中文摘要：

2005年4-12月逐月对长江口九段沙上沙湿地生态系统主要植物进行定位样品采集与生态环境因子监测。通过对该区典型湿地植物群落海三棱藨草（Scirpus mariqueter）、互花米草（Spartina alterniflora）和芦苇（Phragmites australis）3种植物样品中N、P、K元素含量的分析,揭示了上沙主要类型湿地植物N、P、K元素的分布特征与季节变化规律。结果表明：3种湿地植物N、P、K元素分布特征不同,不同植物以及同一植物的不同构件营养元素含量随植物生长节律发生变化。植物中元素贮量与含量之间分布特征并不相同,其原因主要在于生物量是制约元素贮量的主要因素,N、P、K贮量排序均为芦苇〉互花米草〉海三棱藨草。不同构件营养元素含量的变化规律存在差异：4-5月茎中K含量逐渐减少,N含量呈现增加趋势;5-6月各构件P含量呈减少趋势;6-10月叶中N含量普遍高于其他构件。

英文摘要：

From April to December 2005, the main wetland plant species Scirpus mariqueter, Spartina alterniflora, and Phragmites australis in the upper shoal of Jiuduansha at the estuary of Yangzi River were sampled monthly, and their N, P, and K contents were determined. The resuits showed that the test plant species had different distribution characteristics of N, P, and K.The nutrients contents in different species and in different organs of the same species differed with the rhythm of plant growth. Biomass was the main factor limiting the stocks of the nutrients in different plant species and organs. The N, P, and K stocks decreased in the order of Phragmites australis 〉 Spartina alterniflora 〉 Scirpus mariqueter, and their contents in different plant organs varied with time. In stalk, the K content decreased while the N content increased from April to May; in all kinds of organs, the P content decreased from May to June; and in leaf, the N con-tent was higher thanthat in other organs from June to October.