Abstract: D. angustifoia is the dominant species in the typical meadow, marsh meadow and marsh communities of Sangjinag plain. Acccording to these, in this paper we researched the dynamic of aboveground biomass and time sequence in D. angustifoia. The result reveals that: the seasonal dynamic of density in marsh was "W" curve; the seasonal dynamic of density in typical meadow and marsh meadow was bimodal curve; the accumulation biomass was monocurve. In whole growing season, dry-matter has been accumulated. The changing law of seasonal dynamic of aboveground biomass has been revealed by time sequence.

Key words: Aboveground biomass increment, Accumulation biomass increment, Time sequence, D. angustifoia population