Abstract: This paper studied the ecological character, importance value, aboveground biomass and its N content of salt marsh vegetations in Chongming Dongtan wetland in the process of succession. The results indicated that with the increase of altitude, the importance value of Scirpus mariqueter, a representative species at early succession stage, decreased gradually, while those of Spartina alterniflora and Phragmites australis increased. The biodiversity of the vegetations increased with succession. During growth period (from March to October), the aboveground biomass of the three species varied in single hump curve, with the peak in July and August. The N content had a decreasing trend, while the N capacity showed a single-peak curve. The estimated annual N accumulation in aboveground biomass was 383.4 t for P.australis, 50.5 t for S. mariqueter, and 39.3 t for S. alterniflora.

Key words: Urban forests, Structure, Vegetation quantity, Human disturbance