Variation in ecosystem water use efficiency along a southwest-to-northeast aridity gradient in China

[Display omitted] •Water use efficiency was greatest for cropland and forests in the drylands of China.•Water use efficiency was directly controlled by precipitation.•Precipitation affected gross ecosystem production more than evapotranspiration. Quantifying ecosystem water use efficiency (WUE), its spatial variation along an aridity gradient, and its control in response to drought are crucial to understanding regional eco-physiological processes of heterogeneous landscapes. This study examined the magnitude, large-scale spatial patterns in WUE, and underlying drivers by examining published data from 31 eddy-covariance (EC) towers and remote sensing based assessments of normalized difference vegetation index (NDVI) along a southwest-to-northeast aridity gradient in China. Average growing-season WUE at the 31 sites was 1.67 ± 0.98 g C kg−1 H2O. Water use efficiencies among vegetation types were significantly higher for cropland and forest, and lower for shrubland and grassland ecosystems (all p-values