Divergent forcing of water use efficiency from aridity in two meadows of the Mongolian Plateau

• Coldness and dry air drive contrasting WUE responses to dryness (EF) via GEP changes. Greater impact from than ET on meadow under high soil moisture. T/ET had logarithmic relation with LAI, negative linear dryness. The future climate change predicts higher drought risks in deteriorating the functions services of dryland ecosystems. Interpreting sensitivity ecosystem water use efficiency (WUE) aridity could provide important environmental implications conservation carbon budgets drylands. effects temporal changes semi-arid ecosystems, particularly steppes, have been poorly investigated. In this study, we used eddy-covariance data two representative temperate meadows Mongolian Plateau, Changling (2007-2015, China) Bayan (2014-2018, Mongolia), understand inter- intra-annual by evaporative fraction (EF), as well climatic biotic controls gross production (GEP), evapotranspiration (ET) partitioned evaporation (T) transpiration (E). Results showed that response annual EF was positive atmosphere but insignificant cold climate; WUEs were driven divergent meadows. Monthly increased linearly both meadows, logarithmically leaf area index (LAI). a similar instantaneous (WUEp, GEP/T) insensitive change. We also found frequency growing season precipitation affected at sites. conclude determined variations. magnitude further insights biophysical regulations (i.e., LAI) WUEp. This study indicated differences yield, status sensitivities partitioning jointly contributed steppes region.