洱海三种生活型水生植物叶片中碳、氮与总酚含量的比较研究

植物体内的C、N和总酚是影响其被牧食和凋落物降解的重要因素，从而影响C和N在食物链的传递和生物地化循环。本研究测定了云南洱海3种生活型（挺水、沉水和浮叶）26种水生植物叶片中C、N和总酚含量以及C/N比率，并分析了它们与总酚的关系。结果表明:挺水植物叶片的C、N和总酚平均含量为448.08、39.30和24.70 mg/g，浮叶植物叶片的C、N和总酚平均含量为433.32、35.16和28.05 mg/g，沉水植物叶片的C、N和总酚平均含量为378.36、27.31和10.28 mg/g；总体上看，植物叶片C和N含量:挺水植物 浮叶植物 沉水植物；挺水和浮叶植物叶片的总酚含量差异不显著，且均远高于沉水植物叶片的总酚含量；26种植物叶片中C和N与总酚含量均呈显著正相关。在富营养化条件下，3种生活型植物所处生境的光照和CO2供给均差异显著，会对这些植物叶片的C、N和总酚含量有一定影响，此外由于应对生境中的胁迫（草食性昆虫、病原体及紫外线辐射等）压力以及自身的生长策略的不同也可能导致C、N和酚在三者中形成差异；通过对13种沉水植物叶片总酚含量比较，推测光叶眼子菜和微齿眼子菜较为适合作为洱海耐牧食恢复先锋物种；N与总酚正相关的关系可能在富营养化进程中加速湖泊沼泽化。

CONTENTS OF C,N AND TOTAL PHENOLS IN LEAVES OF AQUATIC MACROPHYTES IN LAKE ERHAI,CHINA

Carbon (C), nitrogen (N) and total phenols (TP) in plants play important roles in palatability for herbivores and litter decomposition of the plant tissues, which impact C and N cascading among food web and biogeochemical recycling in lake ecosystem. In this study, concentrations of C, N and TP were examined in leaves of 26 aquatic macrophytes (emergent, floating-leaved and submersed) collected in Lake Erhai. Results showed that the mean values of leaf C, N and TP concentrations were 448.1, 39.3 and 24.7 mg/g for emergent macrophytes (EM), 433.3, 35.2 and 28.1 mg/g for floating-leaved macrophytes (FM), 378.4, 27.3 and 10.3 mg/g for submersed macrophytes (SM), respectively. Leaf C and N concentrations decreased in the order of EM, FM and SM. EM and FM have similar TP concentration, which were higher than that of SM. The correlation analysis found significant positive correlation between leaf C, N concentrations and leaf TP concentrations for all 26 aquatic macrophytes. Light intensity and CO2 availability for three kinds of macrophytes were significantly different, which might affect leaf C, N and TP concentrations. In addition, external stresses (herbivorous insects, pathogens, UV radiation, etc) and different growth strategies might also explain above findings. These results suggest that Potamogeton maackianus and Potamogeton lucens can be used as pioneer species for the recovery of Lake Erhai. The positive correlation between N and TP in leaves of macrophytes may promote the acceleration of lake paludification in the process of eutrophication.