QUANTITATIVE ANALYSIS ON THE MAIN SUBMERGED COMMUNITIES IN HONGHU LAKE. IV. MYRIOPHYLLUM SPICATUM十POTAMOGETON MAACKIANUS+CERATOPHYLLUM DEMERSUM COMMUNITY

Myriophyllum spicatum+spicatum + Potamogeton maackianus + Ceratophyllum demersum community was an important community type in Honghu Lake, with complicated species comppsition. The changes of the quantitative characters of every species coincided with their life history features as the result of relatively fewer harvesting activities of local fishermen in this community. The dominance alternation of M. spicatum.C. demersum and P. maackianus in different seasons was the most outstanding dynamic feature of the community. Peak biomass of the community, about 940 g dw m-2 occurred in summer. Horizontal structure of the community was fairiy homogeneous, and its vertical structure was closely related with the biomass distribution of the main dominant species in water column. Aggregation was the main spatial distribution pattern. In general no significant association was found for every species pares, although their biomass could show somewhat overiap. The significant association of M spicatum and P. maackinus in summer was the result of restoration of the latter after being selectively used. This result also showed the effect of sampling area.