Hydraulic trait trade-offs shape ecosystem productivity, water-use efficiency, and stability across aridity gradients in the Mongolian Plateau

Plant hydraulic traits are central to understanding how ecosystems respond to increasing aridity.While the trade-off between hydraulic safety traits and hydraulic efficiency traits is fundamental to plant drought resistance, their joint regulation of ecosystem productivity, water-use efficiency, and ecosystem stability across aridity gradients remains a critical knowledge gap. To assess the ecological impacts of hydraulic trait trade-offs, we conducted a study across a 1,200 km aridity gradient on the Mongolian Plateau. Our results demonstrate that increasing drought stress drives a shift in plant ecological strategy from hydraulic efficiency traits to hydraulic safety traits.Safety traits negatively affected aboveground biomass (β = –0.47) but enhanced foliar δ¹³C (β = 0.36) and ecosystem stability (β = 0.45), whereas efficiency traits showed the opposite effects. These trait effects were strongly modulated by aridity and explained 43% of AGB, 40% of δ¹³C, and 60% of ecosystem stability variation. Our findings reveal a mechanistic basis for predicting dryland ecosystem responses to increasing drought and offer guidance for climate-resilient vegetation management.