中文摘要：

不同水位梯度下的典型植被多样性特征研究，对湿地保护与恢复工作的开展具有重要借鉴意义。本研究基于为期３年的水分模拟试验，分析了不同水位梯度下，三江平原典型湿草甸、沼泽化草甸及沼泽群落多样性特征动态变化及响应差别。研究发现，沼泽化草甸群落与沼泽群落的３个多样性指数对不同水位梯度的响应较湿草甸群落明显；３个典型群落的Ｓｈａｎｎｏｎ－Ｗｉｅｎｅｒ指数和物种丰富度总体均表现为随水位梯度的升高而下降的趋势，且每个群落均以物种丰富度的响应最为明显；而群落均匀度指数随水位梯度的升高以及淹水时间的延长，呈升高趋势；植物群落组成及格局在胁迫早期受水分条件影响最大，但最终格局是各环境及生物因子共同作用的结果。

英文摘要：

Studies on vegetation diversity under different water gradients were conducted for wetland conserva tion and restoration. Based on 2005-2007 year simulation test, diversity dynamics of typical wet meadow （Ca lamagrostis angusti folia community）, swamp meadow （ C. angusti folia- Carezc lasiocarpa community） and marsh communities （C. lasiocarpa community） under various water conditions were analyzed in the Sanjiang Plain. The Shannon-Wiener diversity index and species richness of the three communities generally decreased while the Pielou＇s evenness increased with the increasing of water level, and the species richness was found to be the most sensitive index; diversity indexes of swamp meadow and marsh communities were more sensitive to water gradients than that of wet meadow community; the community composition and structure were mostly affected by water stress at the beginning, but they were ultimately determined by various environmental and biological factors together.