Abstract:

Waterlevel fluctuation zone is the critical area which influences ecological services of reservior.Restoration of natural herbaceous vegetation in the gentle slope waterlevel fluctuation zone in the Three Gorges Reservior was investigated by ecological methods.The main plant types in study area were annual herbs and perennial herbs.There were 29 species of herbaceous plants,among which,Alternanthera philoxeroidesMart.)Girseb.,Cynodon dactylonLinn.)Pers.,Xanthium sibiricum Patrin.,Echinochloa crusgalliL.)Beauv,Setaria viridisL.)Beauv.,Bidens bipinnata L.and Digitaria sanguinalisLinn.)Scop.were the dominant.Alternanthera philoxeroides (Mart.) Girseb. and Cynodon dactylonLinn.)Pers. were constructive species.Plant communities in waterlevel fluctuation zone were all patchiness.There were roughly four plant distribution zones,ie,Alternanthera philoxeroidesMart.) Girseb. and Cynodon dactylon(Linn.) Pers zone,Echinochloa crusgalli(L.)Beauv zone,Xanthium sibiricumPatrin.and Digitaria sanguinalis(Linn.) Scop Setaria viridis(L.)Beauv.zone.Annual weeds zone were from 145 m to 175 m altitude. Plant communities in waterlevel fluctuation zone could restore after flooding in the absence of human intervention, but the  community structure tended to be simple and species diversity decreased significantly.Species diversity,the biomass and coverage along with waterleverl zone first increased,then decreased,and showed a singlepeak pattern,ie,the lower part