<b>Water challenges in arid planted shrublands: precipitation non-responsiveness and high evapotranspiration potential</b>

Integrating a field precipitation manipulation experiment on <i>Tamarix spp.</i> in arid Northwest China with a global spatial data synthesis, this study investigated evapotranspiration (ET) patterns and hydrological responses in non-zonal large-statured planted shrublands. The field experiment revealed <i>Tamarix</i> transpiration was unresponsive to precipitation, with stand-scale ET primarily driven by bare soil evaporation. Spatial data showed severely water-stressed planted shrublands' ET approximated precipitation, while riparian ET decoupled and increased with potential evapotranspiration (PET). ET was broadly influenced by water availability and atmospheric evaporative demand. Crucially, water-limited planted shrublands exhibited weak responses to precipitation and PET, fundamentally reflecting water availability constraints. The strong influence of LAI on ET, coupled with high GEP-ET slopes, indicated a significant water cost for productivity. These findings challenge the scientific validity of pursuing functions beyond aeolian hazard control for planted shrublands in arid regions, underscoring the critical need for afforestation practices to align with regional water resource constraints.