Effects of interspecific interactions on seed germination between dominant species in the Yangtze River Estuary

Abstract

Seed germination is the key stage of population recruitment. Competition between native and invasive species can greatly influence the seed germination and the stability of the affected populations and communities, which in turn will affect the stability of native ecosystems. In this paper, we studied the interactions between dominant species in Chongming Dongtan wetland at seed germination stage using a germination experiment. We found that both salinity and interspecific interaction significantly affected the seed germination process of dominant marsh plants, but the effects were not consistent among different species. Generally, germination rate of Scirpus mariqueter was inhibited by high salinity, whereas that of Suaeda glauca was promoted by salt. Almost all the species germinated more slowly in salt water than in fresh water. Invasive Spartina alterniflora seeds significantly promoted the germination rate of Scirpus mariqueter in salt water despite of its heavy competitive effects on this native sedge in the adult stage. Besides, the germination rate of Spartina alterniflora was significantly inhibited by Phragmites australis and Suaeda glauca seeds in salt water, whereas its germination speed was significantly inhibited by Phragmites australis in fresh water. Our study revealed the pattern of interspecific interactions in the early life stages of plants, which may improve our understanding of population and community dynamics and provide some guidance to invasive species control and wetland management.