Recruitment processes link the end of reproductive cycles of adult plant and offspring, and have profound effects on plant community assembly. However, little is known about how adult ecological niche affects recruitment processes, especially seed dispersal and germination. By using a seedling emergence greenhouse experiment, we examined seed distribution patterns across four lakeshore plant communities along an elevational gradient in a Chinese floodplain lake, Poyang lake. Seedling emergence was tested along a soil moisture gradient to test the soil moisture requirements of seed germination. We used the mean elevational distribution of adult plants along the lakeshore as a proxy of adult hydrological niches.
Results/Conclusions
We found that with increasing elevational distribution of adult plants, (1) functional group identity significantly affected seed distribution patterns and responses of seed germination to soil moisture; (2) mean soil moisture of seed germination decreased; (3) inter-community variation of seedling density and percentage of seeds deposited in adult-suitable sites increased, suggesting that seed dispersal distance decreased; (4) plant sprouting date, fruiting date and water level at fruiting period decreased, suggesting decreased importance of water flow to seed dispersal; and (5) seed traits tended to promote dispersal by wind. Because wind speed is relatively low and seasonally-flooding water has high energy in this area, these results indicate that seed dispersal distance would decrease with adult elevational distribution. Taken together, our study demonstrates that the adult hydrological niche can affect seed germination and dispersal via interactions between plant phenology and flooding regime.
Given that human activities and climate change have significantly changed flooding regimes and plant phenology, such changes would affect wetland plant community assembly through affecting recruitment processes of plants with different hydrological niches