Grazing significantly decreased aboveground biomass by 48.48%–59.44% compared to GE (P<0.05); however, there were no significant differences between grazing methods (Fig. 1a). The belowground biomass tended to decline with increasing soil depth, and the biomass at the 0–10 cm depth was significantly higher than that of the other soil layers in all methods (Fig. 1b). MG and RG significantly reduced the root biomass at each soil layer at a depth of 0–40 cm, and CG significantly reduced the root biomass at 10–30 cm depth (P<0.05, Fig. 1b). Grazing significantly decreased the total root biomass at 0–40 cm soil depth, while MG and RG decreased the total root biomass significantly compared to the reduction caused by CG (P<0.05, Fig. 1b). The root/shoot ratio (R/S) of 0–10 cm was significantly higher than that of 10–40 cm depth in all methods, and the R/S of CG was significantly higher than that of MG and RG (P<0.05, Fig. 1c). Compared with GE, R/S increased by 55.98% in CG and decreased by 52.96% and 37.14% in MG and RG, respectively (Fig. 1c).

FIGURE 1 Aboveground biomass (a), root biomass in 0–40 soil layers (b), and the root/shoot ratio (c). Note: Different capital letters indicate significant differences (P<0.05) between different soil layers for the same method; different lowercase letters indicate significant differences (P<0.05) between the same soil layers for different methods. Values are represented as mean ± SE.

3.2 Variation of soil