Abstract: We examined plant density, seed production, spatial-temporal dynamics of soil seed bank, and seed dormancy and germination characteristics of Suaeda salsa populations along the gradient of tidal elevations in Chongming Dongtan of the Yangtze River Estuary. Suaeda salsa populations emerged after the control of Spartina alterniflora on the natural tidal flats. The results showed that elevation of tidal flats significantly influenced plant density and seed production of S. salsa. The highest plant density and seed production was observed at elevations ≥ 4.0 m, followed by the 3.8-4.0 m elevation range, and the lowest density and seed production occurred at the 3.6-3.8 m range. No individual of S. salsa was found at the elevations below 3.5 m. After seed maturation and dispersal in autumn, the density of soil seed bank initially increased and then sharply declined as seeds germinated into seedlings under favorable temperature and moisture conditions in spring. Soil seed bank density was significantly correlated with S. salsa population density. Seeds could gradually disperse toward the population front through the tidal and wind-driven forces. The results of seed storage, dormancy and germination experiments showed that seeds of S. salsa matured in the autumn with a non-deep physiological dormancy state, with a germination rate of 14.6%. After a cold stratification treatment in laboratory and storage in the field condition during winter, the germination rate could increase to 68%-82%. After dispersed into soil seed bank and winter vernalization in the field, seeds entered an enforced dormancy. When temperature and moisture conditions became suitable in spring, the seeds could germinate quickly. If the seeds experienced environmental stresses and failed to germinate in spring, they could re-enter into induced dormancy under summer high temperature. Seeds in an induced dormancy state required another process of vernalization to break the induced dormancy and could germinate under suitable conditions. The seeds of S. salsa could survive for many years after entering into the induced dormancy, which belongs to a persistent seed bank.

Key words: Suaeda salsa, salt marsh wetland, seed yield, soil seed bank, seed dormancy, seed germination