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研究了珠海淇澳和广州南沙3种湿地植物互花米草、芦苇和短叶茳芏的碳、氮含量及其稳定同位素的组成,结果表明外来入侵的C4植物互花米草在植物体的C含量、C/N值、底泥的δ13C值(-23.83％)和δ15N值(6.56％)均显著与本地植物芦苇和短叶茳芏的不同,外来入侵种互花米草对土壤微生物的影响依赖于其密集的根系,使其入侵的潮间带土壤微生物种类、酶活性显著升高,体现出互花米草对湿地系统中C、N循环的深刻影响,为此有必要控制该外来入侵植物的蔓延生长.所测定的芦苇和短叶茳芏的δ”C值,表明采样地的芦苇属于C3植物,而短叶茳芏则为C4植物.本研究为进一步探讨这3种湿地植物-土壤系统中的C、N循环提供了基础资料.“,”Carbon and nitrogen content,and stable isotope composition in Spartina alterniflora,Phragmites australis,and Cyperus malaccensis were measured within three wetland system.The results showed that there were significant differences between the invasive species S.alterniflora,a C4 plant and native species of P.australis,and C.malaccensis based on the indexes of carbon content,C/N value,and the δ13 C value (-23.83％) and δ15 N value (6.56％) in sediment.The impact of the alien species S.alterniflora on the sediment microbes relying on increase in rhizomatic density,significantly enhancing the species diversity and enzymatic activity of the tidal zone sediment microbes,which clearly demonstrated the impact S.alterniflora can have on the carbon and nitrogen cycles within the wetland ecosystem.Results suggest countermeasures should be taken to control the expanding growth of the invasive species.Based on the δ13C values of P.australis,and C.malaccensis determined in this study,the P.australis growing at Pearl River estuary is a C3 plant,meanwhile C.malaccensis is a C4 plant.The results provide basic data for further studying on the carbon and nitrogen cycles of these three wetland plants/soil system.