鄱阳湖湿地洲滩植物梯度变化

Changes in floodplain vegetation in Poyang Lake wetlands

湿地洲滩植物物种多样性及生物量是反映湿地生态系统状态的重要指标,也是揭示水位变化下湿地生态系统响应机理的重要途径。基于鄱阳湖湿地野外调查和实验分析数据,利用α和β物种多样性指数,初步探讨了鄱阳湖湿地洲滩植物物种多样性及地上部分生物量的空间分布特征及其差异性。结果表明,鄱阳湖湿地洲滩植物物种多样性随高程变化的差异性显著(P<0.001),蚌湖和泗洲头在高程14-15 m的指数较大,表明这一高程范围内与其他高程范围内的物种更替比较显著,而战备湖和北深湖在高程15-16 m的指数较大,表明这一高程范围内与其他高程范围内的物种更替比较显著,而常湖池的指数变化不明显,表明常湖池各高程范围内的物种更替较小。鄱阳湖湿地洲滩植物年地上生物量的空间差异性较为复杂,与湿地高程呈现单峰曲线关系,即随湿地高程增加而增加,到达一个峰值后开始减少。同一高程范围内下,洲滩前缘与碟形湖泊的物种多样性与地上生物量差异显著(P<0.05),前者最高值在高程13-15 m,后者最高值在高程14-17 m。

The biodiversity and biomass of floodplain vegetation are important indexes to explain the ecosystem of wetlands and key methods to probe the response mechanism to water level change. Poyang Lake is the largest fresh-water lake in China and one of the most important wetlands globally. In a field survey, 3 s technology and DEM data were used to analyze the variation in plant species diversity and biomass along the elevational gradient in Poyang Lake wetlands with α and β biodiversity indexes. The results showed that there was a complex gradient of both biodiversity and biomass characteristics for the floodplain vegetation(P <0.001). The index of biodiversity is highest at 14-15 m in Banghu Lake and Sizhoutou floodplain;the index of biodiversity is the highest at 15-16 m in Zhanbeihu Lake and Beishenhu Lake floodplain, but the index of biodiversity is not obvious in Changhuchi Lake floodplain. The correlation between biodiversity/biomass and elevation was nonlinear, and with increasing elevation, the biomass initially increased to a peak value and then decreased. The maximum volume of biomass measured in the fronted floodplain and the shallow lakes were different(P <0.05);the maximum volume of biomass was located at an elevation of 14-15 m in fronted marshland, and at an elevation of 15-16 m in the shallow lakes.