## 3 Results
### Identification of Key Environmental Factors  
(1) Screening of the main physical drivers of plant communities  
The two principal axes collectively account for 27.85% of the variation observed in the plant communities (Figure 4). Along the first taxonomic axis, each species showed obvious \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **Cross-Section** & **Biomass (g/m\({}^{2}\))** & **Patrick** & **Shannon-Wiener** & **Pielou** \\ \hline \multirow{8}{*}{Near-water} & S1 & \(268.98\pm 160.26\) & \(9.67\pm 1.53\) & \(1.68\pm 0.24\) & \(0.74\pm 0.06\) \\  & S2 & \(351.02\pm 4.16\) & \(8.67\pm 4.16\) & \(1.19\pm 0.52\) & \(0.56\pm 0.11\) \\  & S3 & \(204.97\pm 68.64\) & \(5.33\pm 1.15\) & \(1.05\pm 0.26\) & \(0.63\pm 0.11\) \\  & Z1 & \(159.11\pm 88.48\) & \(8.03\pm 1.05\) & \(1.47\pm 0.53\) & \(0.64\pm 0.11\) \\  & Z2 & \(257.35\pm 234.69\) & \(6.33\pm 2.52\) & \(0.96\pm 0.13\) & \(0.52\pm 0.09\) \\  & Z3 & \(1202.45\pm 1582.95\) & \(4.51\pm 2.12\) & \(1.06\pm 0.21\) & \(0.75\pm 0.11\) \\  & X1 & \(82.91\pm 41.39\) & \(6.33\pm 1.53\) & \(1.15\pm 0.15\) & \(0.63\pm 0.03\) \\  & X2 & \(252.08\pm 180.52\) & \(4.33\pm 1.53\) & \(1.57\pm 0.53\) & \(0.61\pm 0.19\) \\  & X3 & \(379.99\pm 132.75\) & \(6.03\pm 2.65\) & \(1.67\pm 0.53\) & \(0.62\pm 0.17\) \\  & X4 & \(267.34\pm 256.32\) & \(5.06\pm 3.46\) & \(0.93\pm 0.47\) & \(0.62\pm 0.04\) \\  & X5 & \(263.59\pm 81.5\) & \(6.03\pm 2.14\) & \(1.08\pm 0.26\) & \(0.61\pm 0.06\) \\ \hline \multirow{8}{*}{Far-water} & S1 & \(181.07\pm 120.14\) & \(8.33\pm 1.53\) & \(1.41\pm 0.11\) & \(0.67\pm 0.05\) \\  & S2 & \(165.11\pm 43.09\) & \(5.33\pm 2.31\) & \(1.04\pm 0.41\) & \(0.63\pm 0.14\) \\  & S3 & \(116.33\pm 68.12\) & \(9.03\pm 2.83\) & \(1.41\pm 0.21\) & \(0.66\pm 0.19\) \\  & Z1 & \(82.53\pm 25.21\) & \(5.52\pm 0.71\) & \(1.18\pm 0.08\) & \(0.66\pm 0.05\) \\  & Z2 & \(70.11\pm 17.73\) & \(6.52\pm 2.12\) & \(1.02\pm 0.32\) & \(0.61\pm 0.12\) \\  & Z3 & \(70.91\pm 16.62\) & \(6.13\pm 1.41\) & \(1.12\pm 0.45\) & \(0.62\pm 0.17\) \\  & X1 & \(136.57\pm 142.85\) & \(6.67\pm 3.79\) & \(1.15\pm 0.46\) & \(0.75\pm 0.09\) \\  & X2 & \(159.05\pm 58.83\) & \(5.67\pm 1.53\) & \(1.16\pm 0.36\) & \(0.67\pm 0.1\) \\  & X3 & \(230.63\pm 6.12\) & \(5.02\pm 0.02\) & \(1.21\pm 0.02\) & \(0.75\pm 0.01\) \\  & X4 & \(90.33\pm 16.33\) & \(7.67\pm 3.79\) & \(1.33\pm 0.34\) & \(0.68\pm 0.05\) \\  & X5 & \(146.68\pm 92.08\) & \(5.02\pm 1.03\) & \(0.81\pm 0.18\) & \(0.51\pm 0.17\) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The diversity index and biomass in the different lateral area (0 m distance from water, 15 m distance from water). selectivity for soil factors. Axis 1 represents the soil texture of the floodplain of the river, with most communities distributed in the first two quadrants. This observation suggests that there is a high correlation between each plant community and soil moisture content, soil texture, and water flow rate. Most soil chemical properties showed different levels between the two habitats (Figure 5). The first five communities are longitudinally distributed, with communities _VI_ to _VIII_ representing the plants in near-water area. Communities \(X\) to _XII_ represent plant communities located at the far-water area. In the longitudinal distribution, communities _IV_ exhibit stronger correlations with soil texture (Figure 5). Communities \(I\), _II_, and _III_ display weaker correlations with physical environmental factors when contrasted with communities _IV_. This could be attributed to the presence of plants within community _IV_, which possesses strong selective properties. In the lateral distribution, community _VI_ in the near-water area shows a positive correlation with BD (Figure 5). There was no strong correlation between the plant communities between the far-water area and the physical factors. (2) Screening of the main chemical drivers of each plant community  
The two principal axes collectively account for 24.27% of the variation observed in the plant communities (Figure 6).