負密度制約機制課件

植被生態(tài)學結課匯報姓名：高睿專業(yè)：干旱區(qū)植被與生態(tài)學號：2014103059指導老師：劉彤教授植被生態(tài)學結課匯報姓名：高睿Density-dependentmortalityandthelatitudinalgradientinspeciesdiversityJournalTitle：NatureIF：42.351JannekeHilleRisLambers;BrianBeckageBiologyDepartment,DukeUniversityJamesS.ClarkNicholasSchooloftheEnvironmentandEarthSciences物種多樣性的緯向梯度密度制約效應植被生態(tài)學Density-dependentmortalityan

負密度制約機制主要在小尺度上降低群落內同種個體生長率，同時提高個體死亡率，從而為其他物種的生存提供空間和資源，促進物種共存。目前負密度制約假說的檢驗研究主要側重密度制約、距離制約、群落補償效應三個方面。植被生態(tài)學負密度制約機制主要在小尺度上降低群落內同種個

AbstractEcologistshavelongpostulatedthatdensity-dependentmortalitymaintainshightreediversityinthetropics.Ifspeciesexperiencegreatermortalitywhenabundant,thenmorerarespeciescanpersist.Agentsofdensity-dependentmortality(suchashost-specificpredators,andpathogens)maybemoreprevalentorhavestrongereffectsintropicalforests,becausetheyarenotlimitedbyclimaticfactors.Ifso,decreasingdensity-dependentmortalitywithincreasinglatitudecouldpartiallyexplaintheobservedlatitudinalgradientintreediversity.

植被生態(tài)學

AbstractEcologistshavelongThishypothesishasneverbeentestedwithlatitudinaldata.Hereweshowthatseveraltemperatetreespeciesexperiencedensity-dependentmortalitybetweenseeddispersalandseedlingestablishment.

Theproportionofspeciesaffectedisequivalenttothatintropicalforests,failingtosupportthehypothesisthatthismechanismismoreprevalentattropicallatitudes.Wefurthershowthatdensity-dependentmortalityismisinterpretedinpreviousstudies.Ourresultsandevidencefromotherstudiessuggestthatdensity-dependentmortalityisimportantinmanyforests.Thus,unlessthestrengthofdensity-dependentmortalityvarieswithlatitude,thismechanismisnotlikelytoexplainthehighdiversityoftropicalforests.植被生態(tài)學Thishypothesishasneverbeen

ResearchBackgroundWequantifiedseeddispersal,seedbankdensities,seedlingemergenceandseedlingsurvivalat100micrositesdistributedacrossfivetemperateforeststandsover3years.Wethendeterminedwhethertransitionprobabilitiesacrossearlylife-historystageswerelowerathighconspecificseedandseedlingdensitiesorclosetoconspecifictrees,aphenomenonsaidtopromotespeciesdiversity,calledthe“Janzen–Connell”effect.在同種的種子和幼苗密度較高或接近同種的樹木的條件下，是否在早期生活史階段的存活率更低，這種促進物種多樣性現(xiàn)象，被稱為“簡森-康奈爾”效應。植被生態(tài)學

ResearchBackgroundWequantifWetestedtransitionsfromdispersedseedtoseedbank(incorporation),seedbanktogerminatedseedling(germination),germinatedseedlingtoestablishedseedling(establishment),andfirst-yearseedlingtosecond-yearseedling(survival).（種子散布、種子庫密度、出苗率和幼苗存活率）

Wealsodeterminedwhethereffectsofconspecificdensity(seeds,seedlings)ordistance(proximitytoconspecifictrees)onmortalityaregreaterthanareeffectsofotherspecies,arequirementifdensity-dependentmortalityistopromotespeciesdiversity.確定同種密度(種子、種苗)或與母株距離(靠近同種的樹)對死亡率的影響是否大于其他物種的影響，以確定密度制約效應是否能夠促進物種多樣性。植被生態(tài)學WetestedtransitionsfromdisMethodsStudysiteandexperimentaldesignStudieswereperformedinsecondarytemperatedeciduousforestsattheCoweetaHydrologicLaboratory(westernNorthCarolina).Weidentifiedandmappedalltreesmorethan2mtallinfive80×80-mpermanentvegetationplots.(溫帶落葉林)Twentyseedtrapswerelocatedwithineachplot.植被生態(tài)學MethodsStudysiteandexperimeSeedtrapsweremesh-linedbaskets(0.1764m2)suspended1mabovethegroundandcoveredwithwiremeshtodeterseedpredation.Trapswereemptiedfourtimesannually,andseedsidentifiedandcounted.Soilcores(0.0062m2,0.05mdeep)adjacenttoeachtrapwereremovedinautumn1996,1997and1998.InDukeUniversity’sgreenhouses,soilwasspreadoversterilepottingsoil,andseedlings(eachrepresentingaviableseed)werecountedandidentifiedastheyemerged.Inthefield,seedlingswereidentifiedandtaggedinduringsummer1997,1998and1999inquadrats(1.0m2)adjacenttoeachseedtrap.植被生態(tài)學Seedtrapsweremesh-linedbasEstimationandtestingFortransitionsfromlife-historystagek-1tokforspeciesj,weusedthebinomiallikelihoodtoestimatetransitionprobabilities(Pijk)andtotestfordensity-dependentmortalityinTquadrats：Theprobabilityofsurvivalofspeciesjatquadrati,（物種的生存概率）植被生態(tài)學EstimationandtestingFortran截距參量同種影響異種影響P值截距參量同種影響異種影響P值Figure1Theobserved(a)andpredicted(b)relationshipbetweenconspecificseeddensityandseedgerminationforAcerrubrum.a,Eachcirclerepresentsapairedseedtrapandseedlingquadratin1of3years.b,Thebest-fitrelationshipbetweengerminationanddensityofconspecificseeds(seeMethods);dashedlinesare95%bootstrappedconfidenceintervals.Likelihoodratiotestsindicatethatgerminationdecreasesathighconspecificdensities.95%置信區(qū)間Figure1Theobserved(a)andFigure2

Theproportionoftreetaxaexperiencingdensity-dependentmortalityatdifferent

latitudes.Eachbarcorrespondstoananalysistestingacommunityofforesttreesforthe

presenceofdensity-dependentmortality(ouranalysesandpreviousstudies).

Theproportionoftheforestcommunityexperiencingdensity-dependentmortalitydoes

notincreaseattropicallatitudes.植被生態(tài)學Figure2Theproportionoftre植被生態(tài)學植被生態(tài)學ComparisonswithotherstudiesTodeterminewhethermethodologyaccountsfordifferencesamongstudiesintheproportionoftaxaaffectedbydensity-dependentmortality,wecomparedthenumberoftaxaexperiencingdensity-dependentmortalityusinglikelihoodratiotestsandequations1and2(Fig.3a)withthoseobtainedusingfourapproachesinpreviousstudies(Fig.3b–e).因此，雖然密度依賴死亡率的強度（即，效果強度）可能在熱帶森林更高（我們沒有證據(jù)去表明它），密度制約死亡的發(fā)生率（即，受影響物種的數(shù)量）不與緯度相關聯(lián)。植被生態(tài)學ComparisonswithotherstudiesThanksForYourAttention！ThanksFor植被生態(tài)學結課匯報姓名：高睿專業(yè)：干旱區(qū)植被與生態(tài)學號：2014103059指導老師：劉彤教授植被生態(tài)學結課匯報姓名：高睿Density-dependentmortalityandthelatitudinalgradientinspeciesdiversityJournalTitle：NatureIF：42.351JannekeHilleRisLambers;BrianBeckageBiologyDepartment,DukeUniversityJamesS.ClarkNicholasSchooloftheEnvironmentandEarthSciences物種多樣性的緯向梯度密度制約效應植被生態(tài)學Density-dependentmortalityan

負密度制約機制主要在小尺度上降低群落內同種個體生長率，同時提高個體死亡率，從而為其他物種的生存提供空間和資源，促進物種共存。目前負密度制約假說的檢驗研究主要側重密度制約、距離制約、群落補償效應三個方面。植被生態(tài)學負密度制約機制主要在小尺度上降低群落內同種個

AbstractEcologistshavelongpostulatedthatdensity-dependentmortalitymaintainshightreediversityinthetropics.Ifspeciesexperiencegreatermortalitywhenabundant,thenmorerarespeciescanpersist.Agentsofdensity-dependentmortality(suchashost-specificpredators,andpathogens)maybemoreprevalentorhavestrongereffectsintropicalforests,becausetheyarenotlimitedbyclimaticfactors.Ifso,decreasingdensity-dependentmortalitywithincreasinglatitudecouldpartiallyexplaintheobservedlatitudinalgradientintreediversity.

植被生態(tài)學

AbstractEcologistshavelongThishypothesishasneverbeentestedwithlatitudinaldata.Hereweshowthatseveraltemperatetreespeciesexperiencedensity-dependentmortalitybetweenseeddispersalandseedlingestablishment.

Theproportionofspeciesaffectedisequivalenttothatintropicalforests,failingtosupportthehypothesisthatthismechanismismoreprevalentattropicallatitudes.Wefurthershowthatdensity-dependentmortalityismisinterpretedinpreviousstudies.Ourresultsandevidencefromotherstudiessuggestthatdensity-dependentmortalityisimportantinmanyforests.Thus,unlessthestrengthofdensity-dependentmortalityvarieswithlatitude,thismechanismisnotlikelytoexplainthehighdiversityoftropicalforests.植被生態(tài)學Thishypothesishasneverbeen

ResearchBackgroundWequantifiedseeddispersal,seedbankdensities,seedlingemergenceandseedlingsurvivalat100micrositesdistributedacrossfivetemperateforeststandsover3years.Wethendeterminedwhethertransitionprobabilitiesacrossearlylife-historystageswerelowerathighconspecificseedandseedlingdensitiesorclosetoconspecifictrees,aphenomenonsaidtopromotespeciesdiversity,calledthe“Janzen–Connell”effect.在同種的種子和幼苗密度較高或接近同種的樹木的條件下，是否在早期生活史階段的存活率更低，這種促進物種多樣性現(xiàn)象，被稱為“簡森-康奈爾”效應。植被生態(tài)學

ResearchBackgroundWequantifWetestedtransitionsfromdispersedseedtoseedbank(incorporation),seedbanktogerminatedseedling(germination),germinatedseedlingtoestablishedseedling(establishment),andfirst-yearseedlingtosecond-yearseedling(survival).（種子散布、種子庫密度、出苗率和幼苗存活率）

Wealsodeterminedwhethereffectsofconspecificdensity(seeds,seedlings)ordistance(proximitytoconspecifictrees)onmortalityaregreaterthanareeffectsofotherspecies,arequirementifdensity-dependentmortalityistopromotespeciesdiversity.確定同種密度(種子、種苗)或與母株距離(靠近同種的樹)對死亡率的影響是否大于其他物種的影響，以確定密度制約效應是否能夠促進物種多樣性。植被生態(tài)學WetestedtransitionsfromdisMethodsStudysiteandexperimentaldesignStudieswereperformedinsecondarytemperatedeciduousforestsattheCoweetaHydrologicLaboratory(westernNorthCarolina).Weidentifiedandmappedalltreesmorethan2mtallinfive80×80-mpermanentvegetationplots.(溫帶落葉林)Twentyseedtrapswerelocatedwithineachplot.植被生態(tài)學MethodsStudysiteandexperimeSeedtrapsweremesh-linedbaskets(0.1764m2)suspended1mabovethegroundandcoveredwithwiremeshtodeterseedpredation.Trapswereemptiedfourtimesannually,andseedsidentifiedandcounted.Soilcores(0.0062m2,0.05mdeep)adjacenttoeachtrapwereremovedinautumn1996,1997and1998.InDukeUniversity’sgreenhouses,soilwasspreadoversterilepottingsoil,andseedlings(eachrepresentingaviableseed)werecountedandidentifiedastheyemerged.Inthefield,seedlingswereidentifiedandtaggedinduringsummer1997,1998and1999inquadrats(1.0m2)adjacenttoeachseedtrap.植被生態(tài)學Seedtrapsweremesh-linedbasEstimationandtestingFortransitionsfromlife-historystagek-1tokforspeciesj,weusedthebinomiallikelihoodtoestimatetransitionprobabilities(Pijk)andtotestfordensity-dependentmortalityinTquadrats：Theprobabilityofsurvivalofspeciesjatquadrati,（物種的生存概率）植被生態(tài)學EstimationandtestingFortran截距參量同種影響異種影響P值截距參量同種影響異種影響P值Figure1Theobserved(a)andpredicted(b)relationshipbetweenconspecificseeddensityandseedgerminationforAcerrubrum.a,Eachcirclerepresentsapairedseedtrapandseedlingquadratin1of3years.b,Thebest-fitrelationshipbetweengerminationand