3.3. Comparisons of SWC and isotopes in shrub and grassland sites
There was a significant difference in SWC between shrub and grassland sites (p < 0.05) (Figure 4a). However, δ2H in soil water showed no significant difference between shrub and grassland sites (p = 0.068>0.05), in contrast to δ18O (p < 0.05) (Figure 4b). Likewise, significant differences in plant water between shrub and grassland sites for δ18O were observed (p < 0.05), but non-significant differences were observed in plant water (p = 0.06>0.05) for δ2H (Figure 3a). Both δ18O and δ2H values in shallow soil water (0–20 cm) were highly variable, and relatively stable in deeper soil layers for both the two sites (Figure 4b). The isotopic values in surface soil water were enriched in June and July, but were depleted in August and September (Figure 4b). The δ18O and δ2H values in the grassland plants were greater than in the shrubs from May to September, but almost the same in October, indicating that grassland plant water has a stronger dynamic fractionation effect in the process of transportation and is more sensitive to environmental conditions comparing with shrub plant water.