BIOMASS OF MACROPHYTES OF THE POYANG LAKE WITH SUGGESTIONS OF ITS RATIONAL EXPLOITATION

This paper presents the results of investigations on the macrophytes in Poyang Lake, carried out in 1983—1984. Data on biomass, based on sampling along 22 transects (involving 4 habitat zones, 9 plant associations, and 199 sampling points), are presented, and a comparison is made for the middle and the lower Yangtze Basin. The conditions in relation to the biomass and seasonal changes for the plants of different ecological types have been analysed and discussed.Poyang Lake covers an area of about 2800 km2. It has a peak average biomass of 1542 g/m2 (wet weight)during August-September. The biomass of Potamogeton malaianus, Vallisneria spiralis and Hydrilla verticillata accounts for 71.5% of the total.Annual production of aquatic vegetation in the entire lake area amounts to 4,317,600 metric tons in wet weight or 1.3×1012 kcal. The macrophytes suitable for fish consumption account for 86.9% of the total biomass. The capacity of herbivorous fish production is estimated at 15632 metric tons.Suggestions on rationally exploiting and utilising the resources of macrophytes in the lake, such as stocking phytophagous fish, readjusting the composition of the aquatic vegetation, protecting and planting economic aquatic plants, are presented.