4.2. Comparisons between P. fruticosa shrub and alpine
grassland
The δ18O in soil water and plant water showed
significant differences between shrub and grassland sites (p <
0.05) in contrast to non-significant differences in
δ2H, resulting in different slopes and intercepts for
the water line equations of soil water and plant water.
Isotope-fractionated differences were probably associated with local
microenvironment and heterogeneity differences of surroundings between
the grassland and shrub sites despite the same general conditions
(Ellsworth&Williams, 2007).
The water line equations between δ18O and
δ2H were established. Soil and plant water samples
were well described by linear regressions, resulting of laying at an
angle to the LMWL, this is consistent with previous studies (Goldsmith
et al., 2012; Che, et al., 2019). Their slopes and intercepts from soil
water at the grassland site were slightly than those at the shrub site,
suggesting soil evaporation was slightly greater at the grassland site
than at the shrub site. This was probably because the shrub site had a
denser coverage shading the soil surface compared with the grassland
site, as daily evaporation rates were slightly lower than grassland
(Crawford et al., 2014; Schwärzel et al., 2020). Nevertheless, the
slopes and intercepts in plant water lines at the grassland site were
higher than the slope and intercept at the shrub site. The differences
resulted from substantial variabilities for plant water at shrub and
grassland sites, evaporative distinctions of2H/1H and18O/17O on the primary of leaf water
(Farquhar et al., 2007) , and the transpiration from an area of
grassland is greater than the transpiration from a similar area of
shrubs.