Background Riparian plants have the effect of preventing riverbank erosion and collapse, while river development, quarrying and sand dug activities have destroyed the vegetation in the riparian zone, resulting in a decline in plant diversity and changes in soil properties, and the ability of riverbanks to prevent floods is weakened. Therefore, this study tried to explore the differences in species diversity of different plant communities and the differences of their soil anti-scourability, with the purpose of screening out dominant species for vegetation restoration.

Methods Five typical plots of different habitat types (gravel land, flood land, Phragmites australis land, Saccharum arundinaceum land, and bunker land) were selected in the riparian zone of Jinma River and three plots of each type were selected, totaling 15 plots. The name, coverage and other indicators of the herb were recorded for calculating species diversity indices. The undisturbed soil scouring flume method was used to determine the soil erosion resistance. Finally, the correlation analysis of the species diversity indexes and soil erosion resistances were carried out.

Results 1) The riparian zone was rich in herbaceous plants with a total of 39 families, 94 genera and 136 species, mainly Poaceae and Compositae. Shannon-Wiener diversity index H, Simpson dominance index H' and the Pielou uniformity index J_sw changed similarly, the maximum value appeared in gravel land closest to the river, the minimum appeared in P. australis land with the highest terrain. As for species richness index (D), the bunker land was the highest and the S. arundinaceum land was the lowest. 2) With the erosion processing, the sediment yield of runoff in each habitat type decreased continuously, and the soil anti-scourability enhanced continuously. The soil anti-scourability index (I_AS) from the largest to the smallest was P. australis land (24.53 L/g) > flood land (4.10 L/g) > S. arundinaceum land (1.06 L/g) > gravel land (0.31 L/g) > bunker land (0.27 L/g), among which P. australis land, flood land and S. arundinaceum land presented fine soil anti-scour performance. 3) Correlation analysis showed that soil anti-scourability index (I_AS) was negatively correlated with Shannon-Wiener diversity index H, Simpson index H' and Pielou uniformity index J_sw, suggesting that the soil anti-scourability of habitat types with high species diversity was poor.

Conculsions To sum up, bunker land and gravel land have the highest level of species diversity. P. australis land, flood land and S. arundinaceum land have strong anti-scourability. Therefore, as the dominant species of P. australis land, flood land and S. arundinaceum land, plant P. australis, Imperata cylindrica and S. arundinaceum have good effects of water and soil conservation and bank protection. They can be used as a good species choice for vegetation restoration in the riparian zone.