鄱阳湖湿地中低滩典型植物群落的生物多样性及影响因子

Typical plant communities biodiversity and its environmental drivers in the middle and low floodplains of Lake Poyang wetland

周期性水文节律是影响洪泛湖泊洲滩湿地植物群落物种组成与生物多样性的重要驱动力。本研究以鄱阳湖中低滩典型植物群落为研究对象,通过实地样方调查与统计方法分析植物群落的生物多样性格局及其关键环境因子。结果表明:鄱阳湖中低滩代表性群落分别是灰化薹草群落和虉草群落;植物群落的Shannon-Wiener多样性指数均值为1.5,Pielou均匀度指数均值为0.55,生物多样性与物种均匀度偏低。虉草群落的均匀度、多样性指数高于灰化薹草群落,但二者物种丰富度差异不明显。土壤铵态氮、总磷及土壤含水量和高程是影响植物群落结构与生物多样性的关键因子,其中灰化薹草的物种多样性与土壤铵态氮高度相关,而虉草的均匀度则与土壤总磷关系更密切。此外,鄱阳湖中低滩环境下,灰化薹草群落的均匀度随土壤总磷含量的升高呈现U型响应曲线,虉草则是倒U型,这表明,鄱阳湖中低滩环境下,灰化薹草群落和虉草群落生物多样性对单个、同一的环境因子存在不同的适应机制。

Periodic inundation rhythm is one of the most important driving forces influencing the species composition,structure and biodiversity of floodplain plant communities.In this study,typical plant communities in the middle and low floodplains of Lake Poyang wetland were taken as the research object,and the biodiversity pattern of plant communities and their key environmental factors were investigated based on field surveys and statistical analysis.The results showed that Carex cinerascens and Phalaris arundinacea communities were two representative communities in the middle and low floodplains,which were characterised by relatively low species composition and evenness.The Shannon-Wiener diversity index was 1.5 and the Pielou evenness index was 0.55.The evenness and diversity index of the Phalaris arundinacea community were higher than those of the Carex cinerarius communities,but there was no significant difference in species richness between them.In the floodplain of Lake Poyang,soil ammonium nitrogen,total phosphorus,soil water content and altitude were the main factors influencing plant community structure and biodiversity.The biodiversity of Carex cinerascens communities was highly correlated with soil ammonium,while the evenness of Phalaris arundinacea communities was closely related to soil total phosphorus.In addition,inconsistent trends with key environmental factors were observed from the fitting curves of the plant community diversity index:the evenness of the Carex cinerascens community showed a U-shaped fitting curve with increasing soil total phosphorus content,while that of Phalaris arundinacea was U-shaped;these results indicated that typical plant communities in the floodplains of Lake Poyang also had different adaptation mechanisms to environmental characteristics.