洱海常见沉水植物磷含量的种间差异及季节性变化特征

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.

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

Abstract: 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 Vallisneria 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.