3.3. Comparisons of SWC and isotopes in shrub and grassland sites
Soil water content, variations of δ2H and δ18O of shrub and grassland sites were shown in Figure 4. There was a significant difference in SWC of the same soil layers between shrub and grassland sites (p < 0.05), the SWC of shrub site ranged from 15.13 ± 0.06% to 49.87 ± 0.29%, whereas ranged from 19.25 ± 0.02% to 39.76 ± 0.24% in grassland site during the sampling period (Figure 4a and 4d). However, δ2H in soil water showed no significant difference between the two sites (p >0.05) (Figure 4b and 4e), in contrast to δ18O (p < 0.05) (Figure 4c and 4f). Both δ18O and δ2H in shallow soil water (0–20 cm) were more highly variable than deeper soil layers. The isotopic values in surface soil water were enriched in June and July, depleted in August and September. The δ18O and δ2H values in the grassland soil were enriched than in the shrubs from May to September, but almost the same in October, indicating that grassland is more sensitive to environmental changes, plant water has a stronger partitioning effect in dynamic transport comparing with shrub plant water.