湿地植物灰化苔草对淹水的生态响应

研究灰化苔草(Carex cinerascens)对淹水水位及持续时间的生态响应,明确鄱阳湖湿地植物在洪水胁迫下的生存策略。2015年,模拟野外淹水状况,比较了不同水深(未淹水、部分淹水、完全淹水)、不同淹水持续时间(50 d、100 d)条件下灰化苔草的生长、分株及物质分配等的变化情况。总生物量随着水位上升及淹水持续时间延长而下降,水位、淹水时间及两者的交互作用对总生物量均产生极显著影响,淹水会显著降低灰化苔草总生物量,且这种影响随着水位上升及淹水持续时间延长更加明显。淹水显著降低了株高、减少了分株数,退水后分株数因为"秋草"现象有所上升。生物量分配方面,叶、根状茎分配比上升,不定根分配比下降。虽然淹水抑制了灰化苔草的生长,但整个试验期间无植株死亡。灰化苔草通过调整自身生长来适应淹水的胁迫环境。

Response of Carex cinerascens to Waterlogging Stress

Wetland plants are often under periodic or permanent flooding stress because of their habitat. Research has proven that water level fluctuation affects photosynthesis in these plants, resulting in an adaptive strategy that adjusts allocation of plant resources to growth, reproduction and regeneration. In this study, the habitat of a dominant wetland species, Carex cinerascens, found in Poyang Lake wetland was manipulated to investigate the ecological response of C. cinerascens to different water levels and submergence durations. The study focused on resource allocation for growth and ramet development under different conditions. The study aimed to better understand the survival strategy of wetland plants in the Poyang Lake wetland and provide theoretical evidence for wetland resource conservation and vegetation restoration in degraded wetlands. C. cinerascens was cultivated under different water levels (above water control, 30 cm partial submergence, complete submergence) and submergence durations (50d, 100d) in an outdoor water tank from July 5 to October 15, 2015, with six replicates of each treatment. On the last day of each treatment, the plant height and ramet number of the test plants were recorded and the leaves, rhizome and adventitious roots of each plant were dried and weighed. Results show that the total biomass declined with increasing water level and submergence time. Waterlogging significantly reduced the total biomass of C. cinerascens and effect was more pronounced with increasing water level and submergence time. Plant height and ramet number also decreased significantly with increasing water level and duration time, but the ramet number increased during a period of "autumn germination" after emergence. More resource was allocated to leaves and rhizomes and less to adventitious root development upon submergence. The percentage of leaf biomass for C. cinerascens in the 50-day submergence treatment was dramatically higher than that of the control group, but the difference between submergence time treatments was not evident. The percentage of rhizome biomass in 100-day submergence treatment was significantly higher than that of the control group and, at the same water level, the percentage of rhizome biomass increased with submergence time. The biomass of adventitious roots decreased with submergence, but no difference was observed between the two submergence treatments. While submergence inhibited the growth of C. cinerascens, all plants survived. C. cinerascens employs a strategy of resource re-allocation to adapt to flooding and this knowledge increases our understanding of how wetland plants adapt to submergence to help maintain wetland ecology.