中文摘要：

芦苇是长江口地区滨海滩涂湿地主要建群种,如何控制白茅扩散、维持原生植被已成为滨海湿地管理亟待解决的生态问题之一.以长江口崇明东滩湿地为研究对象,通过野外调查滨海湿地芦苇（Phragmites australis）和白茅（Imperata cylindrica）种群特征,比较3个不同地下水位（低、中、高水位）条件下芦苇与白茅幼苗和成株生长特征.结果表明：对幼苗而言,地下水位对芦苇单株生长特征影响不显著,地下水位升高会促进芦苇种群密度增加,而显著限制白茅种群密度增加;对成株而言,在单株水平,中水位芦苇株高、基径、叶面积和地上生物量以及相对生长速率显著高于低水位和高水位,并且芦苇相对于白茅的生长优势在中水位条件下最为明显.除株高和基径以外,白茅的其它生长指标在3个地下水位梯度间均无明显差异;在种群水平,芦苇种群植株密度,叶面积指数,叶、茎和地上生物量随着地下水位升高而逐渐升高,在高水位达到最优.与芦苇相反,白茅种群植株密度,叶面积指数,叶、茎和地上生物量随着地下水位升高而逐渐降低,在低水位生长最好.虽然白茅在单株水平上生长不如芦苇,但是凭借其极强的无性繁殖能力在芦苇群落中迅速扩散,与芦苇竞争光照、水分等资源,并且在地下水位较低的条件下白茅种群生长尤为旺盛.因此,在植物幼苗阶段通过人工水位调控适当提高地下水位可以抑制中生性植物白茅的生长,从而有助于恢复东滩湿地以芦苇为单优势种的湿地群落结构和功能.

英文摘要：

Phragmites australis is a constructive species in the tidal wetland in the Yangtze Estuary of China. Imperata cylindrica, a typical perennial mesophyte, is currently spreading wetlands previously dominated by the reed population and changing the structure and function of native ecosystem. Soil ground water table could affect soil physical, chemical and biogeochemical characters, which in turn influence the morphology and growth ofP. australis and L cylindriea. How to control the spread of I. cylindrica and maintain native community becomes one of the key problems for the wetland management. The relationship between the morphology and growth of P. australis and/. cylindrica and ground water table was investigated by using one-way ANOVA and Pearson correlative analysis in order to find how reed and Cogongrass respond to changes of ground water table in coastal wetland at the shoot level and at the population level. The investigation found that the rise of ground water table improved the population density but no otherwise obvious effects P. australis seedlings. The population density of I. cylindrica seedlings decreased with the rise of ground water table. At the shoot level, plant height, stem diameter, leaf area, aboveground biomass and relative growth rates of P. australis were significantly higher at middle water table than at low and high water tables. Besides plant height and base diameter, other morphological and growth traits of L cylindrica showed no significant differences at the three ground water tables. At the population level, the population density, leaf area index, leaf biomass, stem biomass and aboveground biomass of P. australis increased with the ground water table, while those of L cylindrica decreased. Although the growth of 1. cylindrica was worse than P. australis at the shoot level, 1. cylindrica spread rapidly throughout the reed population by strong agamogenesis ability, especially at low ground water table. Therefore a higher wetland ground water table at the early stage of the growing se