洱海常见沉水植物磷含量的种间差异及季节性变化特征

Interspecific and Seasonal Variations of Phosphorus Content in Submersed Macrophytes in Erhai Lake

P是湖泊生态系统中很重要的生命元素,水生植物对于湖泊中P的生物化学循环至关重要.通过分析不同季节下洱海7种常见的沉水植物地上部分w（P）,研究了洱海常见沉水植物地上部分w（P）的种间差异及季节性变化特征.结果表明：洱海沉水植物地上部分w（P）总体呈正态分布,平均值为2.64 mgg,范围为0.90-6.79 mgg.沉水植物地上部分w（P）的种间差异和季节差异显著,其中7种沉水植物地上部分w（P）平均值为苦草（3.32 mgg）〉轮叶黑藻（2.88 mgg）〉金鱼藻（2.72 mgg）〉微齿眼子菜（2.53 mgg）〉穗花狐尾藻（2.39 mgg）〉篦齿眼子菜（2.34 mgg）〉马来眼子菜（2.27 mgg）;季节间表现为春季（3.46mgg）〉夏季（3.05 mgg）〉冬季（2.20 mgg）〉秋季（1.98 mgg）.环境中w（P）、叶与茎生物量比值和生活史特征可能是决定植物地上部分w（P）的重要因素.此外,由于环境中有效P含量较低,洱海沉水植物地上部分w（P）低于长江中下游湖泊.

Phosphorus （P） is an important element in lake ecosystems. Aquatic plants play a key role in the biochemical cycle of P in lakes. The interspecific and seasonal variations in P content of seven common submersed macrophytes in Erhai Lake were investigated. The results indicated that P contents of submersed macrophytes in Erhai Lake fit the normal distribution, with mean value of 2.64 mg/g and range from 0. 90 to 6. 79 mg/g, but were significantly affected by species and season. P contents of VaUisneria natans（ 3. 32 mg/g） was the highest, followed by Hydrilla verticillata （ 2.88 mg/g） , Ceratophyllum demersum （2.72 mg/g） , Potamogeton maackianus （2.53 mg/g） , Myriophyllum spicatum（ 2. 39 mg/g） , P. pectinatus（2. 34 mg/g） and P. malaianus（2. 27 mg/g）. P contents of the plants were highest in spring（3.46 mg/g）, followed by summer （3.05 mg/g） and winter （2. 20 mg/g）, and were lowest in autumn （1.98 mg/g）. Environmental P availability, leaf-stem biomass ratios and life history traits may determine plant P contents. In addition, P contents of submersed macrophytes in Erhai Lake were lower than those in the middle and lower reaches of the Yangtze River, probably due to lower available P contents in the surrounding environment.