鄱阳湖洲滩湿地植物生长和营养繁殖对水淹时长的响应

水淹时长是影响湿地植物分布的重要因素。在水情不断变化的背景下,鄱阳湖洲滩湿地植物种群和群落的变化规律还不清楚。为了探究淹水时长对鄱阳湖洲滩3种优势植物生长和繁殖的影响,并预测在水文发生剧烈变化后,3种优势植物分布的趋势,采用控制实验模拟了不同水淹时长(0、60、90、120、150 d和180 d)下鄱阳湖湿地3种优势植物(灰化薹草(Carex cinerascens)、南荻(Miscanthus lutarioriparius)和虉草(Phalaris arundinacea))的生长和繁殖情况。研究结果表明:1)南荻在水淹超过120 d后,存活率开始降低,水淹到达180 d完全死亡。而灰化薹草和虉草在淹水180 d后仍全部存活。表明南荻耐淹水的能力弱于其他两种植物。2)水淹显著降低灰化薹草的总生物量,并且总生物量随水淹时长的增加而逐渐降低。而短时间(小于150 d)的水淹没有对虉草总生物量产生显著影响。3)退水初期,灰化薹草的恢复生长趋向于地上部分,而虉草表现为地下和地下部分同步生长。该研究结果可以为预测水文情势变化下鄱阳湖湿地植物种群和群落的动态变化提供依据。

The responses of growth and vegetative reproduction of wetland plants in Poyang Lake to duration of submergence

Flooding strongly determines the distribution and abundance of wetland plants, such as like the zonation along a wetland shoreline. However, the mechanism of flooding affecting the distribution of wetland plants is not full understand. In this study, an outdoor experiment was conducted to examine the responses of growth and vegetative reproduction of three dominant species (Carex cinerascens, Miscanthus lutarioriparius and Phalaris arundinacea) in Poyang Lake to duration of submergence, with a goal to link their strategies to submergence to their distribution along the elevation of Poyang Lake. The results showed that 1) after 120 days submergence, the survival rate of M. lutarioriparius began to decrease and all the individuals died after 180 days submergence, whereas all C. cinerascens and P. arundinacea could re-grow after 180 days submergence, 2) Submergence significantly reduced the total biomass of C. cinerascens by the end of the experiment, whereas a short duration of submergence did not significantly affect total biomass of P. arundinacea. 3) After removing the submergence, C. cinerascens tended to allocate more biomass to leaves at the beginning of the re-grow phase, whereas P. arundinacea did not change the allocation among the treatments. Our results could help us understand and predict the population and community changes of wetland plants in Poyang Lake in response to the changing hydrological conditions changing caused by climate change or dams construction.