PHYTOCOENOLOGICAL STUDIES ON FLOATING-LEAVED ANCHORED AQUATIC PLANTS IN FUTOUHU LAKE, HUBEI PROVINCE──Ⅱ. THE STRUCTURE OF COMM. NYMPHOIDES PELTATA

The structure of Comm. Nymphoides peltata was investigated monthly and for a whole year. The community is composed of 13 plant species which belong to 5 life forms and 11 growth forms. The community shows zonation and patchy distribution, while the distribution of N.Peltata population are contagious, varying from 0.08m2 to 0.64m2. The vertical structure of the community has two layers only: floating-leaved hydrophyte layer and submerged hydrophyte layer. Advanced hydrophyte layer was not observed above the water, nor was an advanced root or rhizome system below the substrate. The population of N. peltata reached peaks in standing crop and in sexual reproduction in late May. Then the population declined and fluctuated around a low level. The replacement of dominant species by another is obviously observed in the community.