The storage and dynamics of carbon were evaluated in a 10-year-old poplar(Populus deltoides Bartr.cv."Lux") plantation in the Lixiahe region,Jiangsu province,China.The total carbon storages of the stand were (136.2±15.9)(mean±standard deviation) t/hm~2.The carbon storages of the trees,understorey plants,A_0 layer and soil were (74.1±8.3),(0.3±0.1),(1.9±0.2) and (59.9±14.2)t/hm~2,respectively.The net primary productivity(NPP) of the trees was (11.1±1.7)t/(hm~2·a),and the annual amount of litterfall was (2.3±0.3)t/(hm~2·a).The annual total carbon dioxide efflux measured in situ with a closed chamber method was (5.5±0.2)t/(hm~2·a).It was suggested that the carbon storage and the NPP in plantations of fast-growing trees such as the I-69 poplar clone were high and could play an important role in determining future concentrations of atmospheric carbon dioxide.