非生物因子对东方香蒲种群有性更新的影响

Effects of multiple abiotic factors on sexual recruitment of Typha orientalis population in the riparian zone of Three Gorges Reservoir

消落带的淹水时机、持续时间与频次对其生态条件、湿地植物更新与生物多样性等有着极大的影响。为解析三峡库区消落带东方香蒲(Typha orientalis)有性更新过程中的多种非生物因子的调节作用,本文基于三峡库区水文的时空变化特点,研究了淹水、温度、光和萌发基质等多种非生物因子对东方香蒲种子萌发和幼苗存活的影响。结果表明:东方香蒲种子是需光性的,且对萌发温度和基质有明显的偏好性;在湖水中,随着入水深度的增加,种子萌发率降低;当入水深度达2 m时,种子萌发率下降至4.5%;模拟淹水试验中,东方香蒲幼苗在全淹56 d后仅有21%的存活率,当淹水时间超过60 d后则存活率为零,而在非淹水和半淹水条件下幼苗却生长良好;据此认为,严重的淹水胁迫是东方香蒲种子难以萌发及幼苗死亡的直接原因;当光、温度和萌发基质等都适宜时,种子才能顺利萌发。综合而言,东方香蒲种群的有性更新受阻是三峡库区消落带水位变化主导下的多种非生物因子共同驱动的。

The timing,duration and frequency of inundation greatly affect ecological conditions,wetland plant regeneration and biodiversity in the water-level-fluctuating zone.Based on the spatiotemporal variation of hydrology in the water-level-fluctuating zone of the Three Gorges Reservoir,we analyzed the effects of multiple abiotic factors such as inundation,temperature,light,and germination substrate on the population sexual recruitment of Typha orientalis to reveal the effects of abiotic factors on sexual recruitment.The results showed that freshly-collected ripe seeds of T.orientalisis were light-required,with obvious preference for temperature and substrate.In the lake water,seed germination rate decreased with increasing water depth.When water depth was 2 m,germination rate decreased to 4.5%.In the simulated flooding trail,seedling survival rates were 21%and zero after 56 and 60 days in full flooding,respectively.However,the seedlings grew well under non-flooded and semi-flooded conditions.It is concluded that severe flooding stress is the direct cause of germination inhibition and seedling death of Typha orientalis.The seeds would germinate well under appropriate combination of light,temperature and germination substrate.The failure of sexual regeneration of T.orientalisis population is driven by a variety of abiotic factors in the water-level fluctuating zone of the Three Gorges Reservoir.