Abstract:

Sea level rise and anthropogenic activities significantly affect the hydrological conditions of shallow groundwater in coastal wetlands. It is unclear how seed persistence responds to changes in the hydrological conditions of shallow groundwater. Seeds from four wild-resource plant species, Phragmites australis, Suaeda salsa, Chenopodium glaucum, and Cynanchum chinense, from coastal areas of the Yellow River Delta were selected for the study. Using indoor simulation methods, we investigated differences in seed persistence at two shallow groundwater levels (moist and saturated habitats), four gradients of shallow groundwater salinity, and under dry conditions based on mean germination time, germinability index, and viability index. Overall, mean germination time, seed germinability index, and viability index were consistent in evaluating seed persistence. The response trends of seed persistence of different plants to shallow groundwater level and salinity were different. Seed persistence was stronger in dry and saturated habitats than in moist habitats. Compared with storage in moist habitats, the seed persistence of P. australis, S. salsa, and C. glaucum was significantly stronger in saturated habitats (P<0.05). The effects of shallow groundwater salinity on seed persistence varied with changes in shallow groundwater level. In moist habitats, based on germinability index and viability index, seed persistence of S. salsa, C. glaucum, and C. chinense increased with the increase in shallow groundwater salinity. However, these trends did not exist when the seeds were in saturated habitats. The results will provide a scientific basis for the protection of resources in the degraded wetlands of the Yellow River Delta.

Key words: Yellow River Delta, resource plants, sea level rise, shallow groundwater level, shallow groundwater salinity