Plant diversity and interspecific associations of different floodplains in the wandering Yellow River

The seasonal flow variation of the Yellow River mainstream and water-sediment regulation by the Xiaolangdi project have formed a special wandering floodplain ecosystem. In order to reveal the community composition, interspecific relationship and community stability of the wandering Yellow River floodplains（Newly-formed floodplain, Second floodplain, Highly-formed floodplain, Levee）, we utilized the typical quadrat method to investigate plants in Zhengzhou Yellow River Wetland Provincial Nature Reserve of the typical wandering Yellow River floodplains from September 2015 to November 2018. We delved into the community species composition, species diversity, interspecific association and community stability based on 149 herb layer quadrats. The results showed that:（1） 445 species were occurred in our four floodplains, belonging to 289 genera and 90 families. Among them, there were 440 species, 286 genera and 87 families of angiosperms, and three species, two genera and two families of gymnosperms, and only one genus and two species of pteridophytes.（2） There were significant differences in dominant species among four floodplains. In general, Cynodon dactylon, Phragmites australis, and Erigeron canadensis were the dominant species. In Newly-formed floodplain and Second floodplain, Glycine soja（Class II protected plant, in China） was subdominant species, which distributed sporadically in patches.（3） The species diversity indices of the Levee were the largest, followed by the Newly-formed floodplain, and those of the Second floodplain and Highly-formed floodplain were smaller.（4） χ~2 test, Jaccard index, Pearson correlation test and Spearman rank correlation test showed that the dominant species pairs were not strongly interspecific linked, and each species was relatively independent.（5） The overall association of Second floodplain showed non-significantly negative association, while that of the rest were significantly negatively associated. Combined with the M. Godron′s stability analysis, the community was in an unstable successional stage. These results indicated that the wandering Yellow River floodplain ecosystem was generally unstable, and the wandering and variable river channel led to the frequent regeneration of floodplain community. This provides important basic data and scientific guidance for national strategies of ecological protection and high-quality development in the Yellow River Basin.