中文摘要：

植物水分利用效率是表征植物生长状态的一个综合性生理生态指标,对植物水分利用效率的研究有助于揭示变化条件下植物对环境的适应能力。通过在鄱阳湖湿地上布设的3个断面,测定了典型植物样品的稳定碳同位素比δ~（13）C以及断面土壤组成,探究了植物水分利用效率的变化规律。研究结果表明：鄱阳湖湿地植物的δ~（13）C值差异较为明显,变化范围为-14.302‰~-33.134‰,δ~（13）C值的大小可以作为鄱阳湖湿地植物水分利用效率的表征指标;植物类型和土壤水分含量是影响植物水分利用效率的重要因素;鄱阳湖湿地内南荻的δ~（13）C值最大,属C4植物,具有较高的水分利用效率,在水分胁迫条件下更容易生存下来,从而发育为鄱阳湖地区的优势植物种群。研究结论对变化环境下鄱阳湖湿地植被的演变趋势研究具有一定的参考价值。

英文摘要：

Water use efficiency of plants,as a comprehensive physical and ecological indicator to the plant growth condition under varying conditions,is helpful to reveal the plant＇s ability to adapt to environment. The variation law of the water use efficiency of plants is discussed by measuring the stable carbon isotope ratio of typical plant samples and soil composition on three sections in Poyang Lake wetland. The results show that the stable carbon isotope ratio,δ^13C values,of plants in Poyang Lake wetland range widely from- 14. 302 ‰ to- 33. 134 ‰ and can be used as an index to reflect water use efficiency level of plants; plant type and soil moisture content are two important factors affecting plant water use efficiency. Miscanthus sacchariflorus in Poyang Lake wetland,having the highest water use efficiency according to its largest δ^13C value,are most likely to survive and develop into the major plant species under water stress conditions. The results have certain reference value to studying the evolution of vegetation in Poyang Lake wetland under changing environment.