3.1 Soil total phosphorus concentration
The total P concentration was significantly affected by soil depth and
marsh degradation degree (p < 0.05, Table 4). However,
no significant differences were observed between the interaction effect
of soil depth and marsh degradation degree (p >
0.05, Table 4). As the soil depth increased, soil total P concentration
generally decreased (Figure 3a–d). However, marsh degradation generally
increased soil total P concentrations, and their significant changes in
soil total P concentration were primarily embodied in the shallow soils
at 0–30 cm depth (Figure 3a–d). The total P concentrations of shallow
soils significantly increased by 31.6%–38.5% and 32.9%–44.2% in
LDM and MDM (p < 0.05), respectively, but slightly
increased in HDM compared with RPM (Figure 3a–d).