Exotic vs. native plant dominance over 20 years of old-field succession on set-aside farmland in Argentina

TOGNETTI, P; CHANETON, EJ; OMACINI M; TREBINO, H; LEON,RJC

BIOLOGICAL CONSERVATION

ELSEVIER SCI LTD

Año: 2010 vol. 143 p. 2494 - 2503

0006-3207

Exoticplantsaremajorconstituentsofspeciespoolsinmodernlandscapes.Managingsuccessionforres-24 torationofdegradedecosystemsthusrequiresanunderstandingofnoveltrajectoriesunfoldinginmixed,25 native/exoticplantassemblages.Weexaminedtrendsinnativeandexoticspeciesabundanceover26 20yearsofold-fieldsuccessiononset-asidefarmlandintheInlandPampa,Argentina.Changesinplant27 coverandspeciesrichnesswereannuallymonitoredonadjacentpermanentplotsestablishedindifferent28 years(1978–1989).Bothnativeandexoticspeciesoccurredinearly,midandlatesuccessionalstages,29 exhibitingsimilarlife-formreplacementpatterns,fromannualforbs,throughannualtoperennial30 grasses.Exoticplantrichnessdeclinedwithplotage.Yet,fourexoticgrassesremaineddominantthrough31 succession(50–70%cover),withplotsinitiatedinlateryearsshowingincreasedexoticcover.While32 nativeperennialgrassesoccurredfromtheonsetofsuccession,increasingfrom5to12spp/plot,they33 onlyshowedtransientpeaksbelow30%cover.Clusteranalysisof113plot-yearsamplesidentifiedalter-34 nativecommunitystatesforearly,midandlatesuccessionalstages,whichwereconnectedbyacomplex35 networkofinterweavingdynamicpathways.Dependingontheplot,vegetationdynamicscomprised36 directionaltemporaltrajectoriesaswellasnondirectionalpathways,andarrestedcommunitystates37 dominatedbyexoticgrasses.Ourresultsillustratetheoverwhelmingroleofexoticspeciesinmodern38 old-fieldsuccession,andtheirpotentialtohinderrecoveryofnativecommunitiesonformeragricultural39 land.Communitystateswithnovel,native/exoticplantmixturescouldbemanagedtodeliverspecific40 ecosystemservices(e.g.forageproduction,carbonsequestration).However,meetingconservationgoals41 mayrequireactiverestorationmeasures,includingexoticplantremovalsandnativegrassseeding.