【作者】 厉恩华；

【导师】 李伟；

【作者基本信息】 中国科学院研究生院（武汉植物园） ， 植物学， 2006， 博士

【摘要】 湖泊富营养化是当今世界面临的重大环境问题，研究大型水生植物在浅水湖泊生态系统营养循环中的作用，对探讨水生植物对湖泊的净化机制、揭示富营养化湖泊的控制和逆转机理以及湖泊的永续利用具有重要的理论和现实意义。本论文以长江中下游富营养型浅水湖泊为研究对象，通过水生植物群落内的沉积物再悬浮、营养吸收、凋落物的腐烂分解以及营养周转等实验，研究了水生植物在富营养化浅水湖泊营养循环中的作用，主要结果如下：沉水植物群落促进沉积、降低再悬浮、减少磷内源负荷，实验期间（212d），苦草和微齿眼子菜群落内因沉积物再悬浮而送入上覆水的TP分别为334和253mg m^-2，而养殖样地为589 mg m^-2；微齿眼子菜群落比苦草群落能更有效地降低沉积物再悬浮，养殖草食性鱼类，破坏水生植被，显著增加沉积物再悬浮，促进内源营养释放；实验结果表明，维持300 mg m^-2的沉水植物生物量，才能有效降低再悬浮作用。AFDW／TN是影响凋落物分解的重要因素，AFDW／TN低的材料分解快，五种分解材料分解的快慢顺序为：莲叶＞菰叶＞菰茎＞微齿眼子菜＞莲叶柄；凋落物分解残渣占生物量的20％，促进湖泊的淤积和沼泽化进程；凋落物腐烂分解过程中75％和80％的N、P营养能够在年内释放出来。苦草生长快(0.055 d^-1)，对N、P的吸收速率高(136.45，33.51 mg m^-2d^-1)，应是富营养化湖泊生态修复、重建水生植被的重点选择对象。微齿眼子菜生长期长，碳的积累速率高(2.63 g m^-2d^-1)，持有的营养量大，对于从底泥中移出营养具有重要意义。苦草和微齿眼子菜群落中TC、TN、TP的循环系数都在0.7以上，说明其所吸收的大部分营养又归还到环境中，水生植物衰败死亡和腐烂分解过程中释放营养盐是水体营养盐的重要来源，是重要的内源营养负荷。营养盐在各相的分配结果表明，水生植物成为系统中仅次于底泥的营养库；营养周转分析表明，通过残渣积累和沉积作用，湖泊沉积物成为湖泊中营养盐的“汇”。更多还原

【Abstract】 Eutrophication of water bodies is a common problem in the world. Studying the effects of aquatic macrophytes on nutrient cycling in the aquatic ecosystem will have great significance in understanding the mechanisms of macrophytes in purifying the water bodies, revealing the principle of eutrophic lakes control and restoration, and utilizing the lakes resource sustainablely.To research the effects of aquatic macrophytes on the nutrient cycling in the shallow and eutrophic lakes in middle to lower reaches of the Yangtze River, several experiments have been performed, such as the effects of submerged macrophytes on the sediment resuspension, breakdown and nutrient dynamics of macrophytes, macrophytes in nutrients assimilating and turnover in two submerged communities. The main results are as follow:Submersed macrophytes can reduce sediment resuspension and decrease internal P loading. During the study period, total phosphorus of 334, 253 and 589 mg m^-2, were brought back to the water column due to the sediment resuspension in V. denseserulata, P. maackianus communities and in aquiculture stand, respectively. The P. maackianus community was more effective in reducing sediment resuspension than the V. denseserulata. Herbivorous fish could destroy the aquatic vegetation, induce sediment resuspension and promote the internal nutrient loading. The results show that exploiting the resources of aquatic macrophytes must be reasonably, maintaining the biomass at 300 g m^-2 is necessary to control the sediment resuspension effectively.AFDW/TN ratio determined the litters breakdown rate, litters with lower AFDW/TN ratio decayed fast. According to the decay rate the sequence of the five litters is: leaves of N. nucifera > leaves of Z. latifolia > culms of Z. latifolia > P. maackianus > petioles of N. nucifera. 20% of their biomass remained as detritus after decay in a year, which promoted the lake silt and swampiness; 75% and 80% of their initial TN, TP lost in a year, respectively. V. natans grew rapidly （0.055 d-1） and absorbed the N, P nutrients efficiently (136.45 and 33.5 mg m^-2 d^-1, respectively). Therefore, V. natans should be used as a preferred aquatic plant in restoring aquatic vegetation. While the P. maackianus with high carbon accumulation rate (2.63 g m^-2 d^-1) and high biomass was of great significance in transferring nutrition from the sediment.In V. denseserulata and P. maackianus communities, the cycle coefficient of TC, TN and TP were all above 0.7, suggesting that most of the nutrients assimilated in plants would be released back to the environment as the plants senescence and decay. Litters of the macrophytes served as a nutrient "source" rather than a "sink".The study stated sediment was the richest nutrient bank, followed by the macrophytes communities. Through detritus accumulation and sedimentation, the sediment would become the nutrient "sink" in the macrophytes communities.更多还原