氮磷配施对藏北退化高寒草甸群落结构和生产力的影响

fertilizationisaneffectivemanagementmeasureforrecoveryofdegradedgrasslands.tobetterunderstandtheeffectsoffertilizationoncommunitystructureandproductivityoflightlyandseverelydegradedalpinemeadows,weconductedafertilizationexperimentinnortherntibetsince2008.thetreatmentswereadditionofnitrogen(n)alone(50kgn·hm-2·a-1,ln;100kgn·hm-2·a-1,hn)oradditionofbothphosphorus(p)andn(50kgn·hm-2·a-1+50kgp·hm-2·a-1,ln+p;100kgn·hm-2·a-1+50kgp·hm-2·a-1,hn+p)ineachofthetwotypesofdegradedalpinemeadows.nadditionalonesignificantlyaffectedplantcommunityco-verageorproductivityinneithertheslightlynortheseverelydegradedalpinemeadow,whileadditionofbothnandpsignificantlyincreasedplantcommunitycoverage,abovegroundandbelowgroundbiomassofthealpinemeadows.thissuggestedthatproductivityofthisalpinemeadowisco-limitedbynandp.hnandhn+psignificantlydecreasedspeciesrichnessandevennessinthelightlydegradedgrassland,indicatingthathnwasnotbeneficialforthelightlydegradedgrasslandtomaintainspeciesdiversityandcommunitystability.nadditionsignificantlyreducedtheroottoshootratiointheseverelydegradedmeadow.inthelightlydegradedmeadow,nadditionalone,especiallywithahighamount(hn),enhancedtheimportancevalues(iv)andbiomassofgrasses,whilefertilizationwithbothnandpincreasedthoseofsedges.intheseverelydegradedmeadow,fertilizationhadlittleeffectonivofgrassesorsedges,butimprovedbiomassofforbs.theresultssuggestedthatln+pcouldbeemployedinrecoveryoflightlydegradedalpinemeadows,butothermanagementmeasuressuchasfencingandreseedingmaybeneededforrecoveryofseverelydegradedalpinemeadows.