Species-specific physiological parameters regulate adaptive resource allocation and allometric growth patterns in C3 ( <i>Leymus chinensis</i> ) and C4 ( <i>Hemarthria altissima</i> ) grasses under changing precipitation regimes

These findings demonstrated that biomass allocation in these grasses is co-regulated by allometric constraints and environmental plasticity, aligning with the complementary predictions of APT and OPT, and mediated by distinct physiological dimensions (i.e., PC1 driving growth and WUE governing allocation). While the C3 and C4 grasses share these regulatory mechanisms, they exhibit divergent physiological sensitivities to precipitation variability, highlighting the necessity of integrating functional trait dynamics when modeling plant responses to changing precipitation regimes.