Camel grazing reshapes root and rhizome economic strategies and trade-offs: synergistic roles of soil water, salinity, and nitrogen availability.

Introduction: Camel grazing drives grassland degradation in arid regions. However, how does it affect the synergistic changes in soil water, salinity, and nitrogen availability? Moreover, how does it reshape the trade-offs between root and rhizome economic strategies? Quantitative studies addressing these questions remain scarce. Methods: This study investigated saline meadow ecosystems under camel grazing in arid regions, comparing three grazing treatments: no grazing (NG), controlled grazing (CG), and free grazing (FG). Nine soil physicochemical properties and nine root and rhizome functional traits of dominant plants were assessed across three soil layers (0-25, 25-50, and 50-100 cm). The findings provide critical insights to support sustainable camel grazing management in arid salt-affected meadows. Results and discussion: Camel grazing depletes nitrogen, accumulates salt, and redistributes water in the 0-25 cm soil layer. Consequently, the root functional trait syndrome shifts from acquisitive to conservative along PC1, whereas the rhizome functional trait syndrome shifts from reproductive to storage along PC2. Notably, nonlinear thresholds trigger these shifts, with threshold values of available nitrogen (AN) <42 mg·kg