## 3 Results and Discussion
### Bacterial Distribution and Composition  
The PCA was conducted and the first two axes explained 90.3% of the sample variation (Figure 3). Thereinto, a variance of 81.8% was attributed to principal component 1, and principal component 2 captured 8.5% of the variance. The samples, from the constructed or the natural wetland, and from the invaded area or the normal wetland habitats, were mostly decentralized and distributed, and showed no obvious aggregation. As a whole, this indicated that the factors of invaded/normal wetland habitats and constructed/natural wetlands might not cause notable changes to the sediment microflora. The composition pattern of the bacterial phyla was analyzed and the cluster analysis of the four wetlands that differentiated between invaded and normal habitats was implemented (Figure 4). Cluster analysis showed that the invaded areas were gathered first, and then clustered with NLE, which followed by NL, XRCW, and XR, accordingly. The finding suggested that the alligator weed invasion was a dominant factor that affected the bacterial phyla composition, while the effect of wetland types was not obvious, due to the scattered cluster between natural and constructed wetlands. \begin{table}
\begin{tabular}{l c c c c c c c c} \hline \hline
**Parameters (0-15 cm)** & **LFOC** & **LFON** & **HPOC** & **HFON** & **SLOPC** & **SLOPON** & **SLOPON** & **SLOPON** \\ \hline Constructed wetlands & 0.791 \(\pm\) 0.32 & 0.043 \(\pm\) 0.022 & 14.20 \(\pm\) 6.23 & 0.313 \(\pm\) 0.24 & 0.168 \(\pm\) 0.07 & 0.010 \(\pm\) 0.008 & 3.068 \(\pm\) 1.18 & 0.064 \(\pm\) 0.056 \\ Natural wetlands & 0.500 \(\pm\) 0.21 & 0.022 \(\pm\) 0.011 & 14.20 \(\pm\) 5.59 & 0.175 \(\pm\) 0.14 & 0.153 \(\pm\) 0.07 & 0.007 \(\pm\) 0.004 & 3.913 \(\pm\) 1.23 & 0.044 \(\pm\) 0.055 \\ \(p\) values & 0.012 & 0.004 & 0.912 & 0.146 & 0.633 & 0.255 & 0.138 & 0.431 \\ Invaded habitats & 0.885 \(\pm\) 0.29 & 0.056 \(\pm\) 0.019 & 17.40 \(\pm\) 5.31 & 0.464 \(\pm\) 0.26 & 0.174 \(\pm\) 0.08 & 0.012 \(\pm\) 0.011 & 3.610 \(\pm\) 1.24 & 0.087 \(\pm\) 0.006 \\ Normal habitats & 0.620 \(\pm\) 0.29 & 0.027 \(\pm\) 0.105 & 12.31 \(\pm\) 5.598 & 0.186 \(\pm\) 0.18 & 0.159 \(\pm\) 0.00 & 0.007 \(\pm\) 0.003 & 3.053 \(\pm\) 1.21 & 0.024 \(\pm\) 0.046 \\ \(p\) values & 0.027 & 0.000 & 0.019 & 0.014 & 0.585 & 0.152 & 0.249 & 0.046 \\ \hline Parameters (15-25 cm) & LFOC & LFON & HPOC & HPON & SLOPC & SLOPON & SHOPC & SHOON \\ \hline Constructed wetlands & 0.572 \(\pm\) 0.45 & 0.026 \(\pm\) 0.018 & 15.27 \(\pm\) 6.36 & 0.295 \(\pm\) 0.18 & & & \\ Natural wetlands & 0.245 \(\pm\) 0.19 & 0.006 \(\pm\) 0.002 & 12.11 \(\pm\) 4.01 & 0.180 \(\pm\) 0.15 & & & \\ \(p\) values & 0.137 & **0.042** & 0.23 & 0.169 & & & \\ Invaded habitats & 0.688 \(\pm\) 0.58 & 0.030 \(\pm\) 0.02 & 16.29 \(\pm\) 6.91 & 0.328 \(\pm\) 0.15 & & & \\ Normal habitats & 0.390 \(\pm\) 0.26 & 0.017 \(\pm\) 0.01 & 13.42 \(\pm\) 5.23 & 0.223 \(\pm\) 0.18 & & & \\ \(p\) values & 0.082 & 0.079 & 0.214 & 0.202 & & & \\ \hline \hline \end{tabular}  
* It showed the significant and extremely significant difference, when \(p\) values were less than 0.05 and 0.01, respectively (in bold). \(\mathrm{S}_{\mathrm{LFOC}}\) means the storage of LFOC.  
\end{table} 
Table 2: The average concentrations (g\(\cdot\)kg\({}^{-1}\)) and storage (kg\(\cdot\)m\({}^{-2}\)) of C and N fractions (mean values \(\pm\) standard deviation) and the two-way ANOVA (constructed/natural wetlands and invaded/normal habitats) for each depths. Figure 3: Principal component analysis (PCA) based on the sampling sites and bacterial phyla composition. Specifically, Proteobacteria (55.94%), Bacteroidetes (5.74%), Acidobacteria (6.66%), and Chloroflexi (4.67%) were the dominant bacterial phyla in the studied areas. Among the dominant phyla, Firmicutes was significantly higher in the constructed wetlands (2.01%) than in the natural wetlands (1.43%; adjusted \(p\) value of 0.044), while distribution of Gemmatimonadetes was the opposite (adjusted \(p\) value of 0.026).