Aims <p>Modeling plant response to drought requires not only an understanding of the plant’s physiological plasticity, but a firm grasp of the quantitative relationship between plant physiological traits and volumetric soil water content (VWC). However, few studies have systematically assessed (i) threshold differences in physiological traits in plants subject to seasonal drought, and (ii) interactions between trait thresholds and plasticity.</p> Methods <p>We assessed the physiological adjustment mechanisms for gas exchange and chlorophyll-a fluorescence in the xerophytic shrub, <i>Artemisia ordosica</i>, during summer drought conditions. This study compared the physiological status of <i>A. ordosica</i> during wet and dry summer conditions of 2019 and 2021.</p> Results <p>We found that most physiological traits in <i>A. ordosica</i> exhibited significant plasticity in response to drought. Among these, transpiration (<i>E</i>) traits showed the highest plasticity index (PI), whereas maximum photochemical efficiency (<i>F</i>_v/<i>F</i>_m) exhibited the lowest index value. PSII-photochemical traits exhibited lower PI than traits associated with gas exchange. Moreover, drought thresholds in physiological traits for <i>A. ordosica</i> adjusted as VWC varied from 0.07 to 0.12 m³&#xa0;m⁻³. There were positive linear relationships between drought thresholds and trait plasticity.</p> Conclusions <p>The results suggest that drought thresholds could serve as reliable indicators for predicting variable physiological responses in desert shrubs during summer drought.</p>