特大洪水对鄱阳湖水生植物三个优势种的影响

THE EFFECT OF CATASTROPHIC FLOOD ON BIOMASS AND DENSITY OF THREE DOMINANT AQUATIC PLANT SPECIES IN THE POYANG LAKE

１９９８年７月─８月长江爆发了全流域性的特大洪水。作者选择通江湖泊鄱阳湖水生植物优势种竹叶眼子菜、苦草和苦草为材料，比较分析了这３个种在特大洪水前后生物量和密度的变化。结果表明：１）水生植物的生物量和密度在特大洪水前后发生了显著性变化（ｐ＜０．０１）；２）受特大洪水影响，水生植物地上部分比地下部分变动幅度大。尤其是竹叶眼子菜和苦草在洪水过后，地上部分全部死亡，地下部分生物量和无性繁殖体的数量也大为减少；３）特大洪水影响水生植物的更新和恢复，同时导致湖泊初级生产力下降。

A whole basin catastrophic flood occurred in the Changjiang River during July-August, 1998. To obtain insight into the effect of the flood on aquatic plants, the biomass and density of three dominant species, i.e., Potamogeton malaianus, Miq, Vallsineria spiralis Linn and Carex spp, in Poyang Lake were analyzed. At the corresponding period of time before and after the flood, biomass and density of aquatic plants changed significantly (p < 0.01). It was suggested that the flood was the main reason for the changes. The effect of the flood on aboveground part of aquatic plants was more serious than on the underground part, and the most serious effect was on submerged plants. Aboveground part of submerged plants died, only few subterranous stems (vegetative propagules) of them remained alive after the flood, 3) the flood influenced the recovery of aquatic plants in 1999, and would lead to lower primary production of the lake.