.05).othermeasuressuchasstanddensity,basalcover,diversityanddominanceindiceswereunrelatedtofragmentsize.forestcanopywascomposedmainlyofcastonopsisindica,c.armata,schimakhasianaandengelhardtiaspicatainallofthefragments.amajorityofwoodytreespecieswerecontagiouslydistributedwhichmadetheforestcommunityhighlypatchyinnature.lowvaluesofsorensen’ssimilarityindexandhighvaluesofwhittaker’sβ-diversityindexbetweenthefragmentssuggestmarkeddifferenceinthespeciescompositionamongthefragments.themaximumstanddensity,basalarea,shannondiversityindexandsimpsondominanceindexwasrecordedina5-hafragment.treesinlowergirthclasses(15–55cmcircumferenceatbreastheight,cbh)accountedfor52–86%ofstanddensityinallfragmentsexceptin0.5-hafragmentswheremiddlegirthclass(55–95cmcbh)accountedfor47%ofthetotalstanddensity.theoveralldensityofseedlings,saplingsandadulttreesformedapyramidalstructure,indicatingthattheperiodbetweenthesaplingandadultstagewasacriticalstageintreelifecycles,asthemaximummortalityoccurredduringthisperiod.thesegrovesaremildly/highlydisturbedbycommunitiesusingforestsfortheirtimberandfuelwoodrequirementsaswellascattleandgoatgrazing.treeregenerationwasapparentlynotlimited,aswasevidencedbyhighdensityofsaplings.thesehumanactivitiesmayhavebeenresponsibleforadecreaseintreediversityinthesmallerfragments.largefragmentsthatwerelessdisturbedharboredspeciesnotpresentinsmallfragments.