3.2 Factors influencing the effects of GE on soil pH changes
The MAT and MAP had significant influences on soil pH both in grazed and GE grasslands at a large geographic scale (p < 0.001) (Fig. S2a–d). The RPC was significantly negatively related to MAP (r = −0.18, p < 0.001), but had no significant relationship with MAT (p > 0.05) across China’s grasslands (Fig. 5a, b). GE caused significant increases in AB and BB across China’s grasslands (p < 0.01) (Fig. S3a, b). Significant negative relationships were identified between RAC and RBC and RPC (RAC–RPC r = −0.25, p < 0.05; RBC–RPCr = −0.39, p < 0.01) (Fig. 5c, d). GE caused significant increases in SOC and SN concentrations in grassland ecosystems (p < 0.05) (Fig. S3c, d). Both the RCC and RNC were negatively related with RPC (RCC–RPC r = 0.37, p< 0.001; RNC–RPC r = 0.28, p < 0.001) (Fig. 5e, f). In addition, strong negative relationships of RCC–RPC and RNC–RPC were observed in the upper soil layers (p < 0.05) (Fig. S4a), but not in the deeper soil layers (p> 0.05) (Fig. S4b).
Dominant species significantly affected the RPC in grasslands following GE (Table 1). Sedge-dominated grassland had higher pH decrease rates at 0–10 cm soil depth than grass-dominated grassland (p < 0.05), whereas grassland dominated by forbs and shrub species showed the highest decrease in pH at 20–30 cm (−6.39%) (p < 0.05) (Table 1) .