简介：Background:ThiscontributionevaluatestheeffectofforeststructureandtreespeciesdiversityonplotproductivityandindividualtreegrowthintheuniqueKnysnaforestsinSouthernAfricausingmappedtreedatafromanobservationalstudythathasbeenre-measuredoveraperiodof40years.Methods:Theeffectsoftreespeciesdiversityandforeststructureontreegrowthandforestproductionareevaluatedonthreelevelsofresolution:a)theforestcommunity(canopy,sub-canopyspecies),b)thesubplots(numberoftreesperha,skewnessofthediameterdistribution,diametercoefficientofvariation)andc)theimmediateneighborhoodofselectedreferencetrees('Mingling','Dominance',Aggregation'and'SizeVariation').Results:Ananalysisofthecommunitylevelidentifiedtwodistinctclusters,oneincludingdominant/canopyspecieswiththehighestgrowthratesandagreatervariationofgrowth,andanotherclusterwhichincludestheremainingsubcanopyspecieswhichhaveasmallermaximumsizeandlowerratesofgrowth.Thearea-basedstructurevariablesonplotlevelhaveahighlysignificanteffectontotalbasalareagrowth.However,theeffectsofforestdensityandspeciesrichnessonproductivitywerenotstraightforward.Maximumbasalareaproductionofabout0.75m~2/ha/yearisachievedatmediumlevelsofrichness(around20speciesperha)andmediumlevelsofdensity(around30m~2/habasalarea)usingpercentileregressionestimates.Therelative'Dominance'ofaselectedreferencetreehadahighlysignificanteffectonindividualtreegrowthonallinvestigatedspecies.Otherneighbourhoodstructurevariableswereonlyoccasionallysignificantornotsignificantatall.Conclusion:Thiscontributionpresentsanewtheoreticalframeworkforanalysingnaturalforeststhatincludescommunity,plotandneighborhoodvariablesofforeststructureanddiversity,andafirstspecificanalysisofthestructureanddynamicsoftheKnysnaAfromontaneForest,basedonauniquesetoflongtermobservations.Thespecies-area(SAR