Abstract
Understanding the characteristics of long-term changes in the water use
efficiency (WUE) of grassland ecosystems is vital for WUE improvement on
the Qinghai-Tibet Plateau. In this study, five vegetation types, namely
alpine shrub, desert, grassland, meadow, and swamp, were evaluated. The
changes in WUE over the past 16 years were calculated using the total
primary productivity and latent heat flux data of the ecosystem from
2006 to 2021. In addition, meteorological data were used to further
explore the relationship between WUE and environmental factors. The WUE
of alpine desert, meadow, and swamp showed an increasing trend. In
contrast, alpine shrub and grassland WUE showed a decreasing trend, with
the WUE of shrub being significantly higher than that of grassland on
the interannual scale. The WUE of all vegetation types showed seasonal
maximum and minimum values in July and January, respectively, and the
WUE of shrubs was significantly higher than that of the other vegetation
types. The structural equation model showed that precipitation,
temperature, and relative humidity were the main positive influences on
the WUE of grasslands on the Qinghai-Tibet Plateau, whereas net
radiation had a negative influence. Climate factors may substantially
impact future changes in the WUE of various ecosystems. The results of
this study provide a theoretical basis for further study of WUE changes
in the grasslands of the Qinghai-Tibet Plateau.